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Landmark ancient-genome study shows surprise acceleration of human evolution

nature.com

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Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#131

Post by rolph »

greazy wrote: post #20
like_any_other wrote: post #7

Is there any species, other than humans, that is found all across the globe (i.e. geographically separated), and has not differentiated into subspecies? Wolves, elephants, tigers, bears, and foxes have all been categorized into multiple subspecies each, distinct but able to interbreed.

The definition of what constitutes a species is a human construct. Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. So your question is hard to answer.

"The definition of what constitutes a species is a human construct."

speciation is reproductive incompatability.

geographic isolation is more like founder effect than speciation.

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#132

Post by rolph »

Archelaos wrote: post #62
John7878781 wrote: post #58

Earlier quoted context omitted.

> Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. Really? I thought the requirements for species classification were: (1) must be able to reproduce and (2) offspring must be fertile. Is it less objective than that?

Polar bears can have furtile offspring with grizzly/brown bears. See: https://en.wikipedia.org/wiki/Grizzly%E2%80%93polar_bear_hyb...

the reproductive incompatability, is based on physiological range.

in general, there are multi organizational levels of reproductive incompatability.

in this case, the geographic distance, orogenic blockade, and ecological confounds of arctic conditions preclude easy mingling of U.arctos x U. maritimus.

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#133

Post by rolph »

stainablesteel wrote: post #107
greazy wrote: post #20

Earlier quoted context omitted.

The definition of what constitutes a species is a human construct. Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. So your question is hard to answer.

my understanding of what classifies something as being a part of the same species is the fact that they can make children that are viable to have children themselves horses and donkeys can breed to make mules, but the mules usually cant reproduce, this is the same with tigons and ligers but sometimes the females are viable so if they can produce children that can produce children, they're the same species. where this…

if you consider that geographic barrier is an environment of immediate lethality, or infecundity, that is physiological incompatability, and would be a speciation.

if you consider that geographic barrier, simply precludes, interaction between individuals, then you will have founder effect, thus one population will be genetically decended from a sample of the larger population.

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

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#134

Post by naasking »

krapp wrote: post #117
naasking wrote: post #96

Earlier quoted context omitted.

> However race is a cultural and social construct. [...] The superficial variations in average height, skin color, etc. do not vary enough to constitute species differentiation Species is also a social construct. Calling race a social construct isn't the persuasive argument people seem to assume. > the vast majority of genetic variation exists within populations (in other words, within "races") and not between them.…

It's the established scientific consensus. Obviously it isn't convincing to racists, but no argument would be given that racists don't approach the subject in good faith to begin with. I think you're being too pedantic, though, because the statement "the average Norwegian and the average Pygmy are more alike than any individual Norwegian is to any other Norwegian" is perfectly sensible within the context of this thre…

> It's the established scientific consensus.

So was the fact that ulcers weren't caused by bacteria. "Established scientific consensus" is another argument people need to stop using.

> You're intentionally omitting necessary context to create a false equivalence between race and species

No, I'm not equating race and species, I'm refuting the argument that race being a social construct makes it meaningless or scientifically useless by pointing out that species is also a social construct while being meaningful and scientifically useful. Therefore the argument that it's a social construct is a red herring.

> But when people say that race is a social construct, they mean it was created to justify white supremacy, slavery and colonialism, and that (unlike species) it serves no useful scientific purpose.

So you agree that calling it a social construct is completely besides the point, and people are not saying what they mean and merely polluting discussions with pointless red herrings.

Now whether race serves a useful purpose is highly debatable. There are plenty of statistical associations with race that are used to this day, eg. race as a risk factor in sickle cell anemia. If your argument is that we usually have better classifications than race in many circumstances, then sure, but note that this still doesn't prove the intended point that race classifications are useless, which is a claim that they never have any use.

Edit: > the statement "the average Norwegian and the average Pygmy are more alike than any individual Norwegian is to any other Norwegian" is perfectly sensible

Just want to be clear that this is still a fundamental category error. These are completely unlike measures and equating them properly yields different conclusions, eg. using pairwise genetic distance measures. See the paper, "Human Genetic Diversity: Lewontin's Fallacy" for where this misunderstanding originated.

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#137

Post by like_any_other »

pegasus wrote: post #124
matt-attack wrote: post #120

Earlier quoted context omitted.

Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions. The slight coloration of a bird’s crest, shape of some lizard’s nose. Yet with Homo sapiens we seem to be allergic to the idea that our drastic swings in physical attributes could possibly qualify as a different species (we obviously call them “races”). But they plainly diverged from each other due to geographic and r…

> Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions It might seem like that to you, but you'd be wrong. Taxonomy prioritizes genetic distance and reproductive isolation over superficial visual traits that humans happen to find striking. While phenotypic variations like skin color or facial structure are highly visible, they represent a microscopic fraction of the over…

> Taxonomy prioritizes genetic distance [..] Two humans from opposite sides of the planet are generally more genetically similar to each other than two chimpanzees from the same patch of forest.

Do you have a source? I've tried looking in the past, but couldn't find good "genetic distance" metrics that could be compared between humans and other species.

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#138

Post by jltsiren »

IncreasePosts wrote: post #68
beloch wrote: post #64

Earlier quoted context omitted.

The DNA of humans and chimps is 98.8% identical. The percent difference between genomes of species is one of those tricky measures that doesn't really give good intuition. I find it much more useful to think in terms of the time since two species shared a common ancestor. e.g. For humans and chimps, that's several million years. For Sumatran and Siberian tigers, it's around a hundred thousand years.

What's the most recent common ancestor between an North Sentinel islander and a Norwegian? Mitochondrial Eve is 150kya

There are estimates that the most recent common ancestor of all humanity lived a few thousand years ago. Isolated peoples are almost never fully isolated, and all kinds of rare events can happen in 100+ generations. Andamanese peoples in particular were in contact with each other, with occasional contacts to the mainland.

Tasmania may have been isolated for ~8000 years between sea level rise and European contact. But the last person of fully Aboriginal Tasmanian descent likely died in 1905.

Re: Landmark ancient-genome study shows surprise acceleration of human evolution

#139

Post by matt-attack »

pegasus wrote: post #124
matt-attack wrote: post #120

Earlier quoted context omitted.

Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions. The slight coloration of a bird’s crest, shape of some lizard’s nose. Yet with Homo sapiens we seem to be allergic to the idea that our drastic swings in physical attributes could possibly qualify as a different species (we obviously call them “races”). But they plainly diverged from each other due to geographic and r…

> Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions It might seem like that to you, but you'd be wrong. Taxonomy prioritizes genetic distance and reproductive isolation over superficial visual traits that humans happen to find striking. While phenotypic variations like skin color or facial structure are highly visible, they represent a microscopic fraction of the over…

I’ve heard this argument but it sounds factually incorrect to me.

Take for example: Icterus gularis [1] vs Icterus galbula [2]

Are you really going to tell me that:

1. They’d refuse to have sex with each other or could not procreate

And:

2. Someone bothered to check if they’re sufficiently distinct genetically?

I suspect these species were deemed “distinct” by early naturalists like Carl Linnaeus or Charles Darwin neither of whom even knew what a gene was.

And to my eye these birds seem a lot closer than an Aboriginal Australian man is to a Norwegian man.

[1] https://en.wikipedia.org/wiki/Altamira_oriole

[2] https://en.wikipedia.org/wiki/Baltimore_oriole

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