Questions tagged [mammals]

Questions related to mammals, animals that nurse their young, have a neocortex, and three middle ear bones.

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60
votes
5answers
45k views

Why don't mammals have more than 4 limbs?

Arthropods have 6 or more limbs and arthropods with 6 limbs appear to move faster than arthropods with 8 limbs so I wonder whether this might have something to do with fast and efficient locomotion. ...
3
votes
1answer
363 views

Is there any evidence for secondarily poikilothermic vertebrate? [closed]

Is it possible that an endothermic physiology can evolve into an ectothermic (poikilothermic) physiology? I have a non-scientific gut feeling that it is irreversible. Whales and dolphins are evolved ...
6
votes
1answer
836 views

Do any birds beside the family Columbidae (or any reptile or mammal) feed their 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 ...
2
votes
2answers
2k views

Why only female mammals have well developed mammary glands?

In course of evolution (possibly), mammary glands became vestigial in male mammals, but became fully developed in females. Is there any plausible explanation for this characteristic?
22
votes
2answers
31k views

How and why did mammals go back to the oceans?

If I understand evolutionary biology correctly, mammals first evolved on land as small, rodent-like creatures, in a time when reptiles were dominant on land. Eventually, they diversified into the ...
9
votes
1answer
3k views

Why do squirrels have twitchy bushy tails?

Whenever I see a squirrel in the woods, it is always the big bushy tail flipping around that gets my attention first. A pray animal with a big bushy flag calling attention to it's self seems to be ...
36
votes
2answers
18k views

Are there any non-mammalian species known that lactate?

Are there any non-mammalian animals that produce milk to feed their young, or are mammals the only milk-producing animals?
23
votes
1answer
8k 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 ...
19
votes
2answers
17k views

Evolutionarily, why do male rats and horses lack nipples?

Developmentally male rats don't have nipples because (reddit) Testosterone release in the fetal male rat happens before the stage of mammogenesis where the teat is formed whereas other species halt ...
9
votes
2answers
830 views

Goats are so fearless but sheep are not. Is there any genetic difference responsible?

As you see in the picture goats (not only wild goats) are so fearless, but I never saw any sheep do this. What is the source of this difference in behavior?
3
votes
1answer
2k views

Is there a difference between pig and cow anatomy that makes religious slaughter of the latter less painful?

This question is not for the squeamish. I was told that non-Kosher animals like pigs have a different anatomy in their neck compared to kosher animals like cows such that the Shechita method of ...
9
votes
2answers
214 views

How can bats achieve good resolution with wide beams?

I have been reading about the echolocation system in bats. papers state that bats tend to produce a sonar beam that has a beam angle (-3db) of about 30-40 degrees. This would be considered a wide beam ...
6
votes
2answers
242 views

Do omnivore mammals vary food preferences based on dietary needs?

I'm wandering if mammals that can eat many different kinds of food (omnivores) vary their preference for food not only based on the availability, but also based on dietary needs? I'm looking at this ...
6
votes
1answer
436 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 ...
5
votes
1answer
2k views

Do mammals and birds have a common warm-blooded ancestor?

Is it homogeneous or did they converge? Did we both evolve from warm-blooded reptiles that are extinct maybe?
4
votes
1answer
77 views

Can bats echolocation discern what insects they are preying on?

Insectivorous bats feed on many different types of insects such as mosquitoes, moths, beetles, and bees. According to the Bat Conservation Trust, bats can discern insects from other objects but I'm ...
3
votes
2answers
135 views

Do dolphins really sleep?

I have always wondered, if dolphins sleep with one eye opened, do they really sleep at all? According to this article dolphins indeed shut down their brains. I already googled it. No help from ...
-1
votes
1answer
108 views

When you lose weight, how does the mass exit your body?

As a thought experiment, consider the case of Angus Barbiery, who allegedly lost almost 200kg in about a year by not eating at all, save for necessary nutrients provided as supplements. My question ...