Darwin’s theory of evolution proposed a new hypothesis, that of natural selection. It theorized that animals living in environments with more difficult living conditions with mutated traits more suited to their environment would survive, as they were more adaptable, while those without would die off. This would continue the line of mutated gene organisms, while effectively making all other forms extinct.

The documentary highlights the similarities and differences between humans and other organisms, such as Chimpanzees. The slight difference between Human and Chimp DNA shows how a very slight difference can have such a huge result. This is evident with the Tiktaalik. The Tiktaalik was a perfect transitional link between fish and land-living organisms. “Much of its body is that of a fish. It’s covered in scales. But it also had something very un-fishlike, an arm-like fin, or, perhaps, a fin-like arm. Tiktaalik had the bone structure that is seen in the arms and legs of every-four limbed animal.” The scientists searched for a DNA link between the Tiktaalik and the Paddlefish and found it. A set of Hox Genes were responsible for the first step of leg development.

This proves the involvement of DNA in evolution, without the Hox gene the Tiktaalik would not have developed in the way that it did, and in turn would not have evolved to walk on land.

http://www.pbs.org/wgbh/nova/evolution/darwin-never-knew.html