Why don't elbows have "caps" like knees ?

Question

Why don't elbows have "caps" like knees ?

Answer 1

I'm going to disagree with the first poster's phrasing...evolution isn't a force, it doesn't "choose" anything, it's not working for a goal. Somewhere along the evolutionary line, we found a use for kneecaps and none for elbow caps. That's all there is to it.

Answer 2

different joint. knee's are built for high impact vertically and therefor need protection in front to prevent horizontal impact damage. elbows are built so that bone takes the place of the cap

Answer 3

Never knew my knees had caps.

I don't even know what caps are.

I'm stupid.

Answer 4

I agree with the first person to answer......but I don't have enough points to vote for him yet......

Answer 5

are you dopedup?

Answer 6

Very good question.  They are fully developed only in placental mammals.  I have no idea why that is.  But the main purpose is additional leverage when extending the leg.  In bipeds, the legs carry much more weight than the arms, and are much stronger.  Even a horse has no patella, since it doesn't need much strength to extend those joints; they usually stay extended.

Answer 7

Evolution didn't find it necessary.