Evolution And History

140 CHAPTER 6 | Macroevolution and the Early Primates

Miocene Apes and

Human Origins

As described above, determining which Miocene apes were

directly ancestral to humans is one of the key questions in

primate evolution. Molecular evidence directs our attention

to Africa between 5 and 8 mya (Figure 6.8). Though any

fossil discoveries in Africa from this critical time period

that it indicates that the gorilla lineage had become dis-

tinct 2 to 4 million years earlier than that. The species is

called Chororapithecus abyssinicus, after Chorora, the local

area where the fossil was found, and Abyssinia, the ancient

name of Ethiopia. While Ethiopia has been the home for

numerous spectacular fossil specimens that are part of the

human lineage, this is the first fossil ape discovery from

this region. Other scientists do not concur, however, and

feel more fossil evidence is warranted before pushing back

the timing of the split.

Millions of years ago

0

5

10

15

20

25

30

35

40

45

OLIGOCENE

MIOCENE

Aegyptopithecus

Proconsul

Sivapithecus

Baboons Macaques Cercopithecus Presbytis Colobus Gibbon-

Siamang

Orangutan Gorilla ChimpanzeeHomo

CERCOPITHECOIDS HOMINOIDS

CATARRHINI

Orrorin

tugenensis?

Sahelanthropus

tchadensis?

(Toumai)

Chororapithecus

abyssinicus?

Australo-

pithecus

Figure 6.8 Although debate continues over details, this chart represents a reasonable

reconstruction of evolutionary relationships among the Old World anthropoid primates. (Extinct

evolutionary lines are not shown.) The 2007 discovery of a fossil ancestor to gorillas has suggested a

new interpretation of the timing and nature of the split between humans and the African apes.

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