palmar dermatoglyphics of twins

PALMAR DERMATOGLYPHICS O F TWINS

H. H. NEWMAN Hull Zoological Laboratory, The University of Chicago

THREE PLlTES (NINE FIGURES)

CONTENTS Par t I. Iiitroductioii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A. Materials and methods . . . . . . . . . . . B. Palm patterns as a n index of general C. Preliminary statement of results . . . . . .

Par t 11. statistical differences between the de left haiids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A. Geueral stateineiit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Statistical analysis of main lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Statistical analysis of patterus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

patterns . . . . . . . . . . . . . . . . . . . -4. Maiii lilies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Coiispicuous examples of asymmetry reversal in palm patterns . . . . .

Par t IV. General discussioii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Dermatoglyphics of identical and fraternal twins compared . . . . . . B. Are palm patterns reliable criteria for the diagnosis of monozy-

gosity and dizygosity in twins? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. How closely similar in palmar characters are identical twins? . . . . . . D. A possible relation between palm patterns and manual dexterity . . .

Par t 111. Iiidividua

E. General summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

331 331 333 335

336 336 339 34.3 346 345 350 355 357 357

361 366 366 365 371

PART I. 1NT.RODT.TCTION A. MATERIAIS AND METHODS

The materials for the present study consist of the palm prints of one hundred pairs of twins that have been carefully diagnosed by methods reported in earlier papers (Newman, '28 a and b) as to t,heir zygot,ic origin. Fifty pairs of twins are diagnosed as monozygotic, o r identical; fifty as dizyg-otic, or fraternal.

331 .4MERICAN JOURN.4L OF PHYSICAL ANTHROPOLOGY, VOL. XIV, NO. 3

JULY-SEPTEKBER, 1930

332 H. H. NEWMAN

The method used in making the prints was the photopaper method, a method which has proved satisfactory on the whole. The main lines have been traced with ink, using a fine-pointed pen, and the rules for tracing lines as outlined by Cummins and others ('29) have been followed. In about 10 per cent of the prints there are regions that have not printed completely and in the tables any doubtful point is indicated by a question mark. On the whole, our prints compare favorably with those seen in most published papers. Doubtless some errors have crept into the records, but I have gone over the whole at least three times, checking the tables against the prints. The methods of formulating the patterns and main lines are those advocated by Cummins, Keith, hfidlo, Montgomery, Wilder, and Wilder ('39) in their paper entitled "Revised methods of interpreting- and formulating palmar dermatoglyphics. ' These methods need hardly be detailed here.l

The plan followed in the treatment of our materials is first to deal with the one hundred pairs of twins as a random sample of human beings. Then the fraternal twins are studied to find out the conditions of the palmar dermatoglyphics uncomplicated by monozygotic twinning. Finally, the identical twins are compared with the fraternals and the differences between them noted, especially with reference to degrees of resemblance and of asymmetry reversal, or mirror imaging.

The science of dermatoglyphics is relatively new and it takes years of experience to handle the materials accurately. The writer has had nearly three years of experience, but does not rank himself among the real experts. Nevertheless, these years of study have been rewarded, especially during the past year, by the discovery of some very remarkable laws of asymmetry and asymmetry reversal. The palm prints seem to constitute a permanent record of all the stresses and con- flicts involved in the establishment of asymmetry conditions between the right and left sides of the individual. In identical ' If the reader desires to acquaint himself with the necessary background for

understanding the details of this paper, the best preparation would be to study the paper of Cummins et al., referred to above.

PALMAR DERMATOGLYPHICS OF TWINS 333

twins certain genetic asymmetries are strongly in coiiflict with reversed asymmetries, due to twinning, and the records of the conflict seem to be all written in the palm prints. If one could only learn the language of the dermatoglyphics, he should be able to read and understand the whole story and perhaps to solve the problems of organic symmetry and asymmetry.

B. PALM PATTERNS AS AN INDEX O F GENERAL BILATERAL ASYMMETRY

Vertebrates are generally described as biZateraEZy sym- {metrical, though it is well known that no true symmetry exists between the aiitimeric halves of the body. Apart from the fact that organs of the left side are not true duplicates of those of the right side, but a t best only mirror-image duplicates, there is no complete mirror-image duplication with respect to any antimeric structure that has been carefully measured and compared. Thus the right arm or leg is never of the same size as the left arm or leg. The two sides of the face are often so decidedly different that a composite photograph made up by piecing together two right halves looks like a different person from that shown by a composite photograph made of the two left halves. The inequality of the two sides of the body is shown most obviously in the viscera. Thus the greater curvature of the stomach turns to the left; the apex of the heart turns to the left; the single aorta turns to the left; the lobes of the liver are different on the two sides. In fact, there is a very far-reaching lack of symmetry with reference to practically all internal structures.

This inequality between the organs of the two sides is more than a mere random inequality, for the asymmetry is in the same direction in a large proportion of individuals. Occa- sional individuals occur with a complete or a partial reversal of the direction of asymmetry in the disposition of the viscera. Such cases are designated as examples of situs invc~sus viscerum. Minor instances of reversals of the typical direc-

334 H. H. NEWNAN

tion of asymmetry are seen in left-handedness and in counter- clockwise crown whorl of head hair. In identical twins it commonly happens that many other inequalities between the two sides, such as differences in shapes of ears, two halves of lips, irregularities in teeth and dental arches, etc., are expressed in mirror-image fashion in the two individuals of a twin pair.

Of particular interest, for the present studies, is the fact that, correlated with mirror imaging in handedness, hair whorl, dental-arch irregularities, ear shapes, etc., are equally striking asymmetry reversals in palm patterns and main lines. A discussion of these data will constitute a main portion of the present paper.

The first part of the paper concerns itself with the analysis of a somewhat new situation, which came t o light nearly two years ago, while the writer was engaged in the study of the palm prints of one hundred pairs of twins. Little by little the impression grew that there is a consistent difference in the expression of palmar patterns and lines between the right and left hands.

Both Cummins and Keith had noted in their statistical treatment of main lines and patterns a difference of some consequence in the frequency with which certain formulae and certain patterns appear in the two hands. Some formulae and patterns appeared more commonly on left hands, others more commonly on rights. No significance has been attached to these findings by the above-mentioned authors, and, inasmuch as their data became known to me only after I had communicated my main results to Doctor Cummins and they therefore had no influence on the progress of my work, I shall not take the time in this place to review them.

Far more significant, I believe, than the statistical differences between patterns of right and left hands are the consistent differences between the right and left hands of individuals. No one has previously published any data dealing with the relation of certain pattern complexes to right and left hands in individuals, and certainly no one has examined

P A L M A R DERMATOGLYPHICS O F T W I N S 335

this situation in twins. Doctor Cnmmins writes me, however, that one of his gra-duate students is workiiig along the same lines, but not with twin material. How closely these studies may be paralleling my own I do not know. At least it may be said with justice to both parties that these studies are going on quite independently.

C. PRELIMINARY STATEMENT O F RESULTS

In order to give the reader some working idea as to the significance of the analyses of the data soon to be presented, it seems well to offer a brief outline of the main results.

In general, it may be said that left hands on the average, and in most individual cases, express their hereditary pattern and main-line characters in a more primitive form. Thus, thenar patterns, which are commoner in primitive than in more specialized races, occur much more frequently in left hands, and when in certain individuals thenar patterns occur in both hands, the pattern is more fully expressed in the left hand. This rule has extremely few exceptions and these exceptions are nearly always correlated with other types of asymmetry reversal. Again, it seems clear from Wilder’s studies of primitive races and of anthropoid apes that the ancestral, or primitive, condition of the palmar main lines is one in which all or most of the lines tend to run somewhat parallel to each other and to the main axis of the hand, and terminate along the proximal border of the palm. The most advanced or specialized condition of the main lines is one in which the lines tend to turn quickly toward the distal border of the palm, confining the whole configuration to a set of more or less transverse lines and loops near the distal border. Now, in general, left hands tend to approach more nearly the primitive condition and right hands the more specialized condition. This difference may be shown very clearly by statistical means, but it is more significant when followed up by studies of individual cases. In a large majority of my cases of twins the left hand in one or several ways shows the more primitive configuration. In the relatively few exceptions

336 EL H. NEWMAN

where the right hand shows the more primitive condition, o r the left hand the more advanced condition, there usually are other clear indications of mirror imaging, or asymmetry reversal, in various other features of the body. This much needs to be said by way of advance information and ma.y aid the reader in following the details of the paper.

PART 11. STATISTICAL DIFFERENCES BETWEEN THE DERMATOGLYPHICS O F RIGHT AND LEFT HANDS

A. GENERAL STATEMENT

As long ago as 1924, Harriet Keith, on the basis of an examination of a large number of palm prints, showed that the right hands usually possess the higher formula when the palms are unlike. Inez Steggerda (’29) finds this same relation exists in her study of the palms of negro-white crosses. The latter author has also shown that thenar and first interdigital patterns are decidedly more numerous among more primitive (negro) races and that there is a decided preponderance on left hands of this primitive pattern. With- out further review of previous literature on these points, I shall proceed with a statistical examination of the right- and left-hand distribution of, first, main lines, and secondly, patterns, in 200 twins, dealing with them merely as 200 human individuals without reference to their twin relation.

Altogether, there are nine elements in the palm complex: five patterns and four main lines. A tenth element is sometimes included, the carpal triradius or triradii. I have found this element so often not included in. my prints that it seems well to omit i t from consideration, though I have noted its occurrence in the formulae. Of the patterns all but one, the hypothenar, show pronounced asymmetry. A very careful scrutiny of the occurrence and degree of expression of this, the commonest and most conspicuous pattern on the palm, reveals no significant differences between right and left hands. Morphologically, the hypothenar region is the ‘heel’ of the palm and, on this account perhaps, it takes no part in the dichotomous divisions that give rise to the metacarpal regions

PALMAR DERMATOGLYPHICS O F T W I N S 337

of the palm and to the digits. Hence we should hardly expect mirror imaging, or asymmetry reversal, in its expression. Well-defined hypothenar patterns (including only loops, whorls, and pronounced radial arches) occur on sixty-six out of 200 left hands and on sixty-four out of 200 right hands. Essentially the same distribution is found in identical and fraternal twins : identicals, thirty-three left and thirty-one right ; fraternal, thirty-three left and thirty-three right. Single and double, radial and ulnar, high and low, hypothenar patterns occur essentially equally on right and left hands.

In contrast with this is the fact that the four other patterns all show a definite and consistent preference for one or the other hand. The first interdigital and the thenar pattern form together a complex very difficult to handle separately, except where one or the other is expressed alone, and this rarely happens. In the following analysis of asymmetry I shall deal with these two elements as one, and for brevity call it the thenar pattern.

Readers of this journal must by now have had an oppor- tunity, if they cared to do so, to familiarize themselves with the more recent methods of determining and reducing to con- cise formulae the dermatoglyphics of human palms. The methods used in this paper are those set forth in the recent paper by Cummins and others, published in this journal and already referred to in the first section of this paper. For explanation of my formulae (given in tables 2 and 3) I must refer the reader to this important paper, which is doubtless destined to serve as a standard for future work on palmar dermatoglyphics. For reference, however, it seems well to republish Cummins’ guide figure (fig. 9). Tables 2 and 3 give in full all the data capable of being shown by tabulations. They do not, however, show minor resemblances and differences in pattern minutiae, which are often most striking in identical twins.

An analysis of my data, together with a restudy of the palm prints, led me to the following conclusions with reference to the general biological significance of the palmar main lines and their asymmetry relations :

338 H. H. NEWMAN

Of the four main lines (fig. 9), ik seems clear that line A represents an independent element, expressing right- and left-handed asymmetry in its own way. Lines B, C, and D, however, constitute an interrelated symmetry system whose axis of symmetry pivots around line C and tends to turn more radialward in right hands and more ulnarward in left hands. Of all the main lines, line C is by far the most variable in its extent and mode of expression. It is the only one of the four main lines that is at all frequently absent or reduced to vestigial form. This line i s able to swing readily to right or to left and in so doing it expresses most clearly the radial or ulnar asymmetry of this triple-line system (B, C, and D). Line D rarely (never in my material) turns ulnarward, for it starts near the ulnar margin of the palm and if it turned ulnarward it would at once run off the palm. The degree of asymmetry in line D is therefore expressed by the extent to which it runs radialward before turning distally and terminat- ing between digits. It may terminate between the thumb and index finger in an extreme radial position, or it may terminate between digits 4 and 5 in an extreme ulnar position. Terminations between these extremes are very common.

