Is human evolution finally over?

[John Cuthber]

Evolution for humans will continue while ever miss Smith can say that she prefers Mr Jones to Mr Blogs and while Mr Baker can say he prefers Miss Butcher to Miss Banker.

[Phi for All]

Evolution for humans will continue while ever miss Smith can say that she prefers Mr Jones to Mr Blogs and while Mr Baker can say he prefers Miss Butcher to Miss Banker.

 

A couple of generations ago, the Baker boys were all hot for Miss Candlestickmaker, so the smell of money has replaced patchouli as a selective pressure.

[John Cuthber]

The direction of evolution will vary depending on what evolutionary pressures are applied- but it will keep going.

[dmaiski]

i guess this is the point where an intelligent, reasonable, and logical, person (in. me) will point out:

 

the authors probably meant human SPECIATION not EVOLUTION has ceased and will never happen (until we move to space/other planets)

[Ophiolite]

i guess this is the point where an intelligent, reasonable, and logical, person (in. me) will point out:

 

the authors probably meant human SPECIATION not EVOLUTION has ceased and will never happen (until we move to space/other planets)

Except that the tone and content of their work suggests the exact opposite. I stand by my original thought that this is third rate research and fourth rate thinking.

[the_Nothing]

My sense is that most people who ask this question are thinking of a scenario where there is no selective pressure and almost everyone survives to pass on their genes. So there are no "bad" genes anymore and we don't "evolve".

 

However, in this case there would be no possible way for evolution to end!

 

In a theoretical situation where no genes give a reproductive advantage then evolution will be dominated by genetic drift. Which basically just means randomness. Some alleles will eventually dominate the population until they are displaced by other alleles - which are generated randomly by old-fashioned mutation, and then eventually - by chance - some other allele will rise up to dominance. This is a mathematical certainty given no selective pressure and the fact that mutation is possible. (In this scenario, if mutation did not exist then we would eventually lose all diversity and become genetic clones of each other. One female clone and one male. That would end evolution I imagine.)

 

The strange truth is that - because of the genetic drift scenario above - the only way that our population will maintain the same frequency of alleles over time (and we are therefore not evolving according to our definition) is IF there is some kind of selective pressure that is weeding out new genes. Furthermore this selective pressure would have to be constant and unchanging so any deviation from the genetic norm would give that person a poorer chance of reproducing and eventually those genes would get weeded out.

 

This scenario isn't necessarily impossible - we see many species that have maintained the same apparent body shapes over millions of years. It just implies that humans haven't yet escaped the restrictions that nature places on us.

 

So when will human evolution end? When we can artificially control the frequency of all alleles in the human population. And we don't decide to change them.

 

Please let me know if I missed something important!!