Why are we near hairless?

[mikenostic]

Do not play switch-em with animals while arguing.

LOL WUT?

Take a lion's neck hair for instance. It is to protect it from other lions biting at its neck. It's very specialized to the lion, not the wildebeest. Same hair, different purpose, because they are different animals.

So wildebeest have fur for different reasons than we have hair. Just because all the plain animals have fur too, is not a very good reasons that humans should as well. In fact we don't, so why assert the contrary?

Forgive me if I'm off, I typed quickly and have to run

By me stating that the plains animals also have fur was more or less a general factual statement. And it seems you are trying to argue my factual statement with two factual, but more specific statements. I don't get it. It's like trying to divide by zero or something.

 

[Search & Destroy]

LOL WUT?


By me stating that the plains animals also have fur was more or less a general factual statement. And it seems you are trying to argue my factual statement with two factual, but more specific statements. I don't get it. It's like trying to divide by zero or something.

A general factual statement, true

me:

“ On the plains and out of the shady and sharp jungle, the hair has less utility.

”
you:

Yet all of the plains animals have fur too; albeit shorter fur.

I thought that yet was an on the contrary. But now I see your point clearly. I knew I missed something. Anyway, carry on

 

[tuberculatious]

Fur is even useful in water.

 

[wynn]

The hairless breeds were created by man.

Man...

That has nothing do with the evolutionary nature being discussed here.

Hairless breeds are prized because they are rare, created breeds.

?

Perhaps humans chose to mate selectively - ie. to mate with the less hairy fellow humans.

Just like some people like hairless animals, perhaps 'our ancestors' preferred the less hairy or hairless natural mutations of humans.

 

[mikenostic]

Fur is even useful in water.

True. But that only applies to animals that don't spend 100% of their time in water. To name a couple...
-polar bears. Their fur helps their buoyancy and since it's hollow, provides a 'greenhouse' warming effect.

-otters. Insulation for warmth.

 

[tuberculatious]

This one spends almost 100% of its time in the water.

 

[CutsieMarie89]

But some people have a lot of hair and left unchecked (unshaven/uncut) would have a great deal of it, enough to be considered a thin coat at least. So perhaps it was a sexual selection thing, but then that kind of runs contrary to hair being a secondary sex trait, meaning it doesn't grow until one is approaching sexual maturity (which includes I guess almost all hair except the hair on the head). Perhaps child like appearances are sexy to people?

 

[iceaura]

The one plausible theory I have seen comes from biologists who study the niche of heat adaptation - many animals have adapted to withstand hotter temps than their prey or predators, and thus can forage or hide or otherwise outcompete others for ecological niches.

Tiger beetles on sandy beaches in the daytime, for example - a rich area of food, and too hot for most beetle enemies or competitors.

The theory is that humans - apparently already upright walkers and tool users, btw - found that ability to travel and hunt and forage and run in the heat allowed them to scavenge and gather over large areas while avoiding heat-vulnerable predators and capturing heat-vulnerable prey, and opened up a large niche for them. This ability would have incremental payoffs (a little less hair is a little more advantage) as required by evolutionary theory, and dovetails neatly with sexual selection and the other observed influences.

 

[wise acre]

'Early humans, with their great intelligence, were more disturbed by having fleas than wolves, chimps, elk, lions etc. were. So early humans 1. selected to mate with the less haired fellows; and / or 2. washed and cleaned themselves.

But grooming creates tight social bonds.

Regularly washed animals (such as domestic cats and dogs) can get problems with their fur - which would suggest that hygiene can be a factor in losing fur or diminishing its quality.'

I think that suggests that the chemicals we use for this are partially poison.

Or perhaps:

'Early humans were nervous a lot (since they had all that great intelligence, so they realized that there are many things to be afraid of, and that really really scared them). Persistent nervousness can cause loss of scalp and body hair.'

This is my favorite.

 

[wise acre]

interesting
i had never factored in parental selection
somewhat more plausible than my own, rather lamarkesque, inclinations

/snigger

Hey,
Lamark is coming back...
epigenetics!

 

[wise acre]

?

Perhaps humans chose to mate selectively - ie. to mate with the less hairy fellow humans.

Just like some people like hairless animals, perhaps 'our ancestors' preferred the less hairy or hairless natural mutations of humans.

Abrasion. Perhaps it was the women. Perhaps intelligence is the factor. IOW women decided they had a preference and did conscious maneuvering.

 

[wise acre]

The theory is that humans - apparently already upright walkers and tool users, btw - found that ability to travel and hunt and forage and run in the heat allowed them to scavenge and gather over large areas while avoiding heat-vulnerable predators and capturing heat-vulnerable prey, and opened up a large niche for them. This ability would have incremental payoffs (a little less hair is a little more advantage) as required by evolutionary theory, and dovetails neatly with sexual selection and the other observed influences.

But in Africa there seem to be many predators that run in the heat. All hairy.

 

[wynn]

But grooming creates tight social bonds.

Sure. But with all their new intelligence, the 'early humans' probably found new ways of bonding, such as making pots, clothes, spears and all that. Surely it is nicer to give a potential mate or friend a nice piece of jewelery (even if it is made out of a boar's claw), than pick them for lice and fleas, no? Perhaps 'early humans' discovered pride and shame!

Or, because their new intelligence was used up for hunting and roasting meat, they neglected bonding, and the fur wasn't useful anymore as a medium of bonding.

I think that suggests that the chemicals we use for this are partially poison.

Or perhaps at some point in the past, 'early humans' used some nasty stuff to wash themselves for long enough to produce lasting changes.

Or perhaps they were exposed to radiation.

This is my favorite.

Absolutely. Seriously, since 'early humans' had greater intelligence than their ancestors, it is only reasonable to ask how this intelligence manifested, and how this in turn can be related to hairloss.


