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Re: Missing Link (was Human Chimp Gorilla)
Timo Niroma (timo.niroma@tilmari.pp.fi)
7 Jul 1996 11:51:54 GMT
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In article <4rlhgq$n7g@newsbf02.news.aol.com>, kenb100231@aol.com
(KenB100231) says:
>
>This discussion of the difference between human chips and 2% variance
>between us and them has been absolutely fascinating. I enjoyed the
>discussion. Thanks for the info.
>
>I would like your thoughts on the so called "missing link". That has
>always interested me. Was R. Leakey correct? Is Johansen correct? Is
>Lucy the missing part of the evolutionary puzzle or will they find
>something older.
>
>Ken Basche
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There is no missing link any more. There has for some time been an
agreement about the fact that the common ancestor of humans and
chimpanzees lived about 5-6 million years ago. The newest DNA analysis
has put the time of divergence a little more recent, to some 4.5
million years ago, when australopithecines began to appear and
chimpanzees clearly went their own way.
There is a great variety of australopithecines and the question today
is, which one of these is "the missing link", because instead of a
missing link there are several possibilities. There were Australopithe
cus aethiopicus, afarensis (Lucy, 3.2 million years old, is one of
these), africanus, bahrelghazeli (the only one found west from the
Great Rift Valley so far), boisei, ramidus and robustus, in alphabethi
cal order. And it is pretty certain that there still are some to be
found and some that never will be.
Afarensis has for a time been regarded as "the missing link", the
species that developed into Homo. Ramidus is today, however, considered
the oldest one, 4.4 million years, and thus "the missing link". One
australopithecine lineage, be it the ramidus or some close relative to
it, developed into Homo habilis about 2.5 million years ago.
Australopithecines died out one after another and the last one around
one million years ago.
Homo habilis was followed by Homo erectus very soon, already about 2
million years ago. Homo erectus was very successful. It was the first
Homo, who went out of Africa, to Europe and Asia. Some 300,000 years
ago Homo erectus developed into archaic Homo sapiens and possibly lived
some time with it. 200,000 years ago Homo erectus was gone, and in
Europe was emerging the Neandertals. Whether they were the descendants
of archaic Homo sapiens, Homo sapiens neanderthalensis or Homo erectus,
Homo erectus neandertalensis, or may be better Homo neanderthalensis,
we don't know for sure, but Homo sapiens neanderthalensis is today
generally accepted (which does not mean the last word in this issue).
About 120,000 years ago the archaic Homo sapiens began gradually
develop into more modern Homo sapiens sapiens. It went out of Africa
about that time (during the Eemian interglacial) and through Middle
East it went to Asia and reached China and Southeast Asia sometimes
before 60,000 years ago. Into Europe they went later, between 40,000
to 35,000 years ago. The Neanderthals vanished (why, is not clearly
understood yet, but there couldn't be niche to both human species and
the weaker (in some way or the other) had to die out.) The last remains
of a Neanderthal are found near Gibraltar and dated as 33,000 years
old. The question of the habitation of the Americas is not yet settled,
far from it. There are many investigations going on that hint that Homo
sapiens lived in South(!) America already 35,000-40,000 years ago, but
the "official view" is still that Homo sapiens came to (North) America
only 14,000-15,000 years ago.
Timo
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