Tagged Questions
3
votes
1answer
74 views
Why do sloths come down from the trees to defecate?
I'm under the impression that most sloths exhibit this behavior, but why? They are slow moving and so have no way of escaping from predators when on the ground. Not to mention the energy they expire ...
4
votes
1answer
65 views
Birds from the Family Columbidae Feed Young “Crop Milk”
Birds from the family Columbidae (e.g., doves and pigeons) produce a fatty, milk-like substance in their crop. The secretion is often referred to as "crop milk." They feed crop milk to their young ...
5
votes
1answer
70 views
What selective factors drove the evolution of lactose in lactation?
As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
6
votes
1answer
494 views
Why can't humans drink sea water?
Why can't humans drink sea water?
It would seem to be a huge evolutionary advantage for an animal to be able to drink sea water rather than have to rely on fresh water, and it's provably not ...
5
votes
1answer
92 views
Why was polyploidy not lethal in certain octodontid rodents?
As discussed in Why is polyploidy lethal for some organisms while for others is not?, polyploidy is normally lethal in mammals.
However, two species of Octodontidae (South American rodents), are ...
