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The Human Nature Review 2002 Volume 2: 70-76 ( 7 February )
URL of this document http://human-nature.com/nibbs/02/jones.html
The End of the Beginning
by Daniel Jones*
Revolutionary Biology: The New, Gene-Centred View of Life
By David P. Barash
213pp, Transaction Publishers (2001)
The Triumph of Sociobiology
By John Alcock
257pp, Oxford University Press (2001)
Academic debates rarely attract as much media attention as do those surrounding human nature and behaviour, and much ink has been spilled in documenting the various arguments and counter-arguments that pervade evolutionary approaches to understanding what it is to be human. The scientists and philosophers involved in these ongoing standoffs have themselves not been shy in airing their views in the popular press, perhaps most notably exemplified by the heated exchanges between Harvard biologist Stephen Jay Gould, who has maintained a consistent resistance to sociobiology and evolutionary psychology, and his detractors philosopher Daniel C Dennett and cognitive psychologist Steven Pinker, in the New York Review of Books1. In eloquent but vicious attacks on one another, these writers have given good cause for journalists to label these disputes as the Darwin Wars.
Reflecting on the nature of human nature is obviously not a new development with the advent of Darwinism, and has indeed been a central concern of philosophy and political thought for millennia. For whatever progress has been made, however, the subject still arouses passion and incites confusion in apparently equal measure.
In February 2001, when the completion of the rough draft of the human genome was jointly announced by super-sequencer Craig Venter of Celera Corp and Francis Collins, head of the American arm of the public sequencing initiative, the UK’s Observer newspaper ran the front-page headline ‘Revealed: The secret of human behaviour’ above an article by the newspaper’s science editor Robin McKie, which claimed that the human genome sequence demonstrated that environment, not genes, is the key to human behaviour. This grand conclusion was based on the discovery of the relatively low number of human genes that were found in the initial analyses of the draft sequence. Venter’s group estimated that were roughly 39,000 genes, whilst the public initiative’s estimate was significantly lower at 29,000, both much lower than the long-held guesstimate of 100,000 human genes. McKie reasoned that the fewer genes there are to guide and determine behaviour, the greater the extent to which behaviour must be determined by environment, and even suggested that science had now shown that humans have more free will than previously thought2. This is a difficult line of reasoning to defend, implying as it does that nematode worms, with 19,000 genes, must be freer than humans, and that their behaviour is determined even more so by environment; fruit flies and bacteria are, in this view, freer still. Apart from the philosophical naïveté of thinking that the age-old and historically intractable problem of free will could be solved by gene counting, it also raises a number of difficult theological questions: why, after all, should God endow yeast with more free will than man?
McKie’s analysis is based on a grossly flawed view of the relationship between genes (and gene numbers) and behaviour, and moreover in the way that evolution shapes behaviour through the differential selection of alternative gene variants. While perhaps unfair to single out one author for criticism, Mckie’s analysis at least makes fairly explicit some of the misunderstandings that dog sociobiology, and so it is worth taking some time to examine the errors he makes. In the first place, the ‘less genes, more behavioural flexibility’ argument is a total red herring. A virus, such as HIV with just nine genes, does not have its viral activity determined by some outside agency or its own free will, but by the protein products of its genome3. The behaviour of bacteria is not more determined by genes than viruses’ by virtue of fact that bacteria have more genes; furthermore, from a phylogenetic perspective, greater complexity and behavioural flexibility is generally correlated with possessing more genes. The idea that having fewer genes equals possessing more freedom makes no sense at all. Perhaps surprisingly, greater freedom from the tyranny of genes may result from having more genes, not fewer. More genes, operating in more complex genetic networks, can build the structures, such as big brains, that are needed for behavioural flexibility.
