Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What happened to our fur?

  1. May 15, 2005 #1
    what happened to our fur???

    why does the human race have no fur, but a tiny bit of hair, when we are related to apes, which clearly have fur, or hair?
     
  2. jcsd
  3. May 15, 2005 #2

    Monique

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Possibly because we started a culture of wearing clothes to stay warm. Individuals born without hair, or little hair, no longer had a survival disadvantage and were thus able to contribute to the gene pool.

    There is a genetic condition, hypertrichosis, where due to a mutation people become extremely hairly. This is discussed here https://www.physicsforums.com/archive/topic/t-17937_Hypertrichosis_....html It is known as an atavism: the reappearance of ancestral characteristics in individual members of a species.
     
  4. May 15, 2005 #3
    I guess somehow it became a sexual attractive traid to be hairless, or better have short thin (blond) hairs.

    Most evolutional changes that cannot really be explained in terms of survival advantages are almost always sexual in origin. Sexual selection is a very powerful tool in evolution.

    Think about it, would you prefer a partner with hypertrichosis?
     
  5. May 16, 2005 #4

    LURCH

    User Avatar
    Science Advisor

    But sexual attraction is (theoretically) determined by survival advantages.

    Parenthetically, you humans have as many hairs/cm2 as a gorrila or chimp or any other ape, human hairs are just finer. Don't know if that's any help, but I think it's pretty interesting.
     
  6. May 16, 2005 #5
    Well, theres alot of sexual attractive features that oppose survival advantages. So it isn't very simple. But of course those factors must come from somewhere.
     
  7. May 16, 2005 #6

    Phobos

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Anyone know of any info/evidence of how hairy the extinct Homo species were? I assume there is little or no info on this...but it would be interesting to see when this transition occurred.
     
  8. May 16, 2005 #7

    Moonbear

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Nothing that I know of. I don't know of any fossils other than bones from such ancient species. But that is important to keep in mind. Just because artists draw those species as hairy doesn't mean they were, or that they were quite as hairy as apes or had such fine hair as modern humans.

    There's still a lot of variation among humans in coarseness and density of hair. Some of this is genetic, and some of it hormonally regulated, but variation nonetheless. If the hair on our bodies grew as thick and long as the hair on our heads, we probably would look considerably more furry.
     
  9. May 17, 2005 #8
    The standard answer you'll get from evolutionary anthropologists is that losing our fur lead to improved cooling capacity through evaporative sweating. Actually, many other features of human physiology can be explained through this principle also.

    Sometimes other reasons are offered, such as:

    * The fact that other mammals that live in close quarters with each other (like humans) are usually fur-less may have something to do with it. Ovservations of these mammals show it's easier for them to keep their body clean of insects that way.
    * Easier Vit D synthesis (I wonder how our furry cousins get their Vit D needs met)
    ...

    In sum, there is no definitive answer but there are many plausible ones.
     
  10. May 18, 2005 #9
    but if i went to a jungle, where you constantly see primates, with their fur, i would probably faint straight away, but to contradict myself, if i were constantly under shad like the primates, it would be cool, and if i stayed there long enough, i would get used to the heat and adapt to sustain my genes
     
  11. May 19, 2005 #10
    I'm not sure I get your point here. I think you're saying it would be too hot in the forest for you to survive until you learned to live in the shade. The point being - I think - sweating doesn't help your chances of survival as much as intelligence?

    Well, intelligence is always our best survival tool. Sweating helps though. Again, an evolutionary anthropologist would tell you that your most distant "human" ancestors likely evolved in conditions close to savannahs - not forests. They're hot and dry and sweating would be most valuable in those types of conditions.

    As for my own opinion I think there are problems with every type of explanation on this topic. I'm still waiting for one to be offered that I can't find any holes in. I'm not holding my breath.
     
  12. May 19, 2005 #11
    When early man left the forests for the plains of Africa, the hairiest simply died, the less hairy survived longer. Evolution applies henceforth. Logical conclusion: baldness.
     
  13. May 19, 2005 #12
    i see, i missed a link in the chain...
     
  14. May 19, 2005 #13
    Guess you guys have never seen an italian. Humans still have many with "fur".
     
  15. May 19, 2005 #14

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    That doesn't explain why "the hairiest simply died" when that didn't happen to other animals.

    One interesting speculation is that during the million year drought of the pleistocene, some pithcantropus left even the plains (there were few forests) for the beaches and became semi-aquatic animals. Hairlessness is a handicap in the water- other animals that spend a lot time in water, elephants, hippos, pigs, not to mentions whales and porpoises, tend not to have little hair.

    (Of course, the hairiness of otters, seals, mink, etc. throws a monkey wrench into that!)
     
  16. May 20, 2005 #15
    Hello HallsofIvy. Hairy dolphins? I hugged a dolphin recently... it wasn't very hairy. Also, humans aren't really bald... they just have a smaller amount of shorter hairs all over. Except after waxing. Also, linking hairiness to water doesn't work - our hairier ancestors were not water-dwellers.

    I think the point of direct descendancy is being missed. Our ancestors were forest-dwellers. They had A LOT of hair, for warmth and protection. This was a handicap for those that spent a great deal of their time under direct sunlight in a largely cloudless sky, especially when they didn't sweat. Keeping to a normal body temperature under that mass of fur under those conditions would have been a toughy. I could barely walk around in South Beach a couple of weeks ago even with my meagre amount of hair. That near-baldness and sweating cools us down is presumably not in question. It follows that the least hairy of our anscestors would have a higher probability of surviving longer, and so reproducing more (or at all) than the more hairy. Same for the less hairy next generation, and so on and so forth.

    You can't really compare our evolution with animals who took a different evolutionary route a long way up the family tree. That other species evolved differently under similar conditions, such as the hairier neanderthal, is a given.
     
  17. May 20, 2005 #16

    LURCH

    User Avatar
    Science Advisor

    I for one am a supporter of the "aquatic ape" model of human evolution. It explains a few other oddities of the speceis that other models don't seem to.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?