previous use of vestigial organs

[vinaya]

what were the uses of vestigial organs of humans before they became useless?
like the appendix, the nictitating membrane .......
because they are still quite useful in other organisms
like the appendix is still useful in herbivores, the nm in birds,........
so, why did they become useless in humans

[vinaya]

pls
i need reply urgently if u dont get my question, pls ask ur doubt

[Morris]

I think some human organs are only a remembering of our origins and evolution; and they become useless because we don't need them.

[MrMistery]

Think of it like this: Herbivores have a diet based completely on vegetation(duh, that's what their name means ) so they need to digest cell walls. They do so by the help of bacteria in the vermiform appendix. But at humans, the most nutrients come not from cellulose, but from other substances, easier to digest. Therefore it was useless to consume energy on having an organ that wouldn't do much... If natural selection would still act upon us as every other organism, these organs would dissapear.. Got it?

[vinaya]

maybe the nm performs the work of eyelids.as v already have some protection the nm got destroyed
errrr is that right.....????????
ummm do birds have eyelids ?

[Poison]

As much as I know, yes they have.

[Leesa]

I don't know why they became useless, but it does seem pointless using the appendix when its simply not neccessary. We have 2 forms of digesting processes, the mechanical digestion, and the chemical digestion. The mechanical is breaking down the food with teeth, and then the chemical : The different enzymes in our digestive system allow the break down of complex molecules. Like Koalas, they use the protozoans in their stomach, to break down the food.

[MrMistery]

they became useless because, considering our diet it was no use keeping those structures and wasting energy
@Leesa
We also have physical digestion