The first convincing chimp fossil has been discovered by scientists.
Unlike our human ancestors, whose fossil remains are relatively plentiful, chimps have always been conspicuously absent from the fossil record. Many experts doubted such specimens could exist because most chimps live in the rain forests of West and central Africa where acidic soil and high rainfall levels hamper fossil preservation.
Early humans, on the other hand, lived in areas more arid areas conducive to fossil preservation but relatively hostile to chimp survival, such as the East Africa Rift Valley. 鈥淚t鈥檚 the last place you鈥檇 expect to find chimps,鈥� says anthropologist Jay Kelley of the University of Illinois at Chicago, US.
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But in a sediment of the Kapthurin Formation in the Eastern Rift Valley, Sally McBrearty of the University of Connecticut and Nina Jablonski of the California Academy of Sciences did find three fossils with the unambiguous characteristics of chimp teeth.
Branching out
The two incisors and a molar, probably all from the same individual, date from around 500,000 years ago. They were found in sediments that include fossils of two early humans 鈥� Homo erectus or Homo rhodensiensis 鈥� suggesting that chimp and human ancestors were contemporaries. A possible fourth tooth is still awaiting analysis.
On their own, the fossils will not tell us much, says palaeontologist Tim White of the University of California, Berkeley, 鈥淪o little of the anatomy is preserved that these fossils do not teach us much new about chimpanzee anatomical evolution.鈥� But, the finding does suggest that chimp ancestors were more capable of adapting to a broader range environments than previously thought. 鈥淭here is no logical necessity why chimps had to remain in the forest,鈥� says McBrearty.
She believes her discovery 鈥渉as opened the door鈥� for others to look for chimp fossils in unexpected places. It might even be possible to find much older chimp fossils from a time near the split in human and chimp lineages. White believes this is quite probable. 鈥淚t is only a matter of time,鈥� he predicts.
