(November 8, 2011 at 1:05 pm)Mister Agenda Wrote:(November 7, 2011 at 11:22 pm)SeekerOfTruth Wrote: So why would something evolve into something that its predecessor cant mate with?
Finally, If it is just gradual change over a long period of time like humans and apes coming from a common ancestor then why cant we mate with monkeys even though we came from the same source? This extends to all life if we all came from a common ancestor then shouldn't dogs be able to breed with pigs and people with dolphins? On the few cases that different species can breed they offspring is always sterile. And if its just that they eventually became so different that they can't breed then why did that happen?
These are legitimate questions that I've had.
Because I can tell you make an effort to understand science and at least refer to readily-available sources, I will take this on sans sarcasm.
One thing is that part of the definition of species has to do with difficulty with interbreeding, creatures that can readily interbreed are usually considered the same species (not always, for historical taxonomic reasons).
I will focus for a moment on one of those exceptions: dogs. Dogs and wolves can interbreed readily, despite obvious phenotypical differences that are greater than some between related species that can't interbreed. The reason for this is that, although dogs have been bred into a wide variety of types, the thousands of years we've been doing so haven't been long enough to bring into play the chief obstacle to interbreeding: genetic drift.
As has been found in nature on small islands that used to be joined(particularly with burrowing mammals who can't readily travel between islands), long separation of populations (25-30,000 years in the island study of which I'm thinking) of the same species will eventually result in speciation even if the selection pressures have resulted in them remaining superficially identical. You could say that it's lack of interbreeding that results in a lack of ability to interbreed. Over thousands of generations of separation (it doesn't necessarily have to be geographical isolation, anything that severely reduces interbreeding will suffice), mutations unique to each seperated population accumulate within that population, but not the other. If the change isn't acted on by natural selection, it will have no particular pattern, the genomes of the separate populations will just get more and more different over time.
Our common ancestor with chimps (our closest living relatives) is estimated as living about six million years ago. Genetic drift alone makes it unlikely that we would be able to interbreed with them. Monkeys are right out. However, it may have been possible, say 5.75 million years ago, for our ancestor then to have bred with the chimp's ancestor of the time.
I hope that answers your question to your satisfaction. I will be happy to provide more information if you need clarification.
Two questions:
What did monkeys and chimps evolve from?
Why are there still monkeys and chimps in the world today? Or did they just fail to get the evolution memo?
