There’s no question that the later stages of human
evolution, from about 40 million years ago (mya), took place in Africa.
However, primitive primates from before that time have been found in Asia, not
in Africa, leading anthropologists to conclude that Asia is the original cradle
of all hominins. At some point, early primates migrated from Asia to Africa
(quite a trek if you consider that at that time there was a large sea
separating the two continents). Researchers from Thailand, Myanmar, France and
the U.S., led by Jean-Jacques Jaeger of the Université de Poitiers, discovered
a new fossil primate (Afrasia djijidae)
that sheds light on when that might have occurred.
The oldest well-documented African anthropoid fossils (Afrotarsius libycus)
are found in North Africa and date from 38 to 39 mya. There is no record of
primates in Africa from before that time. Meanwhile, A. djijidae
was found in Myanmar and dates from about 37 mya. The two creatures are remarkably
similar, although the Asian A. djijidae has slightly more primitive teeth. This strongly
suggests that primates first arrived on the shores of Africa just under 40 mya.
From there, they evolved into a variety of hominins that eventually included Homo
sapiens.
Only four A. djijidae upper molars have been discovered thus far, and it
took six field seasons of sifting through tons of sediment just to find those.
This might not seem like much to go on, but you’d be surprised how much a
paleontologist can learn from teeth. The authors give a two-page description
detailing every facet and angle of the molars.
Below, you can see fossil molars from the two primates
superimposed on a map of the region at that time. Note the Tethys Sea dividing
Africa from Eurasia.
Striking morphological resemblance
between the right upper molars of the
Asian Afrasia djijidae and the contemporaneous African
Afrotarsius libycus supports an Asia-to-Africa anthropoid dispersal during the
middle Eocene. The regions where the two taxa were discovered are positioned on
a paleogeographic map of the Old World during the late Eocene (35 mya).
By the way, the name ‘djijidae’ was chosen in memory of a young girl from the village near where the
teeth were found. I think that’s rather nice.
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