Line B rarely, if ever, turns radialward and its degree of asymmetry is expressed in the extent to which it travels ulnarward before turning to the distal margin between fingers. The tendencies of lines B and D are opposite in asymmetry and therefore mirror images of each other, while line C is like the median part of a bilateral system and most definitely reflects the particular asymmetry tendency of an individual palm.

I n order to give the reader a more concrete idea of the nature of the differences in pattern expression between right and left palms, I have introduced figures 1 to 4, in which the two prints on the left represent rather extreme left-hand types of pa.ttern and the two prints on the right, equally extreme right-hand types of pattern. One may easily note how in left hands the whole pattern and most of the separate lines swing toward the ulnar side of the palm, while in right

PALMAR DERMATOGLYPHICS O F TWINS 339

hands there is a correspondingly strong swing of the pattern and most of the lines to the opposite, radial, side of the palm. Further comments on these figures will be found in the legends.

B.*STATISTICAL ANALYSIS O F MAIN LINES

Statistical asymmetry of maim line C Line C may be entirely wanting and thus fail to indicate

asymmetry. When wanting, it is represented by the symbol ‘0.’ When line C fails to turn back to the distal margin and ends abruptly, still pointing toward the proximal border, it is represented by the symbol ‘X.’ Such vestigial lines are uncertain indicators of asymmetry. When line C swings radialward, it may terminate in positions 9, 10, or 11. When it swings ulnarward, it terminates in positions 5, 6, and 7.

Remembering that there are fifty pairs of each of the two kinds of twins, or one hundred individuals belonging to each of the two categories of twins, it will be realized that actual numbers of each condition shown in the following little tables represent also percentages.

Line-C terminations in identical twins 5, 6, and 7 term. 9, 10, and 11 term. ‘0’ ‘x’

Left hands, 56 34 7 3 Right hands, 25 65 7 3

L i n e 4 terminations in fraternal twins 5, 6 , and 7 term. 9, 10, and 11 term. ‘0’ ‘X’ ?

Left hands, 48 35 7 9 1 Right hands, 24 63 7 5 1

Line-C terminations in both kinds of twins, combined ( i n percentages) 5, 6, and 7 term. 9, 10, and 11 term. ‘0’ ‘X’ ?

Left hands, 52 34.6 7 6 0.5 Right hands, 24.5 64 7 4 0.5

It will be seen that radialward terminations are nearly twice as numerous in right hands as in lefts, and that ulnarward terminations are more than twice as numerous in left hands as in right hands. Cases of absent lines (0), neutral terminations (X), and doubtful cases are about equally numerous in the two hands.

340 H. H. NEWMAN

These differences would be much more impressive were the more or less completely reversed individuals (‘left-handers’ of various sorts) omitted, for in these, as a rule, radial terminations are found in left hands and ulnar terminations in rights. Even as they stand, however, the figures indicate a very strong tendency for the pattern to swing radialward in right hands and ulnarward in lefts. This general principle holds good for lines B and D, as will be shown below.

Statistical asymmell-y of main line D

Line D may terminate in any of the following positions: 7, 8, 9, 10, 11, and 12 (fig. 9). In my material there are no cases of terminations at the most extreme radial position, 12. Decidedly ulnar terminations are those designated 7 and 8; decidedly radial terminations are those designated by 11 ; and intermediate terminations are those designated by 9 and 10. We may, accordingly, tabulate the cases in three categories : 7 and 8 ; 9 and 10 ; and 11.

Line-D terminations in identical twins

7 and 8 term. 9 and 10 term. 11 term. Left hands, 21 45 34 Right hands, 10 33 57

Line-D terminations in fraternal twins

7 and 8 term. 9 and 10 term. I1 term. Left hands, 13 51 36 Right hands, 10 29 61

Line-D terminations in both kinds of twins, combined (in percentages)

7 and 8 term. 9 and 10 term. 11 term. Left hands, 17 48 35 Right hands, 10 31 59

Again we see a great preponderance of radial terminations in right hands and of ulnar terminations in left hands. There is also a definite preponderance of 9 and 10 terminations in left hands, indicating that these terminations are not truly intermediate or neutral, but somewhat on the ulnar side of the asymmetry system.


Statistical asymmetry iiz waailz line B Line B always turns ulnarward, but may terminate in posi-

tions 9, 8, 7, 6, 5", and 5', running from the most radial to the most ulnar position.

Lzne-B terminatzons in identwal twins Termination

9 ' 8 7 6 5" 5' Ahsent '0' Left hands, 0 0 35 6 42 16 1 Right hands, 4 3 51 6 31 5 0

Line-B terminations an fyaternnl twins

Termination 9 8 7 6 5" 5' Absent '0'

Left hands, 0 0 37 11 37 15 0 Right hands, 0 1 59 3 31 6 0

Line-B termznations in both kinds of twins contbinrd (an percentages)

Termination 9 8 7 6 5" 5' Absent '0'

Left hands, 0 0 36 8.5 39.5 15.5 0.5 Right hands, 2 2 55 4.5 31 5.5 0

Here once more we see that extreme radial terminations are confined to right hands ; that moderately radial terminations (7) strongly preponderate in right hands ; that moderately ulnar terminations slightly preponderate in left hands ; and that extreme ulnar terminations (5') are about three times as numerous in left hands as in rights.

Recapitulating, then, it may be said that the three main lines B, C, and D agree in the fact that in each line the right hands tend to express the asymmetry of the system in the radial direction and the left hands iii an ulnar direction. It has been intimated in a previous section that not only is line A consistent with this general tendency, but that the interdigital patterns associated with digits 2, 3, 4, and 5 express their asymmetrical distribution in the same direction as do the lines of the B, C, D system.

Statistical asymmetry in. main line A Main line A is that line which begins in a triradius at the

base of the index finger and proceeds in a diagonal line across

342 H. H. NEWMAN

the palm toward the ulnar side of the hand, or toward the wrist. Judging by the direction of this line in the apes and certain primitive peoples, the line originally terminated well down on the wrist region and the trend of evolution has been one in which the direction of the line has become more and more transverse, culminating in a condition in which the line runs nearly straight across the palm from radial to ulnar sides. From the data now to be presented it will be seen that left hands, on the average, exhibit a more nearly per- pendicular and right hands a more nearly transverse direction of line A. With very few exceptions, the termination of line A in an individual is nearer the wrist in the left hand than in the right. Sometimes the difference is very slight, sometimes great, but the direction of asymmetry is fairly constant. The exceptions to the rule are in most instances associated with other asymmetry reversals.

The normal asymmetry of termination of main line A is frequently disturbed by the presence of hypothenar patterns, and since these patterns occur in right or left hands equally frequently and apparently without any reference to the asymmetry relations between the two hands, quite commonly the natural termination of line A is artificially thwarted. In spite of this interference with the expression of asymmetry, however, the line is an important independent indication of asymmetry relations, reinforcing the indications already shown in the B, C, D-line system.

The various positions at which line A terminates, beginning at the most distal and proceeding ulnarward and proximally down the ulnar border of the palm, are as follows: 5”, 5’, 4, h, 311, 2, and 1.

Line-A terminations im identical twzlts Termination

59, 5’ 4 a n d h 3 a n d 3 h 2 1

Left hands, 3 38 11 34 9 5 Right hands, 10 55 G 24 4 1

Line-A terminations in fraternal twma Termination

5” 5. 4 w i d h 3 and 3h 2 1

Left hands, 1 45 15 31 3 5 Right hands, 11 57 11 19 1 1


Line-A terminations in both Binds of twins (in percentages)

Termination 5” 5’ 4 and h 3 and 3 1 ~ 2 I

Left hands, 2 41.5 13 32.5 G 5 Right hands, 10.5 56 8.5 21.5 2.5 1

It will be noted that lines with the more proximal terminations, ranging from 1 to 4, are decidedly more numerous in left hands, while those with more distal terminations, 5” and 5’, are decidedly more numerous in right hands. The asymmetry between the hands is most sharply brought out by the facts that right hands show over five times as many 5” terminations as lefts, and left hands nearly four times as many 1 and 2 terminations as rights. Also, 5’ terminations are distinctly more numerous in right hands, while 4h, 3, and 3h terminations are considerably more numerous in left hands than in rights.

C. STATISTICAL ANALYSIS O F PATTERNS

The themar pattern The distribution of the thenar pattern in the two hands

exhibits perhaps more definitely than that of any other palmar element the nature of the asymmetry between the two hands and the ways in which asymmetry reversal in this pattern is associated with left-handedness and other forms of reversed asymmetry.

Inez Steggerda (’29) has shown that the hands of blacks, browns, and whites show different percentages of frequency with respect to the expression of this pattern. It occurs in 20 per cent of blacks, 18.53 per cent of browns, and in only 7.54 per cent of whites. She also showed that in each group theiiar patterns occur at least twice as frequently in left as in right hands.

I n my material the distribution was worked out separately for identical and fraternal twins, and then the two groups were combined for statistical consideration. Thus in one hundred identical twins there are twenty-three thenar patterns on left hands and only eight on right hands; in one

344 H. H. REWMAN

hundred fraternal twins there are nineteen thenar patterns on left hands and only nine on right hands ; in both kinds of twins combined (200 individuals) there are forty-two thenar patterns on left hands, as compared with only seventeen on right hands.

Arranging the data in a different form, we find that there are twenty-seven individuals in which the thenar pattern occurs on the left hand only, as compared with only two individuals in which this pattern appears on the right hand only. In fifteen individuals the thenar occurs on both hands, but when this is the case it is practically always more fully expressed on the left hand. Exceptions t o the rule are usually left-handed. These conditions, however, will be discussed more appropriately in part 111, under the head of individual asymmetries.

A s y m m e t r y in t he right- and l e f t - h a d distribu,tion of inler- digi tnls I I , I I I , and IV

The second, third, and fourth interdigital patterns are extremely variable in their expression. Rarely they occur as small but well-defined whorls ; more commonly, they occur as deltas, with an extra triradius ; still more commonly, they are represented by areas enclosed between the arms of main- line loops. C u m i n s and his c,ollaborators recognize as vestigial interdigital patterns local areas of ridge multiplica- tion and ridges whose direction is opposed to the main ridge curvatures. F o r the study of asymmetry it seems well to omit as true patterns all except whorls and deltas, though all forms of patterns are represented in the tables (tables 2 and 3) for those interested enough to scrutinize them.

I n general, it is true that the second, third, and fourth interdigital patterns constitute a system correlated closely with the system of main lines (B, C, and D ) previously discussed as a symmetry unit. Thus, left hands tend to express the interdigital pattern on the ulnar side (fourth interdigital) and right hands tend to express the pattern on the radial side (second interdigital). Hence the asymmetry of these


interdigital patterns is in the same direction as is that of the main lines. Let us examine the distribution of these patterns in the 200 twins, beginning with the second interdigital.

Distribution in right and left hands of second interdigital patterns

Identical twins Fraternal twins Left hands (well-defined), 4 4

Right hands (well-defined), 9 12 Right hands (vestigial), 3s 27

Total left hands, 35 34 Total right hands, 47 39

There is a preponderance of second interdigital patterns on right hands, eighty-six on right to sixty-nine on lefts. There are, moreover, nearly three times as many well-defined patterns on right hands as on lefts. The difference is greater in fraternal twins where there is less reversal of asymmetry.

