why-do-humans-have-so-little-body-hair

Cecil's Columns/Staff Reports
1

A major aspect of the answer to this question is often missing.

It is usually rightfully noted that hair is an insulator. While true, this characteristic is perhaps not particularly critical for such a large mammal in a tropical setting. It is also noted that hair provides protection from the sun. While also true - this is surely not particularly significant for the vast majority of mammals that are largely nocturnal and or live in protective shade of the forest - few rodents or bats (most of the mammals) do NOT need protection from the sun yet they are hairy.

The one factor that is missing is the protection that hair offers from physical abrasion! A layer of hair physically protects mammals as they move through their environment - if you don’t believe me try taking a long hike through thick tropical undergrowth while nude :slight_smile: Hair is wonderful as a protective layer - lightweight and “flexible” so it offers protection while offering no resistance to movement.

So in answering the question - I would add the hypothesize that before/as humans evolved our “naked” bodies we altered our behaviour by moving out into the grasslands/savannah and didn’t need the same degree of physical protection and/or we had “invented” clothing as an alternative.

2

Link to the article.

It’s helpful to put the link in the body of your post because links aren’t active in thread titles.

3

Actually, I’d guess that as we became bipedal and endurance hunters (NOTHING on earth can out-run a human in a long-distance chase, believe it or not), we probably lost the hair because the advantages from better cooling outweighed the advantages from the hair.

We still kept hair in some places where it served/serves some purpose- crotch, head, chest, face.

4

Might the fact that hair is flammable have anything to do with it?

5

Correction: Very few things can. But pronghorns can kick our butts, and ostriches are at least very close.

6

Really? I thought pronghorns were just sprinters, and I thought horses and canines were the only creatures on earth capable of outrunning well-trained humans for very long distances.

7

Some problems with the OP:

  1. Citing the hairiness of small mammals versus needing Sun protection is irrelevant. Small mammals need hair (usually) for insulation to prevent loss of body heat. Exceptions like naked mole-rats have very low metabolism and don’t fully thermoregulate like most mammals.

  2. Many natives people don’t wear significant clothing in warm environs despite living in thick grass, brush or jungle. The ambient temperature guides the amount of clothing, not abrasion risk.

8

Here is a fun read on man-versus-pronghorn, which tangentally addresses the question in this thread.

Also, the Animal Kingdom’s top Marathoners. Note: Pronghorn can finish one in about 45 minutes.