Not sure this has been addressed before. With the advent of cooperative society, man does not surive merely by being able to physically obtain/compete for food. An early hominid that was deficent in hunting skills would be unlikely to be successful enough to reproduce - thus not passing along his genetic material. Nowadays physical/mental prowess does not necessarily translate into greater input to the species genetic pool. So what, if anything, would be driving further human evolution?
Do a search for Darwin Awards for stories about improving the gene pool.
Your example of hunting skills will raise the issue of which skills are genetic, and so subject to evolution, and those which are learned.
All of what you mentioned might be an impetus for evolution, rather than a hindrance to it. Maybe in centuries past, genetic weaknesses killed off segments of our population and that’s what kept the human race within certain parameters; now those parameters have been expanded (for the reasons indicated) and we’ll evolve into something, say, slow and lumbering like the Galapagos tortoises?
Maybe I wasn’t clear. OK - in some old sci fi stories, man of the future has a large cranium, holding a larger brain. That’s silly - there’s no correlation between a large (human) brain and more successful reproduction. We don’t evolve characteristics just because they’re useful. Natural selection favors them though reproductive success. Individual humans who would never have survived to reproduce as individuals do so because of societal support.
Ummm…explain the Thumb.
Cecil on the subject:
Arjuna34
Evolution is not determined by reproductive success alone, but also by survival success. Man evolved into a more intelligent creature not because of better reproductive success, but better survival. It’s survival of the fittest, not the sexiest. I don’t see any reason why man cannot evolve into a being more intelligent. Esp. these days with such technical improvements, you have to be smarter and smarter to survive.
But I do agree with this, but some would say that this is what makes us civilized. We take care of the sick and lame.
Ummm…explain the Thumb. **
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The thumb allows us to maintain attachment to the clear next step of human evolution…built in remote controls.
As for explaining the thumb - random mutations occasionally encourage reproductive success. We don’t have thumbs becaseu they’re useful, we have thumbs because our ancestors who developed them were more successful.
Physical and mental prowess was never all that selection acted upon. This is just as true today as it was for our ancestors two million years ago.
Humanity is still subject to natural selection, especially with regards to disease: susceptibility to cancer, for example. While success in, say, hunting or foraging is no longer required to remain in the gene pool, success in operating within society is, and there are some traits that will be selected for in our current environment and others that will be selected against. Certainly the risk of being eliminated from the gene pool through competition for food, for example, is greatly reduced by our current environment.
In addition to natural selection, we are also still subject to sexual selection. So even in modern society, if having a really big mushroom-shaped head to hold your battleship-sized brain made you more likely to successfully breed with members of the opposite sex, that trait would tend to increase over time. Sexual selection could prove to be a major factor in humanity’s future, as it has in the past.
Starfish also raises a good point, that many traits about humans are the product of both genetics and environment. The portion of intelligence due to environment will not be passed on regardless of the action of selection, while the genetic portion of the trait will be.
Evolutionarily speaking, success in survival is irrelevant except as it influences reproductive success.
A person trapped alone on a desert island may be one hell of a survivor, and live until eighty. But as long as they’re alone on that island, their impact on the next generation is zip.
Reproductive success is also contingent on survival - of the species, not of any one individual. If certain characteristics of a species allows it to survive (to reproduce and foster)they will be retained. Evolution is based on mutations. Those mutations that favor survival will be retained and eventually incorporated into the normal genome of the species. If the species is not able to mutate (or evolve) into one more viable, it will disappear.
Okay, I admit it, I am a Dr. David Suzuki fan. The CBC program The Nature of Things had a two-part series on human evolution that was some cool.
The relevant bit was where he postulated that given current conditions, we won’t be seeing any dramatic evolution of our species. There’s too many of us, and we move around/mix too much. The driving forces behind evolution currently seem to be a small gene pool and isolation.
Extrapolating this info into a WAG, I’d say we won’t be seeing any significant natural evolution until we are distributed to other planets.
However, I could see “designer bodies” for specific environments, or even aesthetic effects. “Artificial” evolution - something planned, rather than waiting for random chance. As long as full disclosure is given and an informed choice is made, I don’t have a problem with that. Okay, I have some twitches about the “super-soldier” idea and stuff, but . . . overall, whyever not?
Tisiphone
Scottws, I think your question is … misworded…or misaddressed. The humans “evolve”, like any other species, not because they were good hunters and now there is no need to hunt. Their genom allows for constant spontaneous mutations. Most of them are lethal or not advantageous to the survival of the species. If trats which are advantageuos, will emerge, they will probably be inherited and the new “subspecies” will proliferate. For instance, if more intelligent “subspecies” will emerge, they will gradually predominate. If a subspecies with 6 digits will emerge, it will probably exist for some time, as long as 6 digits does not put them at disadvantege over 5 digit people. But, since there is no advantage, they will never predominate.
So far I do not see the ability of the human genom to stop to undergo mutations. It appears to be one of the basic laws of nature, like the ability of light to travel in one direction with uniform speed, or the existense of positive and negative charges.
Some species though, like certain sharks and coelocanths, just go on for millennia with little biological change. Why is that?
Scratch, are you sure? Not a single species of shark evolved over the last… million years? Can you check it and get back to us? Personally, I’d surprised, but can offer an explanation: white shark, or whatever, is nearly “perfect”, as is. If a new subspecies emerged “tomorrow” with an extra fin, it may or may not become predominant. But if a new subspecies can beget more numerous progeny…
And are you sure that sharks cartilagenous skeleton is not stronger today than it was 300 million years ago? And that their skin is not smoother?
Shark’s DNA is not different from human’s or bacterium’s, it’s the same basic design, allowing for spontaneous mutations. Most of them do not lead to any advantages in sharks design. But, as far as I know, the sharks are pretty low on the evolutionary tree, “higher” species evolved from them.
The OP contains some misperceptions: early hominids were quite clearly cooperative and lived in cooperative societies. The difference between Homo Sapiens and its predecessors is a matter of degree. Rugged individualism was not the defining characteristic of human evolution, but rather strategic cooperation. Nothing else explains how an otherwise rather poorly endowed scavenger managed to blossom. Of course, this is not at all unique in the animal world, quite the contrary, we find many examples of cooperative behaviour, even altruism. Ergo, the implicit assumptions of the OP are false.
peace, what I said about the sharks was an “IIRC”, a hasty research into it came up with nothing. The “little change” I mentioned, anyway, is comparative. I wouldn’t argue that sharks haven’t evolved at all, just that the lack of change is striking (again, IIRC) compared to other vertebrate species.
There are several factors at work in Evolution…
Natural selection
Sexual selection
Genetic drift
Mutation
Recombination
Gene Flow
Even if our technology and society can put a damper on one of these factors (e.g., natural selection), the rest are still at work.
H. sapiens sapiens will either keep evolving or go completely extinct. That’s how nature works.
BTW, scottws try a search in the Great Debates forum…there have been several good discussions on this topic.
Welcome to the SDMB!