Why has the Bactrian camel evolved to have two humps instead of the one that the dromedary has?
I searched on Google and I found nothing about it.
All I found was that the that humps store fat, that the fat can be converted into energy and water, that this lets them survive in deserts. As far as I know this is true also for dromedaries.
I also found that the Bactrian is smaller than the dromedary, that Bactrians are less numerous and they are at risk of extinction.
No site explains why Bactrian camels have two humps instead of one hump, as in the dromedaries.