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Comment by dan_mctree | Hacker News Reader

Is anyone else surprised at how quick species can seem to evolve in these kinds of ways? Asian and African elephants are supposed to have separated millions of years ago, yet still strongly resemble one another. Yet in a few decades, something as fundamental as the presence of their tusks can shift dramatically. And that in a species with very long gaps between generations.

It makes me suspect there's something else going on here that's not just good old natural selection.

Have they done any tracking to confirm the tuskless elephants are actually being born to tuskless mothers? Or could it be that the parents are actually affecting the way their offspring are born in some lamarckian-esque sense? If there'd be some trick animals can pull to change their offspring in some ways, that ought to be highly effective for long term species survival and should thus be highly selected for.

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Nah, looks like natural selection. The article mentions that "The phenomenon of elephants going tuskless is not new. Researchers found the number of tuskless female elephants in Mozambique increased by almost double over 30 years. This overlaps with a period of civil conflict, where armed forces slaughtered 90% of the elephant population to produce ivory.". That is a LOT of selection pressure. Also, the African Elephant Specialist Group (AfESG) [1] published a graph of elephant populations, the reduction in total numbers is pretty dramatic. You might liken this to the way that humans in small, isolated communities will also start to differentiate in a hurry (forex, that one blue family).

[1] https://ourworldindata.org/grapher/african-elephants

I mean this honestly, but what is the blue family that you are talking about. The first thing that springs to mind is Avatar, and Google isn't helping me out.

https://en.wikipedia.org/wiki/Blue_Fugates

A point evolution event can happen extremely rapidly if there's a clearly selective mortality event.

If a new predator is introduced to a population that selectively kills only certain traits, that mutation can become dominant in the population within just one or two generations.

Imagine if aliens came to Earth and killed everyone over 5'6" tall. That "evolution" would be essentially instantaneous.

That evolution would still take multiple generations, since a 5'5 father and a 5'5 mother will have a 5'8 son on average.

Seems like the relative death rates of tusked vs tuskless would matter. Remember the 32% is a percent potentially on a small number. Say to an extreme 99% of tusked elephants were killed, 99% of tuskless were unharmed. If tuskless is a genetic traight, it takes over very quickly even though total population size is smaller.

Exactly that!

I think it is ridiculous to think that more elephant are born without tusks as a kind of "random selection" or even adaption

What do you mean by quick? Evolution is just random mutations. You're basically trying to diversify and spread risk. If there is huge selective pressure only a handful of genes will survive and when they reproduce they will be over represented compared to the previous generation.

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