Have we halted our own Evolution?

You know, if you think about it, those pockets of humanity, with really negligible amounts of natural selection would make pretty good experimental cohorts, aimed at "confirming" Neutral Theory Would be a really long term study tho'.

---

"The good Christian should beware the mathematician and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of hell." - St. Augustine

I can just see the grant application,
Testing of the neutral theory in human populations. Expected duration of experiments...10,000-100,000 years . PI..not born yet.

The fundamental premise of this question is incorrect. By asking if evolution is halted you presume that there is an end point to evolution or that it should be a continuous process which it doesn’t and isn’t nesercerily .
The question should be, ”is there selective pressure acting on current breeding populations that will result in discernable evolution?’

I take your point that mating is not random from an individual perspective. However what people find attractive in a sexual partner can be seen as being random therefore alleles will not be selected out of a large breeding population. And if there is no selection there is no evolution.

However, an argument could be made that some of the pressure from sexual selection has been removed, as well. Just as selective pressure for good eye sight has diminished due to the invention of glasses, less sexually desirable people have a number of recently developed cosmetic options available. There are breast implants for women. It is possible to stretch leg bones for short men (a la Gattaca, although I doubt anyone has done this for cosmetic reasons).

I have recently been thinking about addiction as a selective force. I was reading "Cracked" by Dr. Drew, and there was a tangential comment about how the same traits that make people more vulnerable to addiction give them tenacity that would aid in survival under harsh conditions. Assuming this is true, addiction could be one of the strongest selective forces in developed countries.Back in "the day" when we were first figuring out how to use bronze and iron, we didn't have things like alcohol and cocaine. This addictive nature/tenacity would only have aided in survival. With modern science we have developed all sorts of addictive agents that are wreaking havoc on some sectors of our population. A good example of this would be the prevalance of alcoholism among American Indians versus the European settlers. The old world cultures knew of alcohol for several thousand years, and as such had evolved a tolerance for it. American Indians hadn't come in contact with it, and as such had a much weaker tolerance.Thoughts? New thread, possibly?

Thankfully for humanity, 'addiction to work' is still a reality for some of us.

You are making the rather tenuous assumption that mate selection (for purposes of actual reproduction) will be based soley on overt physical features, rather that intelligence, or sufficient education to de-frock surgically created 'beauty'. Michael Jackson comes to mind. Besides, nowadays we can just screw the heck out of stupid pretty sex partners using condoms and hold out to marry a passibly attractive intelligent one.

I just have to say my two bits on sexual selection in humans - creativity, not intelligence - is what was selected, intelligence is just a by-product. This is why Mick Jagger is sexy.The other 'bit' is that "beauty" is an averaged condition: the most 'averaged' people are more beautiful.

---

Join the effort to unravel {AIDS\HIV} with Team EvC! (click)

---

we are limited in our ability to understand
by our ability to understand

​

RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

Okay, not removed, but lessened. There isn't really a way to fake intelligence the way there is to fake some physical traits, but that assumes that intelligence is largely based on genetics. My comment was aimed mainly at physical traits, though.

I can see your angle, but I think sexual selection (active mate choice) is still a very powerful force in human evolution. As RazD has pointed out below and in another thread on this subject, creativity and other important correlates of intelligence have become criteria for mate selection in humans and likely led to 'runaway' selection for particular traits, intellect being first and foremost. This process continues in modern human populations. Physical traits might be attractive sexually, but remember we have effectively divorced 'recreational sexual actitivy' from 'reproductive sexual activity'. We might sleep with someone of lower IQ, but we are unlikely to marry and have children with them. And intelligence does have a high degree of heritability, believe it or not.This message has been edited by EZscience, 04-11-2006 08:56 AM

What makes you think that's at all true? Or that what people find sexually attractive has anything to do with mating?I mean if there's one thing that I learned from my intro psychology classes, it's that people's mate choices are typically anything but random, instead, based very much on shared physical characteristics and similar socioeconomic backgrounds. In another thread evidence was offered that (at least tentatively) suggests that immunological histocompatibility as detected by smell is a large determinant of who we find attractive; other evidence suggests that symmetry, detected both visually and by odor, determines genetic robustness and therefore attractiveness.I don't really see any reason to describe people's mating preferences as "random." That's somewhat different than what people find sexually attractive, of course. I mean almost everybody has two different sets of criteria - traits they'd require in a spouse, and a smaller list of traits they'd require in just a fling.Human mating is definately not random, from either an individual or population perspective.

Point taken, but the divorce of recreational from reproductive sexual activity is not 100%. I wouldn't put it anywhere near 100%. Yes. Smart parents --> smart kids. The question is, what has the greater influence, genetics or being raised by smart parents? I would say the latter has the greater influence, but won't discount the former.

Less than 1 out of every 500 acts of penetrative, heterosexual intercourse actually results in a birth. And that's just among the people not using birth control. I'd suggest that the divorce of sexual pleasure from reproduction is a considerably greater divide than you're prepared to admit. Otherwise, what's the point of all that sex?

Quite true, but it doesn't have to be 100% in order for sexual selection to be a powerful force. There are always going to be unplanned pregancies with partners who would not be considered marriage-worthy, but the majority of human births are planned and occur specifically with a mate of one's own choosing. That's all it takes for mate choice criteria to have a big effect on the direction of human evolution, particularly assortative mating scenarios where the same trait is a criterium for choice in both sexes. Most biologists would say that the effects of genetics and environment on phenotype development are multiplicative rather than additive - if either is zero, the product is zero. But don't assume that a role for environmental influences will diminish in any way the power of selection to change a trait. There need only be 'some component' of heritability to the trait for selection to be effective. The trait doesn't have to be discretely heritable.