The Ape in the Tree: An Intellectual and Natural History of Proconsul


May 18, 2007

teaser: By Alan Walker and Pat Shipman

This book, written for the general public, details the history of one of the lesser known branches in our family tree. The subject is the genus Proconsul, a primate that lived in Africa some 18 million years ago during the Miocene epoch.

In this engaging volume, Alan Walker and his wife and fellow paleoanthropologist Pat Shipman describe the early discoveries of specimens that have since been attributed to various species of Proconsul, the more recent discoveries by Walker and his team, and interpretations of the paleobiology of this stem hominoid. The first Miocene primate fossils, discovered in Kenya, were described in the 1920's by Arthur T. Hopwood, and named Proconsul, in honor of Consul, a well-known performing chimpanzee. Hopwood, a researcher at the British Museum of Natural History, was interested in learning more about these fossils, and approached Louis Leakey to help him organize an expedition to the area in which they were found. Walker and Shipman spend some time detailing the tumultuous career of Louis Leakey, who spent quite a bit of time in western Kenya looking for Miocene primates, in between his forays to Olduvai Gorge. In fact, it was Mary Leakey who in 1948 found a beautifully complete skull and jaw of Proconsul africanus.

Further field work by the Leakeys, and then by Walker and colleagues, expanded the number of Proconsul fossils significantly, and today it is one of the best known fossil primates. Walker and Shipman describe the details of field work, and tell many interesting stories of encounters with curious natives, inclement weather, and cantankerous equipment. They are careful to break up the serious discussions of science with stories that describe the personalities of their colleagues or that highlight the excitement of discoveries, which will surely help to keep the interest of the reader.

In the context of describing the discoveries of Proconsul in the field and in the lab, Walker and Shipman are able to touch on many important topics in the field of paleoanthropology, including species recognition in the fossil record, classification methods such as cladistics, the principle of uniformitarianism, determining life history strategies in extinct animals, and reconstructing aspects of paleobiology such as diet and locomotion in extinct animals. They explain these complicated topics clearly, which gives insight to the lay reader into the intricacies of our field. Proconsul is an interesting taxon on which to focus, as it lived during a time in which old world higher primates were diversifying.

Early research focused on the question of whether Proconsul was an ape or a monkey, but years of research on the wealth of Proconsul material has shown us that this question is inappropriate. Proconsul was a creature that lived soon after these two major lineages had split, and it has many characteristics in common with both apes and monkeys. For example, it did not have a tail like living apes, but it was a slow moving arboreal quadruped like many monkeys. It had a pattern of growth intermediate between modern apes and monkeys. It lived during a time in which there were many different species of early apes co-existing in eastern Africa but only a few monkeys, a situation very different from modern times.

Walker and Shipman point out that in order to best understand the place of Proconsul in our history, we should accept it as an early ancestral ape, and then build upon this understanding to redefine our definition of what it means to be an ape.

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