The origin of the genus Homo in Africa signals the beginning
of the shift from increasingly bipedal apes to primitive, largebrained,
stone tool-making, meat-eaters that traveled far and
wide. This early part of the human genus is represented by
three species: H. habilis, H. rudolfensis, and H. erectus. H.
habilis is known for retaining primitive features that link it to
australopiths and for being the first stone tool makers. Little is
known about H. rudolfensis except that it had a relatively
large brain and large teeth compared to H. habilis and that it
overlapped in time and space with other early Homo. Our
understanding of the paleobiology and evolution of the largerbrained
H. erectus is enhanced due to its richer fossil record.
H. erectus was the first obligate, fully committed biped, and
with a body adapted for modern striding locomotion, it was
also the first in the human lineage to disperse outside of
Africa. New discoveries controversially hint that the origin of
H. erectus may not have been African, as is the prevailing
hypothesis, and, furthermore, diminutive and primitive hominins
from Flores may be descendants of an even earlier
dispersal of Homo than H. erectus. In spite of all the questions
that remain to be answered about early Homo, these hominins
are the first to tip the scale from the more apish side of our
evolutionary history toward the more human one.
Acknowledgments I am grateful to William Harcourt-Smith for
giving me the opportunity to write this paper and also to Kevin Stacey,
Christopher Bae, and two anonymous reviewers for their help in
improving an earlier version of the manuscript. I am also pleased to be
indebted to Susan Antón, Nina Jablonski, Pat Shipman, and Alan
Walker for sharing their wisdom about early Homo with me.