barkow 1999 evolutionary psychology for the social sciences

8/14/2019 Barkow 1999 Evolutionary Psychology for the Social Sciences

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Darwinian Algorithms of the Mind:

An Introduction to Evolutionary Psychology

for the Social Sciences

Timothy Ketelaar

Department of Communication Studies

University of California at Los Angeles

Los Angeles, California

hapter to appear in Barkow, J. H. (Ed.) Evolutionary Psychology as the Infrastructure of Culture and Society (EPICS), OxfordUniversity Press.

Draft Copy: 10.27.99

Draft copy, Do not cite, quote, or distribute without

permission of the author

Abstract

volutionary Psychology, defined as the application of the adaptationist programin evolutionary biology to the study of the mind,

often described as a potentially unifying "meta-theoretical" framework for the social sciences (see Barkow, Cosmides, &

ooby, 1992; ; Buss, 1995; Daly & Wilson, 1999; Ketelaar & Ellis, in press). This chapter aims to (a) provide an overview of

e core logic of the adaptationist program in evolutionary biology and (b) suggest how an appreciation of this core logic can be

eful in understanding the sorts of phenomena studied by social scientists. Specifically, it is proposed that an appreciation of the

ossible evolutionary origins of mental processes can allow one to make the inferential leap from the evolution of proteins to the

volution of more complicated phenotypes, including the complex mental processes that play a role in social, cultural, economicnd political behavior.

Darwinian Algorithms of the Mind:


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An Introduction to Evolutionary Psychology for the Social Sciences

his chapter introduces the Adaptationist perspective from evolutionary biology to the Social Sciences. The adaptationist

erspective employs the basic Darwinian idea that living things are comprised of various physicalmechanisms (e.g., eyes, hearts,

ngs, etc.) each "designed" by evolution via natural selection to solve a particular adaptive problem of survival or reproduction.

central implication of this Darwinian insight for the social sciences is Evolutionary Psychology: the idea that the mind can be

nderstood in much the same way; that is, by carving the mind at its adaptive joints in order to describe brains as assemblages of

volved "mental" adaptations (e.g., color vision, food preferences, and object recognition abilities, etc.) each designed to solve a

pecific adaptive "information processing" problem. To illustrate the potential benefits of integrating evolutionary psychology into

e social sciences, this chapter describes the basic nuts and bolts of the core logic of the adaptationist program in evolutionary

ology and (b) suggests how an appreciation of this core logic can be useful for constructing and testing models of the evolved

echanisms underlying the great variety of social, cultural, psychological, economic and political behavior that gives us our unique

uman nature.

Humans as survival machines?

n his book, The Intentional Stance, the Philosopher Daniel Dennett (1991, p. 295-296) asks you to consider a provoking,

ience-fiction inspired, thought experiment. Contemplate, if you will, facing the task of figuring out how to keep your body alive

o that you could experience life in the 25th century. Suppose, for the sake of our science fiction theme, that you were allowed

e use of a special-built hibernation device, a sort of cryogenic chamber that could keep your body alive in a state of perpetual

eep freeze until the year 2401 AD. Dennett argues that you still face an awesome challenge: How to keep this hibernationapsule protected and supplied with the necessary resources such as energy to power the refrigeration unit and food to maintain

our bodies minimum caloric requirements. The simple strategy of asking your uncle Herb to watch over the capsule and then

when he dies), to pass this task on to his children, would be dubious at best. Most human families have trouble even locating the

ames of their far, far distant ancestors, let alone keeping treasured family heirlooms like brooches and hibernation chambers in

afe hands across multiple generations separated by hundreds of years. Trusting your far, far distant descendants to protect your

urvival capsule would be too risky a proposition.

eft to your own devices, Dennett argues that you would be likely to choose one of two obvious -- in the science fiction world of

is example -- alternative strategies. The first strategy would be to find an ideal location where you would build a fixed

stallation in which to house your capsule. That is, you could scout out a location with good access to valuable resources likeater, sunlight, and whatever your installation (with capsule inside) would need to maintain itself in this apparently "ideal" place.

owever, this strategy would have its shortcomings. What if, in the far distant, unforeseeable future, someone decided to build a

eeway on-ramp right where your facility was located? Thus, a second and perhaps more sophisticated solution would be to

uild a giant robot and install the capsule (with you) in it" (Dennett, 1991, p. 296). Of course, you would probably equip your

obile robot with "the requisite sensors and early-warning devices so that it can move out of harms way and seek out new

nergy sources as it needs them" (Dennett, 1991. p. 296). If you can appreciate the distinction between these two strategies, you

an now appreciate the difference, Dennett (1991) argues, between being a plant and being an animal.

his chapter explores the view that our various mental abilities and information-processing devices have evolved to operate as

e "requisite sensors" and "early-warning devices" that serve as standard equipment for our robot-like human bodies, allowing usavoid harm and seek out benefits in our environment, so that the genes that "created" us can survive. While humans are

ertainly not robots in the mechanical sense of nuts and bolts, nor are our brains computers in the sense of silicon chips and

ectrodes, thinking of humans in terms of this robot analogy will hopefully put us in the right frame of mind to think of mental

rocesses as computational machinery that was designed to do something. This chapter argues that before social scientists can

alize the potential fruits of this evolutionary view of the mind, we need to appreciate how evolution works as a sort of blind

ngineering process capable of sculpting complexly designed life forms such as "robot-like" animals with psychological

echanisms for solving various information-processing problems. In essence, we need to appreciate how the biological process

f natural selection could enable life to arise from non-living matter, in a manner that gives rise to a vast array of simple and

omplex organisms possessing specialized mental devices and psychological machinery such as specialized cheater detection

evices, language comprehension systems, and emotions that provoke a certain level of cooperation and reciprocity in socialoups.

Evolutionary Biology as Reverse-Engineering

ocated on the Salisbury plains in the English countryside, just two miles from the small town of Amesbury-Wiltshire, lies a rock

rmation knownas Stonehenge. Although there is nothing in the laws of physics that would preclude these enormous sandstones


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om obtaining such near perfect rectangular shape, or to prevent them from balancing in such superb alignment in a circular

rangement, it seems highly improbable that this rock formation was simply created by the random and accidental effects of the

ind laws of physics operating over the millenia. That is, it appears to have certain features that you believe could not have been

rived at accidentally through random geological events such as earthquakes or the sustained effects of wind erosion. A more

ausible explanation is that this collection of stones was purposefully designed to obtain this particular arrangement. In other

ords, this structure suggests the existence of a designer, someone with a plan and the necessary tools and resources to carry it

ut.

he existence of Stonehenge is no mystery. Anyone can buy a plane ticket or surf the world wide web of the internet to

orroborate the existence of this peculiar rock formation. The more mysterious questions about Stonehenge revolve around its

rigins, not its existence. Just where did these rocks come from? Why was this formation built in the way that it was, and not

ome other way? Why is it located on the Salisbury Plains and not in the town of Amesbury itself? Just as the question of the

xistence of Stonehenge is a given, whereas the question of its origins is shrouded in mystery, so too the existence of life is seen

s a given (life does in fact exist), whereas the question of the origins of life has historically been shrouded in mystery and

ysticism. That is, it was shrouded in mystery until Darwin emerged on the scene.

y proposing that life originated from a blind (without foresight), lawful (not completely random) process of natural (rather than

tificial) selection, Darwin forever changed the intellectual landscape of biology. Darwins theory shifted the focus of attention

way from mystical and religious explanations for the origins of life and towards a scientific account. After Darwin, the question

f the origins of the species became more like detective work or forensic medicine, where the task was to "reverse engineer" the

esign characteristics that comprise the different varieties ofmodern plants and animals. Darwins theory provokes us to considerat while one can account for the characteristics of inanimate objects (stones, clouds) by simply referring to the laws of physics

nd the vagaries of history, an adequate explanation for the characteristics of animals, including the artifacts that they produce,

quires that we appreciate the nature of the biological processes that govern the origins of life. Darwin referred to these

rocesses as evolution by natural and sexual selection. Appreciating how evolution by natural and sexual selection works is

sential to any attempt to "reverse engineer" the adaptive design of complex mental devices such as language and emotions -

that comprise our human nature. Just as the origins of Stonehenge can only be discovered in retrospect, by comparing

ternative accounts derived from competing historical assumptions about the building and design of this rock formation, so too,

e origins of our uniquely human nature can be discovered only in hindsight by illuminating and testing specific assumptions about

e origins and design features of the human brain. To appreciate the utility ofthis Adaptationist strategy of reverse engineering

nd how it may help social scientists to illuminate our understanding of our evolved robot-like animal bodies and our evolvedomputer-like brains, we need to say a bit more about the engineer.