(Just brainstorming.)

 

[wise acre]

Absolutely. Seriously, since 'early humans' had greater intelligence than their ancestors, it is only reasonable to ask how this intelligence manifested, and how this in turn can be related to hairloss.
(Just brainstorming.)

Perhaps hairlessness is causal here not intelligence. Mutations led to hairlessness which led to more complicated strategies in maintaining body temperature which selected for larger brains.

Notice that dolphins and whales, with very large brains, are also mammals - once land based - who are hairless.

Chimps have hairless faces which gave them an edge.

 

[wynn]

Perhaps hairlessness is causal here not intelligence.

Perhaps they are parallel, mutually enhancing eachother?

Living systems are complex; it is therefore likely that in order for a particular trait to result, a complex causation was in place.

 

[iceaura]

But in Africa there seem to be many predators that run in the heat. All hairy.

There aren't - not like humans. The big predators of Africa lay up in the middle of the day for good reason - endurance in the heat is a serious limitation for them (the lions of the hotter regions grow much smaller and lighter manes, leopards and other dangerous predators of hominids hunt in the evening and morning when it's cool, everything beds down in the shade in hot, dry country).

And the advantage is not just predator avoidance, but foraging and scavenging range across dry country away from the safety of trees or other hides, and transport range for discovered food, and migration ability in harsh heat, and so forth. A pack of humans that can travel fast in the heat can rob kills miles away and bring the meat back to safety before evening brings out the leopards and hyenas, can live farther from dangerous water holes and not visit them in the mornings, and similar advantages.

And once the modern form was established, an entire new world of hunting strategies opened up - humans can kill most antelope and similar animals simply by running them down under the sun and hitting them with a rock, for example.

The advantages of the explanation are that it is incremental, it is supported by the known physical circumstances of early human life, it does not require fanciful assumptions like an entire group developing a sexual preference for hairlessness without any advantage (or overcoming a Zahavian handicap of some unspecified kind), and it fits the current physiology of humans compared with other animals - we can in fact travel and work and run in the heat to a very unusual degree, for a mammal, and largely as a consequence of our hairlessness and a couple of related adaptations in blood circulation and sweat glands.

Like I said, it's not a locked in explanation - but it's one of the few with even a lick of sense to them. We see the physiological advantages of hairlessness now, and it's not a great leap to hypothesize them as the advantages driving the acquisition of the trait.

Living systems are complex; it is therefore likely that in order for a particular trait to result, a complex causation was in place.

Equally likely, from a complex system, is a complex reaction to a simple selective pressure.

 

[madanthonywayne]

Here's one recent theory....

http://www.medicalnewstoday.com/articles/65232.php

Did you read this bit of that article?

Harris suggests that Neanderthals must have been furry in order to survive the Ice Age. Our species would have seen them as "animals" and potential prey. Harris' hypothesis continues that Neanderthals went extinct because human ancestors ate them.
​

I've long believed that modern humans wiped out the Neanderthals, but I never thought we ate them. As to the actual hypothesis, I think we lost our hair simply because we didn't need it. Absent a selective pressure to maintain body hair, we lost it.

PS I just read Iceaura's hypothesis and, I never thought I'd have the chance to say this, it makes sense.

 

[wise acre]

There aren't - not like humans. The big predators of Africa lay up in the middle of the day for good reason - endurance in the heat is a serious limitation for them (the lions of the hotter regions grow much smaller and lighter manes, leopards and other dangerous predators of hominids hunt in the evening and morning when it's cool, everything beds down in the shade in hot, dry country).

And the advantage is not just predator avoidance, but foraging and scavenging range across dry country away from the safety of trees or other hides, and transport range for discovered food, and migration ability in harsh heat, and so forth. A pack of humans that can travel fast in the heat can rob kills miles away and bring the meat back to safety before evening brings out the leopards and hyenas, can live farther from dangerous water holes and not visit them in the mornings, and similar advantages.

And once the modern form was established, an entire new world of hunting strategies opened up - humans can kill most antelope and similar animals simply by running them down under the sun and hitting them with a rock, for example.

The advantages of the explanation are that it is incremental, it is supported by the known physical circumstances of early human life, it does not require fanciful assumptions like an entire group developing a sexual preference for hairlessness without any advantage (or overcoming a Zahavian handicap of some unspecified kind), and it fits the current physiology of humans compared with other animals - we can in fact travel and work and run in the heat to a very unusual degree, for a mammal, and largely as a consequence of our hairlessness and a couple of related adaptations in blood circulation and sweat glands.

Like I said, it's not a locked in explanation - but it's one of the few with even a lick of sense to them. We see the physiological advantages of hairlessness now, and it's not a great leap to hypothesize them as the advantages driving the acquisition of the trait.

Equally likely, from a complex system, is a complex reaction to a simple selective pressure.

All very reasonable. But then you'd think there'd be one hairless feline or canine species that slid into a similar advantage.

 

[wise acre]

I've long believed that modern humans wiped out the Neanderthals, but I never thought we ate them. As to the actual hypothesis, I think we lost our hair simply because we didn't need it. Absent a selective pressure to maintain body hair, we lost it.

I'm assuming you mean we did not need it for warmth. ?
If so, is there anything to back this up in natural selection as humans emigrated from Africa? IOW are people in colder regions more likely to have more body hair?

 

[madanthonywayne]

I'm assuming you mean we did not need it for warmth. ?
If so, is there anything to back this up in natural selection as humans emigrated from Africa? IOW are people in colder regions more likely to have more body hair?

We didn't need it for anything. We could wear clothes to take the place of hair when needed, and have all the advantages of not having hair Ice made reference to other times.