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Author Topic:   If evolution is our origin, where will we end up?
crashfrog
Member (Idle past 1498 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 8 of 33 (234251)
08-17-2005 7:23 PM
Reply to: Message 7 by New Cat's Eye
08-17-2005 7:15 PM


Re: we're in the last stage
I just think that natural selection has too little of an affect on humans to have any noticable change, because of the way we have taken matters into our own hands.
I realize how easy it is, living in Western civilization, to assume that the quality of life you enjoy represents the experience of the vast majority of humans currently alive.
Nothing could be farther from the truth. Sadly, for most human beings, lethal selection is very, very much at work.
And it's ludicrous to suggest even just among us Westerners that there's no selection. I don't know anything about your private life but I assume that, like me, you actually have to convince women to have sex with you. You can't just control their minds and make them do it. Thus, mate selection is still very much in operation for both of us; indeed, for every human being.
Selection is very, very much still at work in the human race.

This message is a reply to:
 Message 7 by New Cat's Eye, posted 08-17-2005 7:15 PM New Cat's Eye has replied

Replies to this message:
 Message 9 by New Cat's Eye, posted 08-17-2005 8:14 PM crashfrog has replied

  
crashfrog
Member (Idle past 1498 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 10 of 33 (234265)
08-17-2005 9:00 PM
Reply to: Message 9 by New Cat's Eye
08-17-2005 8:14 PM


Re: we're in the last stage
I think some examples or answers would help me see why this is true
Worldwide, the top causes of death are:
Starvation
Heart Disease
Stroke
and an assortment of diseases.
Pregnancy is the leading cause of death among young women under the age of 15.
These fatal conditions do not attack randomly, but differentially. They're not accidents or forces of nature. They're conditions to which the content of your heritable genes will play a role in regards to whether or not you die from them.
That's selection. Is it evolving us? It's certainly having an effect. Of course, most people have already reproduced by the time they succumb to heart disease or strokes; thus it might be more effective to examine the top causes of death for minors:
Diarrhoea
Pneumonia
Measles
Malaria
HIV/AIDS
and, of course, malnutrition.
Since these conditions, again, represent physical aliments that genetics can influence, and they eliminate humans who have not bred, this represents selection.
Are you talking about the tons of kids starving to death in africa?
Well, yeah. Starvation is a selective pressure in every environment and in every species. It's well-known as a density-depended selective factor.
I just don't see it that way. Pretty much everyone is getting laid.
Right, but not everybody is getting laid with everybody. You're not getting laid with Pamela Anderson (as a stand-in for persons with highly desirable physical traits) and neither am I. Even if you had the opportunity to ask her she'd tell you "no."
That's mate choice, and that's sexual selection. Your genes only get to combine with the genes of certain people (generally, people much like yourself in regards to the "quality" of their genes.)
How much sexual selection do you think is involved in who people are having kids with?
Unless you're having kids with literally everyone, it's all sexual selection. You selected a mate, and she selected you. It wasn't at all random. You had certain characteristics you were looking for, and so did she. You chose from a pool of avaliable mates - unless you two were the only people on a deserted island - and so did she.
Choice. Aka selection.
I think people who choose to have kids are choosing their partner for reasons other than physical attraction.
Oh, sure. Like, access to resources. Or temperment (which has a heritable component.) Or likehood of conception/successful pregnancy ("wide, childbearing hips"). Or body symmetry representing a lack of disease or crippling disfigurement. There's a significant likelyhood, based on studies of what we find attractive, that you chose a mate based on how similar her immune system was to yours - but not too similar (because then she might be your sister.)
You didn't chose a mate at random, and neither did your mate. You look for stuff in a mate and so do your mates. Some of that is heritable and some isn't. But it's all selection.

This message is a reply to:
 Message 9 by New Cat's Eye, posted 08-17-2005 8:14 PM New Cat's Eye has replied

Replies to this message:
 Message 12 by New Cat's Eye, posted 08-18-2005 8:37 PM crashfrog has replied

  
crashfrog
Member (Idle past 1498 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 13 of 33 (234694)
08-18-2005 10:08 PM
Reply to: Message 12 by New Cat's Eye
08-18-2005 8:37 PM


Do you think there will be noticable changes to our phenotype?
Well, there already have been. We have increasingly smaller teeth and jaws because we're adapting to cooked food. There's a new version of the sickle-cell gene that delivers the resistance to malaria without the associated anemia.
What changes in the phenotype would you expect from this selective factor?
Smaller bodies, retention of water, adaptations that improve survivability to malnutrition. Resistance to various diseases.
Well, if you look at it that way then sure. Thats not how I've come to understand sexual selection.
Selection isn't always about who breeds and who doesn't; remember that we reproduce sexually and that your phenotype depends on genetic contributions from two individuals. The survivability of your genes very much depends on your mate choice, because her crap genes could spell the death of your mutual child (and there goes your genes, too.)
It's sexual selection, as far as I can see. It's about non-random changes in allele frequency and mate choice has an influence on that.
Right, but its all selection thats gonna have no noticable affect on us, how could it?
How so? Non-random mate choice has a non-random influence on allele frequencies. That exerts a phenotypic effect.
If you're looking for really spectacular examples of phenotypical change, there's really not much I'm going to be able to show you. Generational time of, what, 20 years or so? Takes a long time for that sort of change, and how long have any human beings existed in an industrial society? Less than 10 generations maybe?

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 Message 12 by New Cat's Eye, posted 08-18-2005 8:37 PM New Cat's Eye has not replied

  
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