Jeffrey H. SchwartzDepartment of Anthropology,University of Pittsburgh,Pittsburgh, PA 15260,U.S.A. E-mail:jhs+@pitt.edu

Ian TattersallDepartment of Anthropology,American Museum of NaturalHistory, Central Park West at79th Street, New York,NY 10024, U.S.A.E-mail: iant@amnh.org

Received 7 May 1998Revision received 28 April1999 and accepted 26 May1999

Keywords: chin, Homo sapiens,Neanderthals, Skhul,Qafzeh.

The human chin revisited: what is it andwho has it?

Although the presence of a ‘‘chin’’ has long been recognized asunique to Homo sapiens among mammals, both the ontogeny and themorphological details of this structure have been largely overlooked.Here we point out the essential features of symphyseal morphology inH. sapiens, which are present and well-defined in the fetus at least asearly as the fifth gestational month. Differences among adults inexpression of these structures, particularly in the prominence of themental tuberosity, are developmental epiphenomena and serve toemphasize the importance of studying this region in juveniles when-ever possible. A survey of various middle to late Pleistocene fossilhominids for which juveniles are known reveals that these features arepresent in some late Pleistocene specimens assigned to H. sapiens, butnot in all of the presumed anatomically modern H. sapiens (i.e.,Qafzeh 8, 9, and 11). The adult specimens from Skhul, as well as theadult Qafzeh 7 specimen, are similarly distinctive in symphysealmorphology. Neanderthals are quite variable in their own right, andthey as well as other middle to late Pleistocene fossils lack thesymphyseal features of H. sapiens. Some of the latter are, however,seen in the Tighenif (Ternifine) mandibles.

� 2000 Academic Press

Journal of Human Evolution (2000) 38, 367–409doi: 10.1006/jhev.1999.0339Available online at http://www.idealibrary.com on

Introduction

More than two centuries ago, Blumenbach(1775) identified the ‘‘chin’’ as being amongthe most fundamental of the features that heconsidered uniquely human. Of course,when Blumenbach presented his discussionof ‘‘what distinguished humans,’’ it was inthe context of ‘‘compared to other extantprimates.’’ But with the acceptance in thenineteenth century of hominid fossils as realentities, and the subsequent documentationof a well-represented and diverse humanfossil record, features such as the chin,which had a specific kind of significancewhen the primary goal of the taxonomistwas to distinguish between humans andother extant primates, became cast in adifferent light. Rather than being static enti-ties, as would be expected of organisms thathad been specially created, morphological

0047–2484/00/030367+43$35.00/0

characteristics became incorporated intoscenarios of evolution. With regard to thechin, which essentially became synonymouswith ‘‘a prominence at the front of themandible,’’ the general concern amongpaleoanthropologists was with how an ape-like jaw could be converted to that of Homosapiens (Hrdlicka, 1911; Robinson, 1913;Wallis, 1917; Gregory, 1922; Howells,1959; Enlow, 1982; Stringer et al., 1984;Daegling, 1993).

Discussion of the human chin has beenapproached from several different perspec-tives. Anatomical descriptions have focusedon the protrusiveness of the symphysealregion, with the mounded structure beingidentified in extant humans as the ‘‘mentalprotuberance’’ (Johnston & Willis, 1954),the ‘‘mental eminence’’ (Lieberman, 1995),the ‘‘mental osseum’’ (Brauer, 1984; Rosas,1995), or the ‘‘tuber symphyseos’’ (Hublin

� 2000 Academic Press

368 . . .

& Tillier, 1981; Inke, 1967). Thus defined,the mental protuberance may continuelaterally on each side to some extent as athickening of the inferior margin of thecorpus. In some individuals, each lateralextremity of the mental protuberance maybear a blunt ‘‘corner,’’ which has beenreferred to as a ‘‘mental tubercle’’ (Johnston& Willis, 1954; Rak, 1998) or ‘‘tuberculalateralia’’ (Hublin & Tillier, 1981; Inke,1967). Above each lateral extremity and toeach side of the mental protuberance, lies adepression, or ‘‘mental fossa’’ (Wolpoff,1996), which would appear to exist as adefault of the midline field of bone beingelevated or protrusive. Collectively, themental protuberance and lateral extremities,especially if they bear tubercles, have beenidentified as the ‘‘mental trigon’’ (Rak,1998), the ‘‘mental trigone’’ (Smith, 1984),or, if the structure is restricted quiteinferiorly along the corpus, the ‘‘trigonumbasale’’ (Brauer, 1984). Just below thealveolar margin, the bone may be curvedinward, presenting a shallow depression thathas been referred to as the ‘‘incurvatiomandibularis’’ (Hublin & Tillier, 1981), the‘‘incurvatio mandibulae’’ (Rosas, 1995), orthe ‘‘impressio subincisiva externa’’ (Inke,1967). Although there is obviously muchmorphological detail to be recognized in thesymphyseal region of H. sapiens, the humanchin has frequently been identified solelyon the basis of the general protrusiveness ofthe symphyseal region (Lieberman, 1995;Smith, 1984; Wolpoff, 1980; Lam et al.,1996).

The development of the human chin istypically described as a postnatal phenom-enon, a simple matter of bone resorptionnear the alveolar margin, with concomitantdeposition of bone more inferiorly (Enlow,1982; see also Aiello & Dean, 1990;Daegling, 1993; Lieberman, 1995). Individ-ual differences or variations in chin develop-ment result essentially from differential ratesof resorption vs. deposition (Enlow, 1982).

It is the basal protrusion which has, ofcourse, been the primary criterion foridentifying the mental protuberance; andthis, in turn, has become the primary ele-ment in the identification of a chin. Fromthis perspective, it is perfectly reasonable toconclude that ‘‘chins are a notoriously vari-able character, as many modern humanslack them’’ (Lieberman, 1995:174). Andwhen the focus of attention in this regionis the degree of symphyseal protrusionanteriorly—which is often judged against thevertical plane of the lips or incisors (seeEnlow, 1982)—there might, indeed, appearto be ‘‘chinless’’ and ‘‘almost chinless’’human beings.

The evolution of the human chin has beendiscussed in various ways. Hrdlicka (1911)ventured the suggestion that this structureevolved as a result not of the specific devel-opment of a protrusion, but of the reductionof the dental arch (which essentially left theprotrusion behind as the anterior marginretreated). This idea was elaborated upon byRobinson (1913), who proposed that it wasthe demands of the tongue and laryngealmusculature that maintained mandiblelength inferiorly as the region above itsupposedly retreated posteriorly. Gregory(1922) added to these notions the possibilitythat the chin provides space at the front ofthe jaw that is necessary for the enlargingcrowns and roots of incisors and canines.Howells (1959) reiterated Robinson’s(1913) proposition and suggested furtherthat bone thickening, which ultimately pro-duced the chin, must have evolved in orderto reinforce the front of the jaw againstmasticatory stresses (which, in apes, wereabsorbed by the internal buttress known asthe ‘‘simian shelf’’). Reisenfeld (1969)thought that he had refuted this kind offunctional explanation by inducing in micewhat he believed to be a chin by extractingthe continually growing anterior teeth andsevering the muscles of mastication (whichdid, of course, have the effect of eliminating

369 ‘‘’’

masticatory stress at the symphyseal region).Wolpoff (1980) adopted a different stanceon the subject by speculating that theappearance of the chin was correlated withexpansion of the neurocranium and a con-comitant shift of the temporal muscles to amore medial angulation. Most recently,Daegling (1993) surveyed the various func-tional interpretations put forth to explain thepresence of the chin, and concluded that thebest was ‘‘the hypothesis that the humanchin represents a structural response toresist vertical bending in the coronal plane.’’

Regardless of the proposed mechanismsbehind the appearance of the chin as astructure, the language of the literature isinvested with the notion of an evolutionarytrend, in which a perceived increase in swell-ing of the symphyseal region ultimately leadsto the formation of the typical human chin.Thus, it is common to read of the supposedexistence of incipient chins in variousNeanderthals (themselves consideredmerely an archaic, primitive version of H.sapiens). These include adult specimensfrom Guattari, S{ipka, and Vindija (Lamet al., 1996; Lieberman, 1995; Smith, 1984;Wolpoff, 1980; Wolpoff et al., 1981) and theArchi Neanderthal child (Ascenzi & Sergi,1971a,b; Mallegni & Trinkaus, 1997;Stringer et al., 1984). Hence, because dis-cussions of later human evolution are ofteninformed by anticipation of discovering sucha transformation series, it is not surprising tofind statements such as: ‘‘[W]hile mentaleminences and trigones are markedly moredeveloped in modern H. sapiens (even theEMH [=early modern human, especiallyfrom Skhul and Qafzeh] sample), a cleartrend towards the EMH condition is presentin the LN [=late Neanderthal] group’’(Smith, 1984:190). Even some of the largermandibles from the middle Pleistocene Simade los Huesos sample have been portrayedas having chinlike symphyseal regions,which have been described as displaying‘‘a well-developed trigonum mentale and

a conspicuous incurvatio mandibulae’’(Rosas, 1995:550).

The impetus for the present review camefrom two different and unexpected sources.First, in the course of conducting a twenty-year analysis of the skeletal remains of peri-natal individuals from the Punic site ofCarthage (n>650 individuals; Schwartz &Houghton, in preparation), one of us (JHS,unpublished data) discovered that it waspossible to identify very small fragmentsof the symphyseally unfused mandibles ofthese highly immature individuals on thebasis of specific features of this region:namely, a continuous everted margin thatproceeds along the edge of the symphysisand laterally around along the inferior edgeand that, consequently, subtends a deepfossa. Second, as a result of realizing that theconfiguration of the brow in some of themost familiar of the supposed early ‘‘ana-tomically modern’’ H. sapiens (i.e., fromSkhul and Qafzeh) was not bipartite (cf.Stringer et al., 1984), as it is in latePleistocene and extant representatives ofthis species (Schwartz & Tattersall, 1999b),we came to realize that these same fos-sils were also not H. sapiens-like inmandibular symphyseal morphology. Forthe record, we must admit that when we firststudied the Skhul specimens, we were notinitially struck by these disparities. But itwas during our second round with thesespecimens, after we had benefited fromstudying at first hand many more middle tolate Pleistocene fossil hominids, that thedifferences in details of brow and mandibu-lar morphology became apparent betweenthese specimens (as well as some specimensfrom Qafzeh) and extant H. sapiens.

Here, we present the results of anextended developmental and morphologicaloverview of the symphyseal region in H.sapiens that focuses on distinguishingbetween those features that are invariablypresent from fetal to adult stages andthose that represent individual variation. We

370 . . .

suggest that only the constellation of mor-phological detail present from fetus to adult(in which H. sapiens appears to be stronglyderived) should be referred to as a chin—although we wonder, given the history ofbroad usage of this term, whether the reten-tion of this term as an anatomical descriptoris actually necessary or even constructive.We also review the middle to late Pleis-tocene hominid fossils from Europe, theLevant, and northern Africa, with anemphasis not only on morphology, but onthe ontogenetic context. We conclude thatone can identify a chin, complete withdetailed morphology, in all late Pleistocenefossils traditionally assigned to modern H.sapiens, but not in all early modern humansfrom this time period; some of the latterpossess a configuration that differs fromthose of both modern H. sapiens and H.neanderthalensis. In addition, the Tighenifmandibles provide further evidence that it isthe specific morphology of the symphysealregion, rather than its simple protrusion orlack thereof, that is potentially phylogeneti-cally and systematically significant.

Materials

Our developmental series of extant H.sapiens from second trimester through birthare in the permanent study and teachingcollections of the anatomy department of theUniversity of Pittsburgh School of DentalMedicine (UPD; n=10) and the AmericanMuseum of Natural History (AMNH; n=8).These series are comparable in detail andessentially identical to collections in medicalschools (e.g., see the series at WashingtonUniversity) and are consistent with thedescriptions and illustrations in standardtextbooks (e.g., Johnston & Willis, 1954).Since we are not presenting these data asnovel discoveries, but are rather using themas the basis for our descriptons and compari-son, corroboration of our descriptions isreadily available. One of us (JHS) also

studied a sample of five hundred recentH. sapiens (Department of Anthropology,AMNH) and, as an outgroup, three hundrednonhuman anthropoid primates (Depart-ment of Mammals, AMNH) (Table 1). Themiddle to late Pleistocene fossils hominidsthat we have analyzed to date and that pre-serve enough of the mandibular symphysealregion to be relevant to this discussion arelisted in Table 2. For the sake of simplicity,and in order to facilitate reader recognition,we present a rather traditional grouping ofthese specimens in Table 2, identifying themconservatively either as ‘‘Neanderthal,’’‘‘Homo sapiens,’’ or ‘‘Other,’’ even thoughwe believe there are more satisfactoryalternatives.

