Why are the African elephants ears bigger than the Asian elephant?

I have a theory that it is hotter and dryer in Africa than in Asia and as the ears are cooling agents, that may be the answer but it is just a theory

Why are the African elephants ears bigger than the Asian elephant?
It is a theory based on Bergman's Rule. This is that surface to volume ratio of the body impacts the rate the body loses heat. Area increases by the square while volume increases at a cubic rate.


http://en.wikipedia.org/wiki/Bergmann's_...


The thermal balance in an animal's core is influenced by:


heat produced by metabolism,


heat stored,


heat flow to skin (affected by the thickness and conductivity of fat, fur, hair, feathers, and scales),


heat flow to the ground


heat lost by evaporation.





Elephants keep an internal temperature just as a mouse does. However they have very little outer surface to a great deal of volume. The volume is generating metabolic heat. When they need to release excess heat they can seek shade, divert their blood flow to the surface of their skin or sweat for evaporative cooling.


Mice have lots of surface to shed heat from compared to their little volumes. Elephant;s generate more heat, to much heat to be released only through skin and sweat. Worse elephants don't sweat.


http://www.upali.ch/skin_en.html


So they are left with increasing their surface area in order to dump the heat just like car radiators have, with convections fins.


Look to mammoths with hairy coats and small ears as a better comparison than Aisan elephants. Mammoths lived in a cold climate so needed to retain heat not shed it.


Look at foxes ears and fur coats. Desert foxes have huge ears and thin fur coats. Arctic foxes have ears almost lost in their thick fur coats.


Elephants use their ears for more than heat dissipation so there could be other factors selecting even larger size than thermoregulation requires.
Reply:"African elephants have larger ears than Indian, or Asiatic, elephants because they live in hotter conditions and are bigger and more aggressive and active. The huge ears of the African elephant, sometimes three and a half feet wide, enable it to hear more acutely. When the animal charges its fans out its ears, augmenting its terrible appearance and striking fear into the heart of any enemy.





The ears also present a large surface for losing body-heat. African elephants, who are at a disadvantage in the heat because of their large size, wave their ears to keep cool and to chase away flies. The African elephant is the biggest and noblest of land animals, reaching a height of 11 feet and a weight of nearly six tons."
Reply:because Noddy wouldn't pay the ransom?
Reply:Sounds good to me - there must be some genetic reason.
Reply:African elephants have larger ears than Indian elephants because the African elephants live under conditions with higher temperatures than its Indian cousin. The African elephant uses this adaptation to cool itself off by using them as fans and to release heat through the blood vessels close to the surface. As breezes blow across the ears' surface, it cools the blood vessels. The African elephant developed its large ears for this two-fold benefit.
Reply:Yes you are correct! Biologists have little or no doubt of that!