In order for McKie’s gene-number argument to make even a little sense, it would have to be the case that specific behaviours, to the extent that they have a genetic component, are governed by single genes, or groups of specifically dedicated genes. If this were so, then the number of genes an organism possesses would be expected to rise with the size of its behavioural repertoire. Given that humans are behaviourally much more complex than flies, and assuming that it were the case that human behaviour is determined in the way described above, then we should have vastly more genes than the humble fruit fly. But we don’t (18,000 versus 29-39,000. Although a twofold difference is significant, do you think you are only twice as complicated as a fruit fly?). As such, whatever extra behavioural flexibility and complexity humans have, it doesn’t reside in the genes, leading McKie (and others) to conclude that it must be granted in some mysterious way by ‘the environment’. This argument, however, is based on a bizarre view of how genes relate to behaviour, and correcting this serves the useful purpose of explaining how evolutionary psychologists view genes, evolution and behaviour4.
Firstly, no one seriously suggests that each specific human behaviour is exclusively under the control of one gene, or a set of genes, so it need not be the case that gene numbers rise as rapidly as behavioural complexity. Secondly, genes operating in a range of environmental conditions can build structures (i.e., brains and nervous systems) that can generate complex and flexible behaviour through the operation of simpler context-dependent rules, again highlighting that there need not be an exact, or even close, concordance between gene numbers and behaviour. Thirdly, genes do not operate as isolated entities, but as part of complex networks, and most human behaviours are expected to be under the influence of many genes (i.e., they are polygenic), and furthermore many, if not most, genes influence the development of more than one trait (a phenomenon called pleiotropy). If genes do not act in the one-gene, one-behaviour manner suggested by McKie, then the argument breaks down.
Both The Triumph of Sociobiology, written by the behavioural ecologist (read sociobiologist) John Alcock, and Revolutionary Biology, by sociobiologist-turned-psychologist David Barash, outline the sociobiologist’s view of the relationship between genes and behaviour, and together provide the conceptual tools needed to avoid the kind of muddles that McKie finds himself in (although he is by no means alone). Barash asks the question “Is there a gene “for” every behaviour?”, and concludes that that “the truth is both simpler and subtler than ‘one gene = one behaviour’”, and this subtlety is expanded on in greater length than is possible here. Alcock treats the reader to a more in-depth analysis of the role of genes in sociobiology, and explodes a number of myths about what sociobiologists actually commit themselves to when talking about genes “for” certain traits.
The frequent mention of genes in sociobiological writings has led critics to focus on the gene-sociobiology connection, and to conclude that sociobiologists advocate a mistaken approach to genetics that has been labelled genetic determinism. As Alcock writes, “If sociobiology were founded on a fundamentally flawed version of genetics, dismissing the entire discipline would be relatively easy”. Genetic determinism is characterised as the view that genes are the most important factor in the ontogeny of features of organisms and that genes rigidly determine the appearance of these traits, from which it supposedly follows that traits are inexorable and unchangeable. Both Alcock and Barash go to great lengths to explain why sociobiologists were never and are not the genetic determinists they are accused of being. Sociobiologists are fully aware that genes themselves cannot do anything, being made of chemically inert DNA. What they can do, however, is direct the synthesis of proteins, which do have functional consequences. Sociobiologists also recognise that the activity of genes (i.e., which proteins are expressed) is itself regulated by the physical and chemical environment of the cell the genes are in; it is therefore ridiculous to suggest that sociobiologists disregard the environment and subscribe to genetic determinism. When it comes to the development of behaviour, sociobiologists are even more keenly aware of the crucial role of environment in bringing about behaviour. As Barash says, “Behaviour is not contained within genes, ready to pop out fully formed, like the goddess Athena emerging from the forehead of Zeus. Rather, behaviour develops over time, under the joint prodding of genetics and experience” [italics in original].