As is usually the case with fossils, most ofthe available specimens are of adult individ-uals. Nonetheless, the later human fossilrecord does contain an important represen-tation of younger individuals. The youngestfossil individual in our sample is the10-month-old Neanderthal from Amud(Rak et al., 1994). The probable agerange for the Skhul child and the typicalNeanderthal children [from Gibraltar(Devil’s Tower), Peche de l’Aze, and Roc deMarsal] is 3–4 years (see Dean et al., 1986;Zollikofer et al., 1995), although an olderage of 5–6 years has also been suggested(Tillier, 1983).

We shall first discuss the morphology anddevelopment of the symphyseal region inextant H. sapiens and of those specimens thatare thought of as closely resembling them.We then turn to Neanderthals, and, finally,to the remaining middle to late Pleistocenefossil hominids. We refer to the central andlateral incisors as I1 and I2, and the anteriorand posterior premolars as P1 and P2.

Results and discussion

Extant Homo sapiensIn adults (Figure 1), the symphyseal regionbears a variably long and raised vertical keel

371 ‘‘’’

Table 1 Human and other anthropoid specimensat the American Museum of NaturalHistory used in this study*

Nonhuman anthropoid primatesNew and Old World Monkeys

Ateles geoffroyi (n=19)Cebus apella (n=20)Cercopithecus cephus (n=19)C. mona (n=1)C. neglectus (n=2)C. pogonias (n=7)Colobus polykomos (n=6)Macaca fascicularis (n=20)Mandrillus sphinx (n=12)Papio anubis (n=1)P. cynocephalus (n=7)Presbytis entellus (n=3)

HominoidsHylobates agilis (n=39)H. hoolock (n=14)Gorilla gorilla (n=21)Pan troglodytes (n=35)Pongo pygmaeus (n=14)

Recent Homo sapiensAfrica (sub-Saharan; n=71)East Asia (n=80)China (n=25)Korea (n=6)Japan (n=13)Ainu (n=4)Siberia (Indian Point) (n=32)Australia

Aborigine (n=26)Europe (n=70)

Hungary (n=9)Czech—Bohemia (n=10)Austria (n=10)Germany (n=13)Italy (n=8)‘‘Yugoslavia’’ (n=10)Greece (n=10)

India (n=26)North America (Arctic; n=139)

Thule (n=33)Near Ipiutak (Point Hope, Alaska) (n=12)Ipiutak (Point Hope, Alaska) (n=46)Tigara (Point Hope, Alaska) (n=48)

North America (Sub-Arctic, Southwest; n=51)Native American, Utah, New Mexico (n=30)Arizona (n=21)

South AmericaBolivia, Chile, Peru (n=41)

*A complete list of specimens is available uponrequest.

that lies along the midline. This keel, whichoriginates at or just below the alveolarmargin, becomes more prominent inferiorlyas it fans out laterally along the somewhatdistended inferior margin of the mandible.In some individuals it terminates in variablythickened, but not discretely separate,‘‘corners’’ (the lateral tubercles). Whenpresent, each blunt terminus of the dis-tended inferior margin lies well anterior tothe mental foramen, which, in turn, liesvariably anterior to the second premolar (seealso Aiello & Dean, 1990; Daegling, 1993;Lieberman, 1995). Together, the symphy-seal keel and the distended inferior marginform an inverted, roughly ‘‘T’’-shapedstructure; it is at the junction of the keel anddistended inferior margin that a mental pro-tuberance is identified. A variably shallow,scallop-shaped depression (mental fossa)lies to each side of the central keel. Thesemental fossae emphasize the keel as well asthe distended inferior mandibular marginbelow. As can be observed even among thehandful of specimens illustrated in Figure 1,variation exists among individuals in thedegree to which these various features areexpressed. However, the essential aspects ofshape, location, and morphological detail ofthe keel, protuberance, distended inferiormargin, and mental fossae, are maintainedthroughout.

The constellation of consistent featuresjust described for the adult is present (andits details crisply delineated) by at least thefifth fetal month (Figure 2). Although thehalves of the mandible are still unfusedacross the midline at this gestational age,one can clearly observe that the verticalsymphyseal margin of each half is raised oreverted, and that this vertical ridge is con-fluent with a similarly everted inferiormargin that diminishes in prominenceposteriorly. Each everted marginal crestingsystem defines a deep fossa. Duringsubsequent intrauterine growth, the twomandibular halves come together at the

372 . . .

Middle to late Pleistocene hominid mandibular specimens used in this study

Specimen CountryAge

(ka B.P.)

Homo sapiensAbri Pataud France 22·0Brno 2, 3 Czech Republic 26·0Chancelade France 17·0?Cro-Magnon 1, 2, 3 France ca. 30?Dolní Vestonice III, XII, XIV, XV, XVI Czech Republic 26–29Engis 1 (adult) Belgium ?Grimaldi (Grotte des Enfants, Balzi Rossi) Italy ca. 36Hahnofersand Germany ca. 36Isturitz (includes children) France 18–30Oberkassel (male, female) Germany 15?Ohalo 1, 2 Israel ca. 19Predmostı 3, 4 (casts) Czech Republic ca. 26Qafzeh 1, 3, 6, 7, 8, 9, 11 (subadult) Israel ca. 92–95Skhul I (child), II, IV, V, VI, VII Israel 80–100+Svitavka Czech Republic 25–30?Vogelherd 1, 2 Germany ca. 32

NeanderthalAmud (child and adult) Israel 40–50Archi (child) Italy ?Ehringsdorf 1009/69, 1010/69 Germany ca. 320?Engis (child) Belgium ?Feldhofer Grotto Germany ca. 40Gibraltar 2 (child) Gibraltar 50?Grotta Guattari 2 and 3 Italy 50–60+Kebara (child and 2) Israel ca. 60Krapina 51, 53, 54, 55, 56, 57, 59 Croatia ca. 130La Chapelle-aux-Saints France 50+La Quina [adult (5) and child] France ca. 65La Ferrassie France 60–70?Le Moustier (subadult) Germany ca. 40Montmaurin France 150–200?Ochoz Czech Republic ?Pech de l’Aze (child) France 45–55Regourdou France ?Roc de Marsal (child) France 50+Saccopastore Italy 120–130Saint-Cesaire France 36S{ipka (juvenile, cast) Czech Republic ?Spy 1 and 2 Belgium ?Subalyuk (adult) Hungary 60–70?Tabun C1 Israel 34Tabun II Israel ?Vindija 75/206, 76/231, 76/226 Croatia ca. 40+Zafarraya Spain ca. 30

OtherArago 2 France 400?Biache 2 (cast) France 150–175?Bilzingsleben Germany 280–400Jebel Irhoud 3 (cast, child) Morocco 90–125+ +Mauer Germany ca. 500Rabat (Thomas Quarry) Morocco ca. 400Tighenif (Ternifine) 1, 2, 3 Algeria ca. 700?

Table 2

373 ‘‘’’

symphysis, with the inverted ‘‘V’’-shapedgap between them closing in a supero-inferior direction (i.e., from the region of thepresumptive alveolar crest down to theinferior margin of the jaw) (see also illus-tration in Johnston & Willis, 1954:296). Atthis stage of growth, the mental protuber-ance is represented merely by the juncture ofthe inverted ‘‘T’’ that emerges with theformation of a single midline symphysealridge and its intersection with the evertedinferior margin. In individuals in whom thetwo mandibular halves have closed up buthave not totally obliterated the symphysealgap, one can sometimes observe a shallowinverted ‘‘V’’ indenting the inferior marginat its midline (Figure 2). It is also importantto note that the everted margins and themental fossae retain their integrity through-out growth in spite of the bone alterationthat takes place around them in conjunctionwith tooth crown and crypt expansion.

Postnatally, the features that are so welldelineated in the fetus become softened andless sharply defined (Figure 3). In two-year-olds, for instance, the symphyseal keel isfaint below the alveolar region. The keel iseven less crisply defined in five-year-olds, inwhom the mental fossae are also shalloweras well as less expansive. The mental protu-berance of postnatal individuals is, however,more prominent than in perinatal individ-uals, not only as a forward projection, butalso as a generally triangular eminence withits base seated along the inferior margin ofthe jaw (forming the so-called trigonumbasale). When viewed from below, the frontof a young child’s mandible is quite thickanteroposteriorly (=buccolingually) in thearea subtended by the variably developedlateral tubercles, although immediatelylateral the bone is thinner (also see metricanalysis by Zollikofer et al., 1995). Inaddition to an overall enlargement of themandible, including in its superoinferiordepth, it is the continued softening or blunt-ing of some features (such as the keel and

fossa) and, at the same time, the potentialenlargement of other features (such as themental protuberance and lateral tubercles),that results in the variation we see amongadults. Further, any increase in depth of themandible with concomitant expansion ofthe domain of alveolar bone (Enlow, 1982)would account for the absence in someindividuals of any trace of the keel near thealveolar border—precisely because alveolarbone is a cellular derivative of tooth-producing stem cells and not of presumptivemandibular osteoblasts (e.g., see Ten Cate& Mills, 1972).

If we apply the term ‘‘chin’’ to the devel-opment of a prominent mental protuberancealone, then those (e.g., Lieberman, 1995)who describe some humans as lacking achin, as well as others (specifically, Enlow,1982) who define chin development as theresorption of bone near the alveolar marginwith concomitant deposition of bone moreinferiorly, are, in general, correct. But, as weillustrate here, the size of the region of themental protuberance, which can vary fromone individual to the next, is independent ofthose features—the inverted ‘‘T’’ and itsattendant mental fossa—that are establishedfetally. In this context, Enlow’s observation(i.e., that differential bone resorption superi-orly in the symphyseal region, along withbone deposition more inferiorly creates aprotuberance that projects farther forwardthan the alveolar region), is exactly what onewould expect in the development of thosefeatures that vary individually in adults, butnot in the formation of the symphysealdetails seen in the fetus.

Late Pleistocene Homo sapiensThe inverted ‘‘T’’ and associated mentalfossae are found in specimens from the latePleistocene sites of Barma Grande, Brno,Chancelade, Cro-Magnon, Dolní Vestonice,Grimaldi, Isturitz, Oberkassel, Ohalo,Predmostı, and Svitavka (see Figure 4). Inmany of these Upper Paleolithic individuals,

374 . . .

375 ‘‘’’

the mental trigon/protuberance is expansive,as well as protrusive, and often (e.g., Brno,Predmostı, Okerkassel) exceeds that seen inthe most markedly endowed individuals inour sample of extant H. sapiens. The Isturitzsample, which contains a number ofjuveniles of varying ages, as well as oldadults, is particularly interesting in terms ofwhat is apparently a populational develop-ment variant: the ‘‘cleft chin.’’ As seen inFigure 5, individuals from this site have aninverted midline ‘‘V’’-shaped cleft that partsthe inferior margin with varying degrees ofopenness and upward extension. As inferredfrom our study of extant H. sapiens, thesimplest and developmentally most reason-able interpretation is that in these individ-uals from Isturitz, as well as in others fromthe site not illustrated here, coalescence ofthe mandibular halves did not proceed fullydown from the alveolar crest to the inferiormargin. Symphyseal clefting among individ-uals simply reflects the differing degrees towhich the symphysis fused along its length.Aside from this developmental peculiarity,however, in every other detail of mor-phology, the Isturitz mandibles are typicallyH. sapiens in possessing the inverted ‘‘T’’and mental fossae.

Figure 1. Mandibles of recent adult Homo sapiens to illustrate the basic configuration of the mentalprotuberance and trigon. Top, UPD #95 (provenence unknown); middle, AMNH 99/108 (Thule, SmithSound, Alaska); bottom, UPD #66 (Indo-Pakistan?). Although the degree to which these features arepronounced, all three possess paired mental fossae and a clearly defined central keel that thickens at themental tuberosity and fans out along the margin of the symphyseal region, terminating bilaterally invariably thickened ‘‘corners.’’ Bar=1 cm.

Middle to Late Pleistocene Homo sapiensfrom the LevantIn this sample, only the adults Qafzeh 8 and9 and the subadult 11 present any indicationof having had an inverted ‘‘T’’ and mentalfossae (Figure 6). The adult Qafzeh 7 doesnot possess these features, nor does anyindividual from the broadly contempor-aneous site of Skhul, including the child,Skhul I (Figures 7 and 8). These obser-

vations are interesting in light of the fact thatof this group only Qafzeh 9 and 11 may haveborne bipartite brows, whereas the supra-orbital margins of the adult specimensfrom Skhul, and of Qafzeh 6, are defi-nitely smoothly continuous (Schwartz &Tattersall, 1996b).

The intact symphyseal region of theQafzeh 11 subadult bears a long, thincentral keel that begins its gentle rise ashort distance below the alveolar margin(Figure 6). Toward the inferior margin ofthe mandible the keel fans out bilaterally intoa short, broad, and somewhat protrudingtriangular mental protuberance, which be-comes most protrusive just prior to curvinginto the less distended inferior margin. Shal-low mental fossae are also discernible oneither side of the keel, and the mental fo-ramen lies just anterior to the root of P2. Ininferior view, although the front of the jaw isnot squared off as it can be in H. sapiens, thesymphyseal region is more thickened antero-posteriorly than the short stretch of bone oneach side of it, posterior to which the corpus,in turn, becomes thicker.

