I’ve always heard that our ears and noses continue to grow long after our bodies have matured past adolescence. From what I’ve seen, that certainly seems to be the case. But why would this be? Why would these two (well, three) appendages keep growing when our pituitary glands/endocrine system have already said “Knock it off” to all the other body parts? (I know the brain keeps developing until age 25, but that’s different.)
Does it have something to do with the ears and the nose being cartilaginous? )Is there any evolutionary advantage? I know some guys who probably wouldn’t mind if one other appendage continued to grow. Maybe that WOULD have some sort of evolutionary advantage.
Finally, is this universal, or are there people who keep the same dainty nose and ears they had at, say, 18?
After puberty, because of the effect of testosterone and estrogen to close the so-called cartilage growth plate, the long bones in your body stop growing, i.e. cartilage grows from the growth plate (located near the end of the long bones) outward (and subsequently turns into bone). That’s why you don’t get any taller once you’re finished puberty. Again, it is the cartilage that grows and then transforms into bone (ossification). The initial cartilage growth occurs as an (indirect) effect of growth hormone.
OTOH, cartilage in other areas and bones, where there is/was no growth plate can continue to grow after puberty. Good examples of this are the base of the nose and the lower jaw (i.e. the part of the lower jaw that attaches to your skull). But, even though the cartilage in those areas can grow, it doesn’t tend to happen because levels of growth hormone get lower as you age.
If, though, you have excessive levels of growth hormone as happens in the condition called acromegaly, then areas such as the nose, jaw, etc., do grow and enlarge.
A classic case of acromegaly. Note the growth of her nose, jaw, and ears, and the general thickening or coarsening of her facial features.Here are some Google image results for acromegaly. Note how basically everyone with the disease looks like they’re related to one another, especially because their noses all look the same.
Bottom line, there is a potential for growth in those areas but it’s not manifest unless there’s enough growth hormone around.
I should also point out that much of the enlargement seen in people with acromegaly is actually due to swelling of the “soft” tissues and has nothing to do with growth, cartilaginous or otherwise.
The brain thing isn’t true. You brain changes all the time, this is what makes learning possible. The majority of new brain cells are created early on in life, so it is true that the rate slows down dramatically in adulthood. But although it was once that that no new neurons grow (the connections always change), we now know that at least in some areas this is not true.
Charlie Sheen cites continual ear growth as a reason he has to keep going after younger females in Two and a Half Men so that he can keep the ear size in check. He has a lot of experience so there is my sitcom cite which is good enough for me.
I’m not convinced that noses and ears grow as we age. As people age, their hair tends to thin, which would make ears more obvious. And the skin on the face tends to thin and lose subcutaneous fat, which would tend to make the nose more obvious.
Maybe that WOULD have some sort of evolutionary advantage.