The PNAS article on ancient Australians is now available with commentaries
also:
http://www.pnas.org/cgi/content/full/98/2/537
Jim Hofmann
-----Original Message-----
From: Glenn Morton
To: Asa@Calvin. Edu
Sent: 1/13/01 10:00 AM
Subject: That embarassing relative: More on Mungo Man
This week's New Scientist has some interesting comments on the
implications
of Mungo man's mtDNA being from ancient people.
"According to Thorne, the findings-due to be published next week
in the
online edition of the Proceedings of the National Academy of
Sciences-threaten to topple the leading theory of human origins, the
'out-of-Africa' model. This proposes that all living people are
descended
from a group of modern Homo sapiens who left Africa roughly 100,000 to
150,000 years ago. Their descendants spread around the world replacing
existing populations of 'archaic' people, such as Neanderthals and the
more
ancient Homo erectus."
"But if anatomically modern humans-from a lineage that emerged
before the
most recent common ancestor of people today-were living in Australia
60,000
years ago, 'a simplistic out-of Africa model is no longer tenable', says
Thorne." Leigh Dayton, "The Man From Down Under," New Scientist,
169(Jan,
13, 2001):2273:6
What the mtDNA evidence proves is that there was interbreeding between
archaic types of Homo and anatomically modern people. There is no way
that
the guy could have gotten the ancient mtDNA without that interbreeding.
Interestingly, one of the press reports says that the Kow Swamp
individual,
which dates to aroudn 13,000 years old also showed hints of being from
an
early diverging lineage of mtDNA but that the authors weren't quite
confident enough in the data.
(see
http://news.com.au/common/story_page/0,4057,1590695%255E11011,00.html)
This same report notes that Thorne's data demonstrates interbreeding
with
archaic populations (and thus the production of fertile offspring):
"In a nutshell, their Regional Continuity model agrees that, yes,
archaic
people began migrating out of Africa about 1.5 million years ago. But
instead of being supplanted by new, improved humans -- who went on to
colonise the planet -- those first "almost" people continued, together,
down
the evolutionary path to full human status. They did this with a little
hanky-panky -- that is, by interbreeding with one another. Eventually,
we
evolved from them ... or so the theory goes." (see
http://news.com.au/common/story_page/0,4057,1590695%255E11011,00.html)
In an article last year, Relethford and Jorde commented on the status
of
genetic evidence concerning the much maligned multiregional view of
human
origins. They wrote:
"What conclusions can be made at this point? We feel that the
genetic
evidence in the present study and elsewhere argues for a dominant role
of
Africa in the origin of modern humans. It is less clear, however,
whether
only Africa was involved in the transition from archaic to modern
humans; it
seems possible that there has been some non-African admixture." John H.
Relethford and Lynn B. Jorde, "Genetic Evidence for Larger African
Population Size During Recent Human Evolution," American Journal of
Physical
Anthropology, 108(1999):251-260, p. 258
**
The multiregional model is frequently portrayed as postulating genetic
input
from all major geographic regions and further requiring that genetic
input
be greatest within each region. This portrayal is incorrect. In the
most
general sense, multiregional evolution requires only that there be some
genetic input from outside of Africa, not necessarily from all regions
outside of Africa." John H. Relethford and Lynn B. Jorde, "Genetic
Evidence
for Larger African Population Size During Recent Human Evolution,"
American
Journal of Physical Anthropology, 108(1999):251-260, p. 258
Thus, the much maligned multiregionalism is maligned for merely
believing
that there was genetic admixture which is another term for
interbreeding.
One report notes that the mtDNA of one of Lake Mungo man's ancestors may
have been inserted into modern humans long, long ago.
"But not only was LM3's mtDNA totally unknown to science, it contained
another breathtaking surprise for the researchers. They noticed that a
small
bit of his mtDNA resembled a so-called "insert", a tiny stretch of bases
often found on chromosome 11 in the nuclear DNA of contemporary people.
"
"Previous studies of the prevalence and distribution of the
peculiar
sequence, done by other scientists, had suggested that the insert was a
relic, deep from our evolutionary past. It must be quite old, they
estimated, older than the most recent common ancestor of all living
people.
Yet no one knew just how old, or where the genetic relic came from. Had
the
Australians, purely by chance, stumbled upon the source of the
mysterious
insert?
"It's quite possible, says team member Simon Easteal, an
evolutionary
geneticist at ANU's John Curtin School of Medical Research.
" 'The sequence from LM3 is related to the insert,' he says.
"'This suggests that someone related to LM3 was the source of
the insert,
which moved into the nuclear DNA of another person at some point in
time. We
can't say where that first person lived, probably in Asia, New Guinea,
or
possibly Australia.' "(see
http://news.com.au/common/story_page/0,4057,1590695%255E11011,00.html)
Thus, we find that an ancient mtDNA was inserted into the nuclear DNA of
some humans. In order for it to be inserted, it had to have been in
their
bodies. Lake Mungo man shows where it came from. But, if this mtDNA was
in
Asia prior to the arrival of anatomically modern men, what ancient
hominid
could it have come from? H. erectus or the transitional form, archaic
Homo
sapiens are the only possibilities. Both of these are not anatomically
modern. Unfortunately for those who wish to maintain the concept that we
couldn't have interbred with H. erectus, the only known 60,000 year plus
fossils found in Southeast Asia are H. erectus. This includes the
38,000
year old Ngandong H. erectus. The earliest anatomically modern human
found
in Southeast Asia/Australia is Mungo man. Where did he get his mtDNA?
Probably from H. erectus. This again, is another piece of evidence that
there was interbreeding with creatures, possibly with H. erectus, that
apologists don't want to admit into the family. We are embarassed by the
concept that we might be directly ancestral to some of these primitive
types. THey are our crazy, embarassing relative. But if there was
interbreeding, then H. erectus was us. He was HUMAN--i.e., that he was
both
part of our ancestry and part of our present day genes. And if H.
erectus
was part of our ancestry, then what is the big deal about the more
modern
Neanderthal? Alan Mann said it very well to New Scientist:
"The DNA, which is the oldest ever recovered from human remains,
shows that
while the man is completely anatomically modern, he came from a genetic
lineage that is now extinct. This finding challenges the prevailing
theory
that all modern humans are descended from a group of people who migrated
from Africa around 100,000 years ago. 'It's remarkable-totally
unpredicted,'
says anthropologist Alan Mann of the University of Pennsylvania. 'What
it
says is that the more we know [about human origins], the more confusing
the
picture becomes.'" Leigh Dayton, "The Man From Down Under," New
Scientist,
169(Jan, 13, 2001):2273:6
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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