Interesting 'Horizon' on TV now.

[David B]

Suggests evidence from lice genetics implies human ancestors lost their hair 3m years ago, and that clothing started about 650k years ago.

Also that the human cooling system, based on nudity and sweat, was a dine qua non of developing a large brain, due to cooling constraints.

David

[Cath B]

Sounds interesting.

Is it being repeated?

[David B]

Sounds interesting.

Is it being repeated?

I presume so, but does it matter?

You can get it for the next week on the BBC website.

It ended with a lot of stuff which readers of Pinker et al will find old news, but the things about dating loss of body hair and adopting clothing were new to me.

Oh, there was a bit on subtle cues concerning detection of fertility as well.

David

[Cath B]

If accurate I reckon it backs up my hunch about baby carriers pre-dating clothes.

Babies would find it hard to cling on to a hairless mother and mothers would find it hard to cling onto the baby while foraging or climbing.

Unless (thinking as I write here) hair on the head was tough enough to cope with a baby clinging on.

And wouldn't baby carrier lice evolve?

Hmmm, more thinking needed.

[lpetrich]

I've found some articles on that question:

Head lice key to clothing history (http://news.bbc.co.uk/2/hi/science/nature/3142488.stm)
Pubic Hair Provides Evolutionary Home For Gorilla Lice (http://www.sciencedaily.com/releases/2009/02/090211101711.htm)

We have three species of lice, each with a different preferred habitat:

Head louse, Pediculus humanus capitis, likes to live in the scalp hair
Body louse, Pediculus humanus humanus or [/i]corporis[/i], likes to live in clothing
Crab louse or pubic louse, Pthirus pubis, likes to live in pubic hair


The head louse and body louse look identical and can interbreed, though they prefer different places to lay their eggs. They likely diverged when their hosts started wearing clothes that cover much of their bodies, which provided new habitat to move into. This happened about 100 thousand years ago or thereabouts, and that date is the approximate date of an early migration from africa that produced most non-African human populations.

The older date, about 700 thousand years ago, is the age of the ancestor(s) of the individual head and body lice that were studied.

Their closest ape-louse relative is the chimpanzee louse, Pediculus schaeffi, and head/body and chimp lice diverged about when their hosts diverged, about 6 million years ago.

The pubic louse is most closely related to the gorilla louse, Pthirus gorillae, and they diverged about 3 million years ago. They would have found it difficult to get started unless they had no competition from head lice, and that would have required losing body hair. So loss of body hair and gain of pubic hair likely happened about then or not very long afterwards.

As to how our ancestors caught gorilla lice, it was likely from hunting and eating gorillas.

Timeline:

6 mya: human and chimp lice diverge along with their hosts
3 mya: human ancestors lose much of their body hair, but grow pubic hair; gorilla lice jump to there
600 kya: ancestor of individual head and body lice
100 kya: the ancestors of body lice move into their hosts' clothing

Dates are rather approximate.

This work says nothing about what clothing Neanderthals might have worn, since their lice likely went extinct with them.

Some primary-literature articles that I found with PubMed:

Molecular evolution of Pediculus humanus and the origin of clothing. (http://www.ncbi.nlm.nih.gov/pubmed/12932325?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsP anel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) - about the divergence of head and body lice
Pair of lice lost or parasites regained: the evolutionary history of anthropoid primate lice. (http://www.ncbi.nlm.nih.gov/pubmed/17343749?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsP anel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) - about human, chimp, and gorilla lice

[Ray Moscow]

I saw the last 10 minutes or so, which consisted mostly of people standing around, looking at naked people, who were also just standing around. After a while, everyone got used to it.

But the sciency commments in the background were pretty interesting.

[Notta]

As to how our ancestors caught gorilla lice, it was likely from hunting and eating gorillas.
Oh, come now. HUNTING gorillas?? I just can't see a protohuman hunting a gorilla - those silverbacks can be very aggressive, and all other hominids are much stronger than humans relative to their size. A grown chimpanzee can kill an adult human.

The idea I heard was that humans used the gorilla's nesting areas.

Again, it seems like a reach. It seems like a much more likely process is having a human male attempt to mate with an immature gorilla female.

[Ray Moscow]

The spear is a great equaliser. Well, more than an equaliser.