The symphyseal regions of the adultsQafzeh 8 and 9 are, unfortunately, some-what damaged (Figure 6). However, inQafzeh 9 the bone on each side of thedamaged midline appears to have beeninflected outward, and the inferior margin ofthe symphyseal region would have beensomewhat projecting. In the even morepoorly preserved Qafzeh 8 mandible thereis in concert definite evidence of a raisedmental protuberance lying close to theslightly distended inferior margin. Thelatter two features together present theconfiguration of an inverted ‘‘T.’’

376 . . .

377 ‘‘’’

Figure 2. Fetal specimens of Homo sapiens to illustrate the early stages of development of the mental trigon.Top right, 5 months (AMNH 99/7321); top left, 6 months (AMNH 99/7322); middle, 7 months (AMNH99/7323); bottom, 8 months (AMNH 99/7324). The right and left contributions to the central keel, whichare seen coalesced or coalescing across the symphysis (from top to bottom) in older specimens, arewell-developed in the 5 month fetus. In all, the raised inferior margin and mental fossae are also clearlydifferentiated. Bar=1 cm.

In contrast to Qafzeh 8, 9, and 11, Qafzeh7 (Figure 7) presents a distinctive symphy-seal configuration. Immediately below thealveolar crest lies a superoinferiorly shortbut moderately deep depression, which islaterally confined to the region of the incisorroots. The remainder of the symphysealregion is adorned with a low, teardrop-shaped bulge. The apex of this bulge ariseswithin the subalveolar depression and itsbody broadens toward the inferior margin ofthe mandible. The sides of this bulge slopegently and smoothly into the contour of thesurrounding bone of the corpus. The inci-sors overhang the subalveolar depressionand the bulge presents a continuous andgently backwardly tilted profile. Conse-quently, when seen in profile, the subalveo-lar depression represents the space betweenthe somewhat procumbent incisor regionabove and the longer slope of the symphy-seal bulge below. In inferior view, althoughthe latter bulge is noticeable, it is also thecase that, buccolingually, the bone of thecorpus is fairly uniformly thick throughoutits length. The mental foramen lies underthe region of P2.

Tillier (1979) has described the mandibleof the juvenile (6–8 years?) Qafzeh 4 ashaving ‘‘modern’’ symphyseal features,including mental fossae, a mental trigon,and lateral tubercles. The illustration sheprovides portrays a reconstructed symphy-seal region that preserves a reasonableamount of identifiable morphology. Of noteis the presence of two well-developeddepressions that lie virtually at the inferiormargin of the jaw, each on either side of themidline, with each reaching its maximumheight well lateral to the midline. Because

they are depressions, they leave betweenthem what appears to be a small elevatedregion of bone low down in the midline. Asseen in profile, however, this midline struc-ture does not protrude beyond the normalsurface of the bone itself. Posteriorly, aspreserved especially well on the right side,the depression extends below a swollenregion beneath the dm2 that must corre-spond to the enlarging P2 in its crypt. Thesedepressions are strongly reminiscent ofthose seen in the Archi 1 Neanderthal child(see discussion below and Figure 12).Superiorly, the bone around the root of thenot fully erupted right permanent centralincisor is markedly indented or creased. Bydefault, this creates the impression that thebone around this depression is elevated,although in reality it is actually a smooth,unembellished surface. Clearly, Qafzeh 4does not display the salient features of thesymphyseal region typical of H. sapiens,which are especially well defined in youngchildren. As such, Qafzeh 4 cannot beregarded as a juvenile precursor of the moremature Qafzeh 8, 9, and 11. Perhaps itreflects the juvenile state of the adultrepresented by Qafzeh 7.

The adult specimens from Skhul that pre-serve the anterior portion of the mandible(II, IV, and V) are not similar to extant H.sapiens and related fossils. Rather, theyresemble Qafzeh 7 (Figure 7). Althoughthere is individual variation in the degree towhich the symphyseal region is broad anddeep (it is most accentuated in Skhul IV, lessso in Skhul V, and least in Skhul II), eachspecimen possesses some amount of sub-alveolar depression as well as some swellingof the symphyseal region. In all three

378 . . .

Fig

ure

3.M

andi

bles

ofre

cent

juve

nile

Hom

osa

pien

sto

illus

trat

eth

ees

sent

ial

feat

ures

ofth

esy

mph

ysea

lre

gion

.T

op,

left

(ant

erio

rvi

ew)

and

righ

t(i

nfer

ior

view

),2

year

sol

d(A

MN

H,

Edu

cati

onD

ept,

unca

talo

gued

);bo

ttom

,le

ft(a

nter

ior

view

)an

dri

ght

(inf

erio

rvi

ew),

5ye

arol

d(A

MN

H99

/779

9).T

hece

ntra

lkee

l,w

hich

broa

dens

atth

em

enta

ltub

eros

ity,

fans

out

infe

rior

ly,

term

inat

ing

bila

tera

llyin

blun

t‘‘

corn

ers.

’’T

hein

feri

orvi

ews

dem

onst

rate

the

thic

knes

sof

the

man

dibl

ein

the

sym

phys

ealr

egio

nan

dth

eim

pact

ofth

em

argi

nal

attr

ibut

esof

the

men

tal

prot

uber

ance

onm

andi

bula

rsh

ape.

Bar

=1

cm.

379 ‘‘’’

Figure 4. Mandibles of late Pleistocene Homo sapiens. Top: Cro-Magnon 3 [Musee de l’Homme (MH)];middle: Abri Pataud (MH); bottom: Predmostı 3 (cast, Anthropos Institute, Brno). Although there isvariation in degree of expression of the inverted ‘‘T’’-shaped configuration of the symphyseal region, allspecimens possess a central keel, thickened inferiorly placed mental protuberance, distended inferiormargin, and mental fossae. Bar=1 cm.

380 . . .

Figure 5. Mandibles of late Pleistocene H. sapiens from Isturitz. Top: Isturitz 68 [Musee des AntiquitesNationales (MAN)]; bottom: Isturitz 70 (MAN). Each displays a low central keel, thickened inferiormargin, and mental fossae. Each also possesses a cleft indenting the inferior margin at the midline thatcorresponds to the incompletely fused symphysis seen in fetuses (see Figure 2). Bar=1 cm.

specimens, the inferior margin of the sym-physeal region is elevated somewhat relativeto the plane of the inferior margin of the restof the corpus. In the less complete Skhul IImandible, a definite subalveolar depressionlies immediately below the incisor alveoli;inferiorly, the bone of the front of the jaw isgently rounded. In the more complete SkhulIV and V mandibles, a configuration com-parable to that observed in Qafzeh 7 is moreclearly discernible: there is a subalveolardepression, from which emanates a low,teardrop-shaped bulge that flows into thesurrounding bone (rather than an inverted‘‘T’’ delineated by mental fossae). In SkhulV, the subalveolar depression is exaggeratedby crushing, especially above and to the

right of the midline, as well as by an alveolarmargin that was reconstructed to overhangthe symphyseal region too severely; and tothe left of the midline, the inferior margin isalso damaged. The mental foramen liesunder P2 in Skhul II and V, and under M1 inSkhul IV. In addition, in Skhul V, a distinctand peaked inferior marginal tubercle liesbelow the level of the first molar and thusposterior to the mental foramen; a similarstructure lies slightly more anteriorly inSkhul II, beneath the mental foramen. Ininferior view, and regardless of the degree ofswelling of the symphyseal bulge, the boneof the corpus of each specimen is essentiallyuniformly thick buccolingually throughoutits length.

381 ‘‘’’

If one were to define the possession of achin purely on the basis of the developmentof a symphyseal protrusion or bulge, withouttaking the details of morphology into con-sideration, then one would certainly identifya chin in Qafzeh 7 and all adult Skhulspecimens (e.g., McCown & Keith, 1939;Smith, 1984; Stringer et al., 1984; Wolpoff,1980, 1996). Clearly, however, while inthese specimens the symphyseal bulge canplausibly be assumed to have resulted frombone deposition and the subalveolar depres-sion from bone resorption—because theseare the only osteogenetic processes availablefor skeletal modification—neither Qafzeh 7nor the adult Skhul specimens possess thedetails of symphyseal morphology seen in H.sapiens. Since we know that the symphysealmorphology of adult H. sapiens is even moreclearly delineated in young individuals,similar details in children from Qafzeh andSkhul would be required to demonstratethat the symphyseal bulge of Qafzeh 7 andthe Skhul adults are versions of the chin inmodern humans. As discussed above, how-ever, the juvenile Qafzeh 4 specimen doesnot display the features of juvenile H.sapiens. This also appears to be the case withthe Skhul I child.

Although the specimen is heavily recon-structed in some areas, bone is preserved onthe right side of the Skhul I child’s mandibleat least as far as the midline of the root of theright first deciduous incisor, as well as inter-nally across the symphysis at least as far asthe region of the left di2 (Figure 8). Thismakes it possible to determine accuratelythe morphology, thickness, and curvature ofthe symphyseal region. In contrast to juven-ile H. sapiens, the Skhul I mandible is broadand somewhat arcuate from side to sideacross the region of the anterior teeth, and,in profile, this region is slightly convex. Infurther contrast to extant H. sapiens of simi-lar age, but as in Neanderthals (see discus-sion below and Zollikofer et al., 1995), theanterior region of the Skhul I mandible is

essentially uniformly thick in inferior view,with maximum thickness being achievedfarther back along the corpus. In addition,since on the right side the bone extendsexternally almost as far as the symphysis aswell as superiorly to a point significantlybelow the alveolar crest, it is evident that thisspecimen lacked a mental fossa, at least onthat side. Since this bony surface is notconcave with an increasingly everted medialcontour, but is essentially flat, it is equallyclear that the symphyseal region boreneither a keel nor a protrusion of anykind. The large mental foramen lies veryposteriorly, under the bony septum thatseparates the roots of adjacent deciduousmolars.

Aside from the impressions created by theroots of the teeth, the symphyseal region ofthe Skhul I child’s mandible is devoid ofsignificant morphology. Like the Qafzeh 4child, it thus lacks in comparable parts thedistinctive and easily identifiable morpho-logical details of juvenile H. sapiens. Thisobservation is particularly revealing becausethe diagnostic features of the symphysealregion of H. sapiens are more pronounced inyounger than in older individuals. Conse-quently, the absence of these features in theSkhul I child certainly provides evidenceof significant developmental differencesbetween this individual and extant H. sapiensof similar age, as has also been demonstratedto be the case with regard to dental growthrates in the Skhul I child vs. H. sapiens(Smith et al., 1997).

If the Skhul I child had become a typicalSkhul adult, then the developmental differ-ences between the entire Skhul assemblage(with which, on morphological grounds, wewould include the Qafzeh 7 adult) and H.sapiens would have been evident from child-hood. However, one cannot accept withoutquestion the biological affinity of the Skhul Ichild with the adults from the same site.Indeed, in its general shape, disposition ofcusps, and presence and orientation of the

382 . . .

383 ‘‘’’

Figure 6. Mandibles of adult specimens from Qafzeh with the symphyseal configuration of H. sapiens.Top: Qafzeh 11 [Tel Aviv University (TAU)]; middle: Qafzeh 9 (TAU); bottom: Qafzeh 8 (TAU). Qafzeh11 possesses a thin central keel that is bound on each side by a mental fossa and which arises from belowthe alveolar region and expands into a well developed, inferiorly placed mental protuberance that expandssomewhat laterally into a thickened inferior margin. Qafzeh 9 preserves a thickened inferior margin, abovewhich the bone becomes everted toward the midline, suggesting that a central keel had been present andbounded by mental fossae. The more fragmentary Qafzeh 8 displays a thickened inferior margin.Bar=1 cm.

‘‘deflecting wrinkle’’ (elongate centroconid),the child’s M1 is a good match for the M1 ofTabun C1 while, unfortunately, such detailsof morphology of adult Skhul M1’s are notpreserved. Thus we cannot be certain of thejuvenile state from which adult Skhul man-dibular morphology emerged. Nonetheless,given that the distinctive features of thesymphyseal region in H. sapiens, so salient inyounger individuals, diminish in clarity withgrowth and bone remodeling, we feel thatwe can at least hypothesize that, in theirjuvenile mandibles, the Skhul (and Qafzeh7) adults would not have been configured asin H. sapiens. Rather, we suggest that, as invarious Neanderthal specimens (see below),the bulge observed in the Skhul adult andQafzeh 7 specimens was created through aprocess of bone deposition upon a morpho-logically featureless symphyseal region,while the subalveolar depression would havebeen produced by bone resorption in theregion of the incisor root tips. However,even if one were to claim that the symphy-seal bulge could have been derived fromthe configuration seen in the fetuses andjuveniles of H. sapiens (i.e., the inverted ‘‘T’’and attendant mental fossae), one wouldhave to admit that the subsequent andtotal obliteration of this configuration wasachieved by a process of development thatdiffered significantly from the extanthominid in terms of the regions and inter-actions of the domains of bone resorptionand deposition.

