Evolution: Explanation and Proof

First of all, whales like dogs, cats, humans etc. are mammals. This alone is evidence that they must have descended from some type of early mammal. The fact that paleontologists found a skull shaped much like the ancestor of a wolf led scientists to believe that whales had evolved from a land mammal. In addition to the skull, fossils of a vaselasaurous proved that they had come specifically from a quadruped, or mammal that walks on all fours. Bones in this ancient whale included knee caps, thigh bones, pelvises, calves, feet, and even toes. Furthermore, scientists see great similarities in the way marine mammals swim and the way land mammals run.

The fossils of whales were found that included feet, toes, kneecaps, ankle bones, etc. proved whales to at one point have legs. A shoulder blade was also found in the midst of these follils which was thought to be 370 million years old and had come from a once marine-like creature. As scientists examined the full sets of bones from these tetropods, they came to the conclusion that the prehistoric whales fin had the same structure as a human arm.

"Evolution is not a goal-directed process; it is a tinkering." This means that evolution like many other things is random. It is only by chance that a successful structure comes about. When advantageous attributes appear, an organism is more likely to survive, therefore reproduce and create more offspring with said trait. New species come from the same basic ancestor which had simply been "tinkered with" several times.

The Cambrian Explosion was a boom in new marine life during the Cambrian period. It occurred around 540 million years ago. Throughout the Cambrian Explosion new species developed with harder parts and shells. Many fossils of this time were found in Burgess Shale in British Columbia. There was a very wide variety of species during this time. In the end most, almost 99%, died out due to environmental changes.

Embryos provide clues about how animals evolved. They do so by random mutations and natural selection. Inside embryos there are what you could call "on/off switches" for each segment of the body. When a genetic mutation occurs, it is simply one of those switches being turned on or off. A change like this for example could alter the place where legs of a fly are supposed to grow. If the given alteration should be advantageous, natural selection will take place. More baby flies would be born with a different placement of legs. In other words, this species of fly would evolve. Human bipedalism came about when primates started to get up and walk on two legs. This allowed them to free up their hands and bring back more food. Most species that attempted this became extinct; although, one tribe survived and moved on in the chain of evolution. Eventually humans came about from an ancestor closest to the chimpanzee. Just like every other act of evolution, humans came about by genetic tinkering.