Evolution as a Blind Engineer

What does it mean to say that something is biologically "designed"? A leading proponent of the reverse engineering approach in

volutionary biology, Richard Dawkins (1986, p. 21) notes:

"We say that a living body or organ is well designed if it has attributes that an intelligent and knowledgeable engineer

might have built into it in order to achieve some sensible purpose, such as flying, swimming, seeing, eating,

reproducing, or more generally promoting the survival and replication of the organism's genes. It is not necessary to

suppose that the design of the body or organ is the best that an engineer could conceive of. Often the best that one

engineer can do is, in any case, exceeded by the best that another engineer can do, especially another who lives later

in the history of technology. But any engineer can recognize an object that has been designed, even poorly designed,

for a purpose, and he can usually work out what that purpose is just by looking at the structure of the object."

he reverse engineering approach to understanding biological design does more, however, than simply claim that the human body

the product of a design process. The reverse engineering approach actually claims to have identified the designer. This is an

mportant facet of this approach because the "argument for design," is itself, not new.

he 18th century theologian William Paley used the argument of evidence for design, more popularly referred to as the "argument

r design," to argue the existence of God, whom Paley claimed to be the conscious, omnipotent designer of the complexity ofuman nature. Paley's argument, somewhat over-simplified (see Dawkins, 1986 for a more complete treatment), went like this: If

e notice a watch lying on the ground and compare it to a nearby stone, we are immediately struck with the greater difficulty of

xplaining the existence of the watch. (Imagine NASAs Martian Explorer detecting a pocket watch on the surface of Mars, lying

ext to a stone that vaguely resembles a football). Because the watch exhibits evidence of special design, the watch impresses us,

least more so than does the stone, with evidence of construction and planning on the part of a designer, that is, as evidence for

e existence of a watch-maker. Paley then turns to a complex biological structure, the vertebrate eye, and draws the analogous


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onclusion, that if the eye displays evidence of complex design, which it surely does (insert a brief example, then reference Boyd

Silk, 1997?) then there must exist an entity who possessed the causal power and foresight necessary to render this design.

aley argued that God was the only plausible force capable of constructing complex designs such as an eye capable of seeing or

mind capable of building a watch. We now know Paley's argument to be wrong. As Dawkins (1986, p. 5) notes:

"All appearances to the contrary, the only watchmaker in nature is the blind forces of physics, albeit deployed in a

very special way."

hat "special way" that Dawkins (1986) refers to, is the process of natural selection:

"Natural selection is the blind watchmaker, blind because it does not see ahead, does not plan consequences, has nopurpose in view. Yet the living results of natural selection overwhelmingly impress us with the appearance of design as

if by a master watchmaker, impress us with the illusion of design and planning." (p.21)

we accept a basic assumption that goes along with the reverse engineering approach, namely that evolution by natural and

exual selection is the only physical process capable of explaining the origins of complex biological designs (see Cronin, 1991),

en we need to develop a basic understanding of how this evolutionary process works in order to study the "design features" of

uman minds. The underlying assumption is that understanding the basic nuts and bolts of natural selection will be as useful for

nderstanding the "design" of mental adaptations -- such as mate preference mechanisms or specialized navigation devices for

rienting oneself in a novel landscape -- as it is in understanding the "design" of physical adaptations, such as eyes. In fact, we

ill see that even this dualist terminology ("physical" vs. "mental" adaptations) is unnecessary if we can merely identify a causal

rocess capable of producing different types of physical products such as eyes and brains.

o appreciate how evolution works like a blind engineer, consider Dawkin's (1982) analogy of the "evolution" of a modern jet

ngine. Although a conscientious, prescient engineer might choose to design such an engine from scratch from a clear drawing

oard, the proper analogy to biological evolution, as Dawkins (1982, 1986) points out, would be to start with a propeller engine

nd have the engineer "evolve" a jet engine from the prop engine. To make this analogy consistent with the evolutionary process

f natural selection, a number of constraints on this engineering process would have to be put in place. First, the engineering

rocess would have to be gradual, mimicking the evolutionary process. That is, the prop engine must "evolve" into a jet engine

ne small step at time, adding a bolt here, removing a screw there, adding a metal plate here, etc. To further complicate matters,

ese small changes must occur blindly and randomly. In other words, a blind engineering process such as natural selection

annot employ foresight in gradually "evolving" the prop engine into the design of a modern jet engine. Dawkins (1982, p. 38,)

otes:

"A jet engine so assembled would be a weird contraption indeed. It is hard to imagine that an aeroplane designed in

that evolutionary way would ever get off the ground. Yet in order to complete the biological analogy we have to add

yet another constraint. Not only must the end product get off the ground: so must every intermediate along the way,

and each intermediate must be superior to its predecessor. When looked at in this light, far from expecting animals to

be perfect we may wonder that anything about them works at all." (emphasis added)

key aspect of Dawkin's analogy is the notion that each intermediate step in the evolutionary process must be superior to its

redecessor. Although Dawkin's analogy is appropriate and sophisticated in many respects, it must be modified in one respect inrder to accurately depict the evolution of an adaptive characteristic. Specifically, Dawkins' jet engine analogy nicely captures the

ualities of gradualism and random change (e.g., Blindness) which operate in natural selection, but his analogy doesn't quite

apture the essence of "phylogenetic history" in describing the intermediate steps that lead to design modifications. This

hylogenetic point can be nicely illustrated by considering several examples of the evolution of various homologous traits such as

e forelimb bones of the blue whale and the brown bear.

istorically speaking, there have existed numerous routes to success at the game of differential gene replication. The proximate

eans by which a blue whale successfully perpetuates its genes is different from the manner in which a brown bear perpetuates

s genes, yet it turns out that both species possess similar genetic designs for the bones that comprise their forelimbs. The

hysical structure of the forelimbs of a whale and a bear is similar, yet these structures function in very different ways in these two

pecies: a whale uses its forelimb bones to support flippers which assist locomotion through water, whereas a bear uses this same

ructure to support an appendage that generates movement on land. One possible explanation for the physical similarities of

ese two structures is that they are merely analogous traits, that is, they are the result of convergent evolution where the same

olution" arose independently in two different species. The focus on the evolution of analogous traits, like the convergent

volution of "eyes" in numerous species merely reflects the operation of a blind watchmaker repeatedly rediscovering a "good

ck" in the myriad of possibilities in biological design space. By contrast, a second possibility for the similarity of these two