Why, then, do sociobiologists talk so much about genes? It is because sociobiology commits itself to postulating the existence of genes that influence, in concert with regularly encountered environmental conditions, the development of behaviours that are proposed to have evolved through natural selection by increasing the reproductive success of individuals of the animal species in question. If the development of a trait is not influenced by genes to some degree, then natural selection has no substrate with which to work. As such, sociobiologists are concerned with providing “ultimate” explanations of the existence of specific adaptations, which means couching the explanation in terms of the natural selection of genes that influence the development of the adaptation; they are not concerned with elucidating the “proximate” genetic and developmental pathways through which adaptations come into being in an individual. Although sociobiologists and evolutionary psychologists are not in the business of identifying genes linked to development and behaviour per se, they can and do draw on studies from the disciplines of developmental and behavioural genetics, which are precisely concerned with deciphering developmental pathways and finding such genes5. It is important to note that hypothesising that genes are involved in the development of particular traits is not to claim that genes should be the prime locus of attention when considering the ontogeny of the trait, and nor is it to suggest that the environment is thereby less important. In fact, such a view is only compatible with a framework that embraces the nature-nurture dichotomy and accepts that gene-environment interactions are zero-sum affairs, in which the importance of one factor diminishes the importance of the other, a position which sociobiologists and evolutionary psychologists have argued strongly against. The reason for the attention given to genes is that differential gene survival is the engine of evolution, not because sociobiologists and evolutionary psychologists want to argue for the primacy of the gene in accounting animal behaviour and human affairs.
Why has so much heat been generated over sociobiology and evolutionary psychology? At stake in this intellectual battle is the mind of man: are we creatures whose mental life and manifest behaviour are largely influenced by the legacy bequeathed to us by evolution though natural selection, as other animals are, or are we somehow free of these Darwinian influences, possibly as the result of a general-purpose big brain that allows us to act as we choose within the confines of a given cultural context? It has been suggested by many, including Gould, that human abilities such as language are not the result of specific neurological adaptations crafted by natural selection specifically for the purpose of speaking, but are essentially by-products of being a brainy chimpanzee. Some important qualifications are in order here. Gould and many fellow critics of sociobiology and evolutionary psychology do not take the absurd view that we are entirely free from our evolutionary history, somehow disconnected from the rest of the animal world. Gould recognises that our evolutionary history has endowed us with the potential to be the kinds of beings we are. What is disputed is the extent to which the mind comprises numerous functionally specialised adaptations, crafted by natural selection because of the survival and reproductive advantages they brought their owners. Gould in particular has suggested that many features of the human mind are not specifically designed adaptations to solve ancestrally faced problems, but are ‘spandrels’, or “nonadaptive side consequences”, which have been co-opted at a later date for other purposes. Evolutionary psychologists, in contrast, argue that this is unlikely. An energetically costly organ like the brain is not likely to evolve so that it might one day be employed in the use of some important function.
Gould and his Harvard colleague Richard Lewontin have mounted several attacks on the idea that sociobiology can help in understanding human nature, and have done so primarily by questioning the methodology and assumptions of the adaptationist programme, which seeks to provide Darwinian answers to the puzzle of the existence of certain physiological and behavioural traits of organisms in terms of natural selection, and more specifically to do so through the lens of the gene-centred view of natural selection most prominently advocated by Richard Dawkins in The Selfish Gene. Rejecting the usefulness or even coherency of the selfish gene concept, Gould and Lewontin have proposed that the adaptationist programme and sociobiology generates little more than untestable and unfalsifiable speculations about the origins of organismal adaptations, which after Rudyard Kipling’s tale of how the elephant got its trunk they have labelled Just So stories. If this charge where true, then sociobiology would indeed be the pseudo-scientific discipline its critics claim it is.
In The Triumph of Sociobiology, Alcock devotes a section to taking Gould to task for making a public whipping-boy of Barash over a report Barash published in the scientific notes section of the American Naturalist in 1976. In this short preliminary report, Barash explored the hypothesis that male mountain bluebirds would behave more aggressively towards male intruders in their nests earlier in the breeding season, when territories and nests are usually defended, as an anti-cuckoldry adaptation. Using stuffed specimens of bluebirds, and a sample size of just two males, Barash obtained results that were consistent with predictions from sociobiological theory. Gould seized on this as an example of the Just So storytelling that Gould maintains is endemic in sociobiological research. To be fair, the empirical content of Barash’s paper was slight, but his predictions were derived from theory and put to the test of the real world. This short report presented not a Just So story, but a preliminary investigation of a phenomenon that Barash acknowledged need to be studied in much greater detail. Indeed, the phenomenon has been studied further and some researchers have rejected Barash’s claim in light of better evidence, demonstrating that it was never just a nice story, but was a genuinely testable scientific hypothesis6.
