First Fossil Chimpanzee

遗传证据表明，黑猩猩（Pan）是现存的与人类最近的亲戚。在过去的30年里，数十名研究人员的辛勤勘探已经产生了人类谱系的化石记录，现在已有数千个标本。但在麦克布里蒂于2005年在《自然》杂志上报道的在肯尼亚Kapthurin地层的发现之前，没有已知的黑猩猩化石。我们最近的亲戚化石记录的缺乏一直是许多猜测的对象。因为现存的黑猩猩种群居住在树木繁茂的西非和中非，而大多数古人类化石发现在半干旱的东非大裂谷，从森林到草原植被的转变，可能是由气候变化驱动的，被认为是500万到800万年前人类和黑猩猩谱系分化的原因。裂谷本身被认为是黑猩猩占领的障碍。Kapthurin组化石表明，潘人的代表大约在50万年前出现在东非大裂谷，在那里他们与一种灭绝的人属物种是同时代的。这表明人类和黑猩猩的祖先可能居住在非常相似的栖息地，并呼吁重新评估植被和气候变化在两个谱系最初分化中的作用。该项目将进一步在Kapthurin组进行勘探和挖掘，以恢复更完整的黑猩猩化石标本。这项研究还将通过研究其他动物的相关化石遗骸，详细检查化石的地质背景，以及对古代土壤和牙釉质化石中的碳酸盐进行稳定同位素分析，来弄清古代黑猩猩生活的栖息地。更广泛的影响包括康涅狄格大学研究生、肯尼亚当地工人和肯尼亚国家博物馆古生物学部门的工作人员的合作，他们都将参与这项研究。他们的任务将包括勘探化石、绘制地图和挖掘，以及化石鉴定、准备和管理。该项目是与NMK长期合作的一部分，这些化石最终将被安置在那里。

Genetic evidence shows that the chimpanzee (Pan) is the closest living relative to humans. Diligent prospecting by dozens of researchers over the last 30 years has resulted in a fossil record for the human lineage that now numbers in the thousands of specimens. But prior to McBrearty's discoveries in the Kapthurin Formation, Kenya, reported in the Journal Nature in 2005, there were no known fossils of the chimpanzee. The lack of a fossil record for our closest relative had been the object of much speculation. Because living chimpanzee populations inhabit wooded West and Central Africa, while most hominin fossil sites occur in the semiarid East African Rift Valley, a shift from forest to grassland vegetation, perhaps driven by climate change, was thought to have caused the divergence between the human and chimpanzee lineages 5 to 8 million years ago. The Rift Valley itself was thought to present an obstacle to chimpanzee occupation. The Kapthurin Formation fossils show that representatives of Pan were present in the East African Rift Valley about 500,000 years ago, where they were contemporary with an extinct species of Homo. This suggests that the ancestors of humans and chimpanzees may have occupied quite similar habitats, and calls for a reevaluation of the role of vegetation and climate change in the initial divergence between the two lineages.The proposed project will further explore and excavate in the Kapthurin Formation to recover more complete chimpanzee fossil specimens. The research will also clarify the habitat in which the ancient chimpanzees lived, through study of associated fossil remains of other animals, detailed examination of the fossils' geologic context, and stable isotope analysis of carbonates in ancient soil and fossil tooth enamel. Broader impacts include collaboration of University of Connecticut graduate students, local Kenyan workers, and personnel from the Palaeontology Division of the National Museums of Kenya (NMK), all of whom will take part in the research. Their roles will include prospecting for fossils, mapping, and excavation, as well as fossil identification, preparation, and curation. The project is part of a long-term collaboration with the NMK, where the fossils will ultimately be housed.