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ructures is that they are homologous traits in which their genetic basis is actually the same, owing to a common ancester. Unlike

nalogous traits such as the eyes of birds, rabbits, and fruitflies, the existence of homologous traits such as the forelimb bones of

whale and a bear, points out that the modern form of a trait is the product of a long phylogenetic history in which the genetic

asis for that trait may have been perpetuated by very different phenotypic means in the annals of history as different species

verged from a common ancestor. Thus it should not even be surprising to observe that the current form of a mechanism may

flect not only the specific adaptive problem that the mechanism was recently "designed" to solve, but also the numerous "design

hanges" manifest over the larger phylogenetic history of that trait. In other words, the forelimb bones of the blue whale and the

rown bear serve somewhat different functions todaydespite their phylogenetic origins froma common ancestor. By focusing on

st one adaptive problem, such as "design for flight," Dawkins analogy of the evolution of a jet engine falls short of capturing the

omplexity of the phylogenetic history of an adaptive trait.

oologist Steven J. Gould (1991) provides a lucid account of this gerrymandered engineering process when he discusses a

ausible account of the evolutionary history of modern insect wings. According to Gould, insect wings most likely evolved from

roto-wings" whose primary purpose was probably not "design for flight," but rather thermoregulation (imagine an insect

ossessing a set of primitive cooling flaps). From this phylogenetic starting point, insects could have easily evolved minor

odifications to these primitive cooling flaps, giving them enhanced aerodynamic properties as well as thermoregulatorybenefits

magine these insects using their cooling flaps now as primitive glider wings). From this point onward increasingly minor

ariations in the "design" of these proto-wings (glider wings) could have eventually led to the development of full-fledged (pun

tended) wings utilized primarily for flight and only secondarily for thermoregulation.

oulds account of the evolution of insect wings -- unlike Dawkins jet engine example -- nicely illustrates that the evolution fromroto-wings to full-fledged wings through intermediate forms is not necessarily driven by the solving of a "single" adaptive

roblem, such as design for flight. In fact, there is no singular, domain-general, adaptive problem to be solved, but rather an

normous variety of more proximate adaptive challenges, the solution to any one of which would have enhanced the replication

f the genetic basis for that solution. It follows that the form of the "solution" that is "selected" by evolution, that is, the very nature

f the adaptations design features, may change over the course of time. Historical forces such as randomness, mutation,or

enetic drift may present a trait with novel adaptive challenges to be "solved," a process that can open up novel paths among the

yriad possibilities in biological design space (see Dennett, 1995). There is nothing heretical about this view of natural selection,

is an inevitable consequence of the meandrous tinkering of a Blind Watchmaker operating over vast, vast epochs of time. It

llows that the evolutionary history of a particular biological design, whether it is an insect wing or a psychological mechanism,

an reflect an evolutionary history of gerrymandered engineering designs whereby the solution to one variety of proximatedaptive challenge is co-opted into the emerging new form of the mechanism as it evolves to solve to a very different adaptive

hallenge. A cooling flap becomes a wing!

hus, a caveat to Dawkins' jet engine analogy is that it presumes (no doubt unintentionally on Dawkins' part) that the evolution

om prop engine to jet engine through intermediate forms is driven by the solving of a single adaptive problem. It follows that

awkins analogy to natural selection, the so-called "evolution" of a jet engine, need not be characterized in terms of the success

f a particular jet engine design in solving just one "adaptive" problem (i.e., the problem of flight), but in terms of the success of a

articular engine design -- relative to competing designs -- in just simply getting itself reproduced by any means; whether

uccessful reproduction is achieved by virtue of success at flight or via some other route. For example, an "artificial selection"

ccount of the evolution of a jet engine design could involve a conniving Defense contractor who saw to it that his "designodifications"were accepted over those of his competitors, simply because he could "artificially" select which design features got

produced and which did not, by virtue of a series of bribes and influence peddling operations. In this case, the most

uccessful" jet engine design is not necessarily the one that flies best, its simply the one design that has the most copies of itself

ing (or flying) around. Similarly, many consumers who witnessed the demise of BETAMAX VCRs (relative to VHS) in the

980s or currently own an IBM-clone personal computer (rather than an Apple Macintosh) know only too well that "artificial

election" does not necessarily drive on the selection of the best "designed" variants of a particular product. Rather it operates in

rms of a competition among variants in terms of their relative ability at just simply getting themselves selected (by consumers in

e case of the "evolution" of electronic appliance markets). By contrast, in the world of "natural" selection, the slight

modifications" to the underlying design of a mechanism -- brought about via genetic mutation -- can be "selected," as Dawkins

982) correctly points out, only if the modification in some way actually improves the "performance" of the mechanism. Yet, ine case of evolution by natural selection, successful "performance" is gauged in terms of differential reproductive success via any

eans, whether it is through the evolution of better solutions to the problem of flight, better solutions to the problem of

ermoregulation, or by some other means.

n sum, evolution by natural selection is a process of differential reproductive success and because there are so many different

utes to reproductive success, biological designs often undergo a number of interesting twists and turns in their phylogenetic


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story before they arrive at their current and often temporary -- on an evolutionary time scale -- state (remember Goulds

ccount of insect wings). This phylogenetic point is crucial to understanding the strategy of reverse engineering in evolutionary

sychology and yet it is a point that is too often missed by those who are too quick to criticize, or even too quick to create ,

volutionary explanations of the many facets of our psychological nature. The point here is not to argue that evolutionary change

ccurs too rapidly for adaptationists to identify what a particular trait or mechanism was actually designed to do, but rather to

mphasize the "non-optimality" of evolutionarydesigns brought about by historical/phylogenetic constraints [see Dawkins (1982),

ee also Dennett, 1995 for a lucid rebuttal to the notion of punctuated equilibrium]. Because there is no single golden road to

productive success, the evolutionary approach to human nature is not simply the study of the singular solution to a single

daptive problem. It is not even the study of differential reproductive success per se. As we shall see, the evolutionarily

nformed" study of human nature is the study of the problemof design for differential reproductive success, manifest in numerousdaptations (mechanisms) each of which solved a particular proximate adaptive challenge in the environments of history

Williams, 1966; Cosmides & Tooby, 19xx).

Debunking three common misconceptions of evolutionary theory

n one sense being inspired by Darwinian insights is conceptually no different than being inspired by a Mozart concerto, one need

ot show the logical link to ones research, one need only demonstrate the products of that inspiration. Such an approach can be

ontrasted, however, with a more rigorous strategy that explicitly identifies a set of basic meta-theoretical assumptions that one

en uses to guide the construction of explanations of particular phenomena. To claim that one has developed an evolutionarily

nformed" explanation of a particular phenomena demands that one can logically deduce this explanatory system (i.e., theory)

om a set of more basic meta-theoretical assumptions (see Ellis & Ketelaar, in press; Ketelaar & Ellis, in press for more detailed

scussion of these issues). In contrast to a merely "inspired" approach, an evolutionarily "informed" approach to the social

iences entails the construction of logically defensible accounts of phenomena that are both inductively consistent with the data

nd deductively consistent with the meta-theoretical assumptions that comprise the adaptationist programin evolutionary biology.

n order to develop an "evolutionarily-informed" account of the psychological mechanisms underlying social, cultural, economic,

nd political behavior and to appreciate why an "evolutionarily-informed approach to these topics may be more useful than an

pproach that is merely "inspired" by evolutionarily insights, it might be useful to consider three common misunderstandings of

odern evolutionary theory: 1) the idea that evolution can be characterized as a competition for the "survival" of the fittest, 2) the

ea that natural selection favors "maximizing number of offspring," and 3) the idea that evolution is "for the good of the species".

one cannot move beyond these common misconceptions, it is hard to see how a more sophisticated appreciation of thedaptationist approach in evolutionary biology can be achieved in the social sciences.

