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tomk80
SFN Regular
Netherlands
1278 Posts |
 Posted - 06/25/2008 : 01:22:25 [Permalink]
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Originally posted by Dave W.
Originally posted by tomk80
Perhaps in that sense one could argue that some people are genetically inferior, for example in the case of people with severe mental or physical handicaps? So severe that they will not have offspring, nor contribute to society? |
Well, really, in from an evolutionary viewpoint, your "success" doesn't depend upon you having kids, but on your kids having kids. A stallion that breeds with a hundred donkeys, all of whom bear young, wouldn't be considered "successful" because while wildly prodigious, his foals would almost certainly all be sterile themselves. Lots of mating with no grandchildren is a biological failure. So the "bad genes" in your examples would likely belong to the parents, not the mentally or physically handicapped kids. |
Correct, but that would depend on whether the parents have other, non-handicapped kids. This is the reason why I chose the kid, instead of the parents. You cannot base your 'estimate' of the reproductive fitness of the parents on a single kid.
| But more to the point, mental and physical handicaps can result from either genetic causes or developmental causes (fetal alcohol syndrome, for example), and who is to say without screening which is which in any particular case? As a parent, I could see a benefit in having a handicapped child tested to learn whether or not the same problems would be likely to present in another child conceived later due to genetic causes (or if it were just a developmental mishap), but certainly that's a personal issue and there's no way in hell I would ever mandate such a thing. |
True, I was going from the assumption of a handicap with a clear genetic cause. |
Tom
`Contrariwise,' continued Tweedledee, `if it was so, it might be; and if it were so, it would be; but as it isn't, it ain't. That's logic.'
-Through the Looking Glass by Lewis Caroll- |
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Simon
SFN Regular
USA
1992 Posts |
Posted - 06/25/2008 : 07:03:40 [Permalink]
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In many cases, genes for genetic disease are only problematic if both chromosomes carry the faulty allele (homozygote).
So, disease only happens if a heterozygote parent mate with another such carrier.
And then, they only have a one in four chance to produce a disabled offspring. And one in four for the offspring not to carry the disabling gene at all.
The toll of an genetic disease is actually quite limited from a fitness point of view.
Not to mention that some of these are actually beneficial when carried heterozygotly. |
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Carl Sagan - 1996 |
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Darwin + Hitler = Baloney
