Homologous traits are those which are similar based on a
descent from a common ancestor. The pelvis of a human which has a coccyx,
tailbone(left), is similar to the pelvis of
the monkey with has a tail(right) . The purpose of
a monkey’s tail is to maintain balance or grab onto trees, depending on
their environment. The coccyx in the
human, is the remnants of what was a tail and evolved away because humans did
not need tails when standing upright.
The common ancestor of the two is said to be Dryopithecus. This ancestor can be seen as part of their
lineage because the body of this primate matches that of the humans and the monkeys.
Analogous traits are those which are shared only based on a
common function, not a common ancestor. The traits which are shared based on
common function are the wings of moths and the wings of birds. Both are to
create flight for the animals, yet they do not share a common ancestor from who
they inherited the ability to fly. The bird wing is constructed on bone, where as the moth wing is constructed of thin layers of chitin, protein.
moth wing structure
Birdwing structure
You are on the right track with your homologous trait, but let me make a key correction. Humans didn't lose their tail due to bipedalism. Tails were lost much earlier in all apes, not just humans, so none of the great or lesser apes possess a tail. There is a good deal of discussion on why the tail was lost, but it may simply be because it wasn't needed.
ReplyDeleteYour analogous trait is correct but very brief! Remember that the first part asks you to describe your two species, so that should have been expanded. Consider these assignments to be papers, not tweets. Don't be afraid to show be what you know.
Hi Sandeep,
ReplyDeleteGreat post, very informative and straight to the point. The homologous part of the assignment was interesting, I was actually going to do it on the 'tails' of humans and monkeys but couldn't explain myself. I see where you were going with the explanation but I got stuck on it since humans don't have a visible 'tail' and monkeys do. I would recommend going further into this explanation and maybe state more information on the 'tail' that humans have. I really like that the pictures you posted showed the bone structure which made it easier for the reader to see where the 'tail' is located, and good job stating the ancestor. As for your analogous section of it, great job and great choice of animal for it. Again, i was thinkin of using that example as well. i would have liked it if you would explain more on the traits i definately do see the similarities. Great points just expand on it some more.