On 23/11/2006, at 8:56 PM, Alberto Monteiro wrote:
Ronn!Blankenship wrote:
Surprising result about human DNA:
<<http://news.independent.co.uk/world/science_technology/
article2007490.ece>>
How serious is this? My skeptic filter brings a question: if
this were true, it would make inter-racial marriages _less_
fertile than incestuous marriages, because chromossomes
with different gene configurations would be harder to pair
up.
Not so much. What's being discovered over the last decade or so is
that the system is prone to some pretty spectacular errors, but the
ways in which it can still produce a viable and often fertile
organism. In about 1/900 people, for example, a chromosomal fusion
occurs that actually changes the total chromosome number (a
Robertsonian translocation), and while some forms of this result in
an abnormality like trisomy 21 (Down's syndrome), if there's no
deletion or duplication of material, then the individual may suffer
no adverse symptoms.
In fact, it is precisely one of these translocations that provides
clear evidence for the chimpanzee/human relationship, where our
chromosome 2 is a fusion of material that is 2 chromosomes in chimps
(there's even the remnants of a centromere in there...).
So I doubt that the fertility issue is a serious one, and even
decreased fertility in F1 of a "mixed marriage" would probably be
compensated for by hybrid vigour in supsequent generations.
Charlie
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