Evolution in modern society.

Great Debates
1

I guess this should go into Great Debates, for lack of anywhere else to go. I’m honestly looking for other peoples’ prospectives and thoughts on this idea.

Evolution. If this term alone offends you, then this thread is not for you.

A coworker and I were discussing several cosmic topics during some downtime at work. Of course, the conversation hit the topic of evolution. The question he asked me was, “Are we still evolving?” His point was that now that we have comfy lifestyles, as opposed to our ancestors, and pretty much all of our wants and needs can be taken care of, is Darwin’s Natural Selection applying to us anymore?

Using that logic, I personally believe not. Now that members of the human race today. who could not survive out in the wild more than 24 hours. are able to raise families with multiple offspring, that kind of negates the Natural Selection.

That last bit raises a debate within itself, but here is the question that I originally intended to post here:

Are other species still evolving?

Case in point, my cats. If I were able to fast forward to one million years from right now, and see the decendents of my cats, would they by approxiamately 5 1/2 feet tall, stand on two feet, and be able to speak and intelligently reason?

If so, in your opinion, what species is next to “rise” to our level?

2

I have no reason to think that we are not still evolving. For one thing, our backs are not evolved enough yet for comfortable upright positions for most of us. That’s why we slump and get backaches.

The appendix is probably on its way out as is the tailbone.

But it takes such a long time to happen that we don’t notice any changes in human beings during our lifetimes.

I think I read that we are becoming taller too.

Maybe dolphins could be on a par with us, but they might have to regress to do that. :wink:

3

Also:

Not so for many societies.

4

Well, natural selection doesn’t select only for survival “out in the wild” but for survival in whatever environment is around.

Evolution isn’t headed toward all animals being “approximately 5 1/2 feet tall, [able to]stand on two feet, and … able to speak and intelligently reason”

Natural selection takes whatever exists and preserves whatever works.

Mutations go on all the time. Environments change. For example “modern society” will change when energy sources finally won’t support it any more. So those creatures able to get along without all of the trappings of “modern society” such as advanced medical care will survive. Those whose ability to reproduce depends on advanced medical care won’t.

I think it’s just that simple.

5

Unfortunately, I believe you have a bit of a misunderstanding regarding evolution and how it works.

If a gene mutates and the resulting change in development helps a member of a species be more successful at spawning, and more offspring are created to pass on that genetic change
OR
if a gene mutates with no specific advantage, but it has no specific disadvantage, and other events cause it to spread out into the population,

then there will be a change in the overall genetic makeup of a species.

With the manipulation of the environment that humans have accomplished, it is unlikely (not impossible) that the first scenario will come to pass. There are too many social factors that control success and too many advances in medicine to allow a simple genetic change to radically alter the direction of the human species (including the ability, itself, to manipulate human genetics). (At a time when many people are concerned with overpopulation, a genetic change that causes women to have multiple children per pregnancy will be “treated” with selective abortions or by women choosing to have fewer pregnancies.)

On the other hand, the second scenario is a less remote possiblity. There have already been any number of science fiction stories in which the depletion of the ozone in the upper atmosphere gives a decided advantage to people with higher levels of melanin, giving the previously oppressed “dark” peoples an evolutionary advantage in avoiding UV related problems.

A genetic change that made a person resistant to cancer might flow through the population, (it may, indeed, be spreading out, now), but it would probably not have an effect on evolution, since most people are able to procreate and raise children prior to the onset of the age at which various cancers begin to appear. On the other hand, if an environmental situation arose that caused children to develop testicular or ovarian cancer at puberty, then people with greater resistance to cancers would be selected by evolution, based on greater numbers of them survivng to produce their own children.

There is no way to know in advance what sort of random mutation might occur that might provide an advantage, so there is no way to know in advance how evolution might change a species.

6

There is a daft miscomprehension among the unwashed masses regarding “natural” selection. It is part and parcel of the old Cartesian division between “the natural world” and “The Saved by God”–humanity. Evolutionary selection has nothing at all to do with survival “in the wild”. We ARE “the wild” for our species. Who takes care of us but ourselves?

