(urth) Mystery of Ascia

[Gerry Quinn]

From: "Lee Berman" <severiansola at hotmail.com>
>>Gerry Quinn:

>>The Swedes have gained and lost genes over time, and the original pattern 
>>of
>>genes and corresponding traits will never be replaced.  They may turn 
>>black,
>>but they will never be the same *shade* of black.  This is precisely 
>>Dollo's Law in action.
>
> Since this topic is not fiction, it is appropriate to say that you are 
> incorrect. It sounds like
> you are implying that sub-saharan Africans are all the same exact *shade* 
> of black. They aren't.
> so there is no exact shade for Swedes to return to.

Don't be absurd.  Obviously we are simplifying the situation slightly for 
conveniencein discussion, but the fact is that this hypothethical Swedish 
tribe will never recover all the traits of their African ancestors.  They 
will have a unique and probably easily recognisable genotype and phenotype. 
Do you seriously doubt it?


> 50,000 years is a very short time in evolutionary history and for you to 
> claim that Swedes have
> lost genes in that brief moment rather than had them shut off is a 
> ridiculous statement to make
> without doing a full multi-population gene sequencing and comparison of 
> both populations. Nobody
> would waste the time and money to do such a worthless assay but it doesn't 
> matter. Admixture
> would do the trick long before genetic adaptation would kick in.

A full paragraph of obfuscation.  Just to adress the essentially irrelevant 
points before I go on to the relevant matters...  (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. (2) As gene 
sequencing technology becomes cheaper and the information from it becomes 
more pertinent, it is probable that an increasing number of studies will be 
done, unless they are prevented by those opposing the gathering of this type 
of information for whatever reason.  (3) We specified that our hypothethical 
population was isolated so your talk of admixture is irrelevant.

Now to the relevant points.  In the first place, I never claimed that the 
Swedes have necessarily lost genes (although it is almost certain that they 
have).  It may well be that most of the gene changes have been in regulatory 
genes which control genes that directly affect phenotypical traits, and it 
is conceivable - though unlikely - that genes have only been gained but 
never lost..  Even in the unlikely event that all this is the case, genes 
are still genes, and regulatory genes gained or lost are still genes gained 
or lost. .

Even if we pretend (however unlikely) that no genes were lost and only 
regulatory genes gained, and if we pretend that adaptation to a return to 
Africa will strongly favour the lost genes, it is surely quite obvious that 
(in accordance with Dollo's Law) there is no reasonable probability of the 
original pattern being restored.

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. 
If this is so, your case  is completely destroyed.  But even if it isn't, 
you are clearly incorrect.


>>The mechanism of shutting off is completely irrelevant. If a gene is shut 
>>off over many generations
>>it is because another gene has changed, or been lost, or gained.
>
> This is an outdated understanding of genetics and organismal development. 
> Expressed traits are now
> understood to be a function of GRNs (gene regulatory networks). A 
> constellation of genes work in
> concert and there are what might be seen as genetic on/off switches. Your 
> argument is the same as
> saying that once a light switch has been turned off in your house it can 
> never be turned on again.

There is nothing outdated about it - I was simply pointing out that the 
genetic equivalent of light switches over many generations are genes 
themselves.  (Over just a few generations they could be epigenetic factors.) 
If you like, a regulatory network that has evolved over 50000 years is 
itself a complex constellation of genes which will never be recovered by 
natural selection, even if the environment is restored to the environment of 
50000 years ago.


> Check any current website on the subject if you don't believe me. Dollo's 
> Law is currently understood
> as relevant to only to major phylogenetic branchings like different 
> classes of vertebrates or even
> orders of mammals. But certainly not for the minute genetic differences 
> between geographical variants
> of the very same species (like Swedes and Africans). Anyway, as already 
> noted, where admixture is
> possible, Dollo's Law becomes completely irrelevant.

Dollo's Law is clearly generalisable to minor traits.  For all I know there 
may be another name for it in such cases, or it may be that the sites you 
consulted provide an inadequate briefing on the issue; it is irrelevant 
either way.  Admixture is also irrelevant to the hypothesis under 
discussion, although it might indeed be relevant to the issue of "natural 
types of countries" - one could hypothesise that if an invading population 
interbreeds with a native population, the better-adapted native traits will 
tend to predominate. Indeed, this does I suppose provide a rationale for the 
possibility of 'natural country types' in some cases - precisely because it 
provides a mechanism for escaping Dollo's Law.


>>Gravity was discovered before more modern understandings of it were 
>>developed.  Does that mean we should
>>throw away the concept?
>
> This statement really is beneath you. The same sort of blunder as "the sky 
> is blue".

Just because I didn't bother to remonstrate with you doesn't mean I accept 
your assertion that the sky is pink, or green, or whatever colour you claim 
it is.


> But I'll address it
> anyway. Yes, gravity was discovered a long time ago but that understanding 
> is archaic. We now know that
> gravity operates at one level on earth but at very different levels on 
> other planets and negligibly in most
> parts of the universe. Let's not forget black holes. Nor string theory. 
> Dollo's Law has been updated in its
> application just like the Law Of Gravity.

But apples still fall, and Dollo's Law still applies.  Modern theories may 
explain them better, but the realitry remains as it always was.  The 
ancients knew nothing about how the scattering of electromagnetic radiation 
by dust particles is affected by wavelength, yet they could see that the sky 
is blue.  And that apples fall.  Dollo's Law is an observation of more 
recent times, but none the less eternally true for that, so long as the 
biological world to which it applies persists.

- Gerry Quinn