According to Ehrlich biological evolution can be described as the, “evolution that causes changes in our genetic endowment” (Ehrlich et al. 2005). Humans have been evolving for a very long time now. The first major point in the evolution of human kind is when the development of bipedalism arose. Bipedalism is the use of two legs for primary locomotion. Chimps had walked on all four, but the process of evolution occurred leading to the use of only two legs for locomotion. The ability to stand on two legs allows one the ability to extend their height and reach things that were previously unreachable. Having the freedom of two arms enable humans to create tools. Diamond says, “the upright posture freed our ancestors’ forelimbs to do other things,…show more content… There is a biological adaptation that occurred about 4.3 million years after bipedalism. The great evolutionary change was that of brain size. The human brain used to be much smaller then what is currently today. The skull of the head had also used to be a different shape. The skull had used to be elongated and not as large. The increase in brain size occurred roughly 700,000 years ago. Chimpanzees are related to humans, but there are many differences in each one’s genetic composition. Humans were able to grow larger brains because “There were 510 elements from the chimp genome that were gone in humans” (________). This alteration was key in the progression of human kind. The addition of a larger brain gave rise to language, innovation, social skills, and problem solving. The brains evolution is one of the key points on the timeline of human kind. The ability to produce and refine these skills that came along as byproducts from the creation of a larger allows humans to become impart unique to other mammals on earth. The increase in brain size enabled our ancestors to live more