On the basis of morphological dissimilar-ity, then, we must conclude that Qafzeh 4and Skhul I are, morphologically, not

specimens of H. sapiens, as also appears tobe the case with regard to all Skhul adultsand Qafzeh 7.

NeanderthalsAlthough variable in its verticality, theanterior surface of the adult Neanderthalmandible is very broad and, if not flat,is often slightly arced from side to side(Figure 9; see also e.g., Wolpoff, 1980:285).In some specimens, this broad surface maybe adorned inferiorly by a pair of peaked orangular distentions of the inferior margin ofthe mandible (identified here as ‘‘inferiormarginal tubercles’’). When present, theinferior marginal tubercle lies below themental foramen, which, in turn, lies quiteposteriorly, beneath either M1 or the bonyseptum separating the mesial alveolus forthis tooth from the alveolus for P2 (seeKrapina 59 and Spy 1 in Figure 9; see alsoWolpoff, 1980:285). In some specimens, theinferior margin of the anterior mandibularplane is elevated. There may also be a shal-low subalveolar depression coursing below,if not also across, the entire region of theoutwardly bowed incisor roots; the moreprocumbent the incisor roots, the more theyoverhang and emphasize the subalveolardepression. In some specimens, the regionbelow the subalveolar depression may beslightly and broadly swollen, providing asmooth curve from side to side in frontalview and a gently convex profile (e.g., seeSpy 1 in Figure 4; see also Grotta Guattari 2in Wolpoff, 1980:285). Clearly, althoughthere is variability within the Neanderthalsample in the presentation of the features

384 . . .

Fig

ure

7.M

andi

bles

ofad

ult

spec

imen

sfr

omS

khul

and

Qaf

zeh

wit

hsi

mila

rsy

mph

ysea

lco

nfigu

rati

ons.

Top

row

left

,S

khul

V[H

arva

rdP

eabo

dyM

useu

m(H

PM

)];

top

row

righ

t,S

khul

IV(T

AU

);bo

ttom

row

left

,S

khul

II(H

PM

);bo

ttom

row

left

,Q

afze

h7

[Ins

titu

tde

Pal

eont

olog

ieH

umai

ne(I

PH

)].

Alt

houg

hdi

ffer

ing

from

one

anot

her

inde

gree

sof

expr

essi

ons

offe

atur

es,

all

man

dibl

esar

ean

teri

orly

broa

dan

ddi

spla

ya

suba

lveo

lar

depr

essi

onbe

low

.Skh

ulIV

and

Van

dQ

afze

h7

clea

rly

poss

ess

asu

balv

eola

rbu

lge

that

ispr

otru

sive

abov

eth

ein

feri

orm

argi

nan

dw

hich

lack

sa

cent

ral

keel

and

atte

ndan

tm

enta

lfo

ssae

.S

khul

IIla

cks

men

tal

foss

aean

dan

infe

rior

lyth

icke

ned

mar

gin.

Bar

=1

cm.

385 ‘‘’’

Figure 8. Mandible of Skhul I (TAU); top (anterior view), middle (left lateral view), and bottom (inferiorview). The reconstruction of the front of the jaw is based on the right side being preserved to the midline:it is very broad and somewhat arcuate from the side. In contrast to juvenile H. sapiens, Skhul I lacks acentral keel and mental fossae, and is thin anteroposteriorly in the symphyseal region. Bar=1 cm.

386 . . .

Figure 9. Mandibles of adult Neanderthals to illustrate features in common and differences betweenindividuals. Top, left (anterior view) and right (left lateral view), Tabun C1 [Natural History Museum,London (NHML)]; middle, left (anterior view) and right (left lateral view), Krapina 59 [HravatskuPrirodoslovni Muzej, Zagreb (GPM)]; bottom, left (anterior view) and right (left lateral view) of Spy 1(Institute Royal des Sciences Naturelle de Belgique, Brussels). In all, the front of the mandible is verybroad and somewhat arcuate from side to side; also, all clearly display a retromolar space between the lastmolar and the ramus. Individual variation is noted in differences in depth of the mandible, developmentor lack of inferior marginal tubercles (noted beneath the very posteriorly placed mental foramina ofKrapina 59 and Spy 1, but lacking in Tabun C1), development or lack of subalveolar depression along theincisor roots (tall and shallow in Krapina 59, shorter in Spy 1, absent in Tabun C1), presence or absenceof slight subalveolar swelling (only somewhat pronounced in Spy 1), and elevation of the inferior marginat the front of the jaw (noted in Krapina 59 and Spy 1, but not Tabun C1). Bar=1 cm.

described above, no adult Neanderthalspecimen possesses, even vaguely or subtly,the inverted ‘‘T’’ and attendant mental

fossae that are otherwise seen in H. sapiens.In addition, the Neanderthal symphysealprominence, when present, does not have

387 ‘‘’’

the same configuration as the symphysealbulge seen in the adult Skhul specimens andQafzeh 7.

Study of the mandibles of juvenilesidentified as Neanderthal on the basis ofvarious cranial features demonstrates thatnone in our sample displays the inverted‘‘T’’ and mental fossae of H. sapiens. Forinstance, the symphyseal region of themandible of the 10-month-old child fromAmud (Rak et al., 1994) (Figure 10) isessentially smooth from side to side acrossthe midline; there is no trace of a long,raised central keel, distended inferior mar-gin, or mental fossae. Surface topography isconfined to the swelling of the region abovethe very laterally and posteriorly placedmental foramina due to the expandingcrypts of developing tooth germs. Themandible is very broad and gently arcedfrontally from side to side, and, in profile, isslightly arced from top to bottom. Whenviewed from above, and in contrast tojuvenile H. sapiens, the broad (from side toside) front of the Amud mandible is thinneranteroposteriorly than the rest of the corpusis more posteriorly. Below the large mentalforamen on the right side, the inferiormargin of the mandible bears a long,blunted inferior marginal tubercle which isbounded on either side by a slight upwarddepression.

As would be expected from a growthtrajectory that is predicted upon the con-figuration seen in the Amud child in con-trast to juvenile H. sapiens, 3–4-year-oldNeanderthals (Roc de Marsal, Gibraltar 2,Pech de l’Aze) also lack the inverted ‘‘T’’and mental fossae seen in extant humans(Figure 11; see also Tillier, 1983). In frontalview, the mandibles of these children arebroad and somewhat arcuate from side toside. In profile, the symphysis may besmoothly vertical or slightly convex andretreating. In contrast to extant H. sapiens ofsimilar age, the Neanderthal symphysealregion, when viewed from below, is also

noticeably relatively thin from front to back,with the corpus being thickest in the regionof the first deciduous molar (see alsoZollikofer et al., 1995). As noted in theAmud child and in the occasionalNeanderthal adult, there may be a discrete,peaked inferior marginal tubercle lyingbelow the posteriorly placed mental foramen(see Gibraltar 2 in Figure 11).

Among the Neanderthal children, theGibraltar 2 (Devil’s Tower) mandible is offurther interest in that a shallow midlinecleft indents the inferior border (Figure 11).This indentation lies at the mandibular sym-physis, which is where fusion of the rightand left mandibular halves occurs. In allother details, this specimen is recognizablysimilar to the other Neanderthal children. Ifwe accept that early symphyseal fusion,which is synapomorphic of Anthropoidea(e.g., see review by Schwartz, 1986),occurred in Neanderthals as it does in H.sapiens—from the top down—then theindentation in the midline of the inferiormargin of the Gibraltar 2 mandible is simplya vestige of incomplete symphyseal fusion,as is obviously the case in the Isturitzspecimens (Figure 5). This, of course, is themost parsimonious explanation of thisfeature in the Gibraltar 2 child. But even ifthis is not a completely accurate interpret-ation, it would be incorrect to identify thisspecimen’s inferior marginal indentation asconstituting a ‘‘hint’’ of a ‘‘chin.’’

The morphology of the Archi child’smandible, which is generally assumed torepresent a juvenile Neanderthal (Ascenzi& Sergi, 1971a,b; Stringer et al., 1984;Mallegni & Trinkaus, 1997) (see Figure 12),can be better understood in light of theGibraltar 2 specimen. In terms of relativechronological age, the Archi individual, inwhich only the deciduous teeth had erupted,would have been younger than the Gibraltar2 child but comparable to the Roc de Marsaland Peche de l’Aze children. In overall man-dibular shape, the uniform anteroposterior

388 . . .

Figure 10. Amud Neanderthal child. The mandible is broad and relatively featureless across theanteroposteriorly thin symphyseal region, which is adorned below the posteriorly placed mental foraminaby distinct inferior marginal tubercles. This specimen (TAU) lacks a central keel, mental fossae, andthickened inferior margin. Bar=1 cm.

389 ‘‘’’

Figure 11. Mandibles of 3–4-year-old Neanderthals. Left column, Gibraltar 2 (Devil’s Tower) (NHML);top (anterior view), middle (right lateral view), bottom (inferior view). Right column, Roc de Marsal(Musee National de Prehistoire, Les Eyzies); top (anterior view), middle (right lateral view), bottom(inferior view). As in adults, the front of the mandible is broad and somewhat arcuate from side to side.With the exception of a slight upward indentation at the midline in the Gibraltar 2 child (which probablyrepresents incomplete symphyseal fusion), both mandibles are essentially featureless across the antero-posteriorly relatively thin symphyseal region. The Gibraltar 2 specimen bears well developed inferiormarginal tubercles below the extremely posteriorly placed mental foramina. Bar=1 cm.

thickness of bone across the broad symphy-seal region, and the thickening antero-posteriorly of the corpus posteriorly, theArchi child is quite similar to the Gibraltar2 child, and thus to other Neanderthalchildren as well (Ascenzi & Sergi, 1971a). Alarge inferior marginal tubercle lies beneatheach large mental foramen, hence beneath

the dm2. Anterior tooth crowns in theprocess of growing within their crypts swellout the mandible externally, creating adepression just superior to the inferiormargin of the bone. In profile, the relativelystraight midline of the jaw is tilted somewhatforward. The central incisor roots notice-ably overhang the symphyseal region. The

390 . . .

Figure 12. Archi 1 Neanderthal child. As in the mandibles of other juvenile Neanderthals, this specimen(Istituto Italiano di Paleontologia Umana) is broad across the symphyseal region, which lacks a centralkeel, mental fossae, and thickened inferior margin (for view of the anteroposteriorly thin symphysealregion see Mallengi & Trinkaus, 1997). The slight indentation of the inferior margin at the midlineprobably reflects incomplete fusion of the symphysis. Anterior to each mental foramen and extending tothe thinned inferior margin is a longitudinal depression, whose posteroinferior extent is bounded by adistinct inferior marginal tubercle. Bar=1 cm.

inferior margin is slightly elevated anteriorto the inferior marginal tubercles.

Although clearly lacking the generalmandibular and specific symphyseal con-figurations of juvenile H. sapiens, the Archispecimen has been described as having‘‘some chin development’’ (Ascenzi & Sergi,1971a,b; Stringer et al., 1984:79; Mallegni& Trinkaus, 1997). In particular, Ascenzi &

Sergi (1971b) thought that ‘‘the slightlyinward curve of the outline which corre-sponds to the alveolar part suggests an initialincurvatio mandibulae anterior’’ and that‘‘[i]n the basal margin a low triangularelevation in the median line, the trigonummentale, is visible.’’ And Mallegni &Trinkaus (1997:657) even ventured to statethat while ‘‘the discrete traits that contribute

391 ‘‘’’

to the development of a mental trigone,the tuber symphyseos, the fossa mentales,the tubercula lateralia and the incurvatiomandibulae, are clearly present on mostimmature Neandertal mandibles . . . Archi 1exhibits generally weak development ofthem.’’ As is evident from the foregoingdescription of immature human andNeanderthal mandibles, however, modernhumans and Neanderthals are not at allsimilar in symphyseal morphology or generalmandibular proportions. And the sameholds true for modern children and thecontrasting Archi child, although the latternonetheless does display an interestingdevelopmental feature in this region.

Compared to the same region in theGibraltar 2 child (Figure 11), the ‘‘chin’’ ofthe Archi child becomes recognizable aswhat it is: a slight indentation at the midlineof the inferior margin of the mandible. Incontrast to the Gibraltar 2 child, the Archichild’s incompletely formed right and leftpermanent tooth crowns, still in their crypts,markedly swell out the bone on either side ofthe midline beyond the plane of the sur-rounding external surface of bone. Thiscreates a noticeable depression beneath,as well as another, but more shallowlydepressed, area medial to, each swollenregion of bone. The latter depressionsdelineate between them a narrow midlinefield of bone, at the base of which lies theinferior marginal cleft. The hint of a chin inthe Archi mandible, therefore, results notfrom any of the morphologically consistentfeatures in H. sapiens that form the inverted‘‘T’’ and attendant mental fossae, but fromthe combined effects of incomplete coales-cence of the inferiormost extremity of themandibular symphysis and the intrusivenessof tooth crown formation.