Natural selection is just a shorthand for “differential reproductive success in response to whatever situation a population happens to be in”.

Natural selection still operates on humans, but the criteria are different for many of us than would hold in a paleolithic hunter-gatherer band.

7

Some folks seem to have a natural immunity to HIV. Even when repeatedly exposed, they don’t get infected.

Let’s think of a place like southern Africa where 50% of the population is affected by AIDS in some areas.

Who is more likely to survive to have children? Do you think this gene of being immune to HIV will be more or less prevalent there in 100 years?

A thousand years ago this gene provided no selective advantage. Just another random mutation. Now it provides some folks with a huge selective advantage.

Evolution in action.

8

Eyesight.

I wouldn’t be surprised if, a few centuries years from now, 100% of the population developed terrible eyesight by a very early age.

9

Now that we’re on the verge of figuring out how to modify our own genes, natural evolution - i.e., evolution based on naturally-ocuuring mutations - isn’t really all that relevant any more. It’s a matter of cycles: natural evolution is a slow process spanning millions of years, while genetic engineering can take mere months. Mankind, I believe, is on the verge of a massive evolutionary leap. It may not happen the way we plan, but it’ll happen.

As for cats… they’ll probably get more adoreable.

10

Johnny Bravo, what would be the mechanism to cause this? While bow hunters probably need very good eyesight, hunter-gatherers and farmers can often get by with less than optimal eyesight. You may be thinking that, with corrective glasses, contacts, and keratomoty, etc., we can “afford” to lose some natural vison, but we have been able to get by without it in most societies for years: what is going to cause a mutation in the future to harm vision?

11

Not necessarily.

Imagine a terrible new disease appears (a la ‘Captain Trips’ from The Stand). If you have the immunity gene, you’re fine. If you don’t, you’ll die within days.

Evolution just sped up.

This isn’t just some crazy hypothetical. It hapens a lot. A river is poluted and the creatures who are naturally resistant survive. The next generation has all resistant genes.

In less than 100 years bacteria have developed immense immunities to many antibiotics.

Evolution can happen darn quick if circumstances are appropriate.

12

I’m not sure that makes sense. Not everybody ends up with glasses NOW. Cecil does write about this, and it would seem to be a byproduct of modern life. That is, it’s believed to be environmental, so I’m not sure why your scenario would happen.

13

I think the problem is there isn’t nearly enough death around these days. Survival of the fittest requires death of the weak. We have evolved into a society where the weak are nurtured, and thus allowed to keep introducing there weak genes into the gene pool.

The HIV immunity gene might be a good example of where evolution will happen, but only if it kills lots of people, and it must kill them before they can have children of there own. That said, it doesn’t really have to be a huge percentage of the population. As long as it is a significant amount, it will happen, but it will just take longer (could be thousands of years). Part of the problem is in a thousand years, we will probably have cured HIV, and that will remove any evolutionary advantage these people have.

I’m not sure I understand why we will evolve bad eyesight. We have bad eyesight because our eyes aren’t designed to stare at a page of a book or a computer screen for long periods of time. We could evolve this ability in a few thousand years, provided those of us with bad eyesight conveniently keep getting run over, falling down open elevator shafts etc.

(Not that I’m advocating death to the weak you understand. Its just the way it is).

14

I’m sorry if I oversimplified my OP, and ticked off some of the Dopers who have posted. I honestly did not expect such scientific responses.

I see how disease will be the main catalyst for evolution in modern society, as opposed to who can or cannot down a mastadon or weather through a bad winter. I see how modern society is now our environment, and we will change according to its factors.

Matter of fact, there recently was a special on one of the Discovery Channels that I caught. It was talking specifically about the Black Plague, and what the world was like before and after. In this special, they documented how a vast majority of the survivors had a particular mutated gene within their DNA. They gave it a designation of something like “R12”. Anyway, come to find out, the people who are infected with HIV, but don’t contract AIDS, are all in possession of this exact same “R12” gene mutation. With this trend, they decided to try and did up some survivors, or find some living samples, of the Influenza after WWI to see if the same gene mutation is present there. But that was in progress, so they do not have an answer yet, that I’m aware of. The scientists that were involved with this study said that once they can single out and harness this mutation, it will be more important than penicillin.

