Saturday, January 7, 2012

Were Neanderthals furry?

What did the Neanderthals look like? Source
Hard to tell, since we know so little about their soft tissues. But they probably had fur.

Were the Neanderthals as furry as bears? The question was raised by one of my readers, and I’ll try to reply at length in this post.

There are three lines of argument:

Lack of tailored clothing

Neanderthal sites show no evidence of tools for making tailored clothing. There are only hide scrapers, which might have been used to make blankets or ponchos. This is in contrast to Upper Paleolithic (modern human) sites, which have an abundance of eyed bone needles and bone awls (Hoffecker, 2002, pp. 107, 109, 135, 252). Moreover, microwear analysis of Neanderthal hide scrapers shows that they were used only for the initial phases of hide preparation, and not for the more advanced phases of clothing production (Hoffecker, 2002, p. 107).

The counter-argument is that some human groups, notably the Yaghan of Tierra del Fuego, have lived in sub-arctic environments with little clothing.

Human body louse

The human body louse (which lives in clothing) seems to have diverged from the human head louse with the advent of modern humans. This dating is based on a comparison of the two louse genomes:

The results indicate greater diversity in African than non-African lice, suggesting an African origin of human lice. A molecular clock analysis indicates that body lice originated not more than about 72,000 ± 42,000 years ago; the mtDNA sequences also indicate a demographic expansion of body lice that correlates with the spread of modern humans out of Africa. These results suggest that clothing was a surprisingly recent innovation in human evolution.(Kittler et al., 2003)

A more recent analysis places the origin of body lice at 83,000 to 170,000 years ago (Toups et al, 2011). The authors conclude: “Our estimate for the origin of clothing use suggests that one of the technologies necessary for successful dispersal into colder climates was already available to AMH prior to their emergence out of Africa.”

There is nonetheless some controversy over the phylogenetic status of these two kinds of louse. Light et al. (2008) argue that there is far too much genetic overlap between them and that they cannot be considered “genetically distinct evolutionary units.” This point has been reiterated by Li et al. (2010):

While being phenotypically and physiologically different, human head and body lice are indistinguishable based on mitochondrial and nuclear genes. As protein-coding genes are too conserved to provide significant genetic diversity, we performed strain-typing of a large collection of human head and body lice using variable intergenic spacer sequences. Ninety-seven human lice were classified into ninety-six genotypes based on four intergenic spacer sequences. Genotypic and phylogenetic analyses using these sequences suggested that human head and body lice are still indistinguishable. We hypothesized that the phenotypic and physiological differences between human head and body lice are controlled by very limited mutations.


This is a recurring problem when one examines two species or subspecies that have recently diverged from each other. The only genes that have diverged are those whose variants clearly differ in adaptive value between the two environmental settings—in this case, head hair and clothing. It is only with time, and reproductive isolation, that differences will develop at other gene loci.

In the meantime, lice—like humans—exhibit the apparent contradiction of distinct phenotypic differences co-existing with very fuzzy genetic differences.

Finger bone ridges

A third reason is given by Cochran and Harpending (2009):

We don’t yet know for sure, but it seems likely that, as part of their adaptation to cold, Neanderthals were furry. Chimpanzees have ridges on their finger bones that stem from the way that they clutch their mother’s fur as infants. Modern humans don’t have these ridges, but Neanderthals do.

References

Cochran, G. & H. Harpending (2009). Neanderthals Steve Sailer’s iSteve Blog, January 10, 2009
http://isteve.blogspot.com/2009/01/neanderthals.html

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe. New Brunswick: Rutgers University Press.

Kittler, R., M. Kayser, & M. Stoneking. (2003). Molecular Evolution of Pediculus humanus and the Origin of Clothing, Current Biology, 13, 1414-1417.

Li, W., G. Ortiz, P-E. Fournier, G. Gimenez, D.L. Reed, B. Pittendrigh, D. Raoult. (2010) Genotyping of Human Lice Suggests Multiple Emergences of Body Lice from Local Head Louse Populations. PLoS Negl Trop Dis 4(3): e641.

Light, J.E.,M.A. Toups, & D.L. Reed. (2008). What’s in a name: The taxonomic status of human head and body lice, Molecular Phylogenetics and Evolution, 47, 1203-1216.

Toups, M.A., A. Kitchen, J.E. Light, & D.L. Reed. (2011). Origin of Clothing Lice Indicates Early Clothing Use by Anatomically Modern Humans in Africa, Molecular Biology and Evolution, 28, 29-32.

20 comments:

Den Berk said...

Could you connect the dots more explicitly for human body lice and neanderthal fur? I don't follow your argument.

Anonymous said...

Hopefully Neanderthal genome analysis will soon lay this to rest!

Likewise for the "Denisova" group.

Though the genetics of hairiness don't seem are anything like as simple as pigmentation. I don't think there is, AFAIK, a good understanding of the mutations which cause hair loss in humans relative to our common ancestor with chimpanzees.

Sean said...