Neanderthals obviously differ from extantH. sapiens in the development and specificmorphology of the symphyseal region of themandible. In no Neanderthal specimen seenby us are there any signs of an inverted ‘‘T’’

and its attendant mental fossae. The onlyfeatures that could possibly be invoked asdemonstrating similarity between these twohominids—the occasional subalveolar swell-ing and the equally occasional inferiormarginal tubercle—are just as clearly notcomparable either in detail or overall mor-phological context. But, exactly as adultH. sapiens retain the fetally established mor-phology of the symphyseal region, so, too,do adult Neanderthals retain featuresseen in their juveniles. In particular, adultNeanderthals retain the broad, somewhatarcuate shape of the symphyseal region,which remains anteroposteriorly uniformlythick. Furthermore, just as the differencesamong adult H. sapiens, in say, the develop-ment of the inverted ‘‘T’’ and mental fossaereflect individual differences within thespecies, so, too, do differences betweenadult Neanderthals reflect variationsbetween individuals of this particularhominid. Such differences occur in thedegrees of depth from top to bottom, flatnessvs. arcuateness from side to side, and/orverticality vs. inclination of the symphysealregion. Individual differences betweenNeanderthals are also found in the presenceor absence of inferior marginal tubercles,subalveolar depressions, low, broad swell-ings below these depressions, and/or in theelevation of the inferior margin of the frontof the jaw. In fact, a qualitative assessmentof symphyseal morphology indicates thatNeanderthals are probably more frequentlyand noticeably variable in morphologicalembellishment of this region than extantH. sapiens.

As evolutionary kin, Neanderthals andH. sapiens—even if not very closely related—would be expected to share many, if notmost, aspects of their skeletal morphology.These would, of course, have been retainedfrom a common ancestry that they sharedto the exclusion of other hominids. Theadditional insight provided by the juvenilesin the Neanderthal sample contributes

392 . . .

significantly to our ability to determinewhether apparent similarities shared byadults of these hominids and H. sapiensare, indeed, present by virtue of commonancestry. When juveniles, especially of closerelated taxa, are distinctly different, asjuvenile Neanderthals and H. sapiens are indetails of symphyseal morphology, itbecomes even more evident that what mightin some adult specimens appear superficiallyas homologous features (such as a sub-alveolar depression or bony build-up in thesymphyseal region) are actually homo-plasies, having arisen through independentcourses of development.

This realization is true even if the cellularprocesses—resorption vs. deposition—thatcreated the features of a particular speci-men are similarly operative among all indi-viduals of all taxa. For, after all, as the onlyactive phases of osteogenesis, how else ifnot through an interactive process of bonedeposition and resorption can skeletalfeatures achieve their adult size and shape?Thus, although it is commonplace whenconsidering the evolution of later hominidsto arrange adult specimens along the linesof a scale naturae as a reflection of changesthat might have occurred in a transfor-mation sequence leading to the morphol-ogy of H. sapiens (Gregory, 1922; McCown& Keith, 1939; Wolpoff, 1980, 1996;Brauer, 1984; Smith, 1984; Lieberman,1995), we suggest that this is not a produc-tive way in which to address the situation.Actually, it is rather Haeckelian. Instead,following a von Baerian approach, weadvocate that, especially when they areavailable for study, juveniles should becompared in order to elucidate develop-mental commonalities. For it is only at thislevel of comparison that the differences andsimilarities among the adults can be fullyunderstood. In light of this, it is patentlyobvious from comparisons between juvenileH. sapiens and Neanderthals that only oneof these species of hominid possesses a

chin in a meaningful morphological andphylogenetic sense.

The Case of Tabun IIThe preserved symphyseal region of theTabun II mandible has been said to displaysome chin development (McCown & Keith,1939; Quam & Smith, 1996; Rak, 1998). Itthus requires separate discussion.

The Tabun II mandible (Figure 13) isanteriorly broad and deep. In even moreexaggerated form than in the mandibles ofsome Neanderthal adults (e.g., Spy 1 andRegourdou), this specimen displays a tall,broad, and shallow subalveolar depressionthat is overhung considerably by the out-wardly curved roots of the permanent inci-sors. Although there has been some damageto the region around the left central incisorroot (which is filled in with plaster), bone ispreserved to the midline on the right side,where it clearly lacks any sign of a verticalkeel. The only elevation of bone in thesymphyseal area is a small smooth fragment(delineated by its edges) that has becomedisplaced from the plane of the bone’s sur-face. In addition, there are no signs of anystructures that might be identified as mentalfossae anywhere within the expected areas ofthe otherwise well preserved symphysealregion. The inferior border of the mostcentral portion of the symphyseal region ismissing and has been reconstructed withplaster. However, more posteriorly, theinferior border of the jaw is present on eachside, extending to some extent mediallyfrom a blunt inferior marginal tubercle. Inthese regions, the inferior border is noteverted. The inferior marginal tubercles liebeneath the large mental foramina, whichare situated below the bony junctionsbetween P2 and M1.

Clearly, had this specimen possessed theinverted ‘‘T’’ and mental fossae that charac-terize H. sapiens, there is sufficient bonepreserved to demonstrate their presence. Intheir absence, therefore, we cannot ascribe

393 ‘‘’’

Figure 13. Mandible of Tabun II (TAU). As is typical of Neanderthals, the front of the jaw is very broadand somewhat arcuate from side to side. As in some Neanderthals, the symphyseal region is very deep,bears a subalveolar depression with a slight bulge below, and is elevated slightly along its inferior margin;there are also inferior marginal tubercles beneath the very posteriorly placed mental foramina. Bar=1 cm.

394 . . .

Mauer. As is well known, the Mauer jawlacks any morphology that could bedescribed as ‘‘chinlike’’ (e.g., Condemi &von Koenigswald, 1997). The symphysealregion is broad and arcs strongly from sideto side (Figure 14). In profile, it curvesgently inferoposteriorly. Anterior to thethickest parts of the mandible, which liebelow the bilaterally doubled mentalforamina (which, in turn, are beneath theP2–M1 alveolar septum), the inferior marginis elevated well above the plane of theinferior border of the posterior corpus. Themargin of this elevation can be described asshallowly bow-shaped: prior to reaching themidline, the bone on each side curves downto form a low inverted peak. From thesubforaminal points of greatest thickening,the inferior border thins anteromedially suchthat the broad central portion of the sym-physeal region is devoid of embellishment,while posteriorly it has thinned maximallyby the level of M3. When viewed frombelow, the broad symphyseal region is moreor less uniformly thick anteroposteriorly,though thickening at its lateral mostextremities.

This specimen is obviously distinctly dif-ferent in its symphyseal region from H.sapiens and the adults from Skhul (plusQafzeh 7). One might claim similaritybetween extant humans and the Mauer jawin the development of inferior marginalthickening, but, in detail, the configurationsdiffer strongly. In H. sapiens (see above),inferior marginal eversion and thickeningoccurs anterior to the mental foramina andare thus restricted to an area that is wellwithin the symphyseal region. In contrast,inferior marginal thickening is most promi-nent in the Mauer jaw at and posterior to themental foramina, while it is lacking anteriorto these foramina. Although similar to someadult Neanderthal specimens in display-ing elevation of the inferior border of the

this specimen to this species. Further-more, since the Tabun II mandible lacks the‘‘tear-drop’’ shaped symphyseal bulge seenin the adults from Skhul, we cannot includethis specimen with that sample, either. In itsbulk, depth, and in various morphologicalfeatures (e.g., subalveolar depression,inferior marginal tubercles), however, thisspecimen is more strongly reminiscent of themandibles of some western EuropeanNeanderthals—particularly those from Spyand Regourdou—than it is of the Tabun C1mandible (cf. McCown & Keith, 1939;Quam & Smith, 1996; Rak, 1998) (seeFigure 9). Rak (1998), however, has arguedthat Tabun II should be regarded as H.sapiens because, like the latter, it differs fromNeanderthals in the depth of the mandibularnotch crest, the position of greatest depth ofthis notch, and the point of termination ofthis crest on the mandibular condyle. Whilethis is true of the left side, the Tabun IImandible displays the Neanderthal con-figurations on the opposite ramus. Rak(1998) also suggests that the Tabun IImandible would not display a marked retro-molar space, as in Neanderthals, if it did nothave a pre-angular notch. But since such anotch becomes defined when the coronoidprocess of the ramus is expanded anteriorly,it is not clear that one can therefore ‘‘fill in’’the notch and eliminate the retromolarspace. In our experience, one can findmandibles of H. sapiens that also display apre-angular notch, but they do not also havea retromolar space.

While it is clear to us that the Tabun IImandible is not H. sapiens, it is less easilydemonstrable that it is a Neanderthal.Nevertheless, this seems highly probableon the basis of the specimen’s broad sym-physeal surface, inferior marginal tubercles,posteriorly placed large mandibularforamina, slightly procumbent anteriortooth roots, and large medial ptyerygoidtubercle (Schwartz & Tattersall, in prep-aration).

Other Middle to Late Pleistocene Western OldWorld Fossils

395 ‘‘’’

symphyseal region, the Mauer jaw is clearlydistinguished from Neanderthals in generalnot only in the contour of the inferiormargin, but also in the development ofinferior marginal thickening, not to mentionother details of mandibular morphology notdescribed here (e.g., Condemi & vonKoenigswald, 1997). Given the lack of

external embellishment in the Mauer adult,we would predict that the symphysealregion of Mauer juveniles would have beensimilarly unadorned.

Figure 14. Mauer Mandible. Although damaged obiquely along the symphysis, it is still obvious that thisspecimen (Geologish-Palaontologisches Institut, Ruprecht-Karls-Universitat Heidelberg) lacked anymorphological embellishment in this region. Inferior marginal thickening, which is highlighted by ahorizontal sulcus above, is noted well posteriorly, beginning in the vicinity of the large inferior marginaltubercle that lies beneath the mental foramina.

Arago. Arago 2 preserves a laterally broadand broadly arced symphyseal region(Figure 15). In profile, the anterior alveoli

396 . . .

Fig

ure

15.

Man

dibl

esof

Ara

go2

(lef

tco

lum

n)an

dA

rago

13(r

ight

colu

mn)

(Uni

vers

ite

dela

Med

iter

rane

e).

InA

rago

2th

em

andi

ble

isbr

oad

and

esse

ntia

llyfe

atur

eles

ssu

rfici

ally

acro

ssth

efr

ont

ofth

ein

feri

orm

argi

n,w

hich

isel

evat

ed;

the

inci

sor

root

sha

dbe

enan

gled

forw

ard,

crea

ting

asu

balv

eola

rde

pres

sion

;an

infe

rior

mar

gina

ltu

berc

lelie

sbe

low

the

post

erio

rly

plac

edm

enta

lfo

ram

en.

Eno

ugh

ofth

esy

mph

ysea

lre

gion

ofA

rago

13is

pres

erve

dto

dem

onst

rate

that

it,

too,

lack

eda

cent

ral

keel

,m

enta

lpr

otub

eran

ce,

thic

kene

din

feri

orm

argi

n,an

dm

enta

lfo

ssa.

Bar

=1

cm.

397 ‘‘’’

are inclined forward and thus overhang thebone below, which curves smoothly downand back into the inferior margin. Theinferior margin rises anteriorly, beginning itsascent in front of the first molar on the leftside and the second on the right. Thus thesymphysis is short superoinferiorly. On bothsides the large mental foramen lies level withthe M1. Although bone missing from themidline deprives us of information concern-ing the existence of a keel, the lack of bothan everted inferior margin and mental fossaebilaterally demonstrates the absence of twoof the major aspects of the symphysealregion in H. sapiens. In addition, the boneof the symphyseal region and well alongthe corpus is more or less uniformly thickbuccolingually.

Only a small portion of the symphysealregion to the left of the midline is preservedin Arago 13. Neither a keel nor a mentalfossa is present. In profile, the alveolarregion is smoothly confluent with the fairlyvertical symphyseal region, which curvesgently back below into the inferior border.On the preserved right side, below andposterior to the fully exposed caninealveolus (which may have been opened as aresult of abscessing), the inferior marginis thickened into a torus that extendsposteriorly to reach the level of the front ofthe second molar. The large mental foramenlies below the anterior root of M1. Theinferior border of the corpus is not elevatedanteriorly. When viewed from below, whatthere is of the external symphyseal surface isrelatively flat across and the bone of theregion is uniformly thick anteroposteriorly.The corpus does not begin to thin untilmuch more posteriorly.

