Robert Foley

HUMANS BEFORE HUMANITY

As its title implies, this book is about the furthest reaches of human evolution. It provides a good readable overview of a long period that generally receives less attention in books intended for the non-specialist reader. Most authors are chiefly interested in the development of language, art, and culture, and even when earlier periods are discussed the focus is mainly on anatomy. Foley starts with the origin of the primates, some 40 million years ago, and pretty well comes to a stop when modern humans appear about 150,000 years ago.

Foley is concerned to remove a number of misconceptions about human origins and what they imply for our view of ourselves. He is, rightly, particularly critical of cultural relativism. Contemporary ideas about humans and their place in the world have derived much more from social theory than from evolutionary thinkers. Foley discusses the reasons why this has occurred in his early chapters, in which he also describes different opinions about humans and how far they can be separated from other apes. Most sociologists merely pay lip service to evolution before going on to treat human beings as if they were now separate from the rest of the animal kingdom, which is where Foley locates them.

Foley asks, and seeks to answer, a number of questions about our origins. The first is 'When did we become human?'. The answer depends on the criteria one uses. It could be about 6 or 7 million years ago on the basis of the molecular evidence for when we separated from the other African apes, about 5 million years ago on the basis of the palaeontological evidence, or about 4 million years ago, when firm evidence for bipedality first appears. In other words, there is no definite answer to the question of when humanity began.

The next question is whether human evolution shows progressive trends. Foley makes it clear that the present uniqueness of our species is misleading; during the period that we were evolving there were numerous other hominids around and the model we should use to picture this is a bush, not a ladder. If more of them had survived we would be less impressed by the gap between ourselves and the chimpanzee. There is certainly a question about why these earlier forms became extinct - something about which we have little knowledge.

We know that we evolved in Africa, but why? To some extent we may be getting a misleading impression from the fact that the parts of Africa where fossils have been found (the east and the south) were particularly well adapted to preserve them, but Foley thinks that Africa was also, for geographic and climatic reasons, specially well suited to the development of a bipedal ape.

Even so, it is not obvious why the bipedal ape should have acquired such a large brain and—much later—a complex culture. This is Foley's interest in his later chapters. Here he makes the point that being human has costs as well as benefits, especially the cost of maintaining a large brain, which takes a long time to develop and consumes a lot of energy. As others have done, he links brain evolution to sociality and the demands of living in large groups. There is no need to postulate extrarodinary reasons for the existence of humans; they arose because the ecological conditions favoured their evolution. Most animals don't evolve large brains because they are better off putting their energy into large muscles or large stomachs. In our case, the ecological conditions allowed the benefit of greater intelligence to outweigh the costs. It is these ecological circumstances that are rare.

In his final chapter Foley returns to his criticism of the social sciences view which emphasises nurture rather than nature. While he has no time for genetic determinism, he shows, convincingly to my mind, that nature matters too. There is no big gap between humans and the rest of the natural world.

We should not let the uniqueness of our species dupe us into believing that we are the product of special forces. Cosmologists studying the origins of the universe need to think in terms of a big bang. Evolutionary biologists are better off with a bout of hiccups. If we had been privileged enough to observe the origins of our species and our lineage, we would have been struck by one thing—nothing very much happened.

14 October 2009