Analogy and Homology

 All species are related to one another regardless of what they look like or which traits they posses. If a person were to go back far enough in time they would see this relationship. There are two ways to explain why two species have similar traits, some which can be seen on the surface others which are more internal.

First way to explain would be to use homology. There is a prime example of human forelimbs (arm) and the forelimbs of a bat's wing. Human beings are known as Homo sapiens. They are the only living species of homo genus. Their closest living relative is the chimpanzee. They are know to have the ability to create such expression as language, reasoning, culture etc. The other spices would be bats. Their scientific name is Chiroptera. There are the only mammals known to have true flight, because of their forelimbs in their wings. Most are fruit eaters, they are present almost all over the world. A bat, a human, an alligator, and a penguin all evolved from a common ancestor, then they should share common anatomical traits. Looking at the forelimbs of the human, and the bat you will find the humerus, radius, ulna, and carpals in each forelimb. Though the limbs look strikingly different on the outside and though they vary in function, they are very similar in skeletal structure. The forelimb of the human beings have a function to be able to reach objects using the mechanisms of the arm and the hands. While the function of the forelimb of a bat's wing is to help them take flight. More significantly, they come from the same structures in the embryo. Although humans and bats seem to have nothing in common their comparison of homologous structures indicates that they are quite similar. Although there has not been a connection made to who is the common ancestor but by looking at the homologous structure suggests that these two species evolved from a common ancestor. The homo sapiens and Chiropteras have one homologous trait which being the forelimb of a human being and a forelimb of a bat's wing.

An example of analogous trait if compared to the human forelimb would be a dolphin's fin. Dolphins are marine mammals closely related to whales. They vary in size and can be found mostly along the continental shelves. They eat fish and squid. They are among the most intelligent animals. The forelimbs of a dolphin are anatomically equivalent to the forelimbs are analogous to arms in humans. But the bones within the forelimbs of dolphins have been shortened and made more rigid by supporting connective tissue. Pectoral flippers enable dolphins to steer and control their speed. The dolphin seem to have a very similar structure to the forelimb of a human being but just shorter. They both have phalanges, carpals, ulna, and humerus. But unlike the human arm, a dolphin fin is not flexible, it can not be bended or shaped. Dolphins have evolved from Cetaceans and if looked at their skeletal structure there are toes, fingers and thumbs, just like the humans have, which later evolved into flippers and tails.