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Human Nature Review 2002 Volume 2: 551-554 ( 12 December )
URL of this document http://human-nature.com/nibbs/02/barber.html
The Science of Romance: Secrets of the Sexual Brain
By Nigel Barber
Amherst (NY): Prometheus Books, 2002
Reviewed by Andrew J. Petto*, Ph.D., Division of Liberal Arts, University of the Arts, 320 S Broad St., Philadelphia PA 19102-4994 USA.
Reflecting on the state of evolutionary psychology, David Buss clearly stated the rationale for this approach to the study of behaviour: "psychological science must be anchored or informed by evolutionary principles" (Buss, 1995a: 81). These principles are used to understand contemporary human behaviour based on "evolved psychological mechanisms" which have 3 key features:
1. They exist in their current form because they solved a particular set of individual survival or reproductive problems recurrently over human evolutionary history;
2. They take only certain classes of information or input and specify to the organism the particular problem it is facing; and
3. They transform the information into output through a procedure that, through behavioural or psychological action, produces observable action and thus solves a particular adaptive problem (Buss, 1995b: 6).
However, Buss clearly articulated the challenge for evolutionary psychology in the scientific application of this concept:
[K]nowing that males in species with internal female fertilisation face the adaptive problem of paternity uncertainty does not tell us precisely which mechanisms males in particular species will have evolved to solve this problem. In this sense, there is simply no substitute for solid empirical work to anchor and refine evolutionary hypotheses about particular psychological mechanisms (1995a, p. 83).
What evolutionary biologist could resist the appeal of such a research programme? After all, if our bodies are modified from those of ancestors, why not our behaviours? Furthermore, this approach recognises the intrinsic shortcomings of early sociobiology — that behaviours found in flies or fishes or even other primates in response to "adaptive problems" do not necessarily explain the "adaptive solutions" in humans.
So, 7 years later, how has Barber answered Buss's clarion call? The Science of Romance appears to be popular science writing instead of professional scholarship, but even for this format the "explanations" seem glib and superficial — a long, long chain of inference between starting assumptions, such as those laid out by Buss (1995a; 1995b), and sweeping conclusions of the sort: "Such a preference [for physically attractive strangers] would have helped our ancestors to choose their mates well. There is nothing specifically human about the power of beauty" (p. 46). Later Barber writes:
Our male ancestors who enjoyed casual sexual relationships with several women would have been more reproductively successful than men who were faithful to a single partner. Their male children would have inherited the genetic basis for having a roving eye through the father's genes. This explains why modern men are more interested in casual sexual relationships than women are (p. 95).
Well, maybe. These men might certainly have more sex (if and only if the females consented), but would they necessarily have more children? In a species conspicuous for its absence of a strict breeding season and external signs of female fertility, random mating is three times more likely not to lead to conception than to succeed.
The real issue in human reproductive strategies is that males can increase the quantity of their offspring by seeking out multiple mating partners, while woman cannot. However, the incentive for a female's seeking multiple partners is to increase the quality of their offspring — something that males cannot achieve by "casual sexual relationships". So, women could also be predisposed to have "a roving eye", but the female eye may be on a different prize. Besides, what are the genes for "a roving eye", and can they only be inherited patrilineally?
The problem, as Levy (2002) observed in his review of Palmer and Palmer's Evolutionary Psychology: The Ultimate Origins of Human Behaviour is clear:
At this point in its young life, [evolutionary psychology] is a hodgepodge: a mixture of promising, well-designed research projects testing interesting hypotheses, popular-magazine–level speculation, of hard science — much of it only tangentially psychological — and just-so stories.
All of these problems feature prominently in The Science of Romance — and one more: Throughout the book Barber confuses proximate with ultimate evolutionary explanations. For example, in the quote above on beauty, one could rightly ask which ancestors — the first animals? the first fishes? the first humans? Where is the hypothesis that places this aesthetic sense in a testable scientific evolutionary context?
Later we read that economic strategies, particularly economic and marriage "markets" for women, relate to the amount of body fat considered appropriate and attractive as the female ideal. The problem with this explanation, of course, is that it conflates relatively recent social, political, and economic changes — a proximate-level explanation — with what were certainly quite different social conditions in early humans, or even other primates or mammals — an ultimate-level explanation. It is no so much that the observed correlation is wrong as that the observations of fashion trends in female fatness over the past two centuries do not automatically inform us of evolutionary foundation of this phenomenon. In essence, this discussion — and other throughout the book — fail the criterion that Buss set out of "solid empirical work to anchor and refine evolutionary hypotheses".
Part of the problem is that the book seems to be based in the "Man the Hunter" model of human evolution from the 1950s and 1960s. While it is true that males mainly hunt and women mainly gather in contemporary subsistence societies, the best current work on human evolution suggests that this arrangement is phylogenetically recent. It may well represent a series of behavioural changes in genus Homo over the last couple of million years, but it most certainly does not represent the behavioural starting point of most of the pre-sapiens hominin species that we recognise, nor does it relate to the behaviours of most nonhuman animals — even those that live in social groups and hunt. A true evolutionary explanation would take these comparisons into account while working to extract contemporary behaviour from competing evolutionary pressures as humans emerged as a recognisable taxon and evolved along one set of possible solutions.