In Revolutionary Biology: The New, Gene-Centred View of Life, Barash has had a perfect opportunity to set the record straight and expose Gould’s ideological opportunism, but he has been remarkably restrained and there is not a single reference to Gould in the whole book (and perhaps this tactic of ignoring name calling is a prudent one, especially as the criticisms of Gould and his coterie have been consistently answered by the targets of their vitriol). Instead of getting entangled in the polemic, accusations and counter-accusations that have often characterised the Darwin Wars, Barash has set himself the task of bringing to light the underlying logic of the gene-selectionist view of evolution and adaptation that drives the approaches of sociobiology and evolutionary psychology.
What does natural selection care about? Another way of asking this question is, Why do adaptations that natural selection builds come into existence? Is it because they benefit individuals, groups, species, or genes? The case against selection for group-level adaptations has been forcefully made over the last three decades, since the publication of George C Williams’ classic Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought in 1966. While theoretical models suggest that group selection may operate in certain situations, it is widely regarded (although there is not universal assent) that most adaptations do not exist to benefit groups at the expense of the individual or any lower-level entity. On the other hand, most adaptations appear to benefit the individual organisms that posses them, which fits Darwin’s idea that natural selection operates primarily on, and for the benefit of, individuals (although he too allowed for group selection). However, there are a number of problems with viewing natural selection as operating to build adaptations to benefit individuals (although alternative views do not have to deny that individuals can benefit from these adaptations, but merely suggest that the ultimate reason they exits is because of benefits accrued to some other entity).
Firstly, there is the problem of death. A very good adaptation for individuals to possess, if evolution really did aim to benefit individuals, would be longevity, and even better, eternal life (within the bounds of physical and chemical law). However, most animals live for less than a year, despite the fact that it’s obviously possible to create life forms that persist for a little longer. Many organisms only stick around long enough to reproduce (and many die soon after achieving this goal).
This brings us on to the problem of sex. From an individual’s perspective, why bother wasting time and energy producing at best half-copies of yourself? This does not help an individual organism at all, so why would natural selection craft individuals who strive to reproduce if, at root, natural selection is ultimately concerned with sculpting adaptations that benefit the individual?
These problems vanish once one adopts the perspective that natural selection is acting to build adaptations that benefit genes that have some causal effect on the development and functioning of those traits. Death ceases to baffle, as it becomes clear that it is unnecessary for an individual to persist indefinitely in order for its genes to flourish; in addition, the very fact of reproduction becomes less mysterious (here I do not mean the evolution of sex, which is still deeply mysterious, at least to me), in that if adaptations exist to benefit genes then it is no surprise that there is a suite of adaptations ensuring that genes are, in fact, passed on. Selfish gene, or selectionist, thinking solves these and a number of other problems, although it does require a host of careful conceptual clarifications lest it be misunderstood, as it seems so wont to be. The Triumph of Sociobiology and Revolutionary Biology do a great complementary job of providing these clarifications.
