Out of Africa: refuted arguments repeated by Jones

Jones Maxime Murphy morphy at cco.caltech.edu
Thu Nov 21 16:46:32 EST 1991


arlin at ac.dal.ca writes:


>1.  relative likelihoods of out-of-Africa and out-of-Eurasia
>hypotheses for explaining *mtDNA* origins.

>In article <1991Nov19.224202.7072 at cco.caltech.edu>,morphy at cco.caltech.edu 
>(Jones)  quotes Larry Moran and responds:

>>>This is an interesting point but I don't see why it is relevant. Let's assume
>>>that Homo sapiens sapiens arose in Eurasia . . .
>>
>>This is simply far less likely than the scenario suggested by the data. Why
>>must we bend over backwards to avoid the conclusion that afrogenesis is the
>>most likely hypothesis?

>Keith Robison made a statement similar to that of Jones (without the
>"why must we bend over" insulting part) earlier this week, and Jones
>should read the objections to that statement before making it
>again.  The out-of-Eurasia scenario is not "far less likely" when one
>uses parsimony to calculate the minimum number of migrations given the
>mtDNA tree of Vigilant, et al (1991).  Rather than being "far less
>likely", the out-of-Eurasia scenario is only *slightly* less likely.

Poppycock. Each extra migration severely damages out-of-Eurasia. The difficulty
of overland transportation at that time makes these monstrous odesseys highly
improbable. Every additional one required is a significant blow to the theory,
and it is misleading to suggest otherwise.

There is a more critical point to be made, however. Why the extra journeys
specifically back to Africa? South I can understand, if only because of a strong
desire to go to the beach in January. But why Africa, in preference to the huge
southern area of Eurasia? Once again, eh journey to Africa in preference to
some other warm spot takes a big bite out of the eurogenitic theory.
 
>This difference in the likelihood of the two scenarios loses its force
>when one considers that a) the tree and its rooting have undetermined
>statistical likelihoods,

All we have here is competitive plausibility. I don't agree that the eurogenetic
hypothesis is as plausible. You have certainly not made a convincing case here
for it.

> and b) the applicability of the parsimony
>method can be questioned on theoretical and empirical grounds.  A 
>separate issue that I will address in a future posting is that the
>question of *mtDNA* origin is not the same as the question of gene-pool
>origin, nor is it the same as the question of species origin.

The applicability of the parsimony method can be questioned, no doubt. So can
any number of other techniques. Once again, we're dealing with competitive
plausibility, not mathematical demonstrations. What more plausible alternative
can you offer?

>2. Confusion about time frame involved.

>Jones continues, quoting Larry and then responding:

>>The penultimate statement is a matter of recorded history. There was a huge
>>influx of Arabs into North Africa and the Horn during the explosive growth of
>>Islam. A similar dispersal of Jews also took place across North Africa. This
>>is not speculation, unlike the migrations required by the eurogenetic theory.

>The comments are irrelevant.  Most of the migration events necessary
>to explain the mtDNA tree probably occurred in excess of 20,000 years
>ago, and thus are not part of recorded history (divergence in the
>mtDNA lineages appears to have occurred over a span of 200,000 years).
>The high mobility of recent humans may be a poor indicator of their
>past mobility.

Whoa! The current locus of the people whose mtDNA is being sampled plays a
critical part in determining migration patterns! How on earth do you argue that
recent mass migrations and large-scale miscegenation cannot confound attempts
to reconstruct more ancient migrations? The massive and widespread Arab diaspora
from Kenya to Mauretania must surely have significantly perturbed the gene pool.

>3.  Extreme confusion about hominoid history.  Jones has the same
>confusions about hominoids that other correspondents displayed last
>week, as he shows in his response to Larry:

>>That's bull. The molecular data strengthens that assertion(not assumption!). It
>>shows the the closest living relatives of homo are genera found only in Africa.
>>If that is not strengthening afrogenesis, what is?
>>Jones

>As I pointed out several days ago, the properties of the closest
>living relatives of _homo sapiens_ would only be relevant to the
>question of human origins if there were no paleontological evidence
>about *extinct* close relatives or ancestors of _homo sapiens_ that
>were already distinct from _pan_ (chimp) and _gorilla_.  Early
>representatives of the genus _homo_ (_habilis_ and _erectus_) arose
>(about 2-3 MYA) in Africa from the australopithecines, which are
>limited to South-Central Africa and thus are thought to have arisen
>there (about 4 MYA). However, this is entirely irrelevant to our
>present discussion, since the genus _homo_ distributed itself widely
>BEFORE _homo sapiens_ became a prominent part of the fossil record:
>that is, _homo erectus_ spread over Eurasia from
>mediterranean europe to the far east about 0.5 to 1 MYA (ever heard of
>"Java man"?).  If we take _homo erectus_ to be the most likely
>candidate for the species giving rise to _sapiens_, then Eurasia and
>Africa are both candidates for the geographic location of this origin.

Your pedantic lecture is unnecessary. I was questioning Larry's sneering at
the rooting of the tree. He appeared to question even the afrogenesis of 
the genus homo, and that is what I responded to.

>To repeat this point one more time: _h. erectus_ arose in africa,
>spread itself throughout Africa, Southern Europe, and Asia, and
>eventually gave rise to _h. sapiens_ (somewhere).  That the chimp and
>gorilla, distant cousins of the world-exploring _h. erectus_, were home-bodies
>who never left Africa is a matter of no significance to the question at
>hand, which is the origin of _h. sapiens_ from _h. erectus_.

Correct but gratuitous.

>Jones also shows a disturbing inability to distinguish arguments from
>insults:

>You say you are a physicist, Jones, but I still think it would help
>for you to investigate a little bit about how scientists work and what
>science is.  This would help you to distinguish statements that can be
>evaluated on logical or factual grounds (such as "the data don't refute
>hypothesis X, nor do they appear to support it strongly") from _ad
>hominem_ arguments (such as "your statements are to me reminiscent of
>statements made in the past by persons with questionable motives,
>therefore they are irrelevant," an attempt at guilt by association).

You have failed miserably to make any arguments other than special pleadings
about the competitive plausibility of eurogenesis not yet being completely 
blown away.

In a situation where competitive plausibility is all that is available, bias
becomes a critical variable, expecially when there is racial exclusivity in
the community doing the investigation. Your reference to "in the past" is 
signally misleading. Questionable motives are to be expected if one community
is trying to justify, say, its monopoly on jobs in biochemical research.

>If you just want to make _ad hominem_ arguments, that's your business,
>but please do the rest of us a favor and include the word "flame" in
>the title of any similar future posting that includes mainly
>non-scientific arguments, so that we can ignore them if we so choose.
>An inability to distinguish between these modes of discourse would be
>a serious problem should you choose to continue in science.

Your arrogance is amusing. I am far more of a scientist than you will ever be,
my patronizing friend. Even as I perform quantum-mechanical calculations that
compel me to abandon the notion of an objective observer, I chuckle at the
crudely positivist attitudes of "scientists" like you.
Jones
-- 
:)



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