Homologous Trait: Both sharks and dolphins possess tails, which help them move quickly through out the depths of the Earth. Their tails are the most distinctive features of mammals when it comes to hunting their prey.  The Doliodus problematicus, described as the 'least shark-like shark', it is thought to have risen from a group of fish known as acanthodians, also called spiny sharks. The Mesonix, the ancestor of the the dolphin, was a special animal that went into the water to feed. It consisted of front and hind limbs that contained bones to support its weight. It was also covered in hair. As you can see, dolphins are much different from their ancestors, trait wise. Both ancestors consisted of having tails. The structure of the shark has not changed, as much as the structures of dolphins has. The acanthodians always had tails behind them, and have been using their tails for the same purpose, for speed and hunting. The mesonix has also always had a tail, even though it was not known for being a species that could only live under water.


Anologous Trait:  Both sharks and dolphins possess flippers and fins, which help them maneuver through the depths of the Earth. Fins are the most distinctive features of mammals. They are composed of bony spines that come from the body with skin covering them and joining them together, sometimes described to be in a webbed fashion, similar to a flipper as seen in sharks.
The reason these flippers and fins are an anologous trait, are because the ancestor of today's dolphin, did not start out by having a fin. The Mesonix was shaped more like a tiger or a lion, with arms and legs, until it evolved into a sea creature. However, the Mesonix's traits of having legs did serve the same purpose of the fins and flippers of sharks and dolphins, Just as flippers and fins were used to maneuver through water, the Mesonix's legs were used to maneuver through land. We know that these traits are analogous and not genetically related from common descent because of how differently the Mesonix and the Doliodus problematicus  are structured. One has always been a sea creature, while the other adapted and evolved into becoming one.

Historical Influences on Darwin

1. After researching all five individuals on the list given, I would say that Thomas Malthus has had the most influence over Darwin's development of his theory of evolution.

2. In 1798, Thomas Malthus published essay on the Principle of Population and its affects on the future improvement of society. Malthus had doubts about whether a nation, or a group of people in general, could ever reach a point where laws and rules would no longer be required, to run a society properly. Malthus argued that the growth of population would always exceed the rate the ability to feed itself. This meant that the human population would always be growing at an unstable rate and the ability to feed the population would get more difficult as the years went on.

3. One point that was directly affected by Malthus's work was when he talked about how individual people w never evolve, but the human population would. He talked about how individual traits of human beings and how they cannot change. It is a generational type of change and it happens between generations. Malthus's theory explains how populations grow and evolve together and that is why individuals cannot evolve, because a population is a group of people and not just one individual.

4. In my opinion, Thomas Malthus was a big influence to the creation of Darwin's theory of evolution. Darwin disagreed with Malthus's idea of the evolution of populations and instead, believed that the population would level out with the production of materials.

5. The church had no affect with Darwin's ideas in any way. He was never hesitant to express his beliefs and still managed to publish his theory to the public, even with all the negative backlash that he received.