Out of Africa: another mistake, this time by me

Keith Robison robison at mito.harvard.edu
Mon Nov 18 23:00:11 EST 1991


arlin at ac.dal.ca writes:

>...Correcting this error does 
>not change the assignments for the most parsimonious solution, nor does
>it alter the force of my argument: 12 "migrations" are needed for the
>out-of-Africa hypothesis and 14 "migrations" for the out-of-not-Africa
>hypothesis.

>Keith was astute in noting my mistake, but then miscontrues its import:
> 
>In article <robison.690432470 at ribo>, robison at ribo.harvard.edu (Keith Robison) writes:
>> However, by doing so you have
>> won your argument in a way O.Henry would love -- you have constructed an
>> alternative scenario in which the root of the tree is not in Africa but
>> in which all paths through the tree at one time pass through Africa. 
>> Put another way, under such a scenario the common ancestor of all humans
>> was not African, but all humans have an African ancestor.
>> 

>Yes, Keith, the most parsimonious solution for the out-of-not-Africa
>hypothesis is such that all paths from the root to an external node pass 
>through the character state "africa."  This is not a clear indication that
>the out-of-not-Africa hypothesis is less parsimonious than the out-of-Africa
>hypothesis: parsimony evaluates a hypothesis, not according to whether one
>finds it humorous or not, but according to the minimum number of evolutionary
>events necessary to explain a distribution of character states under the 
>hypothesis...According to parsimony, the out-of-not-africa 
>hypothesis is only 14/12ths more humorous than the out-of-africa hypothesis.

>Arlin Stoltzfus
>Arlin at ac.dal.ca


I never meant to imply that hypotheses should be accepted or rejected based
on the associated humor value (Hmm.  I wonder if anyone has looked at this..),
in fact I find this idea pretty funny in itself.  All I was trying to do
was emphasize that you have constructed an alternative to the African ancestor
hypothesis by constructing an African ancestor hypothesis. 


(Please don't point out the difference between the hypotheses -- it 
 simultaneously ruins the humor and insults my intelligence).



Anyway, did anyone else catch the reference to African origins on tonight's
"Northern Exposure"?  (I know, this is totally irrelevant).



Keith Robison
Harvard University
Program in Biochemistry, Molecular, Cellular, and Developmental Biology

robison at nucleus.harvard.edu



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