Despite unanimous scientific agreement that humans share a close
common ancestry with monkeys and apes, one of the most controversial
issues in paleoanthropology today is how, when, and where the first
anthropoids—the common ancestors of monkeys, apes, and people—
evolved. In stark contrast to the relatively abundant fossil record for early
humans, the fossil record for anthropoid origins is spotty, incomplete,
and seemingly incoherent. Paleontology, like other branches of science,
abhors such a vacuum. The main purpose of our expedition is to help
flesh out this distant phase of our evolutionary history. Yet the simple
fact that our team is searching for fossils of early anthropoid primates
in Eocene rocks in central China is, in several respects, unorthodox—if
not downright heretical.
Our goal is to test a bold new hypothesis about anthropoid origins—
one that moves the birthplace of these remote human ancestors from
Africa to Asia while it ruptures the established evolutionary timetable by
tens of millions of years. This sweeping idea rests on the wobbly foundation
provided by some fragmentary fossils from another Chinese site
known as Shanghuang that I had recently named Eosimias (“dawn monkey”
in Latin and Greek). If we are to have any hope of gaining scientific
traction, we must find better fossils of Eosimias and animals like it. The

Figure 1. Major differences in cranial anatomy distinguish prosimians from anthropoids.
Illustrated here (from left to right) are skulls of a ruffed lemur (Varecia variegata), a South
American squirrel monkey (Saimiri sciureus), and a human (Homo sapiens). Note the basic
similarity in skull form in the two anthropoids, which differ from the lemur in having a relatively
larger brain, a reduced snout, fused mandibular symphysis and metopic suture, and
a complete postorbital septum. Original art by Mark Klingler, copyright Carnegie Museum
of Natural History.