erhaps the most common misconception of the theory of evolution by natural selection has been its characterization as a

rocess of "survival of the fittest," a view first popularized in the late 1800s by Herbert Spencer (Spencer, 1864). Evolution by

atural selection can be described, metaphorically, as a sort of struggle or competition, as long as we appreciate that the

ompetitors" are not consciously striving to succeed and moreover, that they most certainly are not striving simply to "out

urvive" one another. Just as the arms race among trees vying for access to the precious resource of sunlight in the Amazonian

inforest has lead to rainforests populated with a multitude of amazingly tall trees, each one "competing" to "out reach" its

ompetitors in the battle for sunlight; so too, one might expect that if evolution by natural selection worked by simply selecting the

ery best "survivors," the world would be populated with a multitude of long-living creatures. Yet, the "battle of natural selection"not fought strictly in terms of "survival" per se and this is why instead of observing a world full of long-living creatures, the

orld is instead populated with a multitude of short-lived, but quickly reproducing, organisms (see Figure 1). Success in the

ame of life is not simply a matter of outlasting your competitors. As we shall see, survival (i.e., longevity) is only one-third of the

ame in the grand Darwinian steeplechase of life knownas natural selection.

second common misunderstanding is the notion that "reproductive success" involves maximizing the number of offspring

roduced. Although producing more offspring is generally better than producing fewer, achieving "reproductive success" in terms

f gene replication is more complicated than merely creating greater numbers of offspring than ones competitors. As

volutionary psychologists Daly and Wilson (1983, p. 24) observe, one might ask why it is the case that "nature does not always

resent the appearance of a mad scramble to reproduce. All about us we see restraint and decorum." [insert an

xampleperhaps rabbits]. Fortunately, as Daly and Wilson (1983) point out, there exists a whole literature on clutch size in

rds that nicely illuminates the evolutionary logic behind this seemingly paradoxical restraint on breeding and offspring

roduction. For example, in one avian species known as the yellow-shafted flicker, it has been found that a single female could

y seventy-one eggs (one per day) over the course of seventy-two days, if her eggs were removed from the nest by the

xperimenter as soon as they were laid. Yet, "in the wild" the female yellow-shafted flicker lays a clutch of just a half dozen eggs

ne per day) and raises them to all to fledgling status before embarking on another round of egg laying. In a series of now classic


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udies of European swifts, Ornithologist David Lack showed that offspring production is not restrained per se, so much as it is

ontext-dependent" in an environmentally-sensitive way. It turns out that many avian species regulate (not consciously, of

ourse) their clutch size to produce the number of offspring that has the best chance of surviving to fledging status under different

pes of ecological conditions. Paradoxically, often the best way to maximize your reproductive success as a bird (relative to

our competitors) is by having fewer, not more, offspring. Because raising a nestling to fledgling status involves a large

xpenditure of resources, parents with an unusually large number of nestlings to feed may lose them all during a bad year. The

volutionary logic underlying the commonly observed "restraint" in offspring production is straightforward: under ecological

onditions where resources are scarce and offspring are costly to produce, it is often more efficient to produce a few high quality

ffspring that are guaranteed to survive, rather producing a lot of offspring where only a fraction of them will survive.

or example, the European swift typically lays a clutch of just two eggs, but sometimes three or four. In a series of studies Lack

howed that individual birds could vary their clutch size as a function of food availability. During a good year with ample

sources, larger clutch sizes were produced, whereas under conditions of food deprivation (e.g., a bad year with much flooding)

maller clutch sizes were produced. More important, Lack was able to show that the more typical clutch sizes (2 or 3 eggs) were

e most successful in producing fledglings during bad years, whereas unusually large clutch sizes faired poorly under such harsh

onditions. In fact, during bad years larger clutch sizes actually produced fewer fledglings than smaller clutch sizes. Lack did find

at larger clutch sizes generally fledged more offspring during unusually good conditions (lots of food), but he found no evidence

at these birds were blindly "programmed" to maximize the number of nestlings, irregardless of their chances of surviving to

edging status. Nor did these birds appear to be programmed to "restrain" their clutch size for the good of the group" (see

elow) in order to prevent over-population. Instead, Lack found that clutch size appeared context-sensitive: greater numbers of

ffspring were produced under ecological conditions where their survival rate (to fledgling status) was higher, whereas fewer

ffspring were produced under more precarious conditions. It does not appear that organisms are simply built to blindly produce

e maximumnumber of babies possible: Survival and fecundity are both important.

inally, among the most glaringly wrong "evolutionary" assumptions utilized by social scientists is the common description of

atural selection as a process of "survival of the species." This misconception is especially problematic because it undermines the

asic assumption of genetic self-interest and nepotism inherent in the adaptationist program. These sorts of "for the good of the

oup" or "for the good of the species" explanations of animal and human characteristics can inspire misguided accounts of human

ature that unnecessarily portray people as essentially "cooperative" and genes as essentially "selfish". Yet, modern evolutionary

ology shows us that many forms of cooperation among humans and other social animals are consistent with basic principles of

genetic) self-interest. Even Axelrods (1984) fascinating account of how peace repeatedly "broke out" during trench warfare inWorld War I is predicated upon the basic evolutionary assumption that the costs incurred by putatively altruistic behavior is less

an the benefits received by the so-called altruists (see also Axelrod & Hamilton, 1981).

n order to develop a well-grounded evolutionary account of human nature that is as "informed" as it is "inspired" by evolutionary

eory, these sorts of "for the good of the group" arguments need to be replaced with a more biologically accurate view of how

volution works through differential reproduction. Although reproduction is often thought of as "perpetuation of the species" it

rns out that it is actually in service of the perpetuation of the genes" (see Dawkins, 1989, p. vv). This is the case because the

rm "species" is simply an arbitrary label given to a particular taxonomic category of living entities (see Figure 2). One might ask

hy reproductive success should be judged in terms of one particular taxonomic category (species) rather than another (say

ngdom, class, or phylum)? The primary reason that the modern theory of evolution by natural selection is about "geneplication" and not about "survival of the species" or "the good of the group" is that, strictly speaking, groups do not replicate

emselves. Dawkins (1989, p. 10) nicely illustrates the problems inherent in the "group selectionist" approach with an argument

y reductio ad absurdum:

...it is worth asking how the group-selectionist decideswhich level is the important one. If selection goes on between

groups within a species, and between species, why should it not also go on between larger groupings? Species are

grouped together into genera, genera into orders and orders into classes. Lions and antelopesare both members of

the class Mammalia, as are we. Should we then not expect lions to refrain from killing antelopes, for the good of the

mammals? Surely they should hunt birds or reptiles instead, in order to prevent the extinction of the class. But then,

what of the need to perpetuate the whole phylum of vertebrates?

ather than being about survival of the fittest, maximization of offspring number, or survival of the species, it turns out that natural

election is about success at replication. Good replicators do more than simply produce lots of long-lasting copies of themselves,

good replicator must also be capable of making high fidelity copies of itself. The reason that natural selection occurs at the level

f the genes, and not some other level like species, class, or phyla, is because these alternative levels of selection (groups,

pecies) do not make for good replicaters (see below), whereas genes possess all of the attributes of an excellent self-replicator.


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o what does a good replicator look like? And how can our appreciation of self-replicating genes aid our understanding of our

uman nature, including the evolved psychologicalmechanisms that generate the sorts of behaviors that social scientists study?

The Gene-Selectionist View:

"Reproductive" Success as "Gene Replication" Success:

...the best way to look at evolution is in terms of selection occurring at the lowest level of all...the fundamental unit of

selection, and therefore of self-interest, is not the species, nor the group, nor even, strictly, the individual. It is the

gene, the unit of heredity.

