[ExI] Birthrate falling worldwide - not just in the developed nations

[efc at disroot.org]

On Fri, 1 Nov 2024, david via extropy-chat wrote:

>> 
>> As Adrian says, evolution is probably too slow to have a significant 
>> effect.
>> While economies will have problems with not enough young workers to
>> support an ageing population, there is also the problem that the
>> military will not have enough younger people to fight extended land
>> wars.
>> The robots will have to fight our wars as well as run our factories.
>> The aged humans will help to look after the few grandchildren around.
>> 
>> BillK
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>
> There are two aspects to evolution (well. there's more, but two we are 
> concerned about here)
> 1/ The slow accumulation of mutations
> 2/ Selection within existing range
>
> (1) as you say, is far too slow to have any effect on the birth rate before 
> humans would go extinct.
> (2) however, can be as fast as a single generation.
>
> Consider an insect population where a gene confers a pesticide resistance. If 
> even 1% of the population has that gene, widespread use of the pesticide 
> would see 100% of the population have it within very few generations.
>
> It is the same for humans, if not as extreme.  Children will be born to those 
> who continue to have multiple children despite affluence or lifestyle. There 
> may be a temporary drop in population while those who choose not to (or 
> can't) have children remove themselves from the gene pool, but the harsh laws 
> of evolution say they will be replaced by those who can and will.
>
> -David.

Very interesting. Thank you for explaining David, maybe my initial 
intuition wasn't completely wrong after all?

In terms of 1, I saw in the newspaper the other week about an experiment 
performed by Kerstin Johannesson, professor in marine ecology at the 
university of gothenburg.

After algae had killed off a certain species of winkle (1) on a small, remote 
rock, the moved the population of another species (2) a few hundred meters 
to that rock. She thought the new population would die out, due to it not 
being adapted to that specific rock. In their original habitat, they 
(2) had evolved to survive attacks from crabs, but the winkles in the new 
habitat (1), which she replaced, had evolved to survive big waves.

1 were small and "risk taking" 2 were bigger.

After the move, the female winkle gave birth to "children" about half a mm 
in size. The adults all died off. Among the new generation, a few survived 
due to dormant genes. After 30 generations, the new species (2) looked 
exactly like the original species (1).

In the US similar experiments has been done on fish, and the scientists 
was very surprised at the lightning speed of evolution in this case.