Are humans influenced by natural selection?

Question

First off, i apologise if this is in the wrong place... I really dont see where i'd put it..

Secondly, I kinda have two questions, the title is my main question, the one below is a hypothetical situation im just sort of curious on. =D thanks.

How to word this...

Natural selection is a process that weeds out "weak" individuals and allows room for the stronger ones. What would happen to a species if Natural selection were eliminated. (No food/water shortages, no unbalanced gender populations, no natural enemies and no diseases, as much room as they could possibly need)

Would the "good genes" that helped their survival still be predominate after so many years? Would mutations become a problem? How would evolution effect them after millions of years, living in a "near-perfect" environment?

Well, I understand the humans are still affected, but wouldnt it be to a lesser extent than most species. (also i found the same question already on here... ( ^ _ ^ );; ) But still curious about the "if a species were completely unaffected by natural selection" thing... And sorry ( _ _ )

Answer 1

Yes subject to Nat. Sel. as u can still see on Sudan swamps, tallest community of humans an the world, or Peruvians living high on the Andes where they have extra coding capacity for Hemoglobin.

The conditions you describe were studied theoretically by Hardy and Weinberg, so these conditions are called "Hardy-Weinberg equilibrium" and you can search it on almost any college level ecology text.

What happens to the gene pool on such conditions? with no nat. sel., all "expensive" genes, ones that take a lot of energy to work, disappear or reduce strongly their presence, and a proff is that Capsicum annum or chili as you call it, when taken to spain from Mexico, lost its cappacity to produce capscin, the spicy oil that gives chili its strenght and in nature is a defense versus herbivorous insects not present on spain. And so on.

Answer 2

Weak and strong are subjective terms. Natural selection's big threshing machine only cares about reproductive success.

Domesticated animals provide a pretty decent partial answer to your question about removing species from natural selection. Turkeys that drown because they look up into the rain, sheep that mindlessly walk off cliffs. Although humans bear some responsibility for allowing superbly stupid creatures like those to develop and continue.

I don't know if it's possible to remove an organism from some kind of selection, they all need to reproduce, and unlimited isn't something that can exist in the real world, you'd need that if you could manage to remove all forms of mortality other than natural death.

Without the need to forage, flee, posture or anything else but eat, respire and reproduce, what you'd probably wind up with would be essentially over-sized bacteria, provided you waited long enough.

Answer 3

Your assumption that, 'Natural selection is a process that weeds out "weak" individuals and allows room for the stronger ones' is incorrect.

Natural selection is the process by which individual organisms with favorable traits are more likely to survive and reproduce. Your statement of natural selection sounds more like Spencer than Darwin.

But to provide a short answer; Yes, humans are influenced by natural selection. Secondly, evolution works best if there is a high birth rate and a high death rate. In your proposed environment, there would be a high birth rate and a low death rate. Evolution is still the process. However, genetic variations would be greater. More humans, who would otherwise not survive to reproduce, would do so in your benevolent environment.

Answer 4

Very good questions: To the first one--yes, humans are absolutely under the same rules governing natural selection for all other living organisms.
For the rest of your questions, you must take a step back and look at perspective...If we lived in a world where the things like you said existed (no disease, predators, plenty of food, etc), which in the United States and other parts of the world seems to almost exist currently, there would still be natural selection. There will always be natural selection, no matter how hard we try to eliminate the selecting factors from our world. Instead of women choosing men with the best running skills (which helped them hunt better) they now perhaps choose men with the best sense of humor or the greatest intelligence to mate with. Of course these aren't crucial for merely living, but since we have eradicated the need to hunt, natural selection has moved on to more detailed things to select for, like personality.
Genes will predominate as long as the world keeps selecting for them. Men with larger muscles will continue to be selected, not because they can carry more food as was in the past, but because they look good. Just as perhaps the genes that give us body hair, that once protected us against harsh climates, will continue to be lost because we have heated homes and women prefer less hairy men?!
Mutations are problems, always have been and always will be for the individual. However, for society they are our greatest asset. They give us genetic diversity which allows for natural selection. It is true mutations give us many diseases, they also have given us everything else we have (ribosomes, neurons, even personality). The only way mutations will hurt society as a whole is if we determine a way to prevent them from happening at all.
Ok-- if a species (humans) were completely unaffected by natural selection nothing would happen. They would get no better and no worse at surviving in the world. Unless, everything else was affected by the selection in which case everything else would gradually get closer and closer to humans in complexity, unless humans did something to inhibit or directionalize selection for everything else.

Answer 5

You have a pretty good understanding of natural selection. An environment puts certain selection pressures on an evolving organism. If those selective pressures were gone (no competition for resourcs, no predators or diseases, no unbalanced gender populations leading to sexual selection), then the organism would be free to produce all sorts of variation as long as it wasn't a lethal birth defect. Yes the "good" genes would slowly be diluted with "bad" genes that would normally be weeded out.

But then they wouldn't really be "bad" genes ... as "bad" (in terms of natural selection) just means genes that are not good for survival or propagation. In a "near-perfect" environment there would be no such thing as "bad" genes, except for something so lethal that it caused death or sterility.

Answer 6

of course they are affected by natural selection.

it is perfectly obvious if you read the Darwin awards.

they are bestowed upon the remains of people that committed incredible acts of stupidity, gotten themselves killed because of said acts and have thus improved our gene pool by removing themselves from it.