Twisting the Tale of Human Evolution

COMMENT BOOKS & ARTS details the evolutionary analysis of human mating patterns, showing that monogamous mating goes way back. Human childhood is long compared with that of our ape relatives, and the palaeofantasy explanation is that cognitive development necessitates a long childhood. Zuk runs through extensive data on the supply side, establishing the credibil- ity of the alternative hypothesis that humans have maintained high rates of reproduction MUSEUM, LONDON/SPL HISTORY NATURAL by reducing maternal energy investment in children, instead recruiting grandparents and other relatives to help care for them. There are other such examples. Many clear cases of recent adaptation show that natural selection has kept pace with some rapid environmental shifts. For example, malaria has induced dozens of genetic adaptations in tropical peoples during the past few thou- A recreation of a Neanderthal hunting party in prehistoric Britain. sand years. And diets in the late Pleistocene epoch, which came to a close about 11,700 EVOLUTIONARY BIOLOGY years ago, were very diverse; Neanderthals, for instance, noshed on cooked grains. With advances in our understanding of the global human population and the rapidly shifting Twisting the tale of climates of the most recent glaciation, no single model can encompass this diversity. There are a few real mismatches among human evolution the fake ones Zuk highlights. Diet is one. Pleistocene people did not rely on large John Hawks enjoys a debunking of myths about our stored harvests of starchy grains, fatty meat evolutionary fitness for the twenty-first century. and milk from domesticated animals, or processed sugars — all of which are among the causes of the obesity, type 2 diabetes and dvances in medicine and psychology to feet, legs and backs metabolic syndrome that are so prevalent may be stunning, but why is human- are rife among run- today. Some popular diet regimes attempt to ity plagued with persistent and wide- ners. Palaeofantasy rectify the problem by prescribing a menu Aspread ills, from diabetes to depression? solution: run bare- modelled on one that probably prevailed Some anthropologists and psychologists foot. Some psycholo- before the invention of agriculture 10,000 speculate that an evolutionary mismatch gists have argued years ago. But although cutting out starchy is at work: we are cave-dwellers struggling that humans aren’t grains, sugars and milk, and relying on lean in a high-tech world. But as Marlene Zuk meant for monogamy, meat has helped many people shift to a explains in Paleofantasy, many of these ideas because our ancestors healthier lifestyle, it has driven some adher- amount to little more than pseudoscience were supposed to have Paleofantasy: ents to extremes. What Evolution based on an imagined past. interacted like the ‘sex- Really Tells us As an anthropologist, I observe that Zuk’s The palaeofantasist’s basic idea is this: ually social’ bonobo. About Sex, Diet, use of the term ‘fantasy’ is just an emphatic natural selection tends to make a population Palaeofantasy solu- and How We Live way of describing the hypothesis-forming well adapted to its environment. But change tion: open marriages. MARLENE ZUK that is essential to evolutionary science. We the environment enough, and finely tuned How do these W. W. Norton: 2012. play with hypotheses, explore their predic- adaptations start to fail. Human environ- controversies arise? 336 pp. £17.99 tions and try very hard to falsify them. So ments in particular have changed radically Because scientists try it is, in a way, unremarkable that so many in the past 10,000 years, meaning that many to reconstruct ancient environments by hypotheses proposed by anthropologists human traits may not work well today. piecing together archaeological data, com- about ancient environments now seem to be Except, argues Zuk, it is not that simple. parative primate behaviour and observations wrong — and, in a few cases, even ridiculous. Zuk, a biologist, reviews how our assump- on living, small-scale societies such as the It means that science is working. Genom- tions about the past have shaped the sci- Hadza of Tanzania or the Aché of Paraguay ics, high-resolution climate records, and ence of human biology in relation to factors that have lifestyles similar to those of our microscopic and isotopic evidence have ranging from exercise and diet to mating ancestors. But every living and archaeologi- changed our understanding of what the past and marriage. She ably presents a sceptical cal group has its own distinctive circum- has to offer. With that in mind, let the next and light-hearted view of a long list of pal- stances and history. We can’t blithely assume round of palaeofantasies begin. ■ aeofantasies and supposed solutions. (My that we can reconstruct the environment name appears in the book a few times as a relevant to natural selection in the past. John Hawks is associate professor of sceptic of various poorly supported hypoth- By presenting the state of evolutionary anthropology at the University of Wisconsin- eses and as a researcher investigating well science, Zuk shows that palaeofantasies can- Madison, USA, and runs the weblog http:// supported ones.) For instance, our feet seem not be justified across a range of environ- johnhawks.net. well adapted for running, yet stress injuries ments or with a range of behaviours. She e-mail: [email protected] 172 | NATURE | VOL 495 | 14 MARCH 2013 © 2013 Macmillan Publishers Limited. All rights reserved.

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