Left hands (vestigial), 31 30

- -

Distribution in right and l e f t hands of the third interdigital pattern

Identical twins Fraternal twins Left hands, 41 4s Right hands, 69 65

There is thus a consistent preponderance of this pattern in right hands, largely owing to the fact that line C so commonly takes a short radial loop in right hands, represented in formulae by the number 9.

Distribution in riglzt and left hands of the fourth interdigital pattern

Left hands, 85 86 Right hands, 75 68

Identical twins Fraternal twins

There is a definite preponderance of this, the most ulnar pattern, in left hands, especially in fraternal twins where there is less asymmetry reversal. One gains a better idea of the preponderance of the left hand if he lists separately the well-developed and the vestigial patterns as follows :

Identical twins Frnternnl twins Well-developed patterns on left hands, 62 5s Vestigial patterns on left hands, 23 28 Well-developed patterns on right hands, 42 36 Vestigial patterns on right hands, 33 32

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346 H. H. NEWMAN

Here the preponderance of the fourth interdigital pattern on the left hand is much greater (especially in fraternal twins) and the tendency for left hands to emphasize the ulnar side of the pattern system is more sharply brought out.

PART 111. INDIVIDUAL ASYMMETRY I N LINES AND PATTERNS

In this account the one hundred pairs of twins will be dealt with as 200 individuals. The fraternal twins, being merely of sib relationship, will represent the asymmetry situation as it might be expected to exist among single individuals in general. The identical twins, however, represent but fifty zygotes, divided to form one hundred individuals, and the asymmetry situation will be found to be complicated by a considerable degree of asymmetry reversal due to twinning. The same order of treatment of patterns and main lines that was used in part 11, the statistical part, will be followed in this study of individuals.

A. MAIN LINES

Individual asymmetry in maim line C a. Fraterlzal twims. Of the one hundred individuals, forty-

three show normal asymmetry so distinct that the line is given different numbers in the two hands. I n thirty-five individuals, although the number of the line in the formula is the same in the two hands, its termination is more ulnar in left hands. There are, then, seventy-eight cases out of one hundred in which the normal asymmetry is present.

There are nine ca.ses in which the line is either absent or vestigial in one or both hands, and therefore its asymmetry cannot be judged. There are five cases in which asymmetry reversal is so marked as to be indicated by different numbers in the formulae and four cases in which the number is the same in the formulae for the two hands, but where there is actual reversal.

Finally, there are four cases in which the line has the same termination in both hands-a condition of partial asymmetry reversal.


Of the nine cases showing positive asymmetry reversal, only three are associated with reversals in handedness or hair whorl: twin 858 is slightly left-handed and shows complete reversal of main-line formulae; twin 74B is slightly left- handed and shows reversals also in lines B and D, and twin 75B has a double crown (partial reversal) and has line A equal in the two hands.

There are two cases in which reversal in line C is accompanied by reversals in two other main lines: twins 328 and 2 2 8 show reversal in lines B and D. The other four cases show 110 associated reversals.

b. Ideiztical twins. There are sixty cases in which the normal asymmetry is shown by different numbers in the formulae, fourteen cases in which the number is the same in the formulae but where there is actual normal asymmetry, a total of 74 per cent showing normal asymmetry of main line C. There are five cases that are ruled out for our purposes because of absence or vestigial character (‘0’ or ‘X’) of line C and there are nine cases in which the line is equal in the two hands-a condition of partial asymmetry reversal.

There are three cases of reversal of asymmetry great enough to be shown by different numbers and thirteen cases of real asymmetry reversal shown by same number. The cases of asymmetry reversal are as follows : Twins 23A, 13B, 2A, 37B, 7B, 49A (six cases in all) are more or less left- handed, 37B being ambidextrous. Twins 102A, 13A, 28A, 7A, 14A, 15B (six cases) show complete or partial reversal of crown whorl. In twins 18A there is distinct mirror imaging in several respects between the right hand of A and left hand of B. I n twins 70A and 97B no other reversals are noted.

Once more the percentage of definite reversals is much higher in identical twins than in fraternals and the correlation of line reversals with other bodily reversals is much more striking.

348 H. H. NEWMAN

Individual asynzmetry in main liwe D a. Frate.rna1 twins. There are thirty-eight individuals

showing normal asymmetry sufficiently great to be represented by different numbers and thirty-nine individuals in which line D is shown by the same number, but with actual normal asymmetry. In all, 77 per cent of individuals show normal asymmetry.

In 16 per cent of individuals the line termination is equal in the two hands. Of the remaining seven individuals, five show reversed asymmetry so great as to be represented by different numbers in the two hands, and two show actual reversal, though represented by the same number. The fully reversed cases will now be scrutinized :

Twin 85A is slightly left-handed and shows complete reversal of the whole formula. Twin 93A is left-handed, but with only slight indication of reversal in other main lines. Twins 39A has line B also reversed; 5A has line C also reversed and is even in line B; 5B has line A also reversed; 64A has line B also reversed; 54B has lines A and C reversed. Thus there is very little correlation with reversals in handedness or hair whorl and only a small number (7 per cent) of complete reversals in line D.

b. Identical twins. There are forty-two individuals showing sufficient normal asymmetry to have different numbers in the formulae ; and there are twenty individuals with the same number in the formula, but showing actual normal asymmetry. Thus only 62 per cent of individuals show normal asymmetry in line D. There are eleven individuals so reversed in asymmetry as to be represented by different numbers and six individuals with the same number, but actually reversed in asymmetry. The remaining twenty-one individuals have line D even in both hands, which is partial asymmetry reversal.

The cases of positive reversal are as follows: Twins 44A, 70B, 79B, 72A, 53B, 24B (six cases) are left-handed. Twins 96A, 15B, and 49A have counter-clockwise hair whorl. Twins

PALMAR DERMATOGLYPHICS 0% TWINS 349

3R, 80A, and 43B show mirror imaging between right hand of one twin and left hand of the other. The remaining cases show partial reversal in other pattern elements.

Once again the number of reversals and their correlation with other bodily reversals is much greater in identical than in fraternal twins.

Individual asymmetry i i z nzaiiz liize B There are forty-four individuals out

of one hundred in which the normal asymmetry is great enough to be represented by different numbers and thirty- eight individuals in which line B is represented by the same number, but with actual normal asymmetry. Thus 82 per cent of fraternal twins show normal asymmetry. There are two individuals with reversed asymmetry represented by different numbers and four individuals with the same number, but actual reversed asymmetry. I n addition, there are twelve individuals with line B equal in the two hands.

Those showing positive reversed asymmetry are as follows : Twin 85-4 is slightly left-handed and 92B is fully left-handed. Twins 6411, 8B, 76A, and 3 2 h show no other reversals except those of lines or patterns.

There are fifty-six individuals out of one hundred with normal asymmetry shown by different num bers and 28 per cent with the same number, but actual normal asymmetry. Thus 84 per cent show normal asymmetry. There are seven individuals with reversed asymmetry indicated by different numbers, three cases with the same number but reversed asymmetry, and six cases with the line the same in both hands.

Twins 79B, ?2A, 53B, 24B, and 448 (five cases) are left-handed. Twins 96A, 15B, and 49A have counter-clockwise hair whorl (three cases). Twins 17B and 14B show reversals in other lines.

Once again asymmetry reversals are much more frequent in identical twins and more frequently correlated with other forms of asymmetry reversal.

a. Fraternal twims.

b. Identical twins.

The positive reversals are as follows:

350 H. H. NEWMAN

Individual asymmetry im main line A a. Fraternal twins. There are forty-three out of one hun-

dred individuals with normal asymmetry represented by different numbers and twenty-five individuals with the same number, but actual normal asymmetry. In all, there are 68 per cent with normal asymmetry. There are two cases of reversed asymmetry represented by different numbers, and twelve cases represented by the same number but reversed in asymmetry, and eighteen with line A the same in both hands.

The cases of positive reversal are as follows: Twins 85A and 83B are slightly left-handed. Twin 56A has counter- clockwise hair whorl. The following twins show some other complete or partial asymmetry reversals in lines o r patterns : 54B, 57A, 5B, 50A, 8B, 85B, 83A, 59B. Twins 29B, 21B, and 46A show no other asymmetry reversals.

6. Idemtical twins. There are forty-five out of one hundred individuals with normal asymmetry represented by different numbers, thirty-three in which the line is represented by the same number but with normal asymmetry, a total of 78 per cent showing normal asymmetry. There are six individuals with reversed asymmetry shown by different numbers, and seven with real reversal though the same number, and nine with line A equal in both hands.

A survey of the positively reversed cases shows the following facts: twins 53B, 24B, 418, 49A, 37B, 6B, 97B, MA, 60B (nine cases) are wholly or partly left-handed; twins 96A, 14A, 41B (three cases) have reversed hair whorl; and 91A shows no other reversals.

Again identical twins show a much higher proportion of reversals and much greater correlation with other bodily reversals.

B. PATTERNS

Thenar patterns a. Fraternal twins. There are twelve individuals in which

the thenar pattern occurs only on left hands, two individuals


in which this pattern is found only on right hands, and seven individuals in which some expression of this pattern is found in both hands. I n five of the latter cases the pattern is better expressed in left hands; in one case it is better expressed in the right hand; and in one case it is equal in the two hands.

Thus, out of twenty-one individuals, seventeen (nearly 80 per cent) show left-handed superiority, normal asymmetry, with respect to the thenar pattern, while four (20 per cent) show complete or partial asymmetry reversal. These four cases deserve individual examination. They are as follows :

Twin 88B has thenar patterns on both hands, but better developed on the right hand. He is slightly left-handed. Twin 47A has a thenar on right hand only. There is no reversal in handedness o r hair whorl, but some reversal in the other elements of the palm pattern. Twin 36B has a thenar on the right hand only and he is strongly left-handed. Twin 20B has equal thenar vestiges on both hands and has a partially reversed crown whorl. Here three of the four reversals in the thenar pattern are correlated with reversals in handedness or hair whorl.

There are fifteen individuals showing thenar patterns in left hands only, none showing it in right hands only, and eight showing it in both hands. Of the latter, there are three cases in which the pattern is better expressed in left hands, one in which it is better expressed in the right hand, and four in which it is equal in the two hands, which condition must be considered as partial reversal. Thus there are eighteen out of twenty-three cases (a little over 78 per cent) showing normal asymmetry and five cases (about 22 per cent) showing complet,e or partial asymmetry reversal. The five cases of complete or partial asymmetry reversal are as follows :

Twin 49A has equally developed thenar rudiments on both hands. I n correlation with this partial reversal are the facts that this twin has counter-clockwise hair whorl, is somewhat left-handed, and has a complete reversal of dental arches. Twin 72B has equal thenar vestiges on both hands. He has

b . IdewticaZ twins.

352 H. H. NEWMAN

also counter-clockwise hair whorl. Twin lOOB has the thenar pattern on both hands, but better developed on the right hand. The only correlated reversals consist of distinct mirror imaging between opposite hands of the two twins. Twin 28A has equal thenar patterns in the two hands, has counter- clockwise hair whorl, and is slightly left-handed. Twin 28B (partner of the last) also has equally developed thenar patterns in the two hands, but no correlated reversals. Both theiiar patterns of A are better developed than those of B. On the whole, A shows several evidences of being the reversed, or left-hand, component of the twin pair. Thus three of the five cases of asymmetry reversal are associated with other bodily reversals.

Individual asymwz etry in expression of the second interdigital patterm

This rather rare pattern is positively expressed as true whorls or deltas in only fourteen individuals among fraternal twins and twelve among identical twins.

In fraternal twins eleven individuals (84 per cent) show right-handed (normal) superiority in this pattern and three individuals (17 per cent) show complete or partial asymmetry reversal in this pattern.

Twin 57B has counter-clockwise hair whorl, but there are no other reversals among the main lines and patterns. Twin 26A shows no correlated reversals. Twin 65A has this pattern evenly expressed in the two hands. This is correlated with the practically even balance of the rest of the pattern in the two hands, the only element showing evidence of asymmetry being line C, which shows the normal ulnar asymmetry in the left hand. The only one out of the three cases of asymmetry reversal in the second interdigital pattern of fraternal twins is definitely correlated with other forms of asymmetry reversal.

