Kevin Dorner

Someone started a thread a while back, which I cannot now find, asking for information on confirmed beneficial mutations in humans. The only one I can remember in reply was the best-known: sickle-cell anemia, which is a disease in and of itself, but confers great resistance to the fatal disease malaria.

This was just published today: <a href="http://www.msnbc.com/news/687044.asp?0dm=C1AWN&cp1=1" target="_blank">Lactose tolerance is a mutation</a> meaning that the lactose intolerance allele is the "normal" one.

LianaLi

I've got one wisdom tooth instead of the normal four or so. So no trips for removal for me! Every three people out of one hundred has one or less wisdom tooth.

Of course, I forgot where I read that statistic.

-Liana

kwigibo

maybe a little OT, but isn't there a figure that like, 1 person in a hundred is immune to HIV. I think the ratio was a little higher, but to be safe. There was genetic research into this phenomenon, but it was halted by one of those 'ethics comittees', i guess it's ethical to let more people die . BTW, my info in this area is a little dated, anyone know of this and have recent info?

RufusAtticus

There are a few genes/alleles now known to provide resistance to HIV infection. The most well known is the CCR5 gene, which one in one hundred Caucasions carry. Mutations in this gene affect the protein that HIV binds to to invade a T-Cell. If the protein is malformed, present in low quanities, or completely absent HIV infection is slowed down or even prevented. There is evidence that this allele might have evolved in responce to another epidemic. The black death was first suggested, but the timing is wrong.

I think this page has some info. (I don't know how up to date it is though)

<a href="http://student.biology.arizona.edu/honors97/group12/nojava/aids1.htm" target="_blank">http://student.biology.arizona.edu/honors97/group12/nojava/aids1.htm</a>

-RvFvS

Quetzal

Zimmer talks about the HIV - plague connection in "Evolution - The Triumph of an Idea". Apparently the mechanisms used by the plague bacillus are similar to that used by HIV. I think he concluded that there would be at best a limited immunity that tended to slow the onset, rather than provide actual immunity. We're talking "similar" not "identical".

Jack the Bodiless

Some people (I don't remember how many) are unaffected by CS gas.

So, if the police get into the habit of shooting helpless rioters after gassing them, "super-rioters" will evolve.

Coragyps

Kevin - You may mean <a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001535" target="_blank">my thread, now archived.</a> I have just been discussing this on another board, and will post a little more information on hemoglobin C when I get home this evening. It's kind of a "sickle-cell anemia lite" - malaria resistance with less detrimental health effects.

abe smith

"beneficial mutation" is after all a no-no; betrays human value-judgement.... There are no "beneficial" or "deleterious " mutations in the great non-judgemental non-human scheme. There are only *mutations*, which are sorted out by *survival*; and "good" or "bad" have nothing to do w/ it. After all, the parasites, human & other, have survived..... No offense in my observation; just like to keeep the terms clear, eh? Abe

Oolon Colluphid

I agree with your third sentence, but am perplexed by the first two. Quite right that ‘good’ and ‘bad’ are value-judgements, but surely ‘beneficial’ (understood: to its owner) is pretty neutral, value-wise? It doesn’t have to mean that the mutation is a Good Thing (TM). How else to describe a mutation that enables its owner the better to reproduce? It is of benefit, ie the owner is better off in the game of life with it than without it; hence it is beneficial. I don’t see why, say, a bacterium possessing a mutation allowing it to survive in the presence of tetracycline might not be said to have benefited from it (and this same mutation also being deleterious to the human host is neither here nor there).

Don’t forget that we’re arguing with people who claim that mutations only ever break stuff, they never make stuff. Since you like to keep the terms clear, what term would you use to describe an improvement-variety mutation?

Cheers, Oolon

Coragyps

Another tidbit on hemoglobin C: <a href="http://www.nlm.nih.gov/medlineplus/ency/article/000572.htm" target="_blank">NIH's Medline </a>says: "People with clinical hemoglobin C can expect to lead a normal life." They do, however give a rundown on the complications that can arise. The Nature article that I referenced in my previous post presented data on a large study in West Africa where CC homozygotes had a 93% reduction in malaria incidence compared to kids with "normal" AA genotype.
Sounds sorta beneficial to me.