Clearly, the Arago mandibles presenta morphology different from those so fardiscussed.

Weimar-Ehringsdorf. We discuss the twoEhringsdorf mandibles (1009/69 and 1010/69; Figure 16) in the ‘‘other’’ category

because, while Smith (1984) is inclinedto see the Ehringsdorf material asNeanderthal-like and Vlcek (1993) views itas H. sapiens-like, our preliminary assess-ment of the material suggests a differentinterpretation (Schwartz & Tattersall, inpreparation). The adult mandible Eh1009/69 is relatively narrow across the sym-physeal region, which is slightly curved fromside to side as well as from top to bottom.Between a pair of low but distinct inferiormarginal tubercles that lie just posterior tothe large mental foramina (which, in turn,are situated beneath M1), the inferior borderof the front of the jaw is elevated relativeto the posterior corpus. The roots of theanterior teeth are inclined forward (those ofthe central incisors being especially procum-bent), so that the alveolar margin markedlyoverhangs the symphyseal region. Boneremodeling due to subperiosteal as well as toperiapical lesions has created deep craterson either side of the retained left centralincisor. These greatly accentuate the incli-nation of the anterior teeth, to which thispathology may also have contributed. Bydefault, alveolar bone eversion in conjunc-tion with these massive concavities (particu-larly the larger of the two on the right side)gives the false impression of a faintlymounded symphyseal surface near theinferior margin.

In contrast to Eh 1009/69, the anteriorteeth in the juvenile mandible (Eh 1010/69)are relatively orthal, but the entire alveolarregion is shifted slightly anterior to the planeof the symphysis below. Although brokenand glued inferiorly, and reconstructedbelow and posterior to the region of theleft canine, the symphysis is relatively broadand somewhat arced from side to side.In profile, it is fairly vertical below theanteriorly displaced alveolar region as far asits inferiormost extremity, where it curvesgently posteriorly into the somewhatelevated anterior margin. The expanse ofsymphyseal region that is perfectly preserved

398 . . .

Fig

ure

16.

Man

dibl

esof

Ehr

ings

dorf

(Eh)

1009

/69

(lef

tco

lum

n)an

dE

h10

10/6

9(M

useu

mfu

rV

or-

und

Fru

hges

chic

hte

Thu

ings

isch

es,

Wei

mar

).N

eith

ersp

ecim

endi

spla

ysa

cent

ralk

eel,

men

talf

ossa

,men

talp

rotu

bera

nce,

orth

icke

ned

infe

rior

mar

gin,

and

the

sym

phys

ealr

egio

nin

each

isbr

oad

acro

ss.

InE

h10

09/6

9th

ece

ntra

lin

ciso

rsgr

eatl

yov

erha

ngth

ebo

nebe

low

and

the

infe

rior

mar

gina

ltu

berc

lelie

sle

vel

wit

hth

epo

ster

iorl

ypl

aced

men

tal

fora

men

.B

ar=

1cm

.

399 ‘‘’’

between the canine roots/alveoli and ondown to the inferior border is devoid ofsurface morphology.

Figure 17. Rabat (Thomas Quarry) mandible (IPH). The incisors overhang somewhat the essentiallyfeatureless symphyseal region.

Rabat. The Rabat partial mandible preservesthe entire symphyseal region, which wasbroken postmortem below the roots of theleft anterior teeth, and has been repaired(Figure 17). Despite these attentions, it isobvious that the symphyseal region is well

curved but not broad from side to side. Onthe intact right side is a shallow subalveolardepression, inferior to which the bone isfeatureless, bearing neither a central keel nora mental fossa more laterally. In profile, thesuperoinferiorly not very tall symphysiscurves slightly down and back into theunembellished inferior border. More clearlyseen on the right side, a short longitudinalgroove separates the mental foramen (which

400 . . .

is level with the P2) from the inferior border,which, in consequence, appears to be thick-ened in that region. When viewed frombelow, the bone is relatively uniformly thickanteroposteriorly throughout the symphy-seal region as well as more posteriorly alongthe corpora.

Although taxonomic allocation of thisspecimen is uncertain, it clearly is not H.sapiens or a variation on the European orLevantine hominids discussed above.

Tighenif (Ternifine). Even the least completeof the three Tighenif mandibles, Tighenif 2,preserves a good portion of the front of thejaw (Figure 18). The symphyseal region ofTighenif 2 is narrow and transversely arced.This specimen is particularly interesting inthat it bears a distinct—broad and low—midline keel that emerges just below thealveolar region and fans out as it coursestoward the inferior margin, thereby creatinga well-defined, triangular protuberance. Oneach side of this keel lies a small, shallowdepression, which accentuates the lateralextremities of this protuberance. As pre-served on the left side, there is a distinctinferior marginal tubercle, which lies underthe large mental foramen (which, in turn,is level with the mesial side of P2). Thistubercle is separate from, hence not aterminus or ‘‘corner’’ of, the triangularprotuberance. In profile, the symphysis isstraight and slopes back quite markedly.

The symphyseal region of Tighenif 1,which retains both corpora, is moderatelybroad and strongly arced from side to side.In profile, it forms a smooth arc, from theslightly inwardly inclined anterior toothroots to the posteriorly curved and modestlyelevated inferior border. There is a low butrather broad central keel coursing from thealveolar region to the inferior margin. Thepresence of this central keel creates shallowfossae on either side of the midline. Whenviewed from below, the bone of the symphy-seal region and the portion of the corpora

behind is uniformly thick anteroposteriorly,becoming thickest in the region of M2.

The symphyseal region of the most com-pletely preserved mandible, Tighenif 3, isalso moderately broad and strongly arcedfrom side to side. In profile, the alveolarregion of the anterior teeth is tilted forwardand then up and lingually very slightly, andthe minimally arced symphysis courses backand down to the elevated inferior margin,which begins its ascent from the regionbelow the first molar. There is the faintesthint of a broad, low, midline keel, whichwidens as it courses down from the alveolarregion to become confluent with the slightlythickened inferior border. As is well pre-served on the left side, there is a distincthorizontal sulcus that courses beneath theregion of the cheek teeth to the region ofthe midline keel that serves to emphasizefurther the thickening of the inferiorborder.

Brauer (1984) described a trigonumbasale only in Tighenif 2 and 3, but clearlyTighenif 1 is similar to the other twospecimens in displaying a midline keelthat courses to the inferior border of themandible. Indeed, the keel is actually morepronounced in Tighenif 1 than in the othertwo specimens. It is of potential phylo-genetic and systematic importance that allthree Tighenif specimens are unique amongthe middle Pleistocene fossils we studied indisplaying some of the features distinctiveof the symphyseal morphology of extantH. sapiens. It is of further interest that one ofthese features—the central keel—is observedin fossil jaws that do not also have thesupposed hallmark of the human chin, aclear-cut mental protuberance. This shouldnot be surprising when one considers thatthe mental protuberance of H. sapiens,which is itself a variable character, emergespostnatally, as does the occasional symphy-seal bulge in Neanderthals and presumablyother fossil hominids in which evidence of acentral keel is lacking.

Figure 18. Mandibles from Tighenif (Ternifine) (Museum National d’Histoire Naturelle, Paris). Top:Tighenif 2; middle: Tighenif 1; bottom: Tighenif 3. Although with some variation in degree of expression,all display a central keel, with slightly depressed mental fossae on either side, that broadens into aninferiorly placed mental protuberance; the inferior margin of the symphyseal region is somewhat elevated.

402 . . .

Implications

From a phylogenetic perspective, if weaccept on developmental grounds that H.sapiens is unique among primates (indeed,among mammals) in the details of itssymphyseal morphology, then it is possibleto entertain the following hypothesis: TheTighenif specimens’ possession of a centralkeel and a variably small, low-set triangularprotuberance (a mental trigon or trigonumbasale) could reflect potential synapo-morphy with H. sapiens. Obviously, theseapomorphies would have characterized thelast common ancestor of a clade thatincluded extent H. sapiens as well as thoselate Pleistocene fossils possessing all of thesymphyseal details seen in the extantspecies: i.e., at least the Qafzeh 11 and theTighenif mandibles.

In this regard, we look forward to futurestudy of the Jebel Irhoud juvenile mandible(Hublin & Tillier, 1981) and the KlasiesRiver Mouth mandibles (Rightmire &Deacon, 1991), all of which have beendescribed as having some version of chinformation. As illustrated by Hublin & Tillier(1981), the former specimen may possess acentral keel that expands inferiorly into athickened inferior margin. Casts of thisspecimen appear to show such morphology.In contrast, the Klasies River Mouthspecimens, particularly KRM 13400 and14695, do not appear to have either a centralkeel or a thickened inferior margin, althoughthe central portion of the symphyseal regionis surmounted by an external swelling(Rightmire & Deacon, 1991). A cast ofKRM 13400 appears to be generally consist-ent with this description, although it shouldbe noted that, well lateral to the midline, themargin thickens to its greatest extent belowthe doubled right mental foramina, and thesymphyseal profile is essentially vertical.The AMNH cast of KRM 41815, which isbroken in the original just below the incisoralveoli, does, as described, appear to pre-

serve a triangular mental protuberance,which both tapers superiorly into whatmight have been a central keel and expandsinferiorly into bilateral mental tuberosities.When viewed from below, the symphysealregion of this specimen is relatively straightacross and somewhat thickened from frontto back. It will be interesting to see if theKlasies River Mouth specimens present apicture of diversity as seen in the Qafzehhominids.

Morphologically, the primary implicationof our observations is that a bulging sym-physeal region is not equivalent to a chin.When humans and elephants can both bedescribed as having chins (e.g., Enlow,1982), it is probably time to reconsider theapplicability of the term. Consequently, werecommend that the term ‘‘chin’’ no longerbe used in discussions of mandibular mor-phology and its phylogenetic and systematicsignificance. If, however, one feels the needto retain this term, it should be restricted inusage only to extant H. sapiens and thosefossils displaying the constellation of sym-physeal features of this species. Since it isobvious that bulges and swellings as well assubalveolar depressions of differing degreesof expression and different morphologieshave come to adorn the symphyseal regionsof a diversity of hominids, we further recom-mend that the terms (and the synonyms of)‘‘mentum osseum,’’ ‘‘incurvatio mandibu-laris,’’ ‘‘tuberculum laterale,’’ and even‘‘trigonum mentale’’ also be limited, or evendropped from usage. As anatomical terms,they are used to refer both to sometimessuperficially similar and to sometimesmarkedly different structures in a diversityof adult specimens that may have arisenfrom totally different juvenile configur-ations. As for children, the sometime pres-ence of a gomphotic scar especially lowdown along the midline of the mandible is anaturally occurring result of symphysealfusion. Unless it is distinctly raised andpart of an everted, inverted ‘‘T’’-shaped

403 ‘‘’’

structure that is associated with mentalfossae, it is not a ‘‘hint’’ or a ‘‘trace’’ of amental trigon as seen in H. sapiens. Thus,these terms have become charged with ascenario of ‘‘chin’’ evolution which shoulditself be discarded.

Additional discussion

Throughout this paper, we have attemptedto keep our description of morphologyapart from a phylogenetic and, especially,functional interpretation of it. We have,however, stressed the importance of under-standing the morphology of the adult bystarting first with an appreciation of thedetails of juveniles precisely because this isthe most fundamental way in which toappreciate the similarities or differences thatexist among individuals and between theaverage morphologies of taxa. ComparingNeanderthals with extant H. sapiens andthose specimens that have come to beregarded as fossil H. sapiens, we are fortu-nate that there are, indeed, juveniles avail-able for study. In other cases, such as withthe Mauer or Klasies River Mouth man-dibles, we have tried to inform our com-parisons with insights drawn from casesbased on ontogenetic series.

Although we could leave the discussionwhere we did in the preceding sections,comments we received from various anony-mous reviewers on an earlier version of thispaper have provoked us to pull together theloose ends and to detail more fully ourtheoretical, philosophical, and methodologi-cal position. This might be unconventional,but it may prove useful in clarifying pointswe raised earlier and in focusing attentionon issues that those of different philosophi-cal and methodological persuasions mightalso take into consideration. We haveorganized our comments in the context ofthe kinds of topic that often characterizedebates on modern human origins.

Intermediate, transitional morphological statesWe presented our descriptions and compari-sons of the specimens as we did in order tokeep them separate from our discussion ofthe systematic implications of the data.Often, however, there is a tendency to infusedescription and comparison of specimenswith interpretation of the potential signifi-cance of the described morphologies given aparticular, but not overtly stated, phylo-genetic scenario. Such scenarios tend to bebased on assumptions not only of related-ness, but also of transformation series (inwhich terms such as ‘‘intermediate’’ are apart) and implied functional and/or develop-mental explanations (in which discussinghow morphologies might have come to be inone form or another plays a large role).