In ideBntica1 twins there are 66+ per cent of normal, or right-handed, superiority in the expression of the second interdigital pattern and 33+ per cent of complete or partial

These three deserve attention :


reversals. Considering that there are one hundred zygotes among fraternals and only fifty among identicals, there is a great increase of reversals among identicals, presumably associated with twinning.

The four cases of reversals are as follows: Twin 49A has counter-clockwise hair whorl, is partially left-handed, and shows partial reversal in the thenar pattern. Twin 53B is left-handed. I n palmar details the left hand of B is more like the right hand of A than like own right hand. Tvin 14A has counter-clockwise hair whorl, is slightly left-handed, and is reversed in main line A. The reversal in twin 55A appears not to be correlated with any other reversals. Thus, in three out of four cases of reversal in this pattern there is strong correlation with other bodily reversals.

Ifidiuidual asymmetry in the ezpression of the third interdigital pattern

This pattern occurs in about half of all individuals as a relatively small loop and occasionally as a whorl.

a Fraterlzal twins. In 31 per cent of individuals it occurs in right hands only, in 26 per cent of individuals it is present in both hands, but larger in the right. In 5 per cent it is present in the left hand only (reversed asymmetry) and in 3 per cent it occurs in both hands, but is more definite in the left hand (reversed asymmetry). In 2 per cent it is equal in the two hands and in 33 per cent it is absent in both hands.

A scrutiny of reversed cases shows that in only one case out of eight is the reversal correlated with reversed handedness or hair whorl, viz., twin 85A, who is slightly left-handed and shows complete reversal of the palm pattern. The other seven cases of reversal are all correlated more or less with associated reversals in lines of patterns.

b. Idemticat twifis. In 36 per cent this pattern is present in right hands only; in 21 per cent, though present in both hands, it is more fully expressed in right hands. I n 5 per cent it is present in the left hand only; in 2 per cent it appears in both hands, but is better developed in the left. I n 7 per cent

354 H. H. NEWMAN

it is the same in both hands and in 29 per cent it is absent in both hands.

The reversed and partially reversed cases show t,he following conditions: Twins 79B, 44A, 2A, 24B, 3iB, and 49A (six cases) are left-handed; 878, 87B, 7A, 7B (four cases) are ambidextrous; 96A, 87A, 7A, 14A (four cases) have counter-clockwise hair whorl. Note that 87A and 7B have reversal in both handedness and hair whorl. The four ambidextrous cases all fall among the 7 per cent in which the third interdigital is even in both hands ; hence there is a significant correlation in four cases between handedness and pattern. Here the high percentage of reversals and their correlation with other bodily reversals contrast with the situation in fraternal twins.

Individual asymm.etry in the expression of the fourth interdigital patterlz

a. Fraternal twins. This pattern in the form of well-defined whorls or deltas occurs in 24 per cent of the one hundred fraternal twins. In seventeen individuals (a little over 70 per cent) it occurs more definitely on the left hand, in five cases it occurs more definitely on the right hand, and in two cases it is equal in both hands. The reversed, or partially reversed, cases are as follows :

Twin 57A shows reversal also in main line D. Twin 71B is slightly left-handed in finger tapping. Twin 75B has a double crown in the head hair, which may be considered as a partial asymmetry reversal. Twin 318 is left-handed. Twin 90B has main line D also reversed, other features of the palm showing normal asymmetry. Twin 26A shows equally developed fourth interdigital patterns in both hands, but exhibits normal asymmetry in all other respects. Twin 36B is left-handed. Thus three of the seven individuals showing complete or partial asymmetry reversal in interdigital 4 are more or less left-handed, one shows partial reversal in crown whorl, two show correlated reversals in main line D, and one shows no other reversals.

PALMAR DER.MATOGLYPHICS O F TWINS 355

b. Identical twins. In eighteen out of twenty-five cases (72 per cent) the fourth interdigital is more expressed in left hands-the normal asymmetry. In six cases (24 per cent) there is definite asymmetry reversal and in one case (4 per cent) the pattern is equal in the two hands. The cases showing complete o r partial asymmetry reversal are as follows:

Twins 49A, 72A, 33A, 53B are all left-handed and show various other expressions of asymmetry in patterns and main lines. Twins 14A and 15B have counter-clockwise hair whorl. Twin 1 5 8 (partner of 15B, just referred to) has the fourth interdigital even in both hands, but exhibits normal asymmetry in every other respect. The same remarks as to the contrast between fraternal and identical twins might be made here, but the difference is less striking.

C. CONSPICUOUS EXAMPLES O F ASYMNETRY REVERSAL I N PALM PATTERNS

In our fraternal twins there are only three out of one hundred individuals in which there occur conspicuous reversals of patterns. These are as follows:

Twin 66B belongs to a pair classed as ‘slightly similar fraternals,’ in which there are no correlated reversals in handedness and hair whorl. Twin 5A belongs to the same category as the last, but there is a suggestion that she may possibly be a genetic left-hander completely trained out of her natural tendency. Twin 85A belongs to a pair classed as ‘unlike fraternals and is partially left-handed, probably a genetic left-hander partially trained out of it.

In contrast with these few cases of conspicuous reversal among fraternal twins, characterized by very poor correlation with other bodily reversals, stands the fact that among our fifty pairs of identical twins there are fourteen pairs in which one individual shows conspicuous reversal in palm pattern. Thus there are nearly five times as many such reversed individuals among identicals as among fraternals, or nearly ten times as many per zygote involved. This great excess must undoubtedly be due to something inherent in

356 H. H. NEWMAN

the twinning process. Besides the fourteen conspicuous cases of reversal in pattern there are twenty-nine additional cases in which at least one o r two elements of the palm pattern are completely reversed. Examining the conspicuous cases of reversed pattern, we find that the following are completely or partially left-handed: 80A, 43E, 79B, 728, 53B, and 24B (six cases). The following have completely o r partially reversed hair whorl: 9B, 96A, 28A, MA, and 15B (five cases). Twin 49A has completely reversed hair whorl and also is partially left-handed. Twins 3B and 18B show no correlated bodily reversals.

Thus in identical twins, twelve out of these fourteen cases (over 85 per cent) show a correlation between conspicuous reversals in palm pattern and reversals in handedness or hair whorl.

To illustrate the actual appearance of palms showing con- spicuously reversed palm patterns, I have introduced figures 5 to 8. While figures 7 and 8 are almost the poorest prints in the entire collection, they show the reversal of asymmetry in palm pattern a little more definitely than any others. Figures 5 and 6 show the prints of lef t and right palms, respectively, of twin 68A, a typical identical twin, a right- hander, showing pronounced normal asymmetry. The contrast between the patterns of the two hands is so strong as to cover up almost all genetic resemblance. The right hand has a typical right-handed expression of the pattern and the left hand an equally typical left-handed expression of the same genetic pattern. This illustrates the usual condition, though somewhat exaggerated, found in right-handed individuals.

In sharp contrast with these palms are the two palms just below (figs. 7 and 8) belonging to twin 96A, who is a pronounced left-hander. He has a typical, or possibly rather extreme, left-hand type of pattern on his right hand and a right-hand type of pattern on his left hand. Another way to get this impression is to note that the right hand of 68A (fig. 6) and the left hand of 96A (fig. 7) are mirror images of


- F

68 82 78 77

8.5 84+ 85+ 75

~~

79f

each other, and that the same relation exists between the left hand of 68A (fig. 5) and the right of 96A (fig. 8). The majority of the other fourteen cases of conspicuous reversals of pattern are of the type illustrated by 96A, but are slightly less complete in the extent of their reversals.

PART IV. GENERAL DISCUSSIOK A. DERMATOGLYPHICS O F IDENTICAL AND FRATERNAL TWINS

COMPARED

There are many ways in which the data brought out in this paper shed light on the biology of twins. Some interesting situations come to light when we compare the conditions found in identical twins with those in fraternal twins.

The following table (table 1) gives at a glance the main facts as to normal asymmetry and asymmetry reversal in the two groups of twins and shows the extent to which palm- pattern asymmetry reflects, or is an index of, general bodily asymmetry.

TABLE 1

Showing percentage of all main-line and pattern normal and revel-sed asymmetries, in identical twins ( I ) and fraternal twins ( F )

I

78 84 74 62

7 8 f 66+ 80+ 72 74+

PATTERN OR

LINE

14 6

11 7

15 15+ 11+ 20+ 12+

A B C D

Th I1

I11 IV

Average

13 10 16 17

4 f 334- 9+

24 15+

18 12 11 16

0 0

3+ .2+ 8

REVERSED ASYMMETRY

-

9 6

10 21

17+ 0 g+ 4 Y+

3 2 2 2

3 1 1 2 2

EVEN I N BOTH HANDS -

12 8

14 9

4 3 6 6 7.8

NUMBER CORRELATED WITH HAXD AND WHORL

In this table all the figures except the two columns t o the right represent percentages. In the two columns to the right (number correlated with handedness and hair-whorl reversals) the actual number of cases is given. The percentages for the latter would be in much the same proportion. Main lines are designated in the first column as A, B, C, D ; patterns as T h for the thenar complex, and I I , 111, I P for second, third, and fourth interdigitals. F and I in the second horizontal line mean fraternal and identical twins.

358 H. H. NEWMAN

It will be noted that normal asymmetry is a little over 5 per cent greater in fraternals, when all characters are aver- aged, than in identicals. This means that in identical twins there is an equivalent increase in complete and partial asymmetry reversals resulting from the twinning process. This is not in itself a very striking increase, but it is very significant when taken in connection with the fact that over 80 per cent of the reversals in identical twins are correlated with reversals in handedness or hair whorl, the chief indices used in this paper of bodily reversals of asymmetry.

This is, of course, what should be expected, inasmuch as the more obvious forms of asymmetry reversal, such as those in handedness, hair whorl, dental arches, etc., are very much more numerous in identical than in fraternal twins, and this excess is generally believed to be a consequence of the twinning process.

It should further be emphasized that in fifty pairs of fraternal twins one hundred zygotes are involved and in fifty pairs of identical twins only half this number of zygotes are involved. The chances, theref ore, of genetic reversals are only half as great in identicals as in fraternal twins, but the actual number of reversals is over 5 per cent greater.

This can hardly have any meaning other than that over half of the reversals of asymmetry, including left-handedness, counter-clockwise hair whorl, reversed dental arches, and palm-pattern reversals, are not truly genetic, but in a sense epigenetic, resulting from the process of monozygotic twinning.

An unexpectedly large number of asymmetry reversals are found in fraternal twins. There seem to be more left-handed individuals and those with reversed hair whorls, and correspondingly more reversed palm patterns, than would be expected among ordinary siblings. There are two possible explanations for this. The first possibility is that our methods of seeking out and finding unsuspected asymmetry reversals, especially in handedness, are likely to bring to light more of the genetically partial or complete left-handers than are


commonly found by investigators of this condition in the general population. I believe that there are probably many more genetic left-handers than are ordinarily detected among human beings in general. Therefore, there may actually be no higher percentage of reversed individuals among fraternal twins than among ordinary sibs. If, however, there should turn out to be a significantly higher percentage of reversed fraternal twins than sibs, a second possible explanation might be worth considering. In the cases of triplets and quadruplets, much the commonest situation is one in which dizygotic twinning, the simultaneous ovulation of two ova, is associated with the monozygotic twinning of one or both the ova. It is well known that prenatal mortality is very high among twins, and is doubtless still higher among triplets and quadruplets. If prenatal death were to occur among the latter, it could readily strike one of the two offspring from a single zygote; and there are equal chances that the reversed individual would survive. This would leave a pair of twins that are sibs, but in which one shows asymmetry reversal due to twinning. This situation could hardly fail to occur occasionally. The question remains as to whether it is likely to occur often enough to account for the apparently higher percentage of reversed fraternal twins.

