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I'm not a evolution scientist, so I would love to have some educated response to that : Now that we are over 6 billion humans on earth, with migration way easi

I'm not a evolution scientist, so I would love to have some educated response to that : Now that we are over 6 billion humans on earth, with migration way easier and common place than before, shouldn't on the contrary human evolution been speeded up ? EDIT : I know evolution is not progressive but happen by sudden steps, but I suppose it still stands.

lutusp 14y ago
> Now that we are over 6 billion humans on earth, with migration way easier and common place than before, shouldn't on the contrary human evolution been speeded up ? Evolution speeds up as a result of either an increased natural mutation rate or extreme environmental challenges (lots of death produced by unfitness) -- or both. But we're not seeing either in modern times. > EDIT : I know evolution is not progressive but happen by sudden steps ... No, this isn't true as a rule. In evolutionary theory, the overall rate of change,and the presence or absence of abrupt changes, is entirely dependent on what produces greater fitness. In other words, the rate at which evolution happens, and the shape of the change curve, are themselves driven by considerations of fitness and natural selection.
lmm 14y ago
Migration would slow down many kinds of evolution. Lots of interesting evolution happens when you get divergence in island (literal or metaphorical) populations. Migration does mean that any clearly beneficial changes will spread quickly, and a large population gives more chances for them to arise - lactase persistence is probably an example of this. So humanity probably does adapt quicker than it otherwise would to changes in the environment, if those changes affect most of humanity. In the short term I'd expect to see humanity getting better at a lot of things as races intermingle and previously separate gene pools combine - a lot of things like height or fitness or intelligence seem to be combinations of many genes where "perfect" is in some sense the default; how good you are is a question of how many "bad" genes you've picked up (and most of the bad genes are recessive). I've seen anecdotal suggestion that mixed-race children are healthier (would be interested to hear if there's any proper studies of this). I suspect in the immediate term this will be a bigger effect than that of new mutant genes.
illuminate 14y ago
"shouldn't on the contrary human evolution been speeded up" Why? We're well adapted to our "niche". There is not much different for us to adapt to.

lutusp 14y ago

> Now that we are over 6 billion humans on earth, with migration way easier and common place than before, shouldn't on the contrary human evolution been speeded up ? Evolution speeds up as a result of either an increased natural mutation rate or extreme environmental challenges (lots of death produced by unfitness) -- or both. But we're not seeing either in modern times. > EDIT : I know evolution is not progressive but happen by sudden steps ... No, this isn't true as a rule. In evolutionary theory, the overall rate of change,and the presence or absence of abrupt changes, is entirely dependent on what produces greater fitness. In other words, the rate at which evolution happens, and the shape of the change curve, are themselves driven by considerations of fitness and natural selection.

lmm 14y ago

Migration would slow down many kinds of evolution. Lots of interesting evolution happens when you get divergence in island (literal or metaphorical) populations. Migration does mean that any clearly beneficial changes will spread quickly, and a large population gives more chances for them to arise - lactase persistence is probably an example of this. So humanity probably does adapt quicker than it otherwise would to changes in the environment, if those changes affect most of humanity. In the short term I'd expect to see humanity getting better at a lot of things as races intermingle and previously separate gene pools combine - a lot of things like height or fitness or intelligence seem to be combinations of many genes where "perfect" is in some sense the default; how good you are is a question of how many "bad" genes you've picked up (and most of the bad genes are recessive). I've seen anecdotal suggestion that mixed-race children are healthier (would be interested to hear if there's any proper studies of this). I suspect in the immediate term this will be a bigger effect than that of new mutant genes.

illuminate 14y ago

"shouldn't on the contrary human evolution been speeded up" Why? We're well adapted to our "niche". There is not much different for us to adapt to.