Richard Dawkins (1989, p. 11)

enes are the natural unit of natural selection because they are the only entities actually capable of producing exact copies of

emselves. Meiosis and sexual recombination virtually insure that individuals, let alone entire groups of individuals, will not be

ble to produce exact copies of themselves. After all, how many exact replicas of Socrates or Martin Luther King Jr. do you

otice walking around? Before recent advances in population genetics, including the discovery of a plausible molecular basis for

enetic replicators (e.g., DNA), Darwins theory of evolution by natural selection could provide only a vague account of the

hysical process whereby differences in phenotypic characteristics of individual organisms were selectively retained. Evolution by

atural selection has only recently (in the last half century) become a theory of the differential replication success of genes, as

pposed to say, a theory about differential success of species or individuals. So, if genes are excellent candidates for units of

atural selection because they are capable of producing good copies of themselves, what exactly does it mean to be "good at

aking copies of oneself?"

there were a Latin creed recited by the very first self-replicating molecules, it would probably have been: Longaevitas,

ecunditas, Fidelitas! (Longevity, Fecundity, Fidelity!). This is the case because entities that have the ability to make copies of

emselves that possess relatively greater longevity, fecundity, and fidelitywill, by definition, come to occupy a larger proportion

f the population of all entities (Dawkins, 1989). Biologist Richard Dawkins (1989, pp. 15-16), one of the strongest proponents

f this "gene-centered" view, describes a plausible scenario for the evolutionary origins of the very first replicators (the pre-

ursors to genes), arising in the primordial soup of unordered atoms:

Imagine a large molecule consisting of a complex chain of various sorts of building block molecules. The smallbuilding blocks were abundantly available in the soup surrounding the replicator. Now suppose that each building

block has an affinity for its own kind. Then whenever a building block from out in the soup lands next to a part of the

replicator for which it has an affinity, it will tend to stick there. The building blocks that attach themselves in this way

will automatically be arranged in a sequence that mimics that of the replicator itself. It is easy then to think of them

joining up to form a stable chain just as in the formation of the original replicator. This is how crystals are formed....A

more complex possibility is that each building block has an affinity not for its own kind, but reciprocally for one

particular kind. Then the replicator would act as a template not for an identical copy, but for a kind of negative,

which would in its turn re-make an exact copy of the original positive. For our purposes it does not matter whether

the original replication process was positive-negative or positive-positive, though it is worth remarking that the

modern equivalents of the first replicator, the DNA molecules, use positive-negative replication.

his is just one depiction of how self-replicatingmolecules could have arisen in the primordial soup of evolutionary history. There

e other versions of the origins of life of course, but they all share a focus on self-replicating entities capable of making copies

hich possess longevity, fecundity, and fidelity (see also Williams, 1966).

device that can make copies that last for a while is a better replicator than a device that makes copies that immediately vanish

to thin air. Think of a typical photocopy machine. A photocopy machine that printed with "disappearing ink" purchased at the

cal magic shop would not be as good at replicating images as a photocopier that produced images with a longer lasting ink that

ok years to fade. This capacity to produce long lasting copies can be called longevity. Longevity is important, as Williams

966, p. 23) notes, because "Permanence implies reproduction with a potential geometric increase". Yet longevity is only one

ird of the ball game. Producing copies that last a long time is not enough to insure that you will out-reproduce your competitors

ecause an alternative replication process -- think of the second generation photocopiers that were twice as fast as the first

achines -- can out-reproduce you by simply producing a greater number of copies (fecundity). Determining relative success in

e game of reproduction gets even more complicated because producing a relatively large number of copies is also not enough,

we suggested with our previous bird example (remember Lacks studies of the European swift) where the quality of the copies

attered. If a photocopy machine was capable of producing 50 copies a minute, yet half of these copies had serious printing


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rors, it might turn out that only 25 "good copies" (exact replicas) will actually survive. Thus, a good replicator, just like a good

hotocopy machine, not only produces large quantities of copies relative to its competitors (fecundity), but it also produces

opies that last for a while (longevity), and copies that are reasonable facsimiles of the original (fidelity). Life could have

riginated in this manner via a "natural selection" competition among self-replicating chemistry, molecules capable of building

opies of themselves from the building blocks of unordered atoms in the primordial soup. As Dawkins (1989, p. 18) notes,

volutionary trends toward longevity, fecundity, and fidelity could have emerged in the following sense:

if you sampled the soup at two different times, the later sample would have contained a higher proportion of varieties

with high longevity/fecundity/copying-fidelity. This is essentially what a biologist means by evolution when he is

speaking of living creatures, and the mechanism is the same--natural selection". (Dawkins, 1989, p. 18)

clear implication of this depiction of evolution by natural selection, is that it is not groups that replicate themselves, but rather

dividuals. In fact, modern evolutionary biology shows us that even this claim -- concerning individual replication -- is not true of

exually reproducing species. Strictly speaking, it is not individuals that replicate, but rather their genes. Biologist George

Williams (1966. p. 24) reinforces this view of natural selection when he points out that Socrates unique personage -- his

ndividuality" -- forever perished, along with his unique genotype, when he drank Hemlock:

The loss of Socrates genotype is not assuaged by any consideration of how prolifically he may have reproduced.

Socrates genes may be with us yet, but not his genotype, because meiosis and recombination destroy genotypes as

sure as death.....If there is an ultimate indivisible fragment it is, by definition, "the gene".

o how could natural selection for genes, simple self-replicating molecules, lead to the evolution of complex characteristics such

human eyes, hearts, and livers? Moreover, how can understanding what genes do, provide us with a better understanding of

omplex mental processes, including those mental processes that underlie human behaviors in the social, cultural, economic, and

olitical arenas of human life? To answer these questions we need to appreciate the distinction between a genotype and a

henotype. We can then begin to consider whether the psychological mechanisms underlying human behavior have the

haracteristics of evolved phenotypes.

Genotypes and Phenotypes: Genes and their effects

is tempting to believe that evolution by natural selection works by virtue of selecting differences in phenotypic characteristics --

fferences that we can actually observe such as differences in height, hunting ability, or cheater-detection -- rather than bylecting differences in things we cannot directly see, such as differences in genes. Yet, as evolutionary biologist George Williams

966, p. 23) aptly points out:

The natural selection of phenotypes cannot in itself produce cumulative change, because phenotypes are extremely

temporary manifestations. They are the result of an interaction between genotype and environment that produces

what we recognize as an individual....Socrates consisted of the genes his parents gave him, the experiences they and

his environment later provided, and a growth and development mediated by numerous meals. For all I know, he may

have been very successful in the evolutionary sense of leaving numerous offspring. His phenotype, nevertheless, was

utterly destroyed by the hemlock and has never since been duplicated. If the hemlock had not killed him, something

else soon would have. So however natural selection may have been acting on Greek phenotypes in the fourth centuryB.C., it did not of itself produce any cumulative effect.

henotypes are not good candidates for replicators because they do not last long enough (longevity) as multiple (fecundity) exact

delity) copies of themselves for natural selection to act upon them. Nonetheless, differences in phenotypes are quite important,

volutionarily speaking. Although differences in phenotypes (e.g., keener vision or greater hunting ability) cannot be directly

elected (remember Socrates), differences in the genes that give rise to particular phenotypic effects can be selected. This results

a feedback process whereby certain phenotypic characteristics can enhance the longevity, fidelity and fecundity of the genes

at produced them. Perhaps the most important phenotypic effect of genes is that they indirectly lead to the production of very

pecialmolecules knownas proteins.