Another difficulty that needs comment is the fact that not all left-handers or otherwise reversed twins show associated palm-pattern reversals. In identical twins the following show no trace of reversals in palm pattern, though showing either left-handedness or counter-clockwise hair whorl : Twin 63B has counter-clockwise hair whorl. Twin 40A has a double crown. Twin 9A has a partially reversed crown whorl. Twin 67B is partially left-handed in wrist tapping. Twin 35A has a partially reversed crown whorl. Twin 25A both have reversed hair whorl and are probably derived from a Twin 25B reversed zygote. Twin 43A both are partially left-handed (ambidextrous) and are probably Twin 43B] from a reversed zygote. Twin lOlB is left-handed. Twin 34B is slightly left-handed in finger tapping. Twin 27A both have counter-clockwise hair whorl and are probably derived Twin 27B 1 from a reversed zygote.

360 H. H. BEWMAN

Leaving out the three cases where there was doubtless a genetic reversal, in which we would not expect any necessary mirror imaging between the twins, there are seven remaining cases in which there is no palm-print reversal in those showing other reversals.

Also, it must not be forgotten that there are cases in which palm-pattern reversals are present in individuals showing no observed reversals in handedness or hair whorl. The following cases of this may be listed :

Twin 80A has line D reversed. Twin 7OA,line C reversed. Twin 55A, I1 interdigital reversed. Twin 6B, line A reversed. Twin 44B, lines D and B reversed. Twin 17B,lines D and B reversed. Twin 2B,line D reversed. Twin 41B, line A reversed. Twin 100A, thenar reversed.

Thus there are nine cases of lack of correlation between palm .patterns and other asymmetries. I n most of these listed as lacking correlation between bodily asymmetry reversals and palm patterns, the reversals are slight or incom- plete. Where reversals are complete and positive, there is nearly always a correlation between them.

The cases where a correlation does exist between palm- pattern reversal and other reversals number thirty-two, just twice the sum of those in which there is no correlation. Con- sidering that only slightly over a third of the twins with counter-clockwise hair whorl are also left-handed, and that less than a third of left-handers have also counter-clockwise hair whorl, the degree of correlation between palm reversals and other reversals is rather higher than we might expect.

In monozygotic twinning there are two opposed forces tending to neutralize each other, and especially is this true of the twin derived from the riglit half of the embryo. This individual commonly inherits a genetic basis for normal asymmetry, but, owing to the twinning process, the left-hand twin tends to retain the genetic asymmetry of the original zygote, while the right-hand twin tends to show the reverse, or mirror image, of the normal asymmetry. There is apparently a strong tendency for the reversed twin to return,


or regulate back to, the genetic asymmetry of the zygote ; and this it does more or less completely in proportion to the degree to which embryonic fixation of asymmetry has pro- ceeded before the twinning process begins. Thus sometimes there is in the reversed twin little left of the originally reversed condition and sometimes the residual reversed conditions are numerous and striking. All sorts of intermediate conditions are common.

If this situation be taken into account, it seems to me that palm patterns give us a complete record of the struggle between the forces tending toward reversed asymmetry and those tending to wipe it out. In these records we may read all degrees of success and of failure. Thus palmar dermatoglyphics of identical twins may be looked upon as a legible written story describing the interplay of genetic and epigenetic (inner environmental) forces, a correct interpretation of which may well go f a r toward solving some of our problems of symmetry and asymmetry.

B. ARE PALM PATTERNS RELIABLE CRITERIA FOX T H E DIAGXOSIS O F MONOZYGOSITP AND DIZYGOSITY I N TWINS8

In a previous paper (Newman, ’25 a) I have made the statement that, while not entirely diagnostic of zygosity in twins, the palm patterns are the most valuable single criterion for settling the diagnosis of the few cases that are in other respects difficult to diagnose.

The, statement was made in the paper above cited that “In every pair of obviously monozygotic twins the rule holds that there is a stronger cross resemblance between the hands of one twin and those of the other than between the two hands of the same individual.’’ When twins, whose diagnosis was slightly uncertain on other scores, show this relation, they were diagnosed as identical; and when this relation was not found at all, they were diagnosed as fraternal. In determining whether hands resemble one another or differ from one another, one must not rely too much on resemblance or difer- ences in formulae, for two hands with identical formulae

AXERICAN JOURNAL O F PHYSICAL ANTHILOPOLOGY, VOL. XIV, NO. 3

362 H. H. NEWMAN

may be decidedly different in general appearance and in hereditary details. Again, two hands may differ more or less strikingly in formulae, yet be obviously very similar in appearance and in genetic details. Hence in comparing hands with the idea of using palm-pattern data as a test of genetic relationship, genetic details are obviously more diagnostic.

If one wishes to go over our tables showing the formulae of identical and fraternal twins, it is very easy to convince one- self that in most of the identical twins the right hand of each is more like the right hand of the other than like either left hand. The same is true for the left hands. In about a third of the cases, however, reversal of patterns occurs in one twin and this makes the right hand of one twin more like the left hand of the other twin than like his own other hand. The rule still holds, and may be expressed rather simply in the words of H. S. Jennings: “The patterns on one hand of one twin resemble those on one hand of the other twin more than they resemble those of the other hand of the same twin. ’ ’

‘This rule never holds for any of the certain cases of fraternal twins. When, in the very few cases where the diagnosis is slightly doubtful, the rule fails to work, I believe we are justified in diagnosing such cases as fraternals. Take, for example, the last three cases of twins classed as identicals (table 2)-and these were the only ones at all doubtful-and let us try out the rule:

In twin pair 27, the formulae of the two right hands are identical in all ten items, and the two hands are quite similar in details of pattern in both palms and fingers. The two left hands are very different in their asymmetry conditions, but they are no more unlike each other than they are unlike their respective right hands. The facts that both A and B have counter-clockwise hair whorl and that B is left-handed would hardly accord with a dizygotic diagnosis. The reason for being slightly doubtful about this case is that there exists a rather pronounced difference in facial expression.


Twin pair 41 represents a case where palm-print diagnosis of xygosity would probably break down. Undoubtedly, the two hands of B are more alike than like either hand of A. Both hands of B show rather ext,reme right-hand patterns, with line C absent, and there is an asymmetry reversal of line A. The two hands of B neither resemble each other very closely nor do they resemble the hands of A, except that line A is also reversed. These girls have very unusual hair color and eye color and in general appear too much alike to be classed as dixygotic. The facts that A is definitely left- handed and shows complete reversal in dental arches decide the diagnosis in favor of monozygotic origin. The palm prints help little in this diagnosis.

Twin pair 60 is probably the only really doubtful case among the fifty pairs diagnosed as monozygotic. The crucial element in the diagnosis was the close similarity of the two left palms and the strong differences between the left palms and the respective rights. The fact that B is somewhat left- handed adds weight to a monozygotic diagnosis. There are no real genetic differences to deny this diagnosis, and therefore it stands as given.

Similarly, let us examine the three slightly doubtful cases diagnosed as dizygotic twins.

Twin pair 61, A and I3, shows no real resemblance in palm patterns. In the two left hands there is not a single cor- respondence among the six positive items in the formula. The same is true for the two right hands. Neither does the right of either resemble in a single item the left of the other. The two hands of A also differ in most elements, but are extremely similar in the rather unusual form of hypothenar pattern present in both. The two hands of B are alike in three out of the six positive elements in the formula and have a very similar appearance. These two hands of B are much more similar to each other than they are to either hand of A.

Twin pair 65 represents a case in which the formulae scarcely represent the resemblances and differences. A’s two

364 H. H. NEWMAN

hands are much more alike in many small and peculiar details than they are like either hand of B. B’s two hands are very different from each other. The left hand of B is more like the left hand of A than like her own right hand, but is less like it than is A’s own right hand.

Twin pair 75 is similar to the last case in some respects. The two hands of B are extremely similar except for slight asymmetries, while the two hands of A are neither like each other nor like those of the twin. The resemblance of the right hand of A to that of B is at best very slight. The palm patterns here and in the last case would be conclusive, even without the confirmatory evidence which we have in abundance.

I f one cares to survey the palm formula for fifty pairs of fraternal twins as given in table 3, he will find not a few cases that, on the basis of formulae alone, appear to accord with the rule for diagnosing identical twins: that “the patterns in one hand of one twin resemble those on one hand of the other twin more than they resemble those of the other hand of the same twin.” Thus twin pairs 45 and 84 have the following formulae :

Right hands Left hands No. 45 {A 9-7.9.5”.5’-5’-A“.V.O.L.D. 11.9.7.5‘-t’-A”.O.M.L.M.

B 10-9.0.6.3.-t-A“.O.O.O.Il. 11.9.7.5’-?-A”.O.M.L.O. A 9.7.5”.5’-t-A“/A‘.O.O.V.L. 11.9.7.5’-t’-A”/A‘.O.O.L.O.

9.7.5”.1-t-O/A’.O.M.O.L/M. 11.9.7.5’-t’-A”/AC.O.O.L.O. NO. 84 { In both of these cases the main-line formulae of all right

hands is 11.9.7.5’, which is much the commonest of all right- hand formulae, but the general character of the ridges, the shape of loops and patterns, and many other genetic details are different in all four of these right palms. In other words, genetic differences are more important criteria in applying the above rule than the general trend of main lines or occurrence of patterns. No two formulae could be more identical than those of the right hands of twins no. 84, yet even a casual glance at the two palm prints would bring to light a pronounced lack of resemblance in genetic detail. The appar-


ent resemblances of the right hands is presumably merely a result of the operation of the asymmetry mechanism in that, in all individuals with normal asymmetry such as these are, the right hands tend to approach the typical right-handed formula here shown in all four right hands, and the left hands tend to approach the typical left-handed formula. This brings about a sort of spurious resemblance of right hand to right hand and left hand to left, which implies no genetic relation between the two individuals.

In the case of identical twins, however, there are supposed to be 110 genetic differences among the four hands of a given pair. Hence the only differences are probably due to the asymmetry mechanism. We can thus study the operations of the asymmetry mechanism uncomplicated by genetic differences. Thus, for example, when a thenar pattern occurs in the right hand of one twin and the left of the other, this is clearly a case of asymmetry reversal. When thenar patterns occur in both hands of one twin and neither hand of the other twin, this also is not an indication of a genetic difference, but only another consequence of the asymmetry mechanism, indicating that the twin with thenar patterns was derived from the left half of the embryo, for the thenar pattern is an index of the left hand. Similarly, when both hands of one twin are more right-handed on the whole than those of the other twin, it probably means that this individual was derived from the right side of the embryo.

Since, then, the asymmetry mechanism is the main, if not the only, cause of differences in the palm patterns of identical twins, i t is quite natural that, iii twins without evidences of asymmetry reversal, the rights should more closely resemble rights and lefts resemble lefts; while in twins with asymmetry reversal, rights should resemble lefts and lefts rights- a condition known as mirror imaging.

This perhaps will serve to rationalize the rule for diagnosing identical twins and will indicate why fraternal twins do not abide by the rule except in general trends of main lines.

366 H. H. NEWMAN

C. HOW CLOSELY SIMILAR I N PALMAR CHARACTERS ARE IDENTICAL TWINS?

This question cannot be answered simply or categorically. H. H. Wilder (’04) long ago emphasized the striking resemblance that frequently exists between the palm patterns of identical twins, and I am in a position to reinforce his judgment up to a certain point. In my material it is undoubtedly true that in twins that are so much alike as to be almost indistinguishable, it frequently happens that the right palms of the two are almost identical, and similarly the left palms. In twins that are less strikingly similar physically, there is usually less striking resemblance between the palm patterns, due very largely to a complete or partial asymmetry reversal in both main lines and patterns. No doubt the lack of resemblance in general physical characters, such as features, stature, etc., is also due to the operations of the asymmetry mechanism. The general rule seems to be that the most similar twins show least signs of asymmetry reversal and correspondingly more striking similarities in palm patterns, while the less similar ‘identical’ twins show progressively more asymmetry reversal and correspondingly less similarity in palm patterns.

