Sounds like the poachers are scientists now.
Female African elephants are evolving without tusks due to ivory poaching
271–280 of 320 posts
Re: Female African elephants are evolving without tusks due to ivory poaching
#272Earlier quoted context omitted.
Define "artificial".
Oof, that's a tall order, isn't it? I'm no professional philosopher, and not somebody who works all day making dictionary definitions, but the general sense of natural / artificial here is "not by humans" versus "by humans", although that's not very precise and you'll get into trouble if you read too much into much into it. There are loads of ways in which you'd need to refine this definition in order to account for…
> which is why you demanded that I define it for you, presumably so you could poke holes in whatever definition I provided
Not really. Your original use of the word implied the definition you were using, and my comment was merely to point out that it's the wrong definition (in my opinion, obviously).
In this context it makes more sense to include the intention, because the evolution itself in this case is not something we artificially induced.
The elephants, for example, might have evolved to have green tusks instead, which would have made them not attractive to poachers. They could have grown wings that would made them more difficult to be hunted. The point is, poaching might be artificial, but the elephants responded to a threat (coming from humans or not) with a completely random and natural process.
Re: Female African elephants are evolving without tusks due to ivory poaching
#273Earlier quoted context omitted.
I do not understand how mating with a 1st or 2nd cousin affects the ratio of females to males. Could you explain?
Assume that Bob knocks up both Alice and Eve. Alice has a son, Eve has a daughter. Alice's son knocks up Eve's daughter. Their kid will have two biological grandmothers, but only one biological grandfather. Apparently, historically, this type of thing was quite common and could heavily skew family trees towards the female side of things.
That skews the tree shape, but the odds of each baby are still ~50/50 so the overall population numbers should be stable.
Re: Female African elephants are evolving without tusks due to ivory poaching
#274Earlier quoted context omitted.
Evolution IS selective breeding. The members of a species most fit for their environment are successful in procreation. The female elephants without tusks are surviving at higher rates which is resulting in more offspring with no tusks. This causes a shift in the population where a trait previously with no or little benefit becomes advantageous and the shift in genetic makeup of the whole population evolves.
But we don't commonly run around saying Arabians and Morgans are different because of evolution. Neither do we say that chihuahua's and labradors have evolved into their present form. In my humble opinion "evolution" refers to speciation, which takes very many generations.
It’s just selective evolution. We just use a different word for it to convey more information. It’s the same process though albeit randomly.
Re: Female African elephants are evolving without tusks due to ivory poaching
#275Sounds like the poachers are scientists now.
Do they meticulously record their data? Checkmate.
Re: Female African elephants are evolving without tusks due to ivory poaching
#276Earlier quoted context omitted.
>our ancestors comprise mostly of females in a ratio roughly 3:2 to males. For anyone else wondering how this is possible on an individual level, apparently a lot of people used to reproduce with their first and second cousins.
I do not understand how mating with a 1st or 2nd cousin affects the ratio of females to males. Could you explain?
It doesn't because mating cousins is likely the effect of a skewed population,not the cause.
(im not a historian so this is speculation)
I imagine that early humans had divided roles, and roles assigned to males involved more danger. (bearing in mind that the state of medicine meant that relatively minor incidents by our standards could lead to infection and death in theirs.)
So populations start out 50/50,but skew badly once men age enough to take on dangerous work.
This leads to men having multiple partners and the scenario mentioned in the sibling comment.
Re: Female African elephants are evolving without tusks due to ivory poaching
#277Earlier quoted context omitted.
Human behavior probably has the opposite effect in captive elephants. If a captive elephant is born without tusks then the Mahout is going to kill it rather than invest in rearing an animal that has much reduced utility and will not yield healthy offspring.
Elephants are not really bread in captivity.
While that's generally true, there are exceptions. Elephants at the Oregon Zoo have birthed more than two dozen babies over the past several decades. https://www.oregonzoo.org/node/1948/media
Re: Female African elephants are evolving without tusks due to ivory poaching
#278Earlier quoted context omitted.
What's the difference in this case? Doesn't seem too different from how camouflaged eggs would have developed (maybe just faster because the selection mechanism is so strong). When I think of selective breeding I think of humans picking out which animals (cows/dogs/wheat/etc) get to reproduce.
Right, selective breeding is just a subset of natural selection. Not sure why folks seem to want to exclude humans from nature, like we’re not part of the exact same system.
You’ve got it backwards. ‘Natural selection’ was coined to point out that selective forces exist in the wild other than humans deliberately breeding selected animals, which was well known in Darwin’s time. There’s ‘selection’ by humans and ‘natural selection’ which is by effects other than human selection. The effects of human hunting are a boundary case, where the selection pressure is not intended, but is a ‘natural’ consequence.
Re: Female African elephants are evolving without tusks due to ivory poaching
#279In case anyone is wondering about the size of the effect, https://www.nationalgeographic.com/animals/article/wildlife-... has the numbers. Before the war, 2-4% of female elephants were tuskless. Now 32% of newly born ones are. So it's a significant change, but it's not like this property was coming out of nowhere. It started off about as common as humans having green eyes.
Now I'm worried that in a couple hundred years a third of humans will have green eyes because all the blue ones have been harvested by aliens.
Re: Female African elephants are evolving without tusks due to ivory poaching
#280Selection at work. I speculate that fish size is undergoing similar effect due to fishing-net eye-sizes.