Mystery solved. How and why human ancestors became hairless.

[mistermack]

And do please understand,despite how dramatic it may seem, that to assert that a mystery is solved when it actually is just a load of speculative codswallop that may have critical flaws is intellectually dishonest, Mack.

My title is clearly tongue-in-cheek, just like my previous one. Lighten up!

[Gawdzilla Sama]

Oh, we'll believe that one, won't we.

[mistermack]

Erm, that either implies that the hairy population completely died out (1) or that the furry must have found the hairless attractive (which is required to, in the absence of (1) spread the trait in the gene pool) AND the hairless would've mated with the furry, which could render bare the validity of your sexual selection hypothesis. It would appear to me that until SOME stage at least interbreeding would be possible between the hairy and the not hairy, otherwise the smoothies would have been driven to a bottleneck mediated extinction event.

You have to have some understanding of human history to interpret our evolution. Humans are unique in so many ways. And one of those unusual features is war. One tribe can WIPE OUT a rival tribe in a matter of hours, because we use weapons, and fight as a group.
What would take thousands of years in other species can happen in one day.
Even chimpanzees have mini wars, and often displace their neighbors, but it takes a lot of effort to kill another creature with just you hands and teeth. Human conflict is unlike that of any other creature, we can kill over and over again with little effort. And we do.

So interbreeding would of course be possible between hairy and non-hairy, but if you look at human history, war and extermination would be far more likely, and can be incredibly quick.

YOU might imagine a whole species gradually became relatively hairless. I'M pointing out that it could happen RAPIDLY by replacement of the hairy by the hairless.

Quite right, this should show up as a population bottleneck in the remaining genes. There are several severe bottlenecks identified through the genes of modern humans. You can take your pick.

erm, fail, if you are isolating a small population, to the tune of extremely few humans, you're putting them at risk of extinction by bottleneck effects, there MUST have been interbreeding for the trait to spread through the gene pool.

Nobody is claiming that. There are bottlenecks identified at total numbers in the tens of thousands.
I'm saying that a population of that kind of size could be isolated long enough for an extremely visible difference to evolve, and that visible difference could be enough to spur agression and extermination, rather than interbreeding, when the islolation ceased.

Why this would be unique to humans, is our ability to quickly exterminate, our tribal nature and our sexual selection through appearance.

[Gawdzilla Sama]

He's booted another. How long will it take him to figure this out?

[RuleBritannia]

Mmmm Rainbow Science...

[Svartalf]

It had a lot of words. I think it was the wimmin, got tired of picking lice. Less hair, less lice.

We know rather closely when pubic lice diverged from head lice. The lack of cover between the two areas was most likely responsible for that divergence.

I recently read that pubic lice were mutated gorilla lice rather than head lice... then again, it was wikipedia

[mistermack]

It had a lot of words. I think it was the wimmin, got tired of picking lice. Less hair, less lice.

We know rather closely when pubic lice diverged from head lice. The lack of cover between the two areas was most likely responsible for that divergence.

I recently read that pubic lice were mutated gorilla lice rather than head lice... then again, it was wikipedia

That's right. Gawdzilla has his lice mixe up. Like so much else.
It's headlice and bodylice that diverged.
We evolved much thicker pubic hair at some stage, probably to keep that area clear of human lice. ( they can't hang on to hair that is much thicker )
Then gorilla lice came along, and found our pubic hair IDEAL, as it's similar in thickness to what they are used to.
.

[Gawdzilla Sama]

It had a lot of words. I think it was the wimmin, got tired of picking lice. Less hair, less lice.

We know rather closely when pubic lice diverged from head lice. The lack of cover between the two areas was most likely responsible for that divergence.

I recently read that pubic lice were mutated gorilla lice rather than head lice... then again, it was wikipedia

That's right. Gawdzilla has his lice mixe up. Like so much else.
It's headlice and bodylice that diverged.
We evolved much thicker pubic hair at some stage, probably to keep that area clear of human lice. ( they can't hang on to hair that is much thicker )
Then gorilla lice came along, and found our pubic hair IDEAL, as it's similar in thickness to what they are used to.
.

He's doing it again, wiking instead of thinking.