D. A POSSIBLE RELATION BETmEEN PALM PATTERNS AND MANUAL DEXTERITY

The following suggestions should be taken by the reader as, at present, purely tentative. It has been shown that in a great majority of cases the more right-handed type of pattern is found on the more dextrous hand, whether this be the right o r the left hand. The more advanced pattern, phylogenetically, generally goes with the more dextrous hand. I n this connection two pairs of twins are of great interest. Both individuals of both pairs are ambidextrous in the sense that there was no notable difference between the right and left hands of either twin in degree of dexterity. In twin pair 87 both twin boys were notoriously skilled in sports and equally dextrous with both hands. Both hands of both twins


have rather extreme right-handed patterns. In other words, we have here a case of twins in neither of which is there an inferior, or less dextrous, hand. There is also apparently little or no asymmetry between the two sides either in palm patterns or in dexterity. In a second case, twin pair 28, all four hands have typical left-handed patterns, all four hands having thenar patterns as well as decidedly ulnar formulae of main lines. Various dexterity tests, while not showing left- handedness in either twin, for they had been trained to be right-handed, did show a general low level of dexterity and a general ineptness of movements, which might be taken to mean that all four hands are left hands, or non-dextrous hands.

It would be interesting to study the palm patterns of people exhibiting extraordinary right-handed, left-handed, or ambidextrous dexterity, in order to find out whether to any high degree palm patterns might serve as an index of manual dexterity. This might afford a method fo r predicting the native athletic, musical, or other types of manual aptitude possessed by young children, and might influence their training along lines of promising success.

Palm patterns might also be used to determine whether ap- parent left-handedness in infants is likely to be due merely to a temporary indeterminism of behavior o r to a real bodily reversal of asymmetry. If the palm prints indicated no true reversal, such an infant should be trained to be right-handed; if true bodily reversal be written on the palm patterns, it would probably be damaging to the nervous system to run counter to this reversal by training the infant to neglect his more dextrous hand and to try to make the less dextrous hand take its place. Various disturbances of serious character, such as stammering and extreme nervousness, are said to be not infrequently associated with attempts to train native left-handers to be right-handed.

368 H. H. NEWMdN

E. GENERAL SUMMARY

1. Statistical analysis 1. Of the nine elements making up a palmar-line and pat-

tern complex, all except the hypothenar show pronounced asymmetry in their distribution between right and left hands.

2. The thenar-and-first-interdigital complex is an element in itself and expresses asymmetry in its own way, being much more common in left hands. The left hand thus expresses a more primitive condition than does the right.

3. Interdigitals 11, 111, and I V individually and collectively collaborate with the symmetry system, consisting of main lines B, C, and D, to reflect an ulnar-radial asymmetry. Pat- terns ulnar to main line C (fourth interdigitals) are much commoner in left ha.nds, and patterns radial to line C (second and third interdigitals) are much commoner in right hands. Thus right hands emphasize radial asymmetry and left hands, ulnar. 4. Main lines B, C, and D form a system pivoting, or center-

ing, about line C, and in general it may be said that individually and collectively these lines, or this system, tend to swing more strongly to the radial side in right hands and more strongly to the ulnar side in left hands.

It always swings toward the ulnar side, but terminates, in general, nearer the ulnar or proximal margin of the palm in left hands and nearer the radial or distal margin in right hands. As in the case of the thenar pattern, the left-hand tendency is phylogenetically more primitive.

6. The hypothenar pattern, the commonest and most conspicuous palm pattern, shows not the slightest evidences of asymmetrical distribution between right and left hands. This pattern belongs to the ‘heel’ of the palm and seems not to be involved in the symmetrical or asymmetrical dichotomies that characterize the more distal regions of the palm.

5. Main line A seems to be an independent element.


2. Analysis of individual asymmetry 7. The asymmetries in main lines and patterns that are

discoverable by statistical methods are found to exist in a very large proportion of individuals, normal asymmetry oc- curring in about 80 per cent of fraternal twins and in about 75 per cent o€ identical twins.

8. In fraternal twins there occur with respect to all lines and patterns about 12 per cent of reversed pattern units that are positive in character, and in addition about 8 per cent of cases in which there is no definite asymmetry. These latter cases are interpreted as instances of partial asymmetry revers a1 .

9. In identical twins there are 15 per cent of positive reversals, averaging the incidences of all pattern elements, and there are over 9 per cent of cases showing partial asymmetry rever sal.

10. Thus in identical twins, although only half as many zygotes are involved, there occur 5 per cent more cases of asymmetry reversal than in frateriials ; hence asymmetry reversal is over twice as frequent in identical twins, per zygote involved, as in fraternal twins. This excess asymmetry reversal must be inherent in the twinning process.

11. In fraternal twins there is only a relatively slight correlation between reversals in palmar patterns and those in handedness and hair whorl; whereas in identical twins this correlation is very strong and positive-nearly four times as great as in fraternal twins. Again, this excess correlation seems to be a result of the twinning process.

12. The failure of complete correlation among the various bodily elements capable of expressing asymmetry and asymmetry reversal is explained for identical twins as follows : The earlier twinning takes place, the less complete is the fixation of asymmetry in the two halves of the embryonic primordium and the greater is the tendency for the reversed individual to regulate back to the genetic asymmetry of the zygote, represented by the unreversed individual. Conversely, the later twinning takes place, the more complete is the fixa-

370 H. H. NEWMAN

tion of embryonic asymmetry and the less the tendency for the reversed individual to regulate back to the zygotic asymmetry. Regulation does not take place equally readily in all parts of any given twin individual; consequently, some individuals have regulated completely, at least so far as our data go, and others have regulated hardly at all, showing reversed asymmetry in all structures examined. There are all grades between these extremes.

13. When properly analyzed by one experienced in the interpretation of palm prints, such prints are to a high degree reliable as criteria for classifying monozygotic and dizygotic twins. This is especially true in those very rare cases that still remain doubtful after all other methods of diagnosis have proved inadequate.

14. The reason why in identical twins the patterns on one hand of one twin resemble those of one hand of the other twin more than they resemble those on the other hand of the same twin is as follows : The asymmetry mechanism tends to make right and left hands of the same individual unlike, while the genetic identity of the two individuals brings it about that, where no asymmetry reversal has occurred in one of the twins, the two right hands tend to give a right-handed expression of the common genetic pattern and the two left hands to give a left-handed expression of it. Where asymmetry reversal has occurred, the right hand of one twin will give a left-handed expression, and the left hand of the other twin will give the same left-handed expression, and we have a case of mirror-image resemblance according to which the right hand of each twin is more like the left hand of the other twin than like his own left hand.

15. In fraternal twins we have a contrasting situation. In them genetic differences between the palms of the two individuals are usually greater than are the differences between the two hands of the same individual produced by the asymmetry mechanism. Hence, when examined with respect to genetic details rather than with respect to mere trends of main lines, fraternal twins fail to comply with the rule for distinguishing identical twins just stated in section 14.


16. The degrees of resemblance between the patterns of the palms of identical twins range all the way from superficial identity to a degree of resemblance superficially no greater than that found in some fraternal twins. The differences of greatest moment are the result of the operation of asymmetry reversal accompanied by partial regulation back to the zygotic asymmetry. The conflict between these two tendencies can mess up a palm so badly that it is sometimes impossible to see much resemblance between such a palm and the other palm of the same individual or between it and either palm of the other individual. These cases with one odd palm, but good matching in the other palms, are not uncommon, and remind one of similar conditions in armadillo quadruplets.

17. A tentative theory is expressed to the effect that there is probably a rather close correlation between dextrality in pattern type and manual dexterity. A t least, left-handed individuals usually have a dextral pattern on the left hand. If this be the case, it should be possible to distinguish true left-handed individuals in early infancy by means of their palm patterns, and on this basis it could be decided whether it would be advisable to try to train them to be right-handed or let them develop their own native bent.

LITERATURE CITED

G ~ ~ M N I N S , KEITH, MIDLO, MONTGOMERY, WILDER, AND WILDER 1929 Revised methods of interpreting and formulating palmar dermatoglyphics. Am. J. Phys. Anthrop., XII.

Palmar and plantar epidermal ridge con- figurations (dermatoglyphics) in European-Americans. Am. J. Phys. Anthrop., IX.

CUMMINS, H., AND MIDLO, C. 1926

NEwMAN, H. H. 1917 The biology of twins. Univ. of Chicago Press. 1917 Heredity and organic symmetry in armadillo quadruplets.

1923 The physiology of twinning. Ibid. Biol. Bull., XXX.

-- 1928a Studies of human twins. I. Methods of diagnosing mouo-

1928 b Studies of human twins. 11. Asymmetry reversal, or

STEGGERBA, INEZ D. 1929 Palmar dermatoglyphics in negro-white crosses.

WILDER, H. H. 1916 Palm and sole studies. Biol. Bull., XXX. 1922

Chinese. Am. J. Phys. Anthrop., Tr.

zygotic twins. Biol. Bull., LV.

mirror-imaging, in identical twins.

Carnegiz Inst. Pub., no. 395.

Biol. Bull., LV.

Racial differences in palm and sole prints in Japanese and

WILDER, H. H., AND WENTWORTTI, B. 1928 Badger, New York.

