Over the past year and a half some very old hominid fossils have been found
dating back to nearly 6 million years or more. A. ramidus kadabba has been
found in Ethiopia dating to between 5.2 and 5.8 million years and Orrorin
tugensensis has been found in Kenya dating to between 5.7 and 5.9 million
years. Another possible hominid has been found in sediments dating older
than 6 million years in the Djourab Desert in Chad. (see In Search of the
First Hominids, Science feb 15, 2002, pp1214-1219).
Given that one of the current calibration points for molecular genetics is
the chimp-human split which had been believed to exist between 5 and 6.5
million years ago, the discovery of hominids that old, which are already on
separate evolutionary trajectories, have raised questions about whether or
not the molecular clock needs to be re-calibrated. If a recalibration comes
about, it will have serious implications for current assessments of
anthropology by various apologists.
First, it will slow down the rate of mutation, meaning that fewer
nucleotides will have changed per million years. This will have the effect
of moving Eve further back in time; how far depending upon how slow it
becomes. Since the earliest anatomically modern fossils are around 110-120
kyr and current molecular data places the earliest hominids about 150 kyr,
there is a good fit. But if the molecular data then points to an even
earlier time, then the mitochondrial Eve will no longer be able to be called
an anatomically modern human. She will be an archaic Homo sapien. At least
one geneticist is already claiming that the chimp human split was between
10.5 to 13.5 million years ago (see New Fossils Raise Molecular Questions,
Science Feb 15, 2002, p. 1217). If this guy is correct, this would double
the time and halve the rate of evolution. In this case mitochondrial Eve
would be dated at 300 kyr, and the oldest coalescence date for nuclear genes
would indicate that part of our genetic heritage has been evolving for 4
million years. Apologists like Hugh Ross, would definitely be affected by a
change in the mutation rate.
glenn
see http://www.glenn.morton.btinternet.co.uk/dmd.htm
for lots of creation/evolution information
anthropology/geology/paleontology/theology\
personal stories of struggle
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