we still evolving

Raging Atheist · Jul 11, 2002

Originally posted by Morat

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.

I fail to see how getting a 6 figure job has anything to do with evolution....

Morat · Jul 11, 2002

The same thing a peacock's tail does. Or a robin's red breast.

Sexual selection.

Raging Atheist · Jul 11, 2002

but, since the population is so large, short of being horribly disfigured and mentally handicapped and obese, all at once, just about everyone passes on their genes... I mean, even those guys sometimes find a mate... I would argue that the 6-figure guys are having less children than the average person because they're busying earning all that money... everone knows its middle and lower class america thats having the kids...

and again, what genetic abilities could a guy holding a six-figure job pass on? there isn't exactly a rich-gene... in order for it to be an evolutionary factor, wouldnt the guy's kids all have to end up with six-figure jobs? or at least some kind of comparable success... maybe not... but I still don't think income is an evolutionary factor...

Morat · Jul 11, 2002

Sure, lots of people pass on their genes. But, in general, the more successful pass can afford more kids. At least, you'd hope.

Catholocism seems to be an effective evolutionary strategy.

Success isn't genetic, but some of the factors that promote it are.

But maybe that's true for New York, but not for Texas. All we're doing is varying allele frequencies slightly in small areas.

But the human race as a whole, since it's so big and intermixed, stays roughly the same. Any real change is drift, rather than selection. And, since it's drift, pretty darn slow.

Locally, you get changes in allele frequency based pretty much, generation to generation, on what people are looking for in mates.

kyzra · Jul 11, 2002

natural selection is too slow, and impeded by modern society (given by the fact that we protect the infirm rather than allow them to die out). at this rate, left to natural selection, the human gene pool will actually decline in useful genes.

the future of human evolution will be planned selection.

Morat · Jul 11, 2002

left to natural selection, the human gene pool will actually decline in useful genes.

Why?

kyzra · Jul 11, 2002

Originally posted by Morat

Why?

i already said why in my post. because we protect the infirm, which gives them a chance to breed.

for instance, if someone is born with extremely poor vision, left in the wild, that person would most likely die out. in modern society, it's pretty easy to correct the vision problem (either by lenses or operation), which gives individuals with poor vision a good chance to survive and pass on their poor vision genes.

with animals living in the wild, you don't find many with dulled sences (the ones needed by a particular species, for competing) surviving to pass on their genes.

Morat · Jul 11, 2002

How does that remove alleles from the population? If anything, it prevents alleles from being removed.

Furthermore, how many of the "infirm" managed to reproduce? Not many with Down's syndrome. None with that brittle bone disease.

And regardless, your're misapplying the notion.

Whether or not my poor vision would let me survive in the wild is immaterial. I'm not in the wild, am I? I am successful in my enviroment, though.

Same with those who modern medicine helps. Success in their real enviroment will determine their ability to pass on their genes, not some hypothetical enviroment they will never inhabit.

kyzra · Jul 11, 2002

Originally posted by Morat
How does that remove alleles from the population? If anything, it prevents alleles from being removed.

Furthermore, how many of the "infirm" managed to reproduce? Not many with Down's syndrome. None with that brittle bone disease.

And regardless, your're misapplying the notion.

Whether or not my poor vision would let me survive in the wild is immaterial. I'm not in the wild, am I? I am successful in my enviroment, though.

Same with those who modern medicine helps. Success in their real enviroment will determine their ability to pass on their genes, not some hypothetical enviroment they will never inhabit.

consider this: what would happen if a large percentage of the population becomes dependant on modern medicine for survival in the environment they currently inhabit, and then (by some cataclismic event,) modern medicine is removed from that environment?

survival of a species depends on their ability to adapt to changes in envrionments as well as their ability to compete in their current environment.

Morat · Jul 11, 2002

consider this: what would happen if a large percentage of the population becomes dependant on modern medicine for survival in the environment they currently inhabit, and then (by some cataclismic event,) modern medicine is removed from that environment?

survival of a species depends on their ability to adapt to changes in envrionments as well as their ability to compete in their current environment.

Evolution isn't forward looking. You're making the same mistake (and this isn't an insult) that people who push eugenics make.

Evolution adapts creatures to their current enviroment. Not some possible one.

We adapt to our enviroment. Which had modern medicine. Where success is measure by other things then if we can hunt down tigers.

Should there be a nuclear war, there will be new selective pressures.

But think: Sickle-cell trait is darn beneficial if you're out in the wild. Protects you from malaria.

But in America, it's one of those sickly diseases you were talking about.

Evolution doesn't look forward. It doesn't adapt organisms to changing enviroments unless enviroments change rapidly and on a regular basis.

Evolution adaps species to the enviroment they inhabit. Not the one they used to, or the one they might.

kyzra · Jul 11, 2002

Originally posted by Morat

Evolution isn't forward looking. You're making the same mistake (and this isn't an insult) that people who push eugenics make.

Evolution adapts creatures to their current enviroment. Not some possible one.

We adapt to our enviroment. Which had modern medicine. Where success is measure by other things then if we can hunt down tigers.

Should there be a nuclear war, there will be new selective pressures.

But think: Sickle-cell trait is darn beneficial if you're out in the wild. Protects you from malaria.

But in America, it's one of those sickly diseases you were talking about.