In common with many introductory accounts of gene-selectionist thinking the topic of altruism, in terms of kin selection and reciprocity, is given much attention in Revolutionary Biology, although more recent work suggests that these two ingredients are not enough to explain the presence of the social moral sentiments of humans, or indeed their absence in other animals7. Parent-offspring conflict, stepparent-stepchild conflict, sibling rivalry, and the genetic and psychological battles fought by men and women are all discussed in Barash’s idiosyncratic literary way, against a backdrop of numerous examples drawn from the animal world, as well as the relevant seminal work in human evolutionary psychology, such as Martin Daly and Margo Wilson’s ground-breaking work on the relative risks of living with a stepparent. Parents have an interest in their offspring’s welfare because they carry 50% of the genes of each parent, so it is in the interests of the genes of the parent to guide parents to care for their children: if the child does not survive to reproduce, its own, and the parents, genes will not be passed on. Neglect for your offspring is a bad genetic strategy. But what about step-children? The genetic logic of caring for children of your current partner and their previous partner does not apply here. In lion packs, when a new male joins a group of females the male often kills all the cubs present, safe in the knowledge that they are not his offspring. This kind of infanticide is also seen amongst primate species. Daly and Wilson investigated the relative risks of neglect, abuse and infanticide of genetic children versus step-children in humans, and their results are as startling as they are shocking. Although most instances of infanticide are committed by genetic parents, because there are many more genetic parents than step-parents, infanticide is disproportionately represented by step-parents. As Barash summarises, “In the United States, a child less than two years of age is at 100 times greater risk of being killed by step-parents than by genetic parents” (this is primarily true for step-fathers). This is a truly staggering and disturbing finding. Daly and Wilson are not suggesting that step-fathers have evolved a mental adaptation to kill or abuse step-children, but simply that step-parents in general should demonstrate differential parental solicitude towards genetic and non-genetic children. Child rearing can be trying at the best of times, and it as a tragic fact that even genetic parents can snap and fatally abuse their children; Darwinian considerations lead to the prediction that step-parents should be significantly more likely to succumb to the pressures that face most other parents, and to have a lower threshold for inflicting violence on children supposedly in their care. Importantly, most step-parents do not kill their partners children, which reassuringly illuminates that most people are able to provide care for step-children (even if less so than genetic parents). There is a great opportunity for sociology and sociobiology to collaborate in teasing out the differences in cultural and socio-economic circumstances that lead some step-parents to commit one of the most abhorrent crimes imaginable.
As an introduction to selfish gene thinking, Revolutionary Biology weaves a good course between concentrating on animal and human behaviour, although there is little in the way of characterisation of human psychological adaptations. Issues such as the domain-specific nature of human information-processing systems, and the proximate psychological mechanisms that guide behaviour, are bypassed, which is understandable given the intended scope and readership of the book. This bias may also reflect the different concerns of those in the animal sociobiology tradition and those primarily pursuing human evolutionary psychology, the former focusing on behaviour as it contributes to inclusive fitness and the latter more concerned with elucidating the selection pressures our ancestors faced, and the proximate psychological mechanisms that would be expected to evolve to generate adaptive behaviour. As such, human evolutionary psychology is very much concerned with describing proximate psychological mechanisms, whether or not they currently promote fitness, in light of considerations of our evolutionary history. Whereas psychology is the locus of attention for much work by prominent spokespersons of evolutionary psychology such as John Tooby and Leda Cosmides, Steven Pinker, and David Buss, manifest behaviour is the main focus of Revolutionary Biology.
The Triumph of Sociobiology is a rather different book, which can be read profitably by interested laypersons, students, and experts alike. Brimming with delightful descriptions of the natural history of many insects and animals, it provides a rigorous rebuttal of all the criticisms that have been thrown at sociobiology, from its supposed political motivations, its methodology, and its purported assumptions about gene-environment interactions. No one can come away from this book believing that sociobiology is a right-wing, genetically determinist, scientifically flawed discipline, nor can the reader be left in any doubt whether the subject can illuminate much of the variety of animal behaviour that Alcock so ably lays out. The tactic of labelling sociobiological explanations as “Just So” stories has proved to be a very successful way of denigrating sociobiology, particularly amongst those who have never bothered to read the sociobiology literature, and it’s a great service of Alcock to explain, with well-chosen examples, how sociobiologists and behavioural ecologists actually derive predictions from gene-centred evolutionary theory and hypotheses, and more importantly how they set about testing these hypotheses. To be sure, there is good and bad sociobiology, just as there is good and bad physics, but the charge that all sociobiological theories and explanations are just so many fanciful and speculative stories won’t stick. Sociobiology works, and those that disagree had now better do more than simply express their disdain with its results.
