why do rhesus monkeys have tails?

Question

They are kind of small and stumpy? So what's the point?

Answer 1

That's a bit of a trick question. The easy answer is that they have tails because their ancestors did.

Tails can serve a variety of functions. Some South American monkeys have prehensile tails which can be used to grasp branches and lianas. Clearly, the rhesus macaque isn't doing that. Other monkeys use their tails for balance while quadrupedally walking on branches. Again, the rhesus tail is probably too short for this. Some monkeys also use their tails as heat radiators. A long cylindrical body structure like a tail can be very good for shedding heat, analogous to the large ears of an elephant. Short stubby tails, though, wouldn't be particularly good for this either.

Here's my best guess: it could be, in part, that we're seeing a snapshot in the evolution of a lineage that will eventually have no tail. Other monkey species, the Sulawesi macaque for example, have reduced their tails to the extent that there is no external tail present, much like the condition seen in apes and humans.

Answer 2

Shhh! Don't tell anyone, but rhesus monkeys are macaques that are probably one of those "intermediate" stages in evolution the bible-thumpers keep telling us don't exist. Their tails are slowly being bred out of the population because they no longer serve a purpose. Look at a human skeleton; WE still have the bones of a vestigial tail!

Answer 3

they still hang off of trees. the tail is used as a 5th limb.