we still evolving

[Raging Atheist]

I was wondering if any of the science wizzes could tell me if humans, as a species, are still evolving. With my limited understanding of evolution, I figured that with drugs, cars, fast food and surgery many factors of natural selection no longer applied to us. However, I have spoken with others who also share my limited understanding of evolution and they tried to explain we were still evolving some how.

I think the answer to this question will significantly ground any misconceptions I have of evolution.

 

[Morat]

We have a large gene pool, large generation time, and a great deal of intermixing. Human evolution is going to be slow.

There's a nice new allele (lowers your risk of heart attack drastically) working it's way through the population. Showed up about 400 years ago in Italy. It's not gotten very far. Come back in 20 thousand years or so, and you might find a good chunk of the population with a much lower chance of heart attack.

 

[Raging Atheist]

Originally posted by Morat
There's a nice new allele (lowers your risk of heart attack drastically) working it's way through the population. Showed up about 400 years ago in Italy. It's not gotten very far. Come back in 20 thousand years or so, and you might find a good chunk of the population with a much lower chance of heart attack.

So, you're saying that although its insanely slow because of such a huge population, it is happening? And it only works for stuff that can still kill us such as heart attacks? I take it, then, that we're not getting any smarter or stronger as the years go by either...

 

[Late_Cretaceous]

A predispostion to heart attacks (as occurs in our population) would not be under evolutionary constraints. Most people who die of heart attacks do so long after they have reproduced and passed thier genes on to thier offspring. Currently most human evolution is shaped by sexual preferences rather then envrionmental pressures/opportunities. Take for example the inhabitants of the solomon islands. One population evolved to have the darkest skin on earth, while the population on a neighboring island evolved to have an olive colored skin. SInce both populaitons are related and the climatic condiditons are nearly identical, the most likely explanation is mate selection.

 

[Morat]

So, you're saying that although its insanely slow because of such a huge population, it is happening? And it only works for stuff that can still kill us such as heart attacks? I take it, then, that we're not getting any smarter or stronger as the years go by either...

My point was that new alleles spread slowly in such a large population, with so few isolated groups.

Further, the frequency of existing alleles is slow to change for the exact same reason.

But I would certainly agree with Cretaceous that sexual selection plays the biggest role. After all, what people look for in a mate now is quite different than what they looked for a thousand years ago, or even a couple of hundred.

 

[Raging Atheist]

so, natural selection in conjunction with selective reproduction is the key to evolution, no? seems I did have a firm grasp on evolution... thanks

 

[DrLao]

Originally posted by Raging Atheist
So, you're saying that although its insanely slow because of such a huge population, it is happening? And it only works for stuff that can still kill us such as heart attacks? I take it, then, that we're not getting any smarter or stronger as the years go by either...

Human evolution sort of must be going on. The only way you could have a population that is not evolving is if no mutations were taking place and the allelic frequencies of the individuals leaving the population were identical to the allelic frequencies of the individuals joining the population. Neither seem very likely.

 

[DrLao]

Originally posted by Raging Atheist
so, natural selection in conjunction with selective reproduction is the key to evolution, no? seems I did have a firm grasp on evolution... thanks

"Key" to evolution? Sort of. They are mechanisms of evolution. They cause evolution to occur by changing the genetic make-up of a population.

They aren't the only mechanisms though. Genetic drift, gene flow, and mutations also play important roles.

 

[Raging Atheist]

but does genetic drift and gene flow apply to humans?

 

[Morat]

Sure. What would stop it?

View it as...inertia. The larger the population, and the larger the generation time, the more inertia a species has, and the longer it takes to get even small results.

Isolate a portion, however, and you've suddenly got something a lot smaller to move.

 

[DrLao]

Originally posted by Raging Atheist
but does genetic drift and gene flow apply to humans?

Genetic drift certainly does. It is always going on. Gene flow may or may not apply, depending on how you look at it. There is no net gene flow into or out of our species as a whole, obviously. But the flow between populations within our species could definitely affect the course of our evolution.

 

[Joe V.]

Do any of you suppose medical science will eventually trump anything that might occur naturally? I saw a blurb online recently about a patient who was able to grow his own heart bypass. It's very conceiveable that in this century we could be able to live indefinitely - and that in itself might cause a host of other problems, tho sometimes I think it might actually help us too.

- Joe

 

[James D.]

Another important factor apart from mate selection, is simply who chooses to have children. Studies have shown that people in the developed world are having fewer children and more people are choosing to have no children.
People in the developing world, on the other hand, still have many children.

 

[James D.]

Originally posted by Joe V.
Do any of you suppose medical science will eventually trump anything that might occur naturally?

It already is to an extent. Many people who would've otherwise died out are now able to go on and have kids. There are also social factors such as welfare. -Whereas in the past, a person without a job would be likely to starve to death, nowadays they're sustained on welfare.
One thing is for sure. A high degree of intelligence certainly has a huge effect on a species evolution. Hopefully one day we'll be smart enough to get rid of genetic diseases.

 

[Raging Atheist]

Originally posted by James D.
Another important factor apart from mate selection, is simply who chooses to have children. Studies have shown that people in the developed world are having fewer children and more people are choosing to have no children.
People in the developing world, on the other hand, still have many children.

Here is a social evolutionary theory for you: Catholics, Mormons and what not outnumber atheists and their organzation has survived for so long because they're encouraged to reproduce... something about the second coming of Christ and not having sex for fun...

silly? food for thought at the very least...

 

[James D.]

Originally posted by Raging Atheist


Here is a social evolutionary theory for you: Catholics, Mormons and what not outnumber atheists and their organzation has survived for so long because they're encouraged to reproduce... something about the second coming of Christ and not having sex for fun...

silly? food for thought at the very least...

Yes. Memes can influence genes.

 

[Cyclo Rider]

This is an absurd topic.

Humans have never evolved and never will.

The only differences between now and thousands of years ago are matters pertaining to longevity and technological advances, but if you study any of the ancient civilizations (Egyptians, Sumerians, Chinese, Babylonians), humans were the same back then as today and just as smart.

 

[DrLao]

Originally posted by Cyclo Rider
This is an absurd topic.

Humans have never evolved and never will.

The only differences between now and thousands of years ago are matters pertaining to longevity and technological advances, but if you study any of the ancient civilizations (Egyptians, Sumerians, Chinese, Babylonians), humans were the same back then as today and just as smart.

Regardless of whether there was any change in intelligence from people thousands of years ago to people now, the human species has evolved and is evolving. To deny this fact is to deny some pretty basic and self-evident facts of population genetics. Do you know what evolution is?

 

[Plan 9]

I heard Dr. Richard Leakey speak a few years ago and according to him, human evolution has ceased. We control our enviornment now, so it doesn't act upon us to produce change.

 

[Morat]

There's still drift, which is quite slow. But, while I haven't seen Leakey's comments, I'd say that human physical evolution is fairly static, because of our large population size, lack of insolated groups, and long generation time.

The fact that all our selective pressures are social and sexual does play a role as well.

But there's always evolutionary pressure. Whether it's for individuals that can handle previously noxious enviroments, or higher temperatures, or just people that can hold down a 6 figure job...there's always pressure.

With people, however, the pressure here is different than in Japan, or Europe, or Africa, or China. And none of our groups is isolated.