Jean-Jacques Petter and Francois Desbordes
(Translated by Robert Martin), Princeton University Press, 2013
Wayne Mones
I well remember an illustration from the 1950s showing the path of human evolution from chimpanzee to Homo erectus to Homo neanderthalensis to us – implying that our kind is evolution’s masterpiece and that everything leading up to us was a kind of practice run.
We – at least some of us – now know better. We know that each species on the branching tree of life is a condition, not a destination. We know that, in fact, there are no species in nature. There is only change. Species designations are snapshots of ephemeral conditions which we humans apply to hosts of accumulated changes to help us understand the world. We know that although we are part of a rich lineage of primates we are not descended from apes. In fact we share a common ancestor (most recently) with bonobos. This means that chimps and bonobos are our cousins, not our ancestors. It means that the chimps and bonobos are as highly derived as we are. Modern chimps and bonobos are no more like the animals which first diverged from our last common ancestor (about 5 million years ago) than we are.
A visitor entering the Anne and Bernard Spitzer Hall of Human Origins in The American Museum of Natural History is greeted first by three skeletons. A chimpanzee. A modern human. A Neanderthal. This greeting party grounds the visitor in the symphony of changes which separate chimps and humans. The skeletons clearly show the differences in the design of the hip, the angles of the femurs, the balance point of the skull, the differences in feet, and the differences in brain size and skull shape.
One of the evolutionary developments which led to our success is an enlarged brain and a “theory of mind,” which has enabled us to form extremely complex social relationships and a level of cooperation possessed by no other animal. “Theory of mind” means simply, knowing what another individual is thinking. Hunting with a group is made a lot safer and a lot more efficient if one member of the party can look across a field at his companions and know what each person sees and what each person expects the others to do. We do it so naturally that we don’t even think about it. Remarkably, chimpanzees (with a brain only one third the size of ours) may also be capable of developing a theory of mind – of knowing what their companions see and what is expected of them. But – one cannot train a chimpanzee (even with extensive coaching) to strike two rocks together to get a sharp-edged ax or blade.
There are too many similarities and differences to discuss in a short review such as this because human origins is a big subject.
Our lineage goes back about 60 million years – the blink of an eye after the disappearance of the non-avian dinosaurs – which makes us one of the oldest placental mammals. We fit on the branch of the tree which includes old world monkeys and apes. Like the family trees of other species, ours is more like a bush with a complicated tangle of branches going off in many directions. The major branches are the wet-nosed (Strepsirrhini) primates which include lemurs, and lorises, and the dry-nosed (Haplorhini) primates which includes monkey (new and old world) and apes.
I can think of no better introduction to the non-human primates than Jean-Jacques Petter’s and Francois Desbordes’ Primates of The World recently published by Princeton University Press. The text is authoritative and readable and includes very good sections on the evolution of primates and the roles of environment and competition in influencing primate adaptations. There are also excellent chapters on territorial behavior, social organization, and sociality. The book is richly and beautifully illustrated by Francois Desbordes, and there are excellent life histories for each primate species.
belongs on the shelf of anyone who wants to expand his or her understanding of human origins and of anyone who is captivated by the rich personal experiences, long-term detailed field observations, and passionate conservation messages of Diane Fossey and Jane Goodall.