Z is for Zebu

Oh no I might have eaten you! One day
I'll go veg, not for my new friend, but
for all the social implications the meat
 industry has on the world population

The zebu, or cebú in Spanish, is a friend of the cow family.  Originating from South Asia, he is known for his hump, his floppy ears, and his dewlap.  I looked "dewlap" up, it's the hanging flop from his neck.  Apparently, these beasts cost about 500 USD monthly in feed, which is about 1-2x the average monthly salary here.  I had some today at a grill with a family, the cut turned out to be pretty chewy but not bad.

After being imported to Brazil, they have spread throughout South America (and through Africa, at that) due to their resistance to heat.  I got two answers from googling "How did the zebu get his hump?" :
(1) The people of India selected out cows with increasingly higher
      humps, which could better stabilize yokes and other carried goods.
(2) It serves to store water, and was subject to natural evolution similar to the camel.
Neither site seemed particularly reliable, so if anyone wants to write something with real sources about zebu, please enlighten us.  I cringe at the thought of spreading unverified information, but the theories were both plausible enough.

the glittery ones win the prizes at the fair!
bonus academic exercise: so what's the evolutionary purpose of a dewlap?