1. The tail of a monkey and the tailbone of a human are homologous structures. Monkeys are primates that dwell in trees and eat fruits, seeds, leaves, and nuts off of trees, as well. They have prehensile tails and have been extensively experimented on due to their similarity to humans. Humans have erect posture, walk on two feet, and have high manual dexterity. They do not have visible tails, but remnants of one in the form of a tailbone.
While the monkey has a tail, the human bone is only a small triangular bone at the base of the back. These structures share a common lineage, but what once was a human tail, disappeared during the process of evolution as a vestigial.The monkey’s tail serves to swat away unwanted insects and aid with balance. It also allows the monkey to swing from trees and grab food. The human tailbone functions as a stabilizing bone to help humans in certain positions such as sitting. It is also a connection point for multiple ligaments, joints, and muscles. There is such a difference between these species due to the fact that humans don’t need to be able to swing from trees in order to get their food. There isn’t any need for a tail because of the tree-lacking environment that they live in. In addition to this, humans have multiple mechanisms within the body that help with balance, such as cochlear fluid and kinesthetic sense, rendering a tail completely useless. Although a common ancestor did have a tail, it is now a vestigial for humans.
The common ancestor between humans and monkeys is most likely a species of ape, possibly resembling a gibbon. There is evidence of common ancestry in broken jaw artifacts and teeth. Both species are form the genera of Hominini. Apes do have tails, revealing that the common ancestor did posses this homologous trait.
2. Penguins and fish both have fins. Because one is a bird, and one is a fish, they have no recent common ancestor that could possibly be the source of this feature. Penguins live in colder environments where they have to swim in the ocean to catch their food. Fish live in the ocean and also have to swim to get food, move from place to place, and generally survive.
The fins of the penguin are coated with scale-like feathers, providing a water resistant coating. It is a bird, and most bird wings would not be flexible enough to swim, but penguins fins are flat and tapered to help in the aquatic environment. Fish fins are also coated with scales and are flat, flexible, and strong enough to propel the body through the water. these analogous traits show strong similarities as a result of similar environments. They both have a biological need to swim so that they can find food, escape from predators, and move to different locations. The shape of both species' fins closely resemble each other because of the physical motions that they perform and their aquatic environments.
I don't believe that their common ancestor possessed this trait because fins evolved after the first birds. While both species belong to the phylum chordata, they belong to different classes. Penguins are in the aves class while fish belong to belong to multiple including agnatha, placodermi, and chondrichthyes. Because they belong to different classes, this trait could not be genetically related.
Good opening description of your two species for your homologous section.
ReplyDeleteThe only clarification I would point for your second section is that only some monkeys (New World Monkeys) possess tails that can grasp. Otherwise, good.
Monkeys arose before apes, so apes could not be the common ancestor of monkeys and humans (who are apes). The common ancestor would have to be an archaic monkey, and we know from the fossil record that these early monkeys possessed the tail structure in question. That is what we need to know to confirm that these traits are homologous, arising from common descent.
Analogy:
"Because one is a bird, and one is a fish, they have no recent common ancestor that could possibly be the source of this feature."
That is not a safe assumption. The tiny bones in our middle ear are actually homologous to the bony gill arches in fish. No kidding. So evolutionary distance tells us nothing about genetic relatedness. Otherwise, good description.
Good description of the analogous traits, making good connections between similarities in structure and function.
"I don't believe that their common ancestor possessed this trait because fins evolved after the first birds."
And that, right there, is exactly what I was looking for. What you did was provide evidence that the fin trait arose independently in the penguin. I.e., it did not arise from that common ancestor it shares with fish. That is what we need to know to confirm analogy.
Good images.
Hey, Nicole! Wow, ok, so I learned a lot from your analogy portion of this assignment because man oh man I had trouble with mine. I can tell you really have a great grasp on this assignment. Also, I think it is so cool that you chose the tailbone of a human and tail of a monkey for the homologous structure to talk about. I recently learned what the word vestigial meant and I too found a vestigial structure to talk about in my homologous portion of the assignment, I hope to see a comment from you on my blog to see what you thought of my findings! Awesome work!!
ReplyDeleteHello Nicole,
ReplyDeleteI enjoyed reading your post. I had no idea that a tailbone of a human and the tail of a monkey were so similar. Your description of the two species made it easy for me to understand their homologous traits and how they are used. Great post.