roteins are strings of amino acids that are synthesized under the "instructions" of the genes. Genes themselves are comprised of

latively simple building block molecules consisting of a sugar, a phosphate and a base comprised of one of four nucleotides

e., adenine, thymine, guanine, or cytosine). The sugar molecule in these nucleic acids is deoxyribose, thus these "super

plicator" molecules are known as Deoxyribose Nucleic Acid, or more familiarly, as DNA. Each nucleic acid on a strand of

NA codes for a specific amino acid. Thus, a gene is simply a chunk of DNA, a specific sequence of nucleic acids that codes

r the production of a specific sequence of amino acids. Under the directions of a specific gene, a particular sequence of amino


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cids forms itself into a chain, a type of molecule known as a polypeptide. Proteins are simply molecules comprised of one or

ore of these polypeptide chains.

n the simplest case, a particular protein is coded for by just one gene; that is, by just one sequence of nucleic acids -- a sort of

ne gene-one protein" model of protein synthesis. But this need not always be the case. Hemoglobin, for example is a structural

rotein molecule comprised of two identical halves, each containing 2 polypeptide chains. Thus, in the case of hemoglobin, at

ast two sequences of nucleic acids (at least two genes) are responsible for the synthesis of this globular protein. Although the

ynthesis of proteins from amino acids coded for by the genes is a well-established process, the specific details of protein

ynthesis are well beyond the scope of this chapter (see Boyd & Silk, 1997; Creighton, 1984; Dawkins, 1989; Dennett, 1995;

eeten, 1976 for accessible overviews). For now it is worthwhile to note that:

There is a remarkable biochemical unity in the living world that belies the incredible diversity that we see at the

macroscopic level.All living organisms, from the smallest viruses, to unicellular organisms like bacteria and algae, to

plants, and up to the primates, use the same 20 amino acids in proteins and same bases in DNA and RNA.

(Creighton, 1984, p. 93, emphasis added).

o how then, can such a delimited set of amino acids and nucleic acid bases give rise to the vast array of simple and complex

eatures that populate the world? The first step toward understanding the link between genes, proteins, and phenotypes is to

ppreciate that although there are just 20 distinct amino acids (across all known species), there is a vast number of possible

ermutations of amino acid sequences, which leads to a similarly vast array of possible protein structures that can be formed by

e genes.

ifferent configurations of amino acids -- constructed under the "direction" of the genes can result in the construction of very

fferent protein molecules. Hemoglobin, for example, is a structural protein in humans consisting of a particular sequence of over

74 amino acid building blocks (see Creighton, 1984; also Dawkins, p. 13, see also Boyd & Silk, 1997, p. 52-58). The specific

quence of these amino acid building blocks -- coded for by specific chunks of DNA (genes) -- is quite important in

etermining the properties that these protein molecules possess. The unique structure of hemoglobin, for example, appears to

ave a special affinity for binding oxygen. As a result, hemoglobin molecules are a relatively effective means of transporting

xygen throughout the human circulatory system. A seemingly minor alteration in the genetic recipe for a hemoglobin molecule

an have significant effects. For example, the simple substitution of one amino acid (valine) for another (glutamic acid) in just one

cation in the chain of 574 amino acids that forms hemoglobin can produce a protein structure that is significantly less proficient

transporting oxygen, an often fatal condition known as Sickle cell anemia. This is not to say that every imaginable minor

teration in the sequence of amino acid building blocks that comprise Hemoglobin will necessarily lead to harmful or fatal

onsequences. In actuality there exist over 300 distinct variants of Hemoglobin, most of these differing in a single amino acid

ubstitution at one position on the polypeptide chain, and even these minor alterations -- brought about chiefly by mutation -- are

xceedingly rare and often innocuous (Creighton, 1984). This latter example underscores an important point in population

enetics, that the human species is not a collection of exact copies of one singular human phenotype, but rather a pool of similar

enes. What maintains the overall similarity in the genetic makeup in our species is the natural selective pressure of evolution

perating over vast expanses of time, a selective force that weeds out deleterious variants in proteins by weeding out the

eleterious variants in the genetic recipes that produce them.

may not be obvious at this point that the term "gene" is being used here simply as a hypothetical construct and not as a singular

hysical location on a single chromosome. Following Dawkins (1989, p. 29; see also Williams, 1966), I am using the term "gene"

ere to refer to a portion of chromosome that "potentially lasts for enough generations to serve as a unit of natural selection." In

her words, a gene is simply an assortment of nucleic acids that blindly, but reliably, codes for a specific sequence of amino

cids that in turn leads to the production of a particular protein. This specific "assortment of nucleic acids" need not occupy just

ne location on a specific chromosome, it may consist of a specific combination of nucleic acids scattered about in different

cations. Consider an analogy borrowed from a Classic Episode of a British TV seriesMonty Pythons Flying Circus. One of

y favorite sketches is a rather black comedy set during World War II: British scientists have discovered a joke that is so funny

at if you are exposed to it in its entirety, you will actually die laughing. Sensing the potential benefits of this joke for the war

ffort, the scientists embark on the task of translating the joke into German for use in trench warfare. In one scene the scientists

scover that the joke is so funny that it can be translated only one word at a time. One poor chap tries to translate two words in

row and ends up in hospital for several weeks laughing hysterically. Finally the entire joke is translated, but only after hiring a

ery large team of independent translators, each of whom specializes in just one word. Each translator is a rather mindless

utomaton who is never really aware of what it is being constructed (i.e., a series of words that form sentences that form a joke).

Moreover, these independent translators occupy different locations in physical space, they need not even all be in the same room

the same time in order to eventually produce a single working translation.


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ne might argue that genes, functioning as mindless chunks of DNA translating nucleic acids into proteins, work in a similar

shion. Operating as mindless translators each performing a delimited but reliable task, the various chunks of DNA that

omprise a single "gene" need not actually be located in the very same place in order to reliably translate a particular nucleic acid

equence into a specific chain of amino acids that in turn forms a particular polypeptide. With the help of certain molecules like

essenger RNA -- the molecular equivalent of a translators errand boy -- a particular sequence of nucleic acids scattered about

n ones chromosomes can reliably generate a potentially effective final product, one or more polypeptide chains that forms a

pecific protein. These "virtual" protein synthesizing entities are referred to as "genes" only if they are situated such that they can

urvive meiosis, crossing over, and mutation for enough generations such that they reliably produce phenotypic effects that

nhance the longevity, fidelity and fecundity of the particular assortment of DNA underlying those effects. In other words, a gene

a chunk of DNA that is maintained in the gene pool because it reliably and blindly (without foresight) continues to do what itas "designed" to do: mindlessly translate its code of nucleic acids into a strand of amino acids that forms a particular protein that

omehow enhances the replication success of its genetic basis.

