I don’t want to make an ignorant assumption about the specifics of how evolution works, but how would something like this happen according to current theories about evolution? Would super intelligent people (or however the next evolutionary stage is characterized) begin spontaneously popping up, or would it probably be only one “next-stage” person whose genes would have to spread generationally over time?
How does one species diverge or expand into another? What happens to homo-sapiens in this context?
New species usually arise when a small population within a species becomes isolated over an extended period of time and responds to different selective pressures. Since humans at the present time are more thoroughly mixed than ever before, there is no prospect of a split into two species. Also, there is no reason to think that any new species would be objectively “better” (stronger or more intelligent); rather, we would have two species each of which is better adapted to two different environments.
Expanding on jklann’s completely correct post, if you put a group of people on an island for 10,000 years and left them completely isolated, you would almost certainly end up with divergent species.
You’d need a lot more than 10, 000 years bryanmc. Various groups of humans have been isolated for longer periods than that in Australia, the South Pacific and the Americas. No evidence they became anything like a new species. Isolated human groups tend not to diverge too much from the parental stock, largely because we are so genetically homogeneous to begin with. Any divergent traits more or less have to arise from mutation, and that takes time.
Depends on the conditions and numbers, of course. Smaller group of people, harsher conditions = faster evolution. I’m not too familiar with anthropology, but I believe 10,000 years is about the limit on known human habitation of the Americas and Pacific Islands, and these groups were both large and probably not totally genetically isolated (small, periodic influx of genes from immigrants will help keep the species homogenous). I was picturing a group of about 50 people completely genetically isolated, which would be about 400 generations of divergence. But you’re right – it’s not an exact science here. Make it 100,000 years for safety.
(Just to be argumentative, I’ll point out that speciation could happen with a group of just two people in a single generation – if a single mutation pops up that causes a physical/chemical/biological/behavioral difference that makes the new individuals unable to mate with other humans.)
To further belabor the point, it’s a crapshoot – the time to speciation can only be predicted as a probability based on such things as population size, mutation rate, immigration/emigration rate, and selection pressure; it cannot be stated as a definite period of time.
There is speculation that the Americas have been populated longer than that. There is evidence of a hearth at Monte Verde Chile (or Argentina, can’t remember) from over 30,000 years ago.
Thought as of 10 years ago whenI was getting my degree in Anthropology is that there were three main waves of imigration from Siberia one 30,000 years or so ago, one 12,000 years ago and then one in the 200s or so AD. the first tow were people walking across the Bering Land Bridge during glasial periods, the third was the “Inuit/Eskimo/Canadi-alaskin” native americans who came by boat. or Kyak really. of course they were still migrating back and forth in modern times really.
The definition of a species is based on the inability or at least the lack of natural examples of breeding between groups. so you have different types of sparrows who have different sexual triggers defined as seperate species even if they look exactly the same. The ofspring must be fertile too by the way. no mules.
Technicaly, you can impregnate a rabbit with cat sperm but that just doesn’t happen in nature.
Yep, the number of times I’ve tried to imprgante a rabbit with cats sperm! It just can’t be done.
On another note I believe myself to be a distinct species in homo genus as I have been separted from the rest of the human race for a long time and my attempts to breed with of homo sapiens sapiens have so far been unsuccesful.
You’re right that it’s pot luck bryanmc. I was just pointing out that you need much longer than 10, 00 years to produce a new human species with near certainty.
For an example of a small, completely isolated, highly stressed population look at Tasmanian Aborigines. An isolated population of C5000 isolated for 12 000 years with no clothing, no ability to make fire, no watercraft and only stone tools. Given that the critical population size for large mammal is 500 under ideal circumstances it’s doubtful any lesser number would have survived. Some of the Bass Straight island populations numbered only 500 and they died out within a few thousand years.
So in Tasmania we have what is probably the perfect example of what happens to isolated humans over millennia. The result was no change. The Tasmanian Aborigines remained and still remain as human as anyone else, and even show very little genetic differentiation.
Like I said, us humans are genetically identical by the standards of most mammas.
Sometimes, sometimes not. Numerous species such as wolves and coyotes and humpback and fin whales have an ability to breed and do so routinely in the wild. They remain separate species. Similarly there are numerous plant examples and even animal examples where populations can’t interbreed, and yet remain the same species.
I have the feeling the question was inspired by the X-men. And even if I’m wrong, I’ll broach it -
I think it’s pretty safe to say it’s not going to happen that way - forgetting the whole superpower thing - mutations are not going to appear suddenly out of nowhere scattered among many people - they have to be inherited from someone somewhere who has the first mutation.
But even though it couldn’t be called a new species unless it was genetically isolated - I don’t see why it’s impossible that a mutation could occur and be passed on over multiple generations that would make SOME people wildly more adapted to survival and reproduction than we are now and perhaps ultimately crowd out “modern” humans - i.e. those that don’t have that mutation. It’s also conceivable to me that the mutation “could” make those that have it very different from us - in “feel” a new species even if not in definition.
I heard speculation recently - I have no idea if it’s true or not - that all modern humans have a mutation on a single gene that affects (accounts for?) human language - and that that mutation is about 100,000 years old and may be responsible for the sudden burst of culture and activity and expansion of humans seen at about that time.
If that’s true - and who knows if it is - what happened to the people who didn’t have that mutation for language?
It’s certainly conceivable to me that a new “superbrain” mutation might pop up that would literally make it impossible for modern humans without that mutation to continue.