Persistence hunting


Humans aren't fast but they can run down most animals, exercise leads to sweating and if Neanderthals had a coat of the fine hairs called 'fur', in freezing conditions running would cause sweating. Sweating in sub zero temperatures is dangerous as the sweat can freeze. I believe this was once a problem for anyone seriously exerting themselves in extreme cold while wearing insulated clothing (arctic clothing used to use a lot of fur insulation).

Furry Neanderthals would not be able to use a strategy of running down game in sub zero conditions because they'd have become soaked in sweat; once they stopped running the sweat would freeze.

I'll speculate that Neanderthals' fur and lack of brainpower restricted them to a pack ambush strategy (ie collectively lurking around woodland game trails; popping up to surround the prey; then using thrusting spears to kill the prey as it tried to break through the cordon).

Vieth argues that humans are well adapted to ingestion of vitamin D in large amounts because the process of grooming by furry human ancestors involved ingestion of skin oils rich in vitamin D!

Ben10 said...

Maybe they were hybernating.
Does hibernating cause irregular growth patterns in bones of young bears?

Stephen said...

The general body shape of neanderthals is cold adapted so their hair was likely cold adapted too. Unlike their African ancestors they are less adapted to long distance running in favor of ambush so they may of needed to sweat less.

I would like to know more about the finger bone ridges. In the last thread I speculated that they could be dismissed as vestigial but the Sailor article seemed to imply that they are an acquired rather than a genetic trait. My web searches only bring up brow ridges or knuckle walking. I suppose at a stretch someone could argue the babies are clutching the fur on ponchos.

The Sailor article brings up the issue of their large brains. I suspect that they were quite intelligent but extreme territoriality and clanish instincts limited the spread of ideas, between bands. I think that was the principle Cromagnon advantage flint from 300 miles away was not really that much better but
the links allowed the formation of multiband tribal alliances in war. Isolation in Sapiens also leads to the simplification of culture Tasmanians, Adaman Islanders, and others lost many technologies that were common in the paleolithic. Neanderthals had larger brains than modern people but the Cromagnons that replaced them had even larger brains. I often wonder whether the recent shrinkage is due to greater efficiency of brain mass or whether the late paleolithic is when increased technology crossed the line from demanding more brain power to making things easier. The inventor of the dart thrower and the bow and arrow must of been intelligent but once you have one it takes less skill and strategy to get within range of your prey.

Sean said...

Wolves have bigger brains than border collies.

Ben10 said...

The wiki page
http://en.wikipedia.org/wiki/Hominid_evolution
contains excellent illustrations of sapiens.
Their skin, in these reconstitutions, is still brownish, which is probably true, but two details might be incorrect.
1) the Irise appears visible in the white of the eye, starting at Homo heidelbergensis.
Is there any evidences for that?

2) In these illustrations, from Homo heidelbergensis and after, the hairs of the face switch from fur to real hairs and in addition, these hairs are depicted long and straight, when all african populations have short, sometimes very short, curly hairs. That, i think, is a serious mistake. The illustrations should show typical negroid hairs, perhaps?

Regarding Neanderthal, I don't agree that their big brain was necessarily big to be smarter. The brain is a real energy sink, consuming one fifth of all the available body energy. That's ~20 watts for a modern man's brain, which therefore produce ~ 100 watts total, and this sets the limit for the minimal food intake, about 2000Calories at rest. Now even if you do nothing, your brain imposes this tax on your body, and food doesn't come by doing nothing.
With a bigger brain, Neanderthal is even more penalised. Instead, some of the big neanderthal brain might have been able to shut down in specific areas to save energy during periods of torpor. By entering a winter lethargy with a reduced body temperature, but still able to wake up and stay active at a reduced level, Neanderthals would save themself from the burden to find and insane amount of food...something to consider.

Stephen said...

Neanderthals had a lifestyle that gave them lots of injuries, is it possible that some of their large skull volume was taken up by connective tissue that would reduce concussion risk? The high number of injuries are usually blamed on their preys hooves but a few could also be from fighting and clubbing each over.

Peter Frost said...

Den Berk,

Body lice have their origins in head lice that adapted to the niche of human clothing. Genetic analysis indicates that this evolution took place with the advent of modern humans, when Neanderthals had already been around for hundreds of thousands of years.

Sean,

I've often heard and read the theory that ancestral humans lost their fur as a way to reduce overheating while hunting prey. Has any other predatory mammal lost its fur for this reason?

Ben10,

I don't think Neanderthals hibernated. There is much evidence that they hunted under conditions of subzero temperatures.

We know very little about soft-tissue traits (hair, skin) in ancestral humans because these traits are not preserved. Neanderthals probably had reddish hair because their MC1R allele produces red hair in humans. But perhaps the result was different in a Neanderthal body.

Eventually, we'll know more as we come to understand how the Neanderthal genome functioned.

Stephen,

Like Greg and Henry, I believe that Neanderthals were large-brained because so many of their mental algorithms were hard-wired. Their brains were like a huge Swiss army knife, with separate modules for almost every behavior.

