15 April 2014

Elephant Hair Addendum

In addition to the three items in last Friday’s Elephant News, I had one other that didn’t fit with elephant behavior and intelligence. I’m offering it as today’s addendum.

Princeton University investigators modeled the heat transfer from elephants’ rough skin using theoretical and empirical approaches. They found that an elephant’s sparse hair contributes to cooling the animal.

A baby elephant (multiple websites). Asian elephants have higher
hair densities than African elephants, and juvenile elephants have
higher hair densities than adults.
Although you and I would think hair insulates, their modeling indicated that a crossover occurred around 0.3 million hairs per square meter (194 hairs per square inch) for thick hair covers: warming at higher hair densities and cooling at lower densities.

Sampling from photographs of elephants provided an estimated hair density of 1500 hairs per square meter (1 hair per square inch), far below the crossover point. For comparison, the density of our head of hair is about 2 million hairs per square meter (1290 hairs per square inch). Speaking for myself, I should say “used to be.”

The researchers calculated that the hair cover enhances the elephants’ thermoregulation ability by over 5 percent under all scenarios they considered and by up to 23 percent at low wind speeds. Extrapolating, they postulated that a low-density hair cover could have served an evolutionary purpose.


P.S.

Elephant hair study in PLOS ONE:
www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0047018
LiveScience article on study:
www.livescience.com/23874-elephant-hair-keeps-cool.html

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