—— 
Fig. 2. Upper dentition of Australopithecus afarensis (AL 400-1la) from Hadar, 
Ethiopia. About 3.4 myr old. Scale is 1 cm. 
knee joint. Humans were up and walking on their hind legs by about 
4.2 million years ago. 
This is not something we can tell with any certainty from evi- 
dence so far reported for the earliest claimant of all to hominid 
(human-family) status: an equally fragmentary form from Ethiopia 
that rejoices in the name of Ardipithecus ramidus (White et al. 
1994). Much less like later hominids than A. anamensis is, the main 
importance of A. ramidus is to remind us that from the very begin- 
ning, hominid history has been one of evolutionary experimentation, 
for it represents at best a side branch on the human evolutionary 
tree. Homo sapiens is the exception, rather than the rule, in being 
the lone hominid on Earth. It is useful to keep this in mind as we 
look at the human fossil record since, while there is something in- 
herently linear in any form of story-telling, linearity is not in fact a 
strong signal in human phylogeny. 
Australopithecus afarensis (fig. 2) is the first well-documented 
hominid known, including in its ranks such stars as ““Lucy,’’ who 