Brain size seems to have decreased with the transition from hunting/gathering to agriculture. This may reflect a reduced need to store huge amounts of spatio-temporal information (as needed when hunting over long distances).

Sean said...

I don't think ancestral humans' hairiness was lost to prevent overheating. I'm saying (speculating really) that Neanderthals with true 'fur'( which is highly insulating) would be in trouble trying to use a hunting strategy which required any kind of any kind of sustained exertion.
Why? Well thermoregulation in Neanderthals with a coat of fur would present a special problem which most predatory animals do not face because primates/humans sweat differently to most animals, or so I believe.

Perspiration "Animals with few sweat glands, such as dogs, accomplish similar temperature regulation results by panting, which evaporates water from the moist lining of the oral cavity and pharynx. Primates and horses have armpits that sweat like those of humans. Although sweating is found in a wide variety of mammals,[3][4] relatively few, such as humans and horses, produce large amounts of sweat in order to cool down.[5]"

Stephen said...

QUOTE{I've often heard and read the theory that ancestral humans lost their fur as a way to reduce overheating while hunting prey. Has any other predatory mammal lost its fur for this reason?}

Not that I am aware of but for a million years or so hominids have been unique in there ability to use fire and shelter to keep themselves warm at night, so perhaps this opened up a strategy that was not available to other animals. Humans are among the best long distance runners. Some other animals that have little hair are Rhinos and elephants, which have heat issues due to their shear size.

Anonymous said...

When I first saw the title I read it as: "Were Neanderthals funny?" with the image of cutie Neanderthals below it.

Sean said...

Article in latest New Scientist about Neanderthals says they used the terrain to their advantage in hunting. It seems to be commonly accepted that they did not range far or specialize in hunting in open country.

As far as I can make out Neanderthals hunted in woodland. About them being reddish: that must have been for camouflage. Anne E. Russon (Uni of Toronto author on Orangutans) wrote in to the New Scientist question page about "Why are Orangutans orange?' She says Jared Diamond came up with the idea that Orangutans are orangy because in the forrest all the red orange and violet light is absorbed by leaves, so they blend into the forrest floor. She says Orangutans' colouring works so well as camoflage that she has nearly tripped over Orangutans in their natural habitat more than once.

Anyway, as Neanderthals were furry and as furry creatures get their vitamin D b grooming (the UV-B doesn't get to the skin obviously) "The high 25(OH)D concentrations, and relatively high vitamin D requirements of apes and monkeys are understandable in light of their biology—their body surface area relative to mass is generally greater than for humans, and they are inveterate groomers, consuming by mouth the vitamin D generated from the oils secreted by skin into fur. Although
much of the vitamin D produced within human skin is absorbed directly, birds and furbearing
animals acquire most of their vitamin D orally, as they groom themselves (Bicknell and Prescott, 1946; Carpenter and Zhao, 1999). Vitamin D is generated from the oily secretions of skin into fur. The oral consumption of UV-exposed dermal excretion is the way many animals acquire the “nutrient,”" Source:Vieth)

So for furry animals what is the use of reducing melanin. For furry animals vitamin D is produced on their fur not in their skin. So reddish Neanderthals lay doggo in their furry camo suitand let the prey walk into a trap. But they would get cold lying._



New candidate for introgesssion from Neanderthals 'irisin' "Jan Nedergaard, who studies brown fat at the Wenner-Gren Institute at Stockholm University, Sweden, says that irisin "could be of interest for all obesity-related issues" but was also perplexed by its origins. Bostrom and colleagues speculate that it may be down to shivering. If the muscle contractions of shivering cause the body to produce irisin, which then influences the development of brown fat that generates heat, the hormone may have evolved to help stave off hypothermia"

Ian said...

I wonder whether Neanderthals, like other northerly hunter/scavengers such as bears and wolves, had a better sense of smell compared to modern humans.

Found this video of Svante Paabo talking about the decline in the human sense of smell:

http://www.dnalc.org/view/15150-Losing-our-sense-of-smell-Svante-Paabo.html

Stephen said...

Sorry Ian but it seems smell was not very important to Neanderthals.

http://www.sciencedaily.com/releases/2011/12/111214101818.htm

Ian said...

Thanks for the interesting link, Stephen. I wouldn't have anticipated those findings.

Stephen said...

Here is a good article on the subject.

Stephen said...

Here is a fair article on the subject.

http://www.nytimes.com/2003/08/19/science/why-humans-and-their-fur-parted-ways.html?pagewanted=all&src=pm

ChuckWillsWidow said...

What does the genome results say concerning how hairy Neanderthals were?
Interesting how some skin color results seemed to indicate that they had tawny skin, brown eyes and hair.

ChuckWillsWidow said...

Interesting correlation between the bony ridges found on finger bones on both Chimps and Neanderthal hands but what other supportive evidence was documented from the Neanderthal genome reserch labs regarding how much hair/fur these ancients once had?