TABLE 2

Palmar main lines and patterns in f i f t y pairs of identical twins

NO. LEFT R A l D S

62 A 11.9.7.5’-tt”-Lr/”.0.V.L.0 B 11.9.7.5”-t-L’.O.V.l.D

__-

98 A 11.7.7.3-t-A”.O.O.O.L B 11.7.7.3-t-AU.0.0.0.L

63 A 7 (8) .5” (6) .5”.3-t-A”.O.O.O.L B 7 (8) .5” (6) .5”.3-t-A”.O.O.O.L

40 A 9.7.5”.5’-8-A“.O.O.O.L/D B 9 (10).7.5”(6).5’-?-AU.0~O~0.L/D

3 A 9.7.5”.4-t-AU.O.M.O.L/d B 9.0.5”.4-t-AU.0.0.0.d

9 A 9.7.5”.3-t-AU.V.0.0.L B 9 (10) .0.5” (6) .3-t-A”.V.O.O.M

80 A 9.7.5”.3-?-AU.0.0.0.L B 7.5”.5”.3-?-L“/A”.O.O.O.L

67 A 9.7.5”.3-t-Au.L/V.0.O.L/V B 9.0.5”.3-t-AY.0.0.0.V

55 A 9-7.7.5“.h-t-Lr/A”.0.M.0.L/D B 9-7.7.5”.4-t-AU.O.M.O.L/D

35 A 9 (10) .9.5” (6) .5’-t-A”.L/L.O.L.M B 9 (10) .9.5” (6) .4-t-A“.L/V.O.L.D

96 A 11.9.7.5‘-t’-A“/A‘.O.M.L.M B ll(lO).7.7(6).5’-t’-A”/Ac.O.M.O.l

73 A 9.0.5”.3-t-A”.O.O.O.O B 9.0.5”.3-t-A”.O.O.O.O

102 A 9.7.5‘.2-t-L’.O.O.O.L B 7 (8) .5” (6) S.2-?-L’.O.O.O.L

25 A 7.5”.5‘.3-?-Lr.0.0.O.L B 7.5”.5’.2-?-Lr.0.0.0.L

30 A 11-7.7.7.5’-t”-T’.O.O.O.L/D B 11.0.7.5’-tt‘-L’/L”.O.O.O.d

23 A 11.9.7.5‘-t-A”.O.O.L.M B 7.5”.5”.5’-t-AU.O.O.O.L

94 A 9.7.5”.1-t‘-A“/Ac.O.O.O.L B 11.9.7.1-8-A’.O.O.L.O

68 -4 7.5”.5”.3-t-A”.O/l.O.O.L B 11.X.7.3-t-An.0/L,0.0.M

49 A 11-11.9.7.11/5’-tt’-L’/L“.V.D.W.W B 11-11.9.7.5’-5’-t’-L’/Ac.V.D.W.W

13 A 9.7.5’.3-?-A”.O.O.O.L B 9.7.5’.3-$-A”.O.O.O.L

78 A 7 (8) .5” (6) .5‘.3-8-A”.V.O.O.L B 9.7.5“.3-t-A”.O.O.O.L

57 A 11.9.7.5”-t-A”.O.O.l.O B 11.9.7.5”-t-A”.O.O.l.O

43 A 7.5“.5’.3-t-A‘.0.0.0.L B 9.7.5’.3-t-Au.0.0.O.1

38 A 9 ( 10) .X.5” ( 6) .3h-8-Lr.0.0.0.D B 7-7.5”.5“.3-?-L’.O.O.O.L/D

79 A 9 (10) .9.5” (6) .3-?-Ar.0.0.L0 B 11(10).9.7(6).3-t’-L‘.O.O.L.O

372

PIIQHT HANDS

11 (12) .9.7.5”-tt”-Lr/Lu.0.D.L.M 11.9.7.11/5”-t”-A”/L‘.O.D.L.M 11.9.7.5’-t’-AU/A ‘.O.M.L.O 11.9 (10) .7 (8) .5’-?-A’.O.M.L.O 9.7.5“.3-t-AU.O.O.O.L 9.7.5”.3-t-Au.0.0.0,L 11.9.7.5’-?-A“.O.M.L.V 11.9.7.5’-t-A”.O.M.L.V 9.0.5”.5’-t-A”.O.V.O.D 7 (8) .5” (6) .5”.5’- ?-A’.O.V.O.L 9 (10) .0.5“( 6) .5’-t-A”.O.O.O.O 9 (10) .7.6.5’-t-A”.O.O.O.O 7.5“.5“.5’-t-L”/A”.O.O.O.L 9.9.5”.5’-t-AU.0.0.L.M 11 (10) .9.7 (6) .5’-?-AU.0.0.L.M 11 (10) .9.7 (G ) .5‘-t-A”.O.O.L.M 10-7.9.6.5‘-t-Lr.0.V.L.D 9 (10)-7.9.5” (6) .5’-t-Lr.0.V.L.D 11.9.7.5’-t-A”.L/V.M.L.M 11.9.7.5‘-’S-A”.O.M.L.M 7.5”.5”.5’-t-A”.O.M.O.L 11.11 (l0).9(8).5’-t’-A’/Ac.O.M.L.M 9.0.5”.4-?-A“.O.O.O.O 9.0.5”.5‘-t-A”.O.O.O.O 9.7.5“.3h-t-LI.0.0.0.L 9 (8) .7 ( 6).5”.3h-?-Lr.0.0.0.L 9.7.5’.3-?-V/AU.0.0.0.L 9(10) .7.5”(6).3-T-V/A“.O.O.O.L 11.0.7.5’-t-L~.O.O.O.d 11.0.7.5’-t-L’.0.0.0.d 11.9.7.5’-t-A”.O.O.L.M 11.9.7.5”-t-A”.0 .O.L.M 11.9.7.1-S-AI.O.O.L.0 11.9.7.5’-t’-L’/A‘.O.O.L.O 11.9.7.5’-tt’-L’/A‘.O.O.L.O ll.X.7.5’-t-A”.0.0.0.0 11-11.9.7.11-5’-t’-Lr/L”.V.D.W.W 11-11.9.7.5”-5”-t’-AU/L“.0.D.TV.W 9.7.5”.5’-?-A“.O.O.O.L ll.X.7.5’-?-A”.O.O.O.O 9 (8) .7 (6) .5”.3-t-A”.O.O.O.L 11.9.7.3-I-A”.O.O.L.M 11.11 (10) .9 (8) .5”-t-A”.O.O.L.M 11.9.7.5”-t-A “.O . 0 . 1 .O 9.7.5”.5’-t-An.O.O.O.L/M 7(8)-7 (6) .5”(6).5”.5’-t-AU.O.O.O.L/D 11.9.7.3h- GL’.O.O.L.D 11.9.7.3h-t”-WS.0.0.L.D 11.9.7.5‘-t’-Lr.0.0.L.0 9(8).7(6).5”.5’-tt’-Lr/Lr.0.0.0.L

TABLE 2-Continued

LEFT HANDS RIGHT HANDS

B 99 A B

33 A B

53 A B

44 A B

2 A B

91 A B

100 A B

101 A B

70 A B

37 A B

34 A B

28 A B

7 A B

6 A B

97 A B

17 A B

14 A B

15 A B

69 A B

34 A B

18 A B

37 A B

41 A B

60 A B

8.6.5".5'- ?-A".V.V.O.L ll-7.X.7.5'-t-AU.O.M.O.D 9.9.5".5'-t-A".O.O.l.O 9-7.9.5'.2-t'-AU/Ae.O.M.M.D 7.5".5'.2-t-A'/A'.O.M.M.L 9-7.9.5'.11-5'-t'-A"/AC.V.D.L.D 10-7.7.5"/6.11-5'-t-AU.0.D.V.L/D 9-7.9.5".2-8-L'.O.M.L.D 11-7.7. 2-t-Lr.0.M.M.L/d 11.9.7.5'-t'-Lr/Ac.V.M.L.0 11.9. 7.5'-t'-Lr/A'.V.M.L.O 7.5".5'.3h-t-Lr.O.O.O.L 7(8).5"(6).5'.2-t'-L'/Ac.O.O.O.L 9.7.5".3-t-An.L/V.O.0.1 9.7.5".3-t-Au.L/V.O.0.1 10.7.6.4.-t-Au.O.O.O.L 9(10).7.5"(6) .3-3-AU.O.O.O.L/M 11-9.7.5'-t-L'.O.M.L.M 11-11.9.7.5'-t-Lr.0.V.L.D 10.9.6.5'-t-A".V.M.L.M 10.9.6.5'-tt'-Lr/L".V.M.L.M 9.7.5".1-tt'-O/A'.O.O.O.L 11.7.7.1-tt'-O/L".O.O.O.L 7.5".5".3-8-A".V.O.O.L 7.5".5".3-t-A".V.O.O.L 10.9.6.5'-t-A".O.M.L.M 11.9.7.5'-t-L'.O.M.L.M 11.7.7.5'-I-A".O.M.O.L 11.7.7.5'-t-AU.O/L.M.V.L/d 9(10).7.5"(6).5'-t-A".O.O.M.l/M 9 (10) .9.5"( 6) 3'-t-A".O.O.L.M 7.5'.5'.3h-t'-A"/W'.O.O.O.L 9.7.5'.3h-t'-L'/A'.O.O.M.L/M 11-7.9.7.5'-t'-A"/Ar.O.D.l.W ll-7.9.7.5'-t-V/AU.O.D.l.W 10-7.7.6.3-t-A".O.M.L.D 10-7.9.6.3-8-A".O.M.O.D 11.9.7.5'-t-A".O.O.L.O 11.7.7.5'-t-A".O.O.O.l/M 11.9.7.h-t-L".O.M.L.M 11.9.7.h-t-L'.O.M.L.M 9 (10) .7.5'( 6) .3-t-A".O.O.O.L 11.9.7.3-8-A".O.O.L.O 11.7.7.5'-t-A'.0.M.0.L/V 9.9.5".5'-t-Lr.0.?.L.0 8.6.5".5'-t-AU.0.0.O.L 9.0.5".5'-t-L'.L/L.O.O.O 7.5".5'.h-?-AU.0.0.0.L 7.5".5".3-t-Lr/A".0.0.0.L

373

11.9.7.5'-?-A".V.O.L.M ll-6.9.7.5'-t-AU.0.M.L.D 11.9.7.5'-t-A".O.M.L.M 9-7.9.5".h-t'-Lr/L".0.M.L.D 7.5".5'.4-tt'-A"/L'.O.O.M.L 9-7.9.5".11-5'-t-A.0.D.L.D 9/7.9.5'.11-3h-tt'-Lr/Ac.O.D.L.D 9-7.X.5".2-?-Ar.0.M.0.D 11 (10) .9.7 (6) .3h-t-A'.O.M.L.M 11.9.7.5"-t"-O/L'.O.M.L.O 11.9.7.5'-t'-A"/A'.O.M.L.O 9 (8) .7 (6) .5"-5".2-I-Ar.0.M.D.L 10.9.6.2- ?-A'.O.M.L.M 11.9.7.4-t-A".L/V.O.L.M 11(10).9.7(6) .3-t-A".L/V.O.L.O 11.9.7.5'-?-A".O.M.L.M 10.9.6.5'-8-A".O.O.L.M 11-7.9.7.5"-t-A".O.V.L.D 11.11.9.5" (6) -t-A".O.V.L.O 11.9.7.5'-t-A".O.M.L.V 11.9.7.5'-t-A".O.M.L.M 11.9.7.5'-t'-0/Ac.O.O.L.M 1 1.10.8.5'-tt'-O/L".O.M.L.O 7.5".5".3-?-A".V.O.O.L 7.5".5".3-t-A".V.O.O.L 11.9.7.5'-t-V.0.M.L.M 11.9.7.5'-t-L'.O.M.L.M 11.9.7.5"-8-A".O.M.L.M 11.9.7.5'-8-Au.0.M.L.M 11( 10) .9.7(6).5'-?-A".O.M.L.M 11 (10) .9.7 (6) .5'-1-Am.O.O.L.M 7.5".5'.3h-t'-A"/W*,O.O.O.L 9-7.9.5'.3-t'-A"/Lc.O.O.L.D 9/7.9.5".11-5'-t-A"/Ac.0.D.L.Il 11/7.9.7.11-5'-t'-A"/A'.O.D.L.D 10-7.9.6.3-t-A".O.M.L.D 9/7.9.5".11/3- 8-A".O.D .L.D 11.10.8.5'-I-A".O.M.L.O 11.10.8.5'-t-A"/L".O.O.L.O 11.9 (10). 7 ( 8 ) .h-?-A'.O.M.L.M 9.7.5".2-t'-O/L'.O.M.O.L 11.9.7.3-t-A".O.O.L.O 9 (10) .9.7(6) .3-t-A".O.O.L.O 11.9.7.5'-t-L'.O.M.L.O 11.9.7.5'-t-L'.O.M.L.O 9 ( 8 ) .7 (6) .5".3-t-A".O.O.O.L 10.0.6.4-?-Lr.0.0.0.O 11 ( 10) .7.9 (6) .3-t-A".O.O.L.L 8.6.5".5'-t-An.O.O.O.L

