From: wismith@amelia.nas.nasa.gov (William R. Smith)
Subject: Pliestocene extinctions
Organization: NAS, NASA Ames Research Center, Moffett Field, CA
Date: Thu, 27 Aug 92 16:45:24 GMT
Distribution: na

Bear Giles writes...
	 
	Humans enter Europe and virtually all other large predators
	are eliminated.  Saber-tooth tigers, extinct.  Cave bears, extinct.



Scott I. Chase writes:
	
	I'm not convinced.  In the Americas, Saber-tooth tigers and other
	large carnivores underwent a rather sudden extinction around
	something like 50K years ago.  Meanwhile, the earliest human remains
	are roughly 25K years old.  I have been able to verify the human
	data (it's "Los Angeles Man") but not the timing of the extinction. 
	But if my numbers are correct, then these animals died out on their
	own, with no assist from us, at least on this continent.
	
	Anybody out there with some real knowledge?



The Pliestocene North American megafauna went extict around 12,000 years
ago at the end of the last major glaciation.  This is also the approximate
date that many believe was when humans first entered North American
excluding the Bering Strait area.  Several years ago Martin (sorry, I forgot
his first name) suggested rather strongly that humans were responsible
for the extictions of Mammoth, Mastodons, Saber Tooth Tigers, Giant
Ground Sloths, and the rest of the megafauna, not only in North America, but
South America as well.  There are elaborate calculations about how fast humans
would have to migrate to South America to kill off all the animals.

Larry Agerbaund (I think it was him, and I know I bungled his last name, as
I'm away from my reference books) wrote that since Martin's article the
discussion has divided into two camps and almost all articles in the middle
ground or describing multiple causes have disappeared.  There is another
whole camp that believes that humans were in North America prior to the
last glacation, but "hard evidence" is slow to be accepted.  Their estimates
for the arrival are from 17,000 years ago to 40,000 years ago depending on
who is doing the arguing.

Some linguists are now active in working on the problem of dating the
peopling of the Americas.  One of the best I've seen is by a linguist at
Univ. of Kansas (who's name I don't have at hand).  He's published
jointly with Larry Martin (not the Martin of the human agent of extinction
theory mentioned above), a paleontologist also at Univ of Kansas.  Their
collaboration began when Martin's linguist friend noticed Martin working
on a map of North America and wanted to know why Martin was drawing a
distribution map of native N. American languages.  Martin said that wasn't
what it was at all, but was a map of distribution of Pliestocene fauna and
the environment that supported them.  They have published at least one paper
jointly and several separately describing the distribution of languages
and fauna.

The linguistist argument have to do with diversity being a function of
time.  The older a language is the more dialects and eventually separate
languages it will spawn.  Language diversity in N. America is least in
the areas covered with ice in the last glaciation and greatest along the
Pacific Northwest Coast and the area near what is now New York and
Pennsylvania.  Moderate diversity occurs in the Southeast and Southwest. 
As the ice sheets retreated, as the argument goes, the people moved into
newly opened territory from the adjacent areas taking their language with
them.

There is also a correlation with where the languages were during the
glacation and where they ended up after the glacation that maps extremely
well with how the environments changed at the end of the ice age.  People
who were adapted to a southern forest environment moved along with
the southern forests as it spread into new areas as the climate changed.
Same story for northern forests dwellers and plains people.  The great plains
as we think of them didn't exist during the glacation, nor did the great
basin deserts.  If I remember correctly, these were spruce forests.

I'm not an expert, but an interested spectator.  I apologize for the lack
of references, but I'm working 700 miles form my home where my library
is.


William Smith
Intel, SSD