Evolution doesn't look forward. It doesn't adapt organisms to changing enviroments unless enviroments change rapidly and on a regular basis.

Evolution adaps species to the enviroment they inhabit. Not the one they used to, or the one they might.

i don't see where your coming from. i'm not arguing what evolution is or how it works.

what i'm saying is that modern society creates an artificial environment which impeeds the natural selection process, which is a slow process to begin with. so eventually we will begin a process of planned selection.

it is highly probable that sometime in the (possibly near) future, genes that cause poor vision (or cancer, or disabilities, etc,) will be elliminated, not by natural selection but by human interferance.
this may or may not cause other disadvantages to surface, but those will be dealt with in turn.

Morat · Jul 12, 2002

what i'm saying is that modern society creates an artificial environment which impeeds the natural selection process,

  That's what's wrong. It's not an artificial enviroment. Modern society is our enviroment. That's what we adapt to. It's no more artificual than termite mounds are for termites.

 which is a slow process to begin with. so eventually we will begin a process of planned selection.

   We do it already. It's called "sexual selection".

it is highly probable that sometime in the (possibly near) future, genes that cause poor vision (or cancer, or disabilities, etc,) will be elliminated, not by natural selection but by human interferance.

   Sure. Why not? Heck, we might even add some in. I saw Gattaca too.

this may or may not cause other disadvantages to surface, but those will be dealt with in turn.

   So what's your point? Natural selection will still work on us. Sexual selection will still work on us. Drift will still work on us.

 

kyzra · Jul 13, 2002

Originally posted by Morat

  That's what's wrong. It's not an artificial enviroment. Modern society is our enviroment. That's what we adapt to. It's no more artificual than termite mounds are for termites.

   We do it already. It's called "sexual selection".

   Sure. Why not? Heck, we might even add some in. I saw Gattaca too.

   So what's your point? Natural selection will still work on us. Sexual selection will still work on us. Drift will still work on us.

 

okay, your making an issue of a non-issue. that was my point, simply that we will eventually interfere with natural selection by physically engineering our own genetic codes. that is what i meant by 'planned selection.' not sexual selection, which is common in the wild.

poof. end of point. no arguments over the process of evolution or alleles or anything else.

Plan 9 · Jul 13, 2002

Originally posted by 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.

How can genetic drift cause speciation to occur? 

Morat · Jul 15, 2002

  The hard way. It's a continuum, so you can't put your finger anywhere and say "Here is where speciation occured", but the species at Time point A is definetly different than at Time point B.

   A lot like ring species, in fact.

 

Plan 9 · Jul 15, 2002

We are either working from different definitions of genetic drift, or I'm in over my head. In over my head may be the problem. *sighs*

Jerry Smith · Jul 15, 2002

Originally posted by Plan 9
We are either working from different definitions of genetic drift, or I'm in over my head. In over my head may be the problem. *sighs*

If that is the case, then there is help for it... There is more that science has learned than any one person can hope to know. It is no discredit to not understand something.

It does reflect poorly on a person (as you will see if you browse other threads on this board) to make statements of fact about things you do not understand in order to try to confound science, but what I like about this board is that only one or two of the participants do that. You, on the other hand, seem willing to work with what you do understand and to ask about the rest... Now, about genetic drift:

Starr and Taggart, Biology The Unity and Diversity of Life, Seventh Edition:

pg276

Genetic drift is the random change in allele frequencies through the generations woing to chance events alone. Genetic drift is often most rapid in small populations. It may decrease variation within a population. And it may increase variation between populations.

Now, you may still be asking how genetic drift can cause speciation to occur.  Good question. The fact is that it usually cannot. As long as there is gene flow between populations, the evolutionary changes due to genetic drift will be dampened by gene flow from one population to another. However, when gene flow between populations is stopped: then differences due to genetic drift (usually combined with mutation and natural selection - though not necessarily) can accumulate. Those changes can sometimes even create permanent reproductive isolation in place of a temporary physical barrier.

Morat · Jul 16, 2002

  Heh. I was thinking long-term drift in static populations. Take two snapshots of a static species a million years apart, and your two snapshots are probably different species. At least.

   Coelacanths have been quite static for a long time. They're stuck in the same niche, and don't have a lot of selective pressure. But the modern day ones don't even fit in the same genus as the ones that swam with dinosaurs.

 

Plan 9 · Jul 18, 2002

Originally posted by Jerry Smith
Now, you may still be asking how genetic drift can cause speciation to occur.  Good question. The fact is that it usually cannot. As long as there is gene flow between populations, the evolutionary changes due to genetic drift will be dampened by gene flow from one population to another. However, when gene flow between populations is stopped: then differences due to genetic drift (usually combined with mutation and natural selection - though not necessarily) can accumulate. Those changes can sometimes even create permanent reproductive isolation in place of a temporary physical barrier.

Okay! So genetic drift caused speciation in Darwin's finches but might not cause it (without other factors) in human beings as we now live?

 

Jerry Smith · Jul 18, 2002

Originally posted by Plan 9

Okay! So genetic drift caused speciation in Darwin's finches but might not cause it (without other factors) in human beings as we now live?

 

It can't be doubted that some genetic drift will occur in humans as we now live - there is plenty of room for doubt whether it will have near the impact that it could have under other circumstances.

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