It is interesting that in a recent review of Alcock’s The Triumph of Sociobiology, Steven Rose, who along with Gould has been a continuous thorn in the side of gene-centred adaptationists, raised none of his usual complaints of Just So storytelling and genetic determinism (precisely because Alcock makes it so clear that sociobiology, whatever its faults and limitations, does not commit these errors). It is not clear whether this is simply because of Alcock’s patient and entirely reasonable presentation of sociobiology or because Rose now realises that his overblown rhetoric has no force against the logic, evidence and empirical success of sociobiology, but whatever the reason the intellectual tide seems to be turning in favour of sociobiology.
So where do sociobiology and evolutionary psychology now stand, and have they yet triumphed? It is difficult to say at the moment, but they certainly seem to be becoming part of the wider intellectual culture (e.g., Ian McEwan drawing on evolutionary psychology in the novel Enduring Love). Speaking in 1942 about the Battle of Egypt, Winston Churchill said “Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning”. It might not be too farfetched to suggest, or at least hope, that we are at the end of the beginning of the sociobiological, gene-centred revolution.
I would like to thank Sarah Lee and Simon Brown for helpful feedback on an earlier draft of this review.
1 See Gould SJ: Darwinian Fundamentalism. The New York Review of Books June 12 (1997) 44(1):34-37; Gould SJ: Evolution: The Pleasures of Pluralism. The New York Review of Books June 26 (1997) 44(11):47-52; Dennett DC: ‘Darwinian Fundamentalism’: An Exchange. The New York Review of Books August 14 (1997) 44(13):64-65; Pinker S: Evolutionary Psychology: An Exchange. The New York Review of Books October 9 (1997) 44(15)54-56.
2 There is, of course, no particular reason, aside from a priori commitments, why the headline didn’t read “Revealed: the secret of human anatomy”, or why the article didn’t go on to say that the human genome now shows that bone structure is determined more by environment than previously thought!
3 Of course, the viral activity of HIV is not determined solely by its own complement of genes, but also by those of its host. Individuals with a particular mutation in the gene encoding the CCR5 receptor are apparently resistant to infection by HIV, as the mutation alters the receptor in such a way that HIV cannot bind to it and gain entry into immune cells, as it does in people lacking this mutation. The point still remains, however, that amongst those lacking the CCR5 mutation, viral activity is a product of the small complement of genes, and the protein products they encode, that is part of HIV’s arsenal. Having fewer genes does nothing to give more behavioural freedom to the virus.
4 It is odd that McKie adopts the theoretical position of genetic determinism (i.e., that there are specific genes for specific behaviours, and we have less genes than thought, so therefore less of our behaviours are determined by genes [although, one presumes, he thinks that a small class of behaviours are determined by genes]) in order to show that genetic determinism is wrong! Even if McKie were right, showing that a smaller class of genes than suspected determine behaviour is not the same as showing that the underlying of concept of genetic determinism is conceptually muddled (which is something, perhaps surprisingly, that sociobiologists and evolutionary psychologists have done time and again).
5 Behavioural genetics is surrounded with its own controversies, which will not be explored in detail here.
6 The literature is rapidly filling up with genuinely testable, and tested, evolutionary psychological hypotheses. Perhaps the most impressive are emerging from the Center for Evolutionary Psychology, directed by Leda Cosmides and John Tooby. An example of their recent work is: Kurzban R, Tooby J, Cosmides L: Can race be erased? Coalitional computation and social categorization. Proc Natl Acad Sci USA (2001) 98(26):15387-15392 [PubMed | Full Text]. Also see their paper in press: Price ME, Cosmides L, Tooby J: Punitive sentiment as an anti-free rider psychological device. Evolution & Human Behaviour (2002): in press.
7 For example: Fehr E, Gächter S: Altruistic punishment in humans. Nature (2002) 415:137-140 [PubMed].
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© Daniel Jones.
*Daniel Jones is Editor of Current Opinion in Molecular Therapeutics, London, UK. Email: email@example.com
Jones, D. (2002). The End of the Beginning. Human Nature Review. 2: 70-76.