One evolving species vs speciation.

I think the most likely scenario of this happening so far is presented in the movie The Time Machine remake. The moon breaks up and falls on us. A part of the population goes under ground to escape the disaster while the other part remains on the surface. Life for both groups undoubtedly becomes very harsh.After centuries of living under ground, the first group has adopted well enough that they don't want to go back to the surface. The second group has also survived and begins to thrive again on the planet surface.After 800 thousand years, we effectively have 2 different species of humans.As the vampire-like under ground human sub-species tells our time traveler, "Who are you to question 800 thousand years of evolution?"Other than this scenario, I can't really think of any other way we could prevent gene flow from happening for long enough for the human species to split into two.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

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He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

I don't know. I was just using a couple of words I remembered from my high school biology text book hoping I could impress people.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

So, do the two words I remembered from my high school biology text book impressed you now?

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Probably 100 generations, considering they breed yearly. There have been legends of bottomless holes that would open up and then close in a short time later. Supposedly, some people have thrown objects, including fire sticks, down the hole and they never touched the bottom so that's why they concluded that these holes were bottomless.Anyhow, I wonder if Smith had anything to do with these myths.

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

I was going to refute your original refutation of my use of "gene flow" but I quickly realized that I didn't have the sufficient knowledge to clear it up precisely. So, I just decided to wait for some fool to clear it up for me.See, it's one of those things that I know just enough to apply it to my everday conversation but not enough to do a lecture on.

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

If you insist, then I insist that my scenario is pretty much the best one right now. Kill off 90% of the population of Earth. With the remaining 10%, kill off some more. Then split them in 2 groups. Keep them seperate in two entirely different environments for hundreds of thousands of years.The reason looking to other species is helpful because of our rediculously long lifespan. That's why we study critters that live in a much shorter lifespan, thus giving us more generations in less periods of time.

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!