Proteins as Phenotypes: How proteins bring genes "to Life"

is important to recognize this molecular basis of life. These relatively simple effects of molecular chemistry are of utmost

mportance in applying evolutionary biology to the study of complex phenotypic effects because the proteins produced by the

enes are the central phenotypic route through which genes produce copies of themselves with high longevity, fidelity, and

cundity. Genes do this by producing two main types of proteins: enzymatic and structural. We have already encountered one

xample of a structural protein: hemoglobin, a protein structure that is especially well-suited for transporting oxygen. While

ructural proteins provide much of physical fabric of the human body, enzymatic proteins operate primarily as catalysts for the

hemical reactions that govern the construction of the various bodily components such as cells, organs, and tissues.

his enzymatic function of proteins is absolutely "fundamental to life. Here is the explanation for the cold chemistry in living

ings. The vast majority of chemical reactions within organisms are catalyzed by special catalysts called enzymes, which are

globular) proteins" (Keeten, 1980, p. 70). Without the help of catalysts in the form of enzymatic proteins, the metabolic

rocesses involved in building structural proteins or creating energy by breaking down other structures (like carbohydrates)

ould be too slow to be of any practical use to an organism whose genetic blueprints call for the timely construction of an

aborate phenotype. You could, for example, isolate carbon, oxygen and hydrogen atoms by simply placing glucose molecules

a big cocktail shaker at room temperature and just waiting. After a while some of the glucose will break down into CO2 and

2O and eventually into their constituent parts: carbon, oxygen, and hydrogen. Yet, at room temperature, this process is mucho slow to be of much value in freeing up oxygen and hydrogen for other important chemical processes such as aerobic

etabolism, whereby energy is produced by breaking down carbohydrates, such as glucose (Keeton, 1980; see also Boyd &

ilk, 1997 for a nice overview).

n the experimental chemistry laboratory the threshold of activation energy necessary to produce important chemical reactions is

ften lowered by heating one of the substances until it achieves enough energy to initiate a reaction. Within our own bodies,

nzymatic proteins can achieve a similar result, effectively speeding up chemical processes without the use of a Bunsen burner.

nzymatic proteins do this primarily by coupling together various reactive agents and thereby reducing the amount of activation

nergy required for certain chemical reactions. For example, in aerobic metabolism, special energy rich compounds (ATP

olecules) are generated with the help of several enzymatic proteins. Each of these enzymes is a specially "designed" proteinructure that initiates a specific chemical reaction in a long chain of chemical reactions known as cellular respiration -- that

timately produces 34 ATP molecules (see Keeton, 1980). This energy can then be used by the organism to "fuel" subsequent

actions that build up various structures (anabolic metabolism) or extract still more energy by breaking down other structures

e., catabolic metabolism). In sum:

Proteins determine the properties of living organisms by selectively catalyzing some chemical reactions and not others,

and by forming some of the structural components of cells, organs, and tissues. Genes with different DNA sequences

lead to the synthesis of proteins with different catalytic behavior and structural characteristics. (Boyd & Silk, 1997, p.

59)

perating together, enzymatic and structural proteins create both the substance and fuel of cellular metabolism that allows the

enetic recipes in DNA to reliably unfold into the spectacular phenotypic properties that characterize each species. Black Birds

ossess wings (rather than arms) because their unique combination of genes contains the genetic recipe for constructing wings.

umans, on the other hand, possess arms (and not wings) because their unique combination of genes contains the genetic recipe

r the structural proteins that form the cellular and tissue components of arms (not wings) and the enzymatic proteins that drive

e chemical processes that form those structures and their various sub-components. Without these microscopic sequences of


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NA known as genes, we could not produce proteins, and without these structural and enzymatic building blocks the broad

nge of phenotypic properties ranging fromphysical mechanisms (arms) to psychologicalmechanisms (mechanisms of vision,

emory devices) -- that comprise our bodies would not be possible.

lthough the chemical basis of the genes that comprise the different branches of the grand tree of life -- the specific bases that

omprise the DNA of elephants, octopuses, cactuses, earthworms, bacteria, and humans is the same across all living

rganisms, the actual phenotypes produced in these various gene pools are often quite unique. This is the case because a

elimited number of bases in DNA can give rise to a vast number of possible permutations of amino acid sequences that, in turn,

ves rise to a vast number of possible enzymatic and structural proteins. Thus, different species, by virtue of being essential

fferent pools of genes, can (and often do) possess very different phenotypic structures.

hus far, genetical evolution has been characterized as a blind engineering process that results in a succession of better and better

plicator systems, each one a bit better at replication than its predecessor. At this point it is important to begin distinguishing

etween the entities that compete to out replicate one another (the replicators or genes) and the tools and devices that they

mploy in this competition (the vehicles or phenotypes). Specifically, the great variety of phenotypic properties (e.g., structural

omponents such as cells, organs, and tissues, etc.) that we observe within and across each species can be interpreted as

flecting the vast number of different survival and replication strategies that genes have evolved throughout history. In this

anner, the grand scheme of life can be depicted as a taxonomic tree, where each branch represents a different category of

olutions to the ultimate problemof gene replication as it has been historically manifested in different ecological niches. Different

henotypes exist because there is more than "one road to Rome" for genetic replication. Appreciating that proteins are

henotypic properties and understanding how genes produce proteins are the first steps toward understanding the genetic basisf life. To appreciate the possible evolutionary origins of more complex brain (mental) devices and mechanisms including

ose that might underlie various aspects of social, cultural, economic and political behavior --we need to make an inferential leap

omthe evolution of proteins to the evolution ofmore complicated phenotypes.

Note: The final portion of the manuscript is "in preparation." The following is a very rough draft of a portion of this

final section]

Making the inferential leap from Proteins to more complicated Phenotypic Properties:

Phenotypes as artifacts built by genes

rom an evolutionary perspective, the history of life began with the emergence of genetic "survival machines" in the form of

assive receptacles for genes "providing little more than walls to protect them from the chemical warfare of their rivals and the

vages of accidental molecular bombardment" (Dawkins, 1989, p. xx). From this primordial soup of protectively encased

acterium, viruses, and fungi, emerged biological survival machines in the form of "fixed installations" encapsulating genetic

aterial. These were the precursors to the biological kind known today as the plant kingdom. Another branch of the biological

orld spawned animals, the "lumbering robotic survival machines" created by genes as a way of ensuring their -- the genes --

urvival into the next generation. At this point, one might ask why replicators would evolve to expend precious energy and

sources building survivalmachines in the formof fixed locations (e.g., plants) or "lumbering robots" (e.g., animals)? The answer

that replication success is a relative commodity; it is determined relative to your competitors. This quickly leads to genetic

rms races" for better and better means of out-replicating the competition. It turns out that building survival machines is one of

any excellent strategies for successful competing in a world full of other replicators. In this view, a phenotype is just a genes

ay of making another gene. In other words, a phenotype is simply a type of survival machine produced by a gene to insure its

urvival into the next generation (Dawkins, 1982, 1989).

While it may be relatively easy to envision genetical selection influencing the types of protein that evolve (e.g., better and better

emoglobin molecules), it is not always easy to make the inferential leap from proteins to more complicated phenotypic

roperties, especially those that involve behavior. For instance, how does one explain the genetic basis of a chameleons ability to

ter its body color to cryptically blend into its environment in order to decrease its risk of predation (see Drivers & Humphreys,

988)? For this reason, it may be more useful to begin by considering a more static phenotypic property that appears to beomewhat less far removed from protein synthesis. Consider, for example, one of the most over-used examples of natural

election: the evolution of dark vs. light coloration in peppered moths (Biston betularia) in Birmingham, UK. Kettleworths

955) original studies of the relation between industrial pollution in England and the relative frequency of dark versus light

olored forms of the peppered moth have provoked a lively debate. Central to this debate are questions about the

ethodological adequacy of Kettleworths original studies, in which he claimed to demonstrate natural selection for the dark form


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uring periods of heavy industrial pollution when black soot covered the trees and made it more difficult for birds to locate and

at the dark (rather than the light) form of this moth. Critics debate whether Kettleworth actually established that cryptic

oloration per se was the best explanation for changes in the prevalence of the darker form and whether he had actually provided

valid "control" condition (the unpolluted woods near Dorset) for comparison to the polluted woods near Birmingham (see

udge, 1999; Hagen, 1999). What has not been debated, is the claim that differences in the genes for coloration (melanization)

ould be differentially selected for on the basis of their different phenotypic properties.

hat is, no one argues that it would be impossible for there to exist two variants of the genes for coloration in a species (one for

arker coloration and one for lighter coloration) and that one of these two variants could, in principle, be selected over the other

ue to its ability to enhance the longevity, fidelity and fecundity of the particular assortment of DNA underlying those effects.