This points to the other main problem with The Science of Romance; its approach to evolution is strictly "adaptationist" — that is, every "evolved psychological mechanism" is portrayed as an outcome of adaptation to or evolution for some particular situation. Furthermore, Barber's gloss of natural selection merely as "a means by which unsuitable types get weeded out" (p. 24) badly misrepresents contemporary understanding of this process or its place among the forces that shape evolutionary history. In that regard, both this book and evolutionary psychology need to mature to the point of taking up and applying contemporary evolutionary theory to human behaviour in all the dimensions that this theory has to offer — exaptations, contingencies, unintended consequences, and evolutionary compromises among competing demands on the organism.
But there is another serious problem with this book — it seems to be two different books bound together in one cover. The first half seeks to make the case that many of our behaviours with respect to wooing and securing mates have deep evolutionary roots and consequences (which is, of course, indisputable). Then, beginning with Chapter 7, it seeks to apply those principles to explain specific aspects of the ways that we acquire and conduct these behaviours in contemporary Western societies. If the purpose of this part of the book is to bring evolutionary principles to bear on the specific behaviours of humans in specific modern situations, then it is an utter failure. Too many of the examples are so far from testable evolutionary hypotheses that it is not clear what evolutionary hypothesis Barber is suggesting. Consider, for example:
The cross-generational cycle of single parenthood has been rationalised by evolutionary psychologists as reflecting an adaptive mechanism that helped our hunter-gatherer ancestors to adjust to the different social conditions they encountered (p. 215).
Of course, "single parenthood" has no evolutionary meaning per se. It is meaningful only in contrast with nuclear and extended nuclear families that we Westerners see as normative. However, cross-cultural studies show a variety of arrangements for rearing young children, and studies among other species show even more. And for every example like the Ache of Paraguay that Barber cites to support the survival value of an involved male parent (pp. 95–6), there are counter-examples, such as those on the Hadza (e.g., Hawkes et al., 1997) that show that other social arrangements serve the same purpose. The problem is that the argument is based on the incorrect notion that any pre-industrial "hunter-gatherer" society serves equally well as a proxy for our earliest human ancestors.
Studies of biological evolution recognise correctly that specific uses of specific structures in specific contemporary environments are shaped by the evolutionary history of the organisms so endowed and based on local responses to persistent local conditions. However, evolutionary biologists also know that the actual outcome of the organism–environment–evolutionary-history interaction that we observe is but a part of the range of possible evolutionary outcomes. The most interesting — and perhaps the most important — thing is to understand how and why this outcome prevails from among all the possibilities and why others have perhaps failed to do so. And that is where The Science of Romance ultimately fails the test as an evolutionary explanation.
In the end, Barber seems to want to help us demystify the social and cultural contexts in which sexual behaviour occurs by explaining it in terms of its evolutionary roots and the adaptive forces that have shaped its current manifestations. This is a noble goal. However, the connections between Barber's "evolutionary" explanations and contemporary issues in reproductive strategising amongst humans are weak and speculative. What we owe to a general readership — especially a general readership learning evolutionary thinking from a trade book — is a clear depiction of contemporary evolutionary thought and its scientific application to specific problems. The Science of Romance delivers only, as Levy (2002) lamented, little more than a hodgepodge mixing "interesting hypotheses, popular-magazine–level speculation … and just-so stories".
Buss, D. M. The future of evolutionary psychology. Psychological Inquiry 1995a; 6(1): 81–7.
Buss, D. M. Evolutionary psychology: A new paradigm for psychological science. Psychological Inquiry 1995b; 6(1): 1–30.
Hawkes, K., O'Connell J. F., Blurton Jones, N. G. 1997. Hadza women's time allocation: Offspring provisioning and the evolution of long post-menopausal life spans. Current Anthropology 38: 551–77.
Levy, N. Book review of Palmer, J. A., Palmer, L. K. Evolutionary Psychology: The Ultimate Origins of Human Behaviour. Human Nature Review 2002 17 Sept; 2: 378–81. Also available at http://human-nature.com/nibbs/02/palmer.html.
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© Andrew J. Petto.
* Andrew Petto is a bioanthropologist specializing in the study of nonhuman primates. He is Associate Professor of Liberal Arts at the University of the Arts, Philadelphia PA, and teaches courses in general biology, human variation, pseudoscience, and anatomy, He edits Reports of the National Center for Science Education and is the co-editor of Scientists Confront Creationism, revised edition, to be published in 2003 by W. W. Norton Co.
Petto, A. J. (2002). Review of The Science of Romance: Secrets of the Sexual Brain by Nigel Barber. Human Nature Review. 2: 551-554.