When I specifically mentioned my cats, I had a hint of facetiousness in there. Both of my cats are neutered, and live inside of the perfect climate controlled bubble known as my house. What I was alluding to was specifically the evolution of a species’ brain. All other factors being equal, left alone, I feel that it is natural for a brain to try and push its own boundaries and grow in size and function. Any thoughts on this?

15

Still, I think we’re about to see a massive influx of man-made non-lethal mutations into the human gene pool

Good points, BTW, although I don’t think the bacteria example is relevant. The speed of evolution, after all, is dependent on the organism’s life cycle. Humans reproduce every 25 years or so; bacteria reproduce daily. A single-celled organism could easily pack in a million years of of human evolution in a century.

Besides, there are so damn many of them. There are six billion humans on the planet, and I probably have more than six billion bacteria in my kitchen. The larger the pool, the greater the variations.

16

Again, what would be the mechanism?

You need a mutation that increases the “capacity” (whether it be size or the number of folds or whatever) of that organ for intelligence, followed by a sufficient advantage to keep it in the gene pool long enough to make a difference, or, at least, no disadvantage, (for example, the requirement for more food to support it), while the mutation ripples through the population.

In humans, the best guess seems to be that bigger brains did not even begin to evolve until our ancestors began walking upright and using their hands, at which point more brain capacity allowed that ancestor to find ways to use the hands to enhance survivability. My wife has several snakes of various sizes with pretty small brains. They even “act dumb” from time to time. Yet they are quite efficient hunters. What advantage would the extra energy required to build a bigger brain confer on a snake? The same is true for cats. Would a cat with a larger/heavier head be more or less able to leap for a bird or chase down a rodent? Cats can already “outthink” their current prey to the point where they can catch food. What advantage would a cat gain from thinking more?

Similarly, for the (proto-)human brain to be successful, that organism also had to have several mutations to promote neoteny in regards to skull shape as well as earlier births to allow a child to be born without having a head too large to pass through the birth canal. Kittens would not have this latter problem, but we don’t know what other problems devoting energy to larger brains would create.

Since large brains are relatively rare in nature, with millions of species getting by with fairly small brains, it does not seem to me that there is any evolutionary trend toward higher capacity brains or intelligence.

17

To explain further, Johnny, what we do not have is a mechanism to select FOR bad vision but weaker mechanisms to select AGAINST it. As most vision problems can be corrected there is no difference today in the ability to support a family between those with perfect and those with imperfect eyesight, thus no evolutionary advantage for perfection. This argues, as I think you do, for a spread of genes that result in bad vision. However, these mechanisms have been in force for some time and have, in both industrial and agrarian societies, caused any shifts that are likely to occur. A century from now I can see no difference in the distribution of vision abilities (though that might be because I have my close-vision glasses on at the moment :wink: ). A mutation in a single individual (as mass, identical mutations don’t happen) that caused worse vision AND included a reason to make that person and his descendents MUCH more likely to reproduce and spread the mutation would not be able to spread it throughout the world’s population in four or five generations.

18

Let’s also keep in mind that many adaptations that would help us in our day-to-day lives would have no particular reproductive advantage, and therefore would not become prevalent.

19

Assuming our lifestyle doesn’t change significantly for the future (ha!), the only evolving I anticipate the human race doing would be greater longevity, resistance to heart disease, and other such “keep us alive longer so we can watch TV and boink others” attributes.

20

Not quite. Natural selection has little to do with death, but rather surviving long enough to reproduce. Salmon die immediately after they reproduce, the hypothetical salmon who did not spawn and survived longer would be an evolutionary loser. Male lions who don’t get a pride might live for a long time, but are also losers. After we reproduce, and possibly increase the chances of our progeny reproducing, what happens to us is irrelevant.