Basically, however, the facts are that H.sapiens has a distinctive symphyseal con-figuration from its ontogenetic outset andthat many other hominids, especiallyNeanderthals, do not share any version ofthese apomorphies. From this it would seemreasonable to conclude that Neanderthalsand those specimens that are morpho-logically similar to them in symphysealmorphology are not members of the speciesH. sapiens. But if one was committed to theinterpretation that there was only a singlespecies, which encompassed a diversityof morphologically distinctive specimens—such as all or most of those we discusshere—then one would be obliged to explainhow members of the same species could havecome to be morphologically different fromone another. We, however, are trying tounderstand as best we can what the detailsof difference and similarity are from thebeginning. Only afterward can we bring thisinformation to bear on our phylogenetic andsystematic hypotheses, and, if we so choose,to offer explanations for how and evenperhaps why certain features came to be theway they are.

Our appreciation of development also dif-fers significantly from the more prevalent

404 . . .

one in the literature: essentially, if develop-ment is taken into consideration at all, itis done secondarily, after specimens ofadult individuals have been sorted into aHaeckelian scale naturae that is regarded asreflecting a transformation sequence. Thislicense is prevalent in paleoanthropology, asis indicated in the oft-published diagrams offossil adult crania arranged in a presumedphylogenetic sequence. In such a scenario,for example, the symphyseal morphology ofadult Skhul and Qafzeh specimens are seenas being intermediate between Neanderthalsand modern H. sapiens, with this inter-mediate morphology being attained develop-mentally from the nondescript symphysealregion seen in the Skhul I child. In contrastto this type of approach, we, like von Baer(1828) and Huxley (1863), emphasize thecommonalities between juveniles, sincethose form the substrate upon which adultmorphology is predicated (see also Schartz& Tattersall, 1996b). In this light, especiallyif the Skhul I child represents the juvenilestate of the Skhul adults, it becomes strik-ingly clear that the symphyseal bulge of thelatter is not just a variant of the chin of H.sapiens. Even if this were not the case, it isdifficult to sustain a compelling comparisonbetween adult morphologies if their juvenilestates, as in Neanderthals and H. sapiens, areso clearly different.

One might also argue, on the basis ofarranging specimens in a morphologicalscala naturae of presumed evolutionarychange, that a more anterior position of thealveolar process, as seen in the facially prog-nathic Neanderthals and some early Homo,merely masks the development of H. sapiens’symphyseal morphologies in specimens ofthese representatives of the genus. Conse-quently, the symphyseal morphologies ofH. sapiens are not truly absent after all.Although this kind of argumentation is com-monplace in paleoanthropology (e.g., ‘‘itlooks this way because of such and such,otherwise it would be identical to something

else’’), we must strongly reiterate that sucharguments merely constitute a defense of aparticular hypothesis of relatedness that onehas already embraced. They do not contrib-ute to the generation of theories of related-ness. More specifically, in terms of the aboveexample, facial prognathism, or its lack, hasno bearing on the matter at hand. JuvenileNeanderthals are not overtly facially prog-nathic relative to the adult state. The profileof a juvenile Neanderthal’s mandibular sym-physis can be vertical or anteriorly inclined.Yet, especially in cases of the former con-figuration, the juvenile Neanderthal’s sym-physeal region is devoid of any specificallyH. sapiens-like morphology.

In H. sapiens, juvenile mandibles areessentially vertical in profile and yet possessthe characters already described above. If amental trigon later develops to becomenoticeably protrusive, it does so as a result ofdeposition of bone in that region (Enlow,1982). Further accentuation of such a pro-trusive mental trigon can be provided by thedevelopment of a depression or an incur-vatio mandibularis above it, which derivesfrom the process of bone resorption (Enlow,1982). Thus, the inward curve above andthe protruding mental trigon below that wesee in the mandibular profile of H. sapiensresults from the modification of an essen-tially vertical symphyseal face, not, as thetypical Neanderthal-to-H. sapiens scalanaturae based on adult specimens wouldprompt one to speculate, from the retreat ofthe face during the emergence of the latterhominid. Furthermore, since the degree offacial prognathism characteristic of adultNeanderthals develops from the moreorthognathic condition of the juvenile, ifthere was any basis for the ‘‘anterior alveolarposition masking H. sapiens’ features’’hypothesis, we would expect to observethese features in the juvenile Neanderthals.But we do not.

It might also be appropriate here toexplain why we must discuss features as

405 ‘‘’’

discrete entities, rather than as stages in atransformational continuum: The geneticsand properties of development make itincreasingly clear that novel characters willappear instantaneously and, therefore,define new species from the start (seereviews by Schwartz, 1999a,b). AsGruneberg (1943) demonstrated decadesago, a structure (such as a tooth) must reacha certain minimal threshold of developmentor it will be aborted. The evolution of thehorse presents an unambiguous example(Schwartz, 1999c). In three-toed taxa, thelateral digits always consist of three phalan-geal elements, even if they are small relativeto the size of the central digit. With theappearance of the first single-toed horses,the lateral digits are entirely absent. Fromthe perspective of regulatory genes, and,therefore, of the developmental advent ofstructures, the picture is also of the abruptappearance or disappearance of features(Schwartz, 1999a,b). For example, in thecase of the vertebrate eye, studies on the Rxgene in the mouse demonstrated that indi-viduals that were either homozygous orheterozygous for the active gene had both aneyeball and bony socket, whereas homo-zygotes for the experimentally-mutatedinactive or recessive Rx gene lacked bothstructures. There was no in-between state.Since, as has been known since Bateson’s(1909) time, nonlethal mutations typicallyarise in the recessive state, it would only bethrough a process of heterozygosis leadingto the production of homozygotes for themutation that a new feature would emergein a population (see discussion in Schwartz,1999a,b). But when it did, it would appearas if out of nowhere and in its full-blownstate in a number of individuals (Schwartz,1999a,b). This process has most recentlybeen documented in a report on the spon-taneous appearance of a mutation affectingthe Hodx-13 gene in a laboratory colony ofmice (Johnson et al., 1998). At some point,and by a mechanism that remains unknown,

the mutant recessive would be converted tothe dominant state (Johnson et al., 1998).

With this in mind, the novel configurationof the symphyseal region of H. sapiens can beappreciated: whatever regulatory changesoccurred that affected bone deposition andhence shape in this region, these apparentlyapomorphic morphologies would haveemerged without a trail of transitional stagespreceding them. A similar phenomenonwould explain the development of theautapomorphic medial projection in thenasal region of Neanderthals (Schwartz& Tattersall, 1996a).1 In 3–4-year-oldjuveniles, this structure is already present asa vertically oriented bony projection thatemerges directly from the wall of the nasalcavity and that becomes larger in adults.No equivalent structure exists in the nasalregion of juvenile extant primates, H. sapiensincluded, which retain the primitivemammalian condition of a low, variablyhorizontally oriented conchal crest, alongwhich a separate concha articulates. Inadults of these taxa, the concha may fuse tothe wall of the nasal cavity.

1Subsequent to our publication on the structures ofthe nasal cavity in Neanderthals, we restudied the Spymaterial and discovered that we had erred in our initialevaluation of the Spy 1 specimen. Although wewere unable to publish a note of correction prior toFranciscus’ (1999) article, we were able to eliminatethis error from two other publications that were still inpress (Schwartz & Tattersall, 1999a; Schwartz et al.,1999). At present, a medial projection is docu-mented in the following Neanderthal specimens: Engis,Gibraltar 1, La Chapelle-aux-Saints, La Ferrassie 1,Monte Circeo 1, Roc de Marsal, St Cesaire, Shanidar1, and Subalyuk.

VariationAs noted in Table 1, the specimens of extantH. sapiens we studied represent a globalsampling. But, this fact aside, we must pointout that we are not engaged in a study ofhuman variation. We are endeavoring toundertake a systematic analysis of hominids.The latter concern entails a totally differentemphasis than documenting variation within

406 . . .

a population or species. It involves thedelineation of potential apomorphies,which, if autopomorphic, contribute to thedelineation of species, or, if synapomorphic,to the delineation of sister taxa and clades.In this particular study, we have delineatedwhat we believe to be various apomorphiesof the symphyseal region of H. sapiens. Assuch, and for systematic purposes, it istherefore irrelevant whether one specimenhas a more robust symphyseal keel thananother. What is relevant is how manyspecimens possess the apomorphic features.

It is only after one accepts systematichypotheses—how many species there are,and which specimens represent whichspecies—that one can then embark, if onewishes, on studies of variation. But suchstudies do not shed light on the origins andrelationships of the taxa involved, only onthe ways in which individuals within thesame taxon differ slightly from one another.In this light, it hardly matters if the inverted‘‘T’’ with its mental tubercles is more pro-nounced in an Aleut than in a WestAfrican, or if the symphyseal profile of oneNeanderthal is more forwardly sloping thananother. But it is surely significant that noNeanderthal specimen, no Skhul speci-men, and not all Qafzeh specimens displaythe everted and inverted ‘‘T’’-shapedconfiguration of the symphyseal region.

TerminologyDuring our now multiyear comparativestudy of hominids, we have become increas-ingly impressed by how inadequate andrestrictive anatomical terminology based onthe morphology of H. sapiens often is whendescribing other hominids. For instance,while H. sapiens does indeed have an‘‘arcuate eminence’’ that is large prenatallyand persists into the adult state, this con-dition is rarely found in specimens of anyother hominid, much less any othermammal (see Schwartz & Tattersall,1996b). So far, we have been able to

describe an arcuate eminence only injuvenile Neanderthals and one adultNeanderthal specimen, Gibraltar 1. Clearly,if one chose to retain the term ‘‘arcuateeminence’’ one would be better off referringto the area in question as the ‘‘region of thearcuate eminence’’ (which technically wouldbe defined as the area capping the superiorsemicircular canal), and then describing itsconfiguration. With regard to the terminol-ogy applied to the chin of H. sapiens, amentum osseum may refer to a bulge thatstraddles the midline of the jaw, but it isobvious that a bulge can emerge upon totallydifferent substrates: compare, for instance,the bulge of Spy 1, that of Skhul V, and thatof Cro-Magnon 3. Clearly, while a bulgemay be produced by the same process ofbone deposition (which is the only processfor increasing the size or thickness of a bonystructure), this does not de facto meanthat all symphyseal bulges are the samestructure. Similarly, while an incurvatiomandibularis may be enhanced by boneresorption in that region, as well as thedevelopment of a bulge below and alveolarprognathism above, this does not mean thatthe details of the symphyseal regions of thisarray of hominids are identical.

In short, the application of terminologythat had been devised for very specific fea-tures to a field of differently configureddetails that may be present in the samegeneral region not only hinders productivecomparisons but, in terms of human evol-ution, continues to obscure the differencesthat exist between H. sapiens and otherhominids.

Conclusions and summary

The uniquely configured symphyseal regionof H. sapiens forms early in fetal develop-ment and the basic shape and architecturethen established are retained into adulthood.The salient features of the symphysealregion of this extant hominid species are a

407 ‘‘’’

raised central keel that flows into a dis-tended inferior margin, a low-lying triangu-lar mental tuberosity at the confluence of thekeel and the inferior margin, and mentalfossae that lie on either side of the keel andabove the distended inferior margin. NoNeanderthal included in this study, whetherjuvenile or adult, possesses these distinctivefeatures. Instead, the mandibles of bothjuvenile and adult Neanderthals are broadand somewhat arcuate across the midline.Those features that occur variably inNeanderthal adults (e.g., a subalveolardepression, a swelling below this depression,inferior marginal tubercles that lie below thevery posteriorly placed mental foramina)represent aspects of individual variationappended during postnatal growth.

Among fossils usually considered torepresent H. sapiens, those from the latestPleistocene and the earlier Qafzeh 11 (andpossibly Qafzeh 8 and 9) display the sym-physeal features seen in living humans. Incontrast, all of the Skhul adults and theother adult Qafzeh individuals differ bothfrom H. sapiens and from Neanderthals inhaving symphyseal regions adorned with avariably developed teardrop-shaped bulge.The Skhul I child has a featureless symphy-seal region. With the exception of fossilmoderns, in the entire sample under con-sideration here it is only in the Tighenifmandibles that one finds a central keel.

The latter observation suggests that thedevelopment of a central symphyseal keel isa synapomorphy of a clade that includesextant H. sapiens and those fossils similarlyconfigured in details of the symphysealregion, plus the Tighenif specimens. Withinthis clade, H. sapiens and similarly config-ured fossil specimens are distinguished bythe consistent possession of a thickenedinferior margin that forms an inverted ‘‘T’’with the central keel, plus a variably protru-sive triangular mental protuberance at thejunction of these structures and well definedmental fossae bilaterally. Clearly symphyseal

morphology, especially as considered withina developmental framework, lends supportto previous suggestions of notable taxicdiversity within the genus Homo (e.g., How-ell, 1994; Santa Luca, 1978; Schwartz& Tattersall, 1996b; Tattersall, 1986;Zollikofer et al., 1995): a diversity that is atpresent substantially underestimated.

