It's just how evolution works. The geologists made far too much of "mountains and oceans" being important, but then again, their deal is rocks, not living beings with agency.
If you look at other species, you'll see that differences in looks and behaviour often go hand in hand, which is where the lousy definition of "species" comes from (people confounding it with "race" and "ethnicity", for instance; it should be limited to "groups that can interbreed and make fully fertile offspring", which would means Coyotes and Golden "Jackals" also belong as races of the wolf/dog species, Canis lupus. Just because coyotes have a different culture does not make them a different species. It'd be like classifying Dutchmen and Pygmies as different species, Or Englishmen and Japanese because 1) they live on islands on opposite sides of the world, sound different, can't communicate, and might even fight if put in a cage together. Their dens look different, they look different, they act different. An alien thinking like Linneaus would say "different species". Of course, they'd also think we see upside down ....
So you have two groups that smell different, look different, act different. It's known that it's more or less "normal" to prefer "one's own kind" (of course, there's always that minority of oddballs known as "xenophiles", who might outbreed with another race, but that just keeps too much inbreeding from happening within a given population.) If they refrain from brreding with one another long enough, they will eventually become different species from "drift", and they don't even need "mountains and oceans" to do that - they just need taboos, inhibitions against mating with "the other", racism.
And the differences can start small, and unnoticed. A different ideology leading to a different slang leading to a different dialect. The minority is ousted, shunned. Or, a new "recessive" variant geneset pops up, and isn't detectable in the population until it spreads enough so that individuals with it start mating several generations down the road. These new variants look and act a little different, have different opinions, smell different. They might be tolerated, but eventually enough of them are around to prefer one another, and they breed true. Then the usual happens.
It's just how evolution works. The geologists made far too much of "mountains and oceans" being important, but then again, their deal is rocks, not living beings with agency.
If you look at other species, you'll see that differences in looks and behaviour often go hand in hand, which is where the lousy definition of "species" comes from (people confounding it with "race" and "ethnicity", for instance; it should be limited to "groups that can interbreed and make fully fertile offspring", which would means Coyotes and Golden "Jackals" also belong as races of the wolf/dog species, Canis lupus. Just because coyotes have a different culture does not make them a different species. It'd be like classifying Dutchmen and Pygmies as different species, Or Englishmen and Japanese because 1) they live on islands on opposite sides of the world, sound different, can't communicate, and might even fight if put in a cage together. Their dens look different, they look different, they act different. An alien thinking like Linneaus would say "different species". Of course, they'd also think we see upside down ....
So you have two groups that smell different, look different, act different. It's known that it's more or less "normal" to prefer "one's own kind" (of course, there's always that minority of oddballs known as "xenophiles", who might outbreed with another race, but that just keeps too much inbreeding from happening within a given population.) If they refrain from brreding with one another long enough, they will eventually become different species from "drift", and they don't even need "mountains and oceans" to do that - they just need taboos, inhibitions against mating with "the other", racism.
And the differences can start small, and unnoticed. A different ideology leading to a different slang leading to a different dialect. The minority is ousted, shunned. Or, a new "recessive" variant geneset pops up, and isn't detectable in the population until it spreads enough so that individuals with it start mating several generations down the road. These new variants look and act a little different, have different opinions, smell different. They might be tolerated, but eventually enough of them are around to prefer one another, and they breed true. Then the usual happens.