ndeed, there is ample evidence for this[review one or two brief, clear examples of selection for coloration for crypsis or

dvertising toxicity]. Once you know how genes "work," it is possible to actually spell out the logic of how different types of

enes could code for different types of amino acids, which in turn could code for different enzymes or protein structures that

ould reliably produce differences in the pigmentation of the organism. This is a long inferential chain indeed, but one that has

een vindicated by history (see Williams, 1966, other references). In sum, one can use basic assumptions about genetical

volution by natural selection to construct several plausible models of how particular variants in phenotypic design could, in

rinciple, solve particular proximate problems (e.g., cryptic coloration, elaborate coloration for advertising toxins, etc.) that

ould have enhanced the fitness -- in ancestral environments -- of the genes underlying a particular phenotype.

he application of the Adaptationist program to the social sciences (evolutionary psychology in particular) has been described as

hierarchical structure consisting of multiple levels of analysis (see Figure 3). At the top of this hierarchy lies ones basic meta-eoretical assumptions. For evolutionary theorists, the meta-theoretical level consists of the general principles of genetical

volution drawn from modern evolutionary theory, as outlined by W. D. Hamilton (1964) and instantiated in more contemporary

elfish gene" theories of genetical evolution via natural and sexual selection (reviewed above, but see Cronin [1991], Dawkins

976, 1982, 1986], Dennett [1995], Mayr [1983], Tooby & Cosmides [1992], and Williams [1966, 1992] for complete

ccounts). Once a particular set of core assumptions becomes established among a community of scientists, the day-to-day

orkings of these scientists are then characterized by the use of, not the testing of, these meta-theoretical assumptions. Thus, the

eneration of several (often competing) evolutionary explanations from a single set of meta-theoretical assumptions (about

volution by natural and sexual selection) is simply a function of the multiple levels of explanation in science rather than evidence

f unfalsifiability or faulty epistemology (see Ellis & Ketelaar, in press; Ketelaar & Ellis, in press). Just as a delimited set of DNA

ases can give rise to a vast number of phenotypic outcomes, so too, a delimited set of basic assumptions about evolution byatural and sexual selection can give rise to numerous evolutionarily-plausible accounts of the very same phenomena.

rmed with these basic assumptions about natural selection and wealth of knowledge from numerous disciplines, the task of the

volutionarily-informed social scientist is to construct and test construct plausible alternative middle-level theories (see Figure 3).

middle-level theory elaborates the basic assumptions of the meta-theory into a specific domain of inquiry such as mass media

ffects on public perceptions of crime or political behavior in particular economic conditions. In this sense, the application of the

daptationist program to the social sciences involves generating and testing hypotheses about the origins and structure of the

echanisms that produce social, cultural, economic and political behavior. As such, the task of identifying the "best" evolutionary

xplanation for a particular social science phenomenon is a process of sorting through a stockpile of several "evolutionarily

ausible" explanations rather than a process of identifying the one "evolutionarily optimal" mechanism for solving a particulardaptive problem. After empirical evidence has been gathered, one of the alternatives may emerge as the "best" available

xplanation of the phenomenon of interest (see Ellis & Ketelaar, in press; Ketelaar & Ellis, in press). So what might an

volutionarily informed social science look like? Answering this question involves appreciating a central implication of the

daptationist program: Evolutionary Psychology.

The inferential leap from Phenotypes to Psychology: Minds as Phenotypes?

central assumption here is that ideas, thoughts, and mental representations are no more "in our genes" than beaver dams are in

e genes of beavers or spider webs are in the genes of spiders. Rather our elaborate capacity for ideas, thoughts, and

presentations may be an (extended) phenotypic property of the genes that construct our minds. Just as beaver genes produce

ertain structures and mechanisms that will reliably produce beaver dams in certain environments (e.g., small waterways in

ooded areas) but not in others (barren deserts), it may be that humans possess genes that produce certain brain structures and

entalmechanisms that reliably produce particular ideas, thoughts, and representations in certain environments but not in others.

the case of beavers and spiders we refer to these abilities (the capacity to build a dam or a web) as behavioral traits. In

umans we just as often refer to these types of skills as mental capacities, suggesting that these behaviors are undergirded by a

et of evolved mental or psychological mechanisms. The implications of applying an adaptationist perspective to the study of the


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rain"mechanisms that generate human behavior are enormous.

ere I plan to add a few paragraphs developing the idea of mental mechanisms as phenotypes and how this inference is

arranted fromour understanding of evolutionary by natural and sexual selection]

Implications for the Social Sciences

plan to work through one or two brief examples of why it would be useful to put in the "missing" link (i.e., evolved

sychological mechanisms) between evolutionary selection pressures and human behavior, by constructing models of the

ental/psychological processes that mediate the sorts of behaviors that social scientists study. (see Tooby & Cosmides, 1987

Missing Link paper).

n particular, Imthinking ofworking through an example ofwell-knownMassMedia effects on emotion and thinking.

want to illustrate what is missing from the current picture painted by sociologists (see Glassner, 1999) who have established a

nk between Mass Media presentations of crime and the emergence of a psychology of fear.

ll try to develop two models of the mechanisms underlying this effect:

Agenda setting processes vs.Mechanism Calibration processes

nd discuss the novel insights provided by an evolutionary perspective.

n example of the logic of an Agenda setting function Model of the Media/Press

"The press may not be successful in telling its readers what to think, but it is stunningly successful in telling its

readers what to think about" (Bernard Cohen, 1963)

n example of the logic of a mechanism calibration model of the Mass Media

"Though the beauty industry is not a conspiracy against women, it is not innocuous either. We calibrate our eye for

beauty against the people we see, including our illusory neighbors in the mass media. A daily diet of freakishlybeautiful virtual people may recalibrate the scales and make the real ones, including ourselves, look ugly".

(Pinker, 1997, p. 487)

Final Conclusions?

arwins theory of evolution by natural and sexual selection spawned the idea that life arose from the non-living, not in the sense

f Frankensteins monster, but rather in the sense of self-replicating molecules that we refer to in isolation as "genes," and in

ollections as "organisms," such as plants and animals. Darwins original theory, when coupled with recent advances in

opulation genetics and molecular biology -- such as the concept of "inclusive fitness" and the isolation of the so-called "DNA"

asis of our "genes" -- allows us to fashion a sensible explanation of how complexity could have arisen from simplicity, how

nordered atoms could have formed themselves into stable structures, and ultimately, how "life" could have arisen eons ago from

on-living" stuff and formed itself into the vast array of simple and complex creatures that populate our modern world (see

awkins, 1976, 1982, 1986; Dennett, 1995).

ecognizing the implications of Darwins theory, we may come to see that the fact that humans are historically more closely

lated to some forms of living matter (e.g., the biological kingdomanimalia) than to other forms of life such as plants or fungus,

as enormous significance for our understanding of human behavior. There are important biological reasons for human beings to

e especially concerned about their interactions with animals as opposed to other forms of life, such as plants and fungus.

nimals have minds, plants and fungi dont, and this distinction has important implications for understanding our evolutionary

ndowment of adapted devices and mechanisms. It would appear that many of our adapted characteristics are psychologicalechanisms that have been especially designed for social living among other animals (especially other humans). Using Darwinian

sights into the nature of these adaptations -- a view known as the Adaptationist Program in Evolutionary Biology this

hapter suggests that these insights will be especially illuminating in our attempts to understand the nature of "mental" devices and

echanisms that underlie the great variety of social, cultural, economic and political behavior that comprises our human nature.

barkow 1999 evolutionary psychology for the social sciences

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