TABLE 3

Palmar main-line formulae and patterns of fifty pairs of fraternal twins

61 A B

65 A B

74 A B

57 A B

39 A B

22 A B

26 A B

71 -4 B

86 A B

95 A B

16 A B

75 A B

31 A B

89 A B

45 A B

84 A B

66 A B

5A B

10 A B

50 A B

52 A B

12 A B 8A

B 83 A B

90 A B _ _ -

9 (10) .7.5" (6) .2-tt'-Lr/Ac.O.O.O.L 11-11.7.7.5'-t-L'.O,O.O.L/D 11-6.7.5" (6) .5'-t'-Lr/L".0.0.0.L/D 10-10.X.6.3-?-AU.O.M.B.D 11.7.7.3- %A".O.O.O.L 9-6.9.5".5'-t"-L'/A".O.O.L.D 7.5".5".3h-t-L'/A".L/W.O.O.L 11 (10) .7.7 (6) .3-t-V/A".O.O.V.L 11.7.7.3-t-V/A".O.O.O.L/M 11.9.7.4-8-LU.L/L.0.L.M 11 (10) .9.7(6).1-t'-L'/Ac.V.M.L.M 11-7.9.7.11-S'-t'-A"/A'.O.d.L.d 1 1.X.7.5'-t-AU.L/L.O.V.V 7.5".5'.2-t-A".O.O.O.L 9.0.5".4-t-AY.O.O.O.M 9.7.5'.3-I-A".V.M.O.L 9.9.5'.3-t-A".L/B.O.l.O 9 (8) .7 (6) .5'.2-t-L'/A",O.O.O.L 9.7.5'.3-t-Au.O/L.0.O.L/M 11-6.9.7.5'-t-L'/AY.L/L.O.L.d 9.9.5".5'-t-L'/A".O.M.L.M. ll-11.9.7.5'-t-AU.0.d.L.D 10.9.6.5'-t-Tr.O.V.L.U 7.5".5'.4-t'-AU/Ac.0.0.0.L 7.5'.5'.3-t-A".O.O.O.L 9. 7.5".4-?-Au.0.0.0.L 9.0.5".5'-t-A".O.O.O.O 9-7.9.5".5'-t-A".V.O.L.D 10-9.0.6.3-t-AU.0.0.O.D 9. 7.5".5'-t'-A"/A'.O.O.V.L 9.7.5".1-t'-O/Ac.0.M.0.L/M 7.5".5".4-t-V/A".O.M.O.L 9-7.7.5".5'-t-Lr/A".0.M.0.L/D 9.9.5'.3-t-Au.O.O.l.M 7.5".5'.3h-t-Lr/A".O.0.O.L 11 (10) .7.C(6).4.-t-AU.0.M.0.L 1l.7.7.3h-tt"-Lc/L'.O.M.O.L 11.7.7.5'-t'-O /L".O.O.O.L 9.7.5".5'-t-Au.V/L.0.0.L/V 10.7.6.1-t'-Tr.0.M.0.L/M 8.6.5'.1-t"-O/L".O.M.O.L 11.9.7.4.-t-A".O.M.L.M 11(10).9.6.h-8-L'/A".O.O.L.M 7(8) .5"(6) .6'.3-tt"-W.O.O.O.L 11.9.7.5'-?-L'.O.O.L.O 10.9.6.5'-t-L'.O.M.L.M 9.7.5".3h-t-Lr.0.M.0.L 10.9.6.5'-?-A".O.M.L.M 9(10).9.5"(6).5'-t-AU.0.0.L.M

9.7.5".2-t"-L'.O.O.O.L 11-10.9.7 (6) .5'-t-Lr.0.V.1.D 11.9.7.5'-?-A".O.M.l.O ll-6.9.7.&?-AU.O.M.L.D 11.7.7.5'-?-A".O.O.O.L 9/7.9.5".4-t "- W/A '.O.M.L.D 7.5".5".5'/12-t-Lr/A".V.D.0.L 9 (10) .9.5" (6) 3'-t-V/A".O.M.L.M 11.9.7.5'-tt"-\V"O.O.L.O 11 (10) .9.7.5'-t-V/A".V.M.L.M 11.9.7.5'-t'-L'/A'.O.O.L.M 11-7. ?.7.5"-t-AU.0.0.?.d 11 (12) .O.7,5"-t'-A"/Ac.O.0.O.V 9.7.5".3-t-Au.0.0.0.L 9.7.5".4-t-A".O.O.O.L 9.7.5'.3- ?-A".O.M.O.L 9.9.5".3-7-Au.V/0.0.L.0 10.9.6.3h-t-L'.O.O.L.O 9.X.5'.5'-t-AU.0.0.0.M 11.9.7.11-5"-?-Lr/A".0.L).L.M 11 (10) .9.7( 6) .5'-t-Lr/A".0.D.L.D 11.9.7.5'-t-A".O.B.L.M 11-6.9.7.5'-t-Lr.0.D.L.D 9-8.7/6.5".4-t'-0/AC.O.O.O.L/D 7.5".5'.3-t-A".0 .O.O.L 11.9.7.5'-?-A".O.O. 1.0 9.0.5".5'-t-A".0.0.0.0 11.9.7.5'-t-A".O.M.L.M 11.9.7.5'- I-A".O.M.L.O 11.9.7.5'-t'-d"/Ac.O.O.L.O 11.9.7.5'-t'-A"/Ac.O.O.L.O 9-'i.X.5".5'-t-V/Au.O.M.O.L 7.5".5".5'-t-V/A".O.M.O.L 7.5".5'.3h-t-Lr/A".O.0.M.O.L 7.5".5".3-8-A'.O.O.O.L 11.9.7.5'-t-A".O.M.L.M 11.9 (10) .7 ( 8 ) .5'-t-L'.O.M.L.M l1.9.7.5'-t'-o/L".o.o.L.o 11.9.7.5'-8-A".O.O.L.V 11.7.7.5'-t'-O/L'.O.O.O.L 9.7.5".3-tt"-S.O.O.O.L 11.9.7.1148-A".O.D.L.M 11.9.7.4-8-A".O.O.L.M 7(8).5"(6).5'.3h-?-Lr.0.0.O.L 11.9.7.5'-B-Lr.0.0.L.O 7.5".5".11-5'-t-A".O.D.V.L 9.9.5".5'-8-Lr.0.M.L.M ll.9.7.5'-t-Lr.0.0.L.M 9-8.9.5".5'-t-L'.C).O.L.D

374

TdB LE S-Coiitinued

10.X.6.5’-$-Ar.0.0.V.V 9.9.5”.3-t-A“.O.O.L.O 9 (8) .7 (6) .5‘.3-t-A”.V.O.O.L 7.5”.5”.1-t’-O/L“.O.M.M.L 9. 7.5”.3-t-AU.O.M.V.l 11.7.7.5’-tt’-L’/L”.O.O.O.L 9.0.5”.5’-t-AU.0.0.0.O 11.9.7.5”-t-A“.O.O.l.V 11.7.7.5’-t-L’.O.O.O.L 11 (10) .9.7 (6) .5‘-t-AU.0.M.L.V 11/7.9.7.5’-t-A”.O.M.L.D 11.9. 7.5’-t’-V/AU.O.M.L.V 11-7.9.7.5‘-?-A”.O/L.M.L.W 7.5“.5’.5’-t’-AU/Ac.L/V.0.0.L 11.7.7.5‘-t-AU.0.0.0.L 9.7.5’.3-t-A”.O.O.O.L 7.5”.5’.3h-t-Lr.0.0.0.L 9.7.5”.5’-t-A4”.0.0.0.L/M 9.0.5”.5’-?-AU.0.0.O.M 11-7.9.7.5’-t-A”.O.M.L.D 7.5”.5’.3-t-A”.O.O.O.L ll.X.7.5’-?-L’.O.M.O.M 11.0.7.5’-t-A“.O.O.O.O 9.7.5”.4-t-A”.O.O.O.L 9(8).7(6) .5”.3-t-A”.O/L.O.O.L 9-7.0.5”.3-?-0.0.0.0.d 11 (10) .9.7 (6) .5’-t-A”.O.hI.L.M 11-6.9.7.3-t--4”.L/L.O.L.D 9-7.9/7.5“.4-t’-A“/Ac.0.O.L.L/M 11.0.7.5’-t-V/A”.O.O.O.O 9.O.5’’.5’-t-Au.L/1.O.0.O 9.7.5”.3h-t-AU.O.M.V.L/V 9.7.5’.3- B-L’.O.O.O.L/M 11.7.7.5‘- t’-A‘.O.O.O.L 9.9.5”.1-t-A”.O.O.L.O 9 (10) .9.5” (6) .4-t-A”.O.O.L.O 9.X.5”.3-4-Lr.0.O.O.0 9.9.5’.3-t-A”.O.O.L.M 9.9.5”.4-tt’-A”/L”.O/L.O.L.M 10.X.6.5’-t’-Lr/Ac.O.O.V.O 11.9.7.5’-t’-O/Ac.0.0.L.M 7.5”.5”.3- ?-A”.O.O.O.L 9.9.5’.4-t-A“.L/O.O.L.O 9 (8) .7 (6) .5”.4-t-A”.O.O.O.L 9.7.5”.4-t-A‘.0.0.D.L/V 10/7.7.6.3-t-A”.O.O.L.D 11-6.9.7.5’-t-V/A”.O.M.l.D

...

___ NO.

82 A B

83 A B

88 A B

81 A B

59 A B

58 A B

47 A B

77 A B

29 A B

21 A B

42 A B

19 A B

93 A B

11 A B

36 A B

4A B

56 A B

92 A B

76 A B

32 A B

30 A B

46 A B

54 A B

45 A B

64 A B

. .. . --_

11 ( 10 ) .9.7 ( 6) .5’-t-A”.O.O.L.O ll.X.7.5’-t-Au.0.O.V.M

I 11.9.7.5’-t-A”.O.O.L.O 9.7.5”.3-t-A”.O.O.O.L 9-7.0.5”.5‘-?-0.0.0.0.d 11.9.7.5”-t-A”.L/l.M.L.M 11.9.7.5’-t-A”.O.O.L.O 10-7.9.6.4-t-A’.O.O.L.W 11.0.7.5’-t-V/AU.0.0.O.O 9(10).0.5”(6).5’-t-A”.0.0.0.0 9.9.5 ”.5 ’-?-A”. 0.0. L. M 9.9.5’.3-?-A”.O.O.L.M 11.9.7.5’-t’-Ac.0.0.l.0 9.9.5”.1-tt’-AU/L”.O.O.I1.0 9.7.5”.4-tt”-L”.O.O.O.L 9.7.5”.3h-8-Lr.0.M.0.L 11.9 ( 8 ) .7 (6) .5’-9-A”.O.M.L.M 11.9.7.5’-B-A“.L/O.M.L.M

LEFT HANDS RIGHT H.4NDS .

11 (10) .9.7 (6) .5‘-tt’-A“/L“.O.M.L.O

__-- 10- 7.9.6.5’-t-V/A’.V/L.%.l.D 1 1.9.7.5’-t-V/A‘.0.0.1.V

P A L M A R D E R M A T O G L Y P H I C S O F T W I N S H. 1%. NEWMAA‘

P L A T E 1

Figures 1 aiicl 3 a re typical patteriis of left liaiids; figuies 2 aiicl 4, of riglit The formulae of the four palms shown are as follows:

1 7.5”.5’.5’-t’-A“/Sc.L/V.0.0.L. Note the well-developed tlicuar. 3 7 (8) .5” ( 6 ) .5’.3-tt”-W.O.O.O.L. Note primitive liypotlieiiar.

liaiids.

2 11( 12).9 (10) .7 (8).5”(6)-tt’-L’,’L’.O.D.L.M. 4 11.9 (10) .7 (8) .5’-t-L’.O.M.L.M. Reduced to tm-0-thirds natural size.

376

P.4LhlAR DERMATOGLYPHICS O F TIVINS H. H. NEWMAN

PLATE 2

Figures 5 to 8 represent t,Tpicnl p:ilm prints of idelltical ttq-iiis. Figtires 5 and 6 exhibit pronounced normal asgmiiictry 1)etwceii tlie two palliis of twill GSA, while figures 7 and 8 represent pronounced ~ c ~ e r s r d asyi~iiivtry in the 1)aIiiis of twin 9GA. The formulae f o r the two pairs of p:iliiis read : is follows:

Left hnnds lZiyI1t hnrl<l.s

G8A, 7.5”.5”.3-t-A”.O/l.O.O.L 9GA, 11.9.7.5’-t’-A”/A‘.O.M.L.M 7..5”.5”..?’-t-A“.O.M.O.L

11 .O. 7 ..?’-t t‘-L r/Ac .O.O. T,. 0

377

PALMAR DERMATOGLYPHICS OF TWIPiS H . H. NEWMAN

PLATE 3

0 A print of a riglit hand illustrating the method used by Cummins et al. in formulating main lines. A, B, C, D are tlie four main lines, start ing at their respective triradii, a, b, c, d. These lines a re formulated b y their terminations in positions 11, 9, 7, 5” (distal to the main crease), 5’ (from the crease down to 4), 4, 3, 2, and 1. When one main line joins another, its termination is in this second line, and for this purpose such terminations a re designated 12, 10, 8, and 6. When one line passes within two ridges of another, this is indicated by bracketing the number of tha t line in a f te r tlie number of the termination. For example, the formula for the palm liere shown is 11.9 (10) .7 (8) .5’/3-tt’t”- V/L”.O.O.L.O. Main line A has two alternative terminations, 5’ and 3. For further explanations, see tlie paper by Cummins and others, from wliicli this figure is taken.

378

palmar dermatoglyphics of twins

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