Analogy & Homology

Homologous Trait

The two species that I selected for my homologous trait are dolphins and humans. Although these two seem to appear different and live in completely different settings, they both share a similar homologous trait and a common ancestor. Humans and dolphins both share the same bone structure including the formation in their extended limbs. Although one would not even consider a dolphin's flipper and human's arm to have any similarities, with further examination, one is able to see the similarity homologous traits. The similar traits that exist in the limbs of a human and dolphin include the carpals, phalanges, ulna, radius and the humerus bone fragments. Anyone can distinguish the fact that their is a difference in size and also the shape between the two. The reason for that is that they both live in different environments and use the functions of each of their limbs in different ways and different methods. Dolphins use their flippers for steering through the water and making sharp turns. In order to turn fast they use their back flipper because that helps push them forward. Their use of flippers is also used as communication be being able to touch and feel other dolphins. Humans on the other hand, also use their hands for many different tasks, (which everyone knows how). We use our hands and arms to eat, drive, write, drive and many other common tasks.  Their common ancestor will be a mammal, the reason for this is that all mammals share similarities in limb structures.

Analogous Trait

Humans and octopus are two species who both share a similar analogous trait. Humans and octopuses have similar traits but do not have them because of a common ancestor. Believe it or not, the trait between these two is their eyes. The human eye is very similar in structure to the eye of an octopus. An octopus eye is very similar to the eyes of vertebrates. The unique part is that they have been shown to have evolved independently. Both eyes have evolved lenses and also very similar structures. The difference though is that the eyes of octopuses is superior to the human eye in that they do not have blind spots. This is the only real difference between the eyes. The both have lenses to refract light, a pupil to restrict incoming light, following a retinal surface that is distributed along the back of the eye. These two do not carry the same trait because of a common ancestor. Scientists are still trying to figure out deeper information on octopuses besides knowing that they are one of the mysterious creatures in the seas. Scientists and researchers believe that they are "aliens." Although it might sound crazy, their findings lead them to believe that, even as a joke. Octopuses have 33,000 genes which is roughly 10,000 more than a human. That alone, we can come to the conclusion that they do not have a similar ancestor so they are not homologous to humans.