The homologous trait I have selected for discussion is hair.
Two species that exhibit this homologous trait are orangutans and humans.
Orangutans are orange, tree-dwelling great apes and humans are, well, us. Like
the orangutans, we possess hair on our heads and bodies, but the properties and
purposes of this hair differ greatly between the two species. Orangutan hair is
dense and covers most of the body in an even distribution with similar texture
and length. Humans, on the other hand, have a high concentration of thicker,
darker hair on the scalp and a few certain other areas while having generally
thin hair distribution everywhere else, in sharp contrast to the orangutan’s
dense full-body covering. According to outside Internet research I conducted on
this topic, there are varying theories about the reason for the homology
between ape and human hair. These theories include the difference in climate
experiences of apes and humans, the loss of hair by humans as a way to rid the
body of pests and parasites, and even the loss of thick body hair by humans as
a response to human developments in temperature regulation (such as the use of
clothing and more advanced shelters). The common ancestor of both species is the
early hominid, which, like other mammals, had body hair.
Human
Orangutan
An analogous trait can be observed in the hair of orangutans
versus the hair of dogs. A dog is a canine originally domesticated from wolves.
As described above, orangutans possess thick, dense hair covering most areas of
the body. Like the orangutan, dogs possess similar hair, which is generally
thick, dense, and found on almost all area’s of the dog’s body in equal
proportion. I believe that the common ancestor of dogs and orangutans must have
been a mammal and therefore possessed body hair similar in at least some
fashion to the hair of orangutans and dogs.
Dog
Orangutan
Good job Phil! I enjoyed reading your post and examining your pictures. I liked how you used orangutans in both your ananlogous and homologous portions. You mentioned that orangutan could possibly have a common ancestor with both humans and dogs. So if we look far back enough do you think that humans and dogs have a common ancestor as well? Great post!! Keep it up!!
ReplyDeleteGood background on the homologous trait. Be careful on the common ancestor, however. Humans and non-humans apes branched off long before early hominids developed, so the common ancestor goes back well before 6 million year ago.
ReplyDeleteRe: Analogous trait: As you stated, the common ancestor of the dog and the orangutan was a mammal that had hair as well and passed it on to its mammalian descendents. That makes this a homologous trait, not analogous. For it to be an analogous trait, the two modern species must have developed their traits independently due to environmental pressures, not due to inheritance.
First, I have to say that I like that you chose hair; while other chose limbs and such things. I really enjoyed your post, and the research you did. I think it’s very interesting that humans have lost a lot of hair because of human development such as us wearing clothes, and to regulate body temperature. Little things like hair, is not something that we really think about much and how it relates to other species. I found your post to be very useful and full on interesting information.
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