[GenesForLife]

One, I'm pointing out, Mack, that the said replacement could be problematic, since if the hairless came later, they'd be up against a larger number of hairy opponents, this would have to put hairlessness to have evolved at a very early stage in a very small population for a very long stretch of time, you could potentially test this by looking at the fossil record followed by the development of a competitive advantage in combat if that were to be the case (as in an increase in cranial capacity, correlated with intelligence) , when you assert that an allele is sexually selected for, as in reproduction you either have to allow for a spectacularly large separation time between two populations, relatively early in the piece, OR for sexual selection and mating choice to be irrelevant, based on the inheritance pattern the requirements for the trait to become prevalent during the postulated period of isolation would be variable, but the more parsimonious explanation is that hairlessness was transmitted through interbreeding rather than replacement of the hairy through elimination by the hairless. Occam's razor does a good job here.

Two...a fucking textbook on elementary genetics is NOTa dictionary, if you want to pass wild speculation off as valid explanations you'd do well to acquaint yourself with the basic concepts and terms in the field you're working with, no?

[mistermack]

One, I'm pointing out, Mack, that the said replacement could be problematic, since if the hairless came later, they'd be up against a larger number of hairy opponents

That's a perfectly fair point. I would have thought the same. HOWEVER, the reality goes against what looks logical. The history of human evolution is characterised by waves of out-of-africa type expansions of new variants, rather than slow evolution of a homogeneous species.

With this in mind, it's perfectly in keeping with known human history to accept that a small population can rapidly expand and displace their rivals. And with our tribalism, weapons, and violent warlike nature, we are the most likely of any species to develop in that way.

this would have to put hairlessness to have evolved at a very early stage in a very small population for a very long stretch of time, you could potentially test this by looking at the fossil record followed by the development of a competitive advantage in combat if that were to be the case (as in an increase in cranial capacity, correlated with intelligence)

That's probably hoping for too much from the thin fossil record. Also, there are other things than combat that can give you the edge. My piece was about weapons, so I concentrated a bit on that aspect, but with a species that has highly developed cultural behaviour, there are many other behaviours that will be running alongside violent struggle.

Looking at the fossil record, it seems that over-and-over again, it's displacement, rather than interbreeding, that occurred. If that happened worldwide, it's just as likely on a smaller local scale. It seems to be something about human nature that makes it likely.

Two...a fucking textbook on elementary genetics is NOTa dictionary, if you want to pass wild speculation off as valid explanations you'd do well to acquaint yourself with the basic concepts and terms in the field you're working with, no?

Genes, I'm saying this in a friendly, trying-to-be helpful kind of way. Your prose is EXTREMELY difficult to follow. And I'm comparing it to that of some very eminent scientists.
Read that piece you wrote again. I don't think there is ONE full-stop. Or paragraph. And you pile jargon on top of jargon.
You have to read it many times to get your meaning.

I'm not criticising as a debating point, I think you will hold yourself back, if you don't make what you write easy to read. I like your points, but they are SUCH hard work.

It's not the technical words you employ, it's just that they are piled high, one on top of another. Keep it as simple as possible, and it will pay off, I give you my word on that.

[Gawdzilla Sama]

"Your prose is EXTREMELY difficult to follow"

It's called being ignorant of the topic.

Somebody got the Reader's Digest version of a genetics textbook?

[Tero]

Lice lice lice. You forgot the wimmin. This is obviously sexual selection.

[mistermack]

There's a fatal flaw in the reasoning. We lost our fur a long time before we started wearing clothes.

Sorry I missed replying to that.
Did we though? I don't think that's been established.
And if you look at all the other african mammals of a similar size, NOT ONE has lost it's fur.
So how could humans exist for millions of years, without fur, or clothes or shelter?

It's no good pointing to africans walking around with little on. They can take cover in bad weather. They can get under a warm skin blanket at night. They can light a fire.
How does a thirty kilo naked ape cope with long cold nights in torrential rain?
.

[Gawdzilla Sama]

How does a thirty kilo naked ape cope with long cold nights in torrential rain?
.

Same way they do today.

[Svartalf]

How does a thirty kilo naked ape cope with long cold nights in torrential rain?
.

Same way they do today.

That is, they wore clothing and used shelter (and possibly fire) long before they left tropical environments or ventured environments with great thermic amplitude like deserts.