Our Anthropoid Roots 



Those curious primates from Pondaung, 



and other leads in the quest for an early ancestor 



By Russell L. Ciochon and Gregg F. Gunnel! 



Who says that scientists can't change their 

 minds, that science progresses only 

 when those who cling to outmoded 

 views die off? In October 1985, Natural History pub- 

 lished an article about two fossil primates, Amphi- 

 pithecus and Pondaungia, which were known from 

 fragmentary specimens discovered in the Pondaung 

 (or Ponnyadaung) Hills of Burma (now Myanmar). 

 The author of that article, following in the tracks of 

 Barnum Brown, the legendary fossil collector from 

 the American Museum of Natural History, had been 

 able to study new specimens unearthed by Burmese 

 paleontologists. On that basis he proposed that the 

 two genera might represent the missing link between 

 prosimians, or lower primates, and anthropoids, or 

 higher primates. That author was one of us — Cio- 

 chon — and taking into account new evidence, he 

 now withdraws that conclusion! But those curious 

 primates are still part of the intriguing story of pri- 

 mate origins, and ultimately, of us. 



Living prosimians comprise the lemurs and their 

 relatives in Madagascar, as well as several small noc- 

 turnal forest creatures: the galagos and pottos of 

 Africa and the lorises of southeastern Asia. Living 

 anthropoids comprise the New World monkeys, 

 Old World monkeys, apes, and humans. Tarsiers, 

 which occur on certain islands in southeastern Asia, 

 are hard to place — they might be prosimians, but 

 they could easily be the closest living relative of the 

 anthropoids. 



The tarsier aside, though, the picture of primate 

 evolution seemed fairly straightforward twenty years 

 ago: Prosimians appeared in the fossil record in the 

 northern continents of both the Old and New 

 worlds about 55 million years ago, and anthropoids 

 appeared in Africa around 35 million years ago, pre- 

 sumably having evolved from some prosimian an- 

 cestor. Although there was disagreement about 

 which fossil prosimians gave rise to the higher pri- 

 mates, Amphipithecus and Pondaungia looked like 

 good candidates. At the time Ciochon 's article was 



written, they had both been dated to about 40 mil- 

 lion years ago, and they both shared some traits of 

 both prosimians and anthropoids. 



In the past two decades, however, that overall pic- 

 ture has dramatically changed. The anthropoid lin- 

 eage now seems to be as old as the prosimian one, 

 and both may have arisen as long ago as 60 million 

 years. The birthplace of the anthropoids is also up 

 for grabs. Some paleontologists now argue that an- 

 thropoids first arose in Asia, not Africa. In that view, 

 their appearance in Africa must have been the re- 

 sult of subsequent dispersal. 



The rivalry between Africa and Asia for the af- 

 fections of primatologists recalls the debate 

 over human origins in the early twentieth century. 

 In his 1871 book, The Descent of Man, Darwin sur- 

 mised that humans evolved in Africa, the native con- 

 tinent of our closest relatives anatomically, the go- 

 rillas and chimpanzees. But some specialists, such as 

 Henry Fairfield Osborn, who was president of the 

 American Museum from 1908 until 1933, felt sure 

 that humans first appeared in Asia. Fossils of Homo 

 erectns (so-called Peking man and Java man) had al- 

 ready been discovered on that continent. The mu- 

 seum's famed Central Asiatic Expeditions to Mon- 

 golia — led by the swashbuckling explorer Roy 

 Chapman Andrews — were financed because their 

 backers expected they would yield the predecessors 

 of Homo erectns. Fortunately, the expeditions paid off 

 handsomely in sensational discoveries of dinosaur 

 fossils, for no very early human fossils ever came to 

 light. The fossil evidence for human origins all 



Aegyptopithecus and its habitat are depicted in an artist's 

 reconstruction, based on 32-million-year-old fossils. The 

 same region today is much drier and hotter: it lies in Egypt's 

 Fayum desert, about sixty miles southwest of Cairo. About 

 the size of a capuchin monkey, Aegyptopithecus was an 

 early anthropoid, the primate group whose living represen- 

 tatives are the monkeys, apes, and humans. 



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NATURAL HISTORY March 2006 



