PRINCETON UNIVERSITY PRESS, OCTOBER 2015
All the earliest fossil members of the human family, and our closest living relatives, gorillas and chimpanzees, are exclusively African. Given this fact, biologists since the time of Charles Darwin have accepted that the African ape and its subfamily the hominines, a group that comprises gorillas, chimpanzees, and humans, evolved in Africa. This conclusion was seemingly confirmed more than 50 years after Darwin’s assumption by the discovery of the earliest ancestors of humans in Africa. My research on the fossil record of ape evolution reaches another conclusion: the hominines began to evolve in Europe, not Africa.
In my latest book, The Real Planet of the Apes: A New Story of Human Origins, I provide concrete evidence for this hypothesis and show how a broader consideration of the fossil record of ape evolution explains many of the anatomical features that make us human.
In 1871, Darwin famously opined that it is somewhat more likely that the common ancestor of living African apes and humans evolved in Africa than elsewhere. But the very next line in Darwin’s Descent of Man suggests that Europe and not Africa may be the birthplace of the hominines. Darwin knew that one fossil ape, Dryopithecus, from France, had more than enough time to disperse into Africa and give rise to living hominines. But attention shifted to Africa as many fossil apes were discovered from the 1920s to the present. Now, following the discoveries of many well-preserved ape fossils in Europe, it is becoming increasingly clear that Darwin may well have been onto something, even though his speculation has long since been forgotten.
Apes originated in Africa and became quite abundant by 18 million years ago. These ancestral apes shared features of both monkeys and apes but they looked overall more like monkeys, making their way through forest canopies with arms and legs of equal length. Apes dispersed into Europe from Africa about 17 million years ago, when they were still abundant and diverse in Africa. The first apes to reach Europe were already distinct from their African forebears, with thickly enameled, flat-cusped molars for crushing and grinding foods that grew in the more seasonal environments.
Few ape fossils are known in Eurasia or Africa between 17 and 13.5 million years ago but by about 12.5 million years ago we find the first evidence of hominines in Europe, from the same ape Darwin knew about, Dryopithecus. In its face and teeth we see the best evidence that Dryopithecus and its close relatives were indeed ancestors of African apes and humans. Dryopithecus was the first ape with an upper jaw that closely resembled that of gorillas. Its teeth were also gorilla-like with their thin enamel and raised cusps. The skeleton of Dryopithecus shows the first evidence of orthogrady (more upright posture) and suspension (swinging below branches as opposed to walking on top of them) in a fossil great ape. Ten million–year-old fossil apes from Spain and Hungary had large brains, in the size range of living great apes, and highly suspensory limbs. Rudapithecus, a fossil ape from Hungary, was similar to African apes in overall skeletal organization, with brow ridges, a long, low braincase, and a face more tucked under the braincase than in orangutans. And Ouranopithecus, an ancient ape from Greece, resembled modern gorillas even more.
I believe that our direct ape ancestors evolved in Europe and not Africa and that this scenario explains much about human origins. Europe experienced severe climatic upheaval between about 16 and 12 million years ago as the climate shifted from subtropical to more seasonal. This climatic context helps to explain the appearance of mobile upper limbs, upright posture, and large brains—all evolutionary responses to the challenges of life in a more seasonal environment. These changes in the European Miocene presage the origin of the human lineage. Following the receding tropics southward across land bridges that emerged during global periods of low sea level, European apes reinvaded Africa around 10 million years ago, along with many other mammals, including bovids, giraffes, carnivores, and rodents, that typify the African landscape today. That African homecoming started European apes, not their African kin who had stayed put, on the evolutionary road to Homo sapiens. Without the developments I describe in The Real Planet of the Apes, it is hard to imagine how bipedalism, dexterous hands, and greatly enlarged brains in humans would have evolved.
David Begun is a paleoanthropologist at the University of Toronto. Read an excerpt of The Real Planet of the Apes.