Acknowledgements

We thank Drs C. Stringer (London), A.Langaney, J.-J. Hublin, D. Grimaud-Herve,S. Condemi, H. Thomas, and H. de Lumley(Paris), M.-H. Thiault and S. Tymula(St.-Germain-en-Laye), R. Orban (Brussels),E. Poty (Liege), R. Ziegler (Stuttgart), H.-E.Joachim (Bonn), N. Farsan (Heidelberg),A. Hoffman (Berlin), S. Dusek (Weimar),J.-J. Cleyet-Merle (Les Eyzies), B.Vandermeersch (Bordeaux), V. Merlin-Anglade (Perigeux), S. Simone (Monaco),G. Spadea and A. de Lucchessi(Ventimiglia), A. Bieti (Rome), J. Radovcicand M. Paunovic (Zagreb), V. Dobosi and I.Pap (Budapest), M. Dobisıkova (Prague),M. Teschler-Nicola (Vienna), J. Jelinek(Brno), Y. Rak (Tel Aviv), J. Zias(Jerusalem), J. Svoboda (Dolní Vestonice),D. Pilbeam (Cambridge, MA), G. Kordos(Thessaloniki), A. Akerraz (Rabat Souissi),Ben-Ncer Abdelwahed (Rabat Chellah),and H. Langdon (Pittsburgh), and Direc-trice Joudia Hassar-Benslimane (InstitutNational des Sciences de l’Archeologie et duPatrimoine, Rabat) for permission to studyand photograph specimens in their chargethat were essential to this study. TheSpy specimens are in the collection of theRoyal Belgian Institute of Natural Sciences,gift of the heirs of Professor Max Lohest(1857–1926). All photographs are copy-right � J. Schwartz. We thank Y. Rak, T.Harrison, R. D. Martin, and four anony-mous reviewers for comments on aspects ofthis paper. J.H.S. was funded by the L. S. B.Leakey Foundation and the University of

408 . . .

Pittsburgh, and I.T. by the Ogden MillsFund (AMNH).

References

Aiello, L. & Dean, C. (1990). An Introduction to HumanEvolutionary Anatomy. New York: Academic Press.

Ascenzi, A. & Sergi, A. (1971a). Il giacimentocon mandibola neandertaliana di Archi (ReggioCalabria). Accd. Naz. Lincei 50, 763–771.

Ascenzi, A. & Sergi, A. (1971b). A new Neanderthalchild mandible from an Upper Pleistocene site insouthern Italy. Nature 233, 280–283.

Baer, K. E. von (1828). U}ber Entwicklungsgeschicteder Thiere: Beobachtung und Reflexion. Konigsberg:Borntrager.

Bateson, W. (1909). Mendel’s Principles of Heredity.Cambridge: Cambridge University Press.

Brauer, G. (1984). A craniological approach to theorigin of anatomically modern Homo sapiens inAfrica and implications for the appearance of modernEuropeans. In (F. H. Smith & F. Spencer, Eds) TheOrigins of Modern Humans: A World Survey from theFossil Evidence, pp. 327–410. New York: Alan R.Liss.

Condemi, S. & von Koenigswald, W. (1997). DerUnterkeifer von Mauer. In (G. A. Wagner & K. W.Beinhauer, Eds) Homo heidelbergensis von Mauer:das Auftreten des Menschen in Europa, pp. 200–214.Heidelberg, HVA: Akademischer Verlag.

Daegling, D. J. (1993). Functional morphology of thehuman chin. Evol. Anthrop. 1, 170–177.

Dean, M. C., Stringer, C. B. & Bromage, T. B. (1986).Age at death of the Neanderthal child from Devil’sTower, Gibraltar and the implications for studies ofgeneral growth and development in Neanderthals.Am. J. phys. Anthrop. 70, 301–309.

Enlow, D. H. (1982). Handbook of Facial Growth.Philadelphia: W. B. Saunders.

Franciscus, R. (1999). Neandertal nasal structures andupper respiratory tract ‘‘specialization’’. Proc. Natl.Acad. Sci. 96, 1805–1809.

Gregory, W. K. (1922). Origin and Evolution of theHuman Dentition. Baltimore: Williams & Wilkins.

Gruneberg, H. (1943). The Genetics of the Mouse(English translation). Cambridge: CambridgeUniversity Press.

Howell, F. C. (1994). A chronostratigraphic and taxo-nomic framework of the origins of modern humans.In (M. H. Nitecki & D. V. Nitecki, Eds) Origins ofAnatomically Modern Humans, pp. 253–319. NewYork: Plenum.

Howells, W. W. (1959). Mankind in the Making.Garden City. NY: Doubleday.

Hrdlicka, A. (1911). Human dentition and teeth fromthe evolutionary and racial standpoint. Dom. DentalJ. 1911, 1–15.

Hublin, J.-J. & Tillier, A.-M. (1981). The Mousterianjuvenile mandible form Irhoud (Morocco): a phylo-genetic interpretation. In (C. B. Stringer, Ed.) Aspects

of Human Evolution, pp. 167–185. London: Taylor &Francis.

Huxley, T. H. (1863). Man’s Place in Nature. NewYork: D. Appleton.

Inke, V. G. (1967). Eigenschaften und Bedeutung derGranzflache zwischen Basal und Alveolarteil desmenschichen Unterkiefers. Nova Acta Leopold. 33,161–195.

Johnson, K. R., Hope, O. S., Donahue, L. R., Ward-Bailey, P., Bronson, R. T. & Davisson, M. T. (1998).A new spontaneous mouse mutation of Hoxd13with a polyalanine expansion and phenotype simi-lar to human synpolydactyly. Hum. Mol. Gen. 7,1033–1038.

Johnston, T. B. & Willis, J. (Eds) (1954). Gray’sAnatomy, 31st edn. London: Longmans, Green.

Lam, Y. M., Pearson, O. M. & Smith, C. M.(1996). Chin morphology and sexual dimorphismin the fossil hominid mandible sample fromKlasies River Mouth. Am. J. phys. Anthrop. 100,545–577.

Lieberman, D. E. (1995). Testing hypotheses aboutrecent human evolution from skulls. Curr. Anthrop.36, 159–197.

Mallegni, F. & Trinkaus, E. (1997). A reconsiderationof the Archi 1 Neanderthal mandible. J. hum. Evol.33, 651–668.

Mathers, P., Grinberg, A., Mahon, K. & Jamrich, M.(1997). The Rx homeobox gene is essential forvertebrate eye development. Nature 387, 604–607.

McCown, T. D. & Keith, A. (1939). The Stone Age ofMount Carmel: The Fossil Remains from the Levalloiso-Mousterian. Oxford: Clarendon Press.

Quam, R. M. & Smith, F. H. (1996). Reconsiderationof the Tabun C2 ‘‘Neanderthal’’ (abstract). Am. J.phys. Anthrop. (Suppl.) 22, 192.

Rak, Y. (1998). Does any Mousterian cave presentevidence of two hominid species? In (T. Akazawa, K.Aoki & O. Bar-Yosef, Eds) Neanderthals and ModernHumans in West Asia, pp. 353–366. New York:Plenum.

Rak, Y., Kimbel, W. H. & Hovers, E. (1994). ANeanderthal infant from Amud Cave, Israel. J. hum.Evol. 26, 313–324.

Reisenfeld, A. (1969). The adaptive mandible: anexperimental study. Acta Anat. 72, 246–262.

Rightmire, G. P. & Deacon, H. J. (1991). Comparativestudies of late Pleistocene human remains fromKlasies River Mouth, South Africa. J. hum. Evol. 20,131–156.

Robinson, L. (1913). The story of the chin. Knowledge36, 410–420.

Rosas, A. (1995). Seventeen new mandibular speci-mens from the Atapuerca/Ibeas Middle Pleistocenehominids sample.. J. hum. Evol. 28, 533–559.

Santa Luca, A. P. (1978). A re-examination ofpresumed Neandertal-like fossils. J. hum. Evol. 7,619–636.

Schwartz, J. H. (1986). Primate systematics and aclassification of the order. In (D. Swindler & J.Erwin, Eds) Comparative Primate Biology, vol. 1,

409 ‘‘’’

Systematics, Evolution and Anatomy, pp. 1–41. NewYork: Alan R. Liss.

Schwartz, J. H. (1999a). Homeobox genes, fossils, andthe origin of species. Anat. Rec. (New Anat.) 257,15–31.

Schwartz, J. H. (1999b). Sudden Origins: Fossils, Genes,and the Emergence of Species. New York: John Wiley &Sons.

Schwartz, J. H. (1999c). Evolutionary provocations:Paul Sondaar, the evolution of the horse, and a newlook at the origin of species. In (J. de Vos, Ed.)Festschrift for Paul Sondaar. Deinsea.

Schwartz, J. H. & Houghton, F. (in preparation). Thecremated skeletal remains from Punic Carthage.In (L. E. Stager & J. Greene, Eds) The AmericanExcavations at Carthage.

Schwartz, J. H. & Tattersall, I. (1996a). Significance ofsome previously unrecognized apomorphies in thenasal region of Homo neanderthalensis. Proc. Natl.Acad. Sci. 93, 10,852–10,854.

Schwartz, J. H. & Tattersall, I. (1999b). Toward distin-guishing Homo neanderthalensis from Homo sapiens,and vice versa. Anthropologie 43, 129–138.

Schwartz, J. H. & Tattersall, I. (1999a). Toward adefinition of Homo sapiens and Homo neanderthalensis:I. The nasal region. In (J. Gibert, F. Sanchez, L.Gibert & F. Ribot, Eds) The Hominids and TheirEnvironments During the Lower and Middle Pleistoceneof Eurasia, pp. 299–310. Orce: Museo de Prehistoriay Paleontologıa.

Schwartz, J. H. & Tattersall, I. (1999b). Variability inhominid evolution: putting the cart before the horse?In (M. Antunes, Ed.) Last Neanderthals in Europe:Odontologic and Other Evidence. Lisbon: Academy ofSciences.

Schwartz, J. H. & Tattersall, I. (in preparation). Atlas ofFossil Hominids, Volume 1: Homo (Europe). NewYork: John Wiley & Sons.

Schwartz, J. H., Tattersall, I. & Laitman, J. L. (1999).New thoughts on Neanderthal behavior: evidencefrom nasal morphology. In (H. Ullrich, Ed.) HominidEvolution: Lifestyles and Strategies, pp. 166–186.Gelsenkirchen/Schwelm: Edition Archaea.

Smith, F. H. (1984). Fossil hominids from the UpperPleistocene of Central Europe and the origin ofmodern Europeans. In (F. H. Smith & F. Spencer,Eds) The Origins of Modern Humans: a World Surveyof the Fossil Evidence, pp. 137–209. New York: AlanR. Liss.

Smith, P., Gomorri, J. M., Spitz, S. & Becker, J.(1997). Model for the examination of evolutionarytrends in tooth development. Am. J. phys. Anthrop.102, 283–294.

Stringer, C. B., Hublin, J.-J. & Vandermeersch, B.(1984). The origin of anatomically modern humansin western Europe. In (F. H. Smith & F. Spencer,Eds) The Origins of Modern Humans: A World Surveyfrom the Fossil Evidence, pp. 51–135. New York: AlanR. Liss.

Tattersall, I. (1986). Species recognition in humanpaleontology. J. hum. Evol. 15, 165–175.

Ten Cate, A. R. & Mills, C. (1972). The developmentof the periodontium: The origin of alveolar bone.Anat. Rec. 173, 69–78.

Tillier, A.-M. (1979). Restes craniens de l’enfantMousterian Homo 4 de Qafzeh (Israel), la mandibuleet les maxillaires. Paleorient 5, 67–85.

Tillier, A.-M. (1983). Le crane d’enfant d’Engis 2: unexemple de distribution des caracteres juveniles,primitifs et neanderthaliens. Bull. Soc. Roy. BelgeAnthrop. Prehist. 94, 51–75.

Vlcek, E. (1993). Fossile Menschenfunde vonWeimar-Ehringsdorf. Stuttgart: Konrad Theiss Verlag.

Wallis, W. D. (1917). The development of the humanchin. Anat. Rec. 12, 315.

Wolpoff, M. H. (1980). Paleoanthropology. New York:Alfred A. Knopf.

Wolpoff, M. H. (1996). Human Evolution. New York:McGraw Hill.

Wolpoff, M., Smith, F., Malez, M., Radovcic, J. &Rukavina, D. (1981). Upper Pleistocene hominidremains from Vindija Cave, Croatia, Yugoslavia. Am.J. phys. Anthrop. 54, 499–545.

Zollikofer, C. P. E., Ponce de Leon, M. S., Martin,R. D. & Stucki, P. (1995). Neanderthal computerskulls. Nature 375, 283–285.

Note added in proof: Since this manuscript went to press, we did study the Klasies River Mouth specimens. Ourpreliminary suggestions were borne out.