Mystery of Ascia

Lee Berman · 22 Jan 2011, 13:11 · from 2011-January.txt.gz

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From: severiansola at hotmail.com (Lee Berman)
Date: Sat, 22 Jan 2011 08:11:24 -0500
Subject: (urth) Mystery of Ascia
Message-ID: <SNT123-W390C07B32E242BB61C3B27CFFB0 at phx.gbl>

Gerry, I just can't maintain that tone you prefer to communicate in for 
paragraph after paragraph. So I'll just gently mention a few corrections
of your last post for whomever might be following then let it drop.

>(1) 50000 years or 2000 generations is in fact a quite substantial time 
>in human evolutionary history, and it is rather obvious that significant 
>genetic changes have taken place in human populations over such timescales.

The sort of evolutionary change from which Dollo's Law was formulated takes 10's 
of millions of years. Humans and chimpanzees share 98% of the same genetic code. 
This amount of change is currently estimated to have taken around 18 million years.

The huge amount of genetic difference many people assume exist among modern
Homo sapiens sapiens is largely an illusion perpetrated by dietary and other 
environmental differences, clothing and hair style differences, and a xenophobic
bias which pushes us to exaggerate visual differences, probably an ancient
tribal recognition trait.

Swedes and Africans were not genetically separated for 50,000 and thus are even 
closer than the 99.998% similarity that time frame suggests. Walking seems like
slow transportation but given thousands of years it works quite well to provide a
genetic continuity across our entire species. And anywhere you can walk or boat,
you can walk or boat back. 

Some think of Swedes as "pale skinned, blonde and blue eyed" but the majority are 
not of this stereotype. Genes for dark coloration remain fully available there.

As a thought experiment, let's pretend an experimenter grabbed a random sample of 
1000 babies from the different races and sub-races around the globe that people (though
not scientists) say they recognize. All those babies are raised in an isolated commune 
with the same diet, sunlight exposure, clothing, hairstyle etc. As adults, this commune 
would not have recognizable "races". It would demonstrate a single species with slight 
gradations of diversity, which is what the world population of humanity is, from a 
genetic perspective. It is only when you focus exclusively on extremes and ignore 
gradations and environmental and cultural differences that genetic "races" can be 
"clearly" identified.

>In fact, even if we ignore genetic drift within Homo Sapiens lineages, 
>current thinking is that 1-4% of the genetic heritage of European and Asian 
>populations come from outcrossing with the subspecies Homo Neanderthalensis. 

There has been much debate in the past 50 years but the current majority opinion is that
Homo neanderthalensis (proper nomenclature= genus capitalized, species lower-case)
was, as that name implies, a different species than Homo sapiens sapiens. Meaning
there was no interbreeding. Neanderthals originated in Africa then spread out as far
as Europe. Later, Homo sapiens evolved in Africa and spread out even further.

It is just hypothesis. There is no way to know, without experimentation, whether Homo sapiens 
and neanderthals 1. could not produce offspring (like humans and chimps)* or 2. could only 
produce sterile mules (like horses and donkeys) or 3. actually could interbreed with viable 
offspring. 

It doesn't matter. If "neanderthal genes" are present in the Homo sapiens gene pool they 
have been spread across our species, not concentrated in Europe or something like that.
In the real world of the human species you can't ignore admixture. It part of who we are.
We see "races" through a current snapshot of humanity around the globe. But 10,000 years 
ago that snapshot would have looked a lot different. In 10,000 years that snapshot will
look very different again. These differences will have occurred without significant genetic 
changes. 

The occasional (might be 1 in 10 million) dark baby born to light parents in Sweden or pale
baby born to dark parents in Africa and the even rarer occasion of a baby born with a tail 
demonstrates that the genetic potential of our ancestors remains in our genome, waiting to
be turned on, whether by accident, or perhaps someday, by necessity.

*(the main reason humans and chimps cannot interbreed is not genetic dissimilarity but chromosomal
differences [different number]. I don't know if it has ever been tried but if these species 
attempted to interbreed, the chromosomes would not match up properly during fertilization to allow 
a viable embryo to form)

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