There are a lot of progressions and interactions going on in the universe and for everything to survive, these progressions are important. The same is for humans. For humans to exist, they must undergo some process which is commonly known as evolution. Humans have evolved through evolution. Aristotle was the first biologist that identified humans as rational animals that have a distinctive ability to reason and make judgments, due to which they are different from other animals.Cela-Conde and Ayala assert in their book that all organisms tend to have common ancestors (1). According to them, “Biological evolution is a process of descent with modification” (1). If we go into the depth of this statement, we come to know how we evolve from what we were and what we are today. hominidae is the term used to describe the lineage spreading from the final common ancestor of man and apes. Hominid is the term given to a species in the family. According to paleoanthropology, the history of human evolution shows that the common ancestor to both man and apes existed “about 5.5 million years ago”, states Professor Grover Krantz. Ramapithecus was one of the most ancient hominids whose fossils were found at that time. Paleoanthropologists believe that the bipedal adaptation of the ancient hominids evolved when that ancient hominid decided to live at the border of forests under the trees instead of inside the forests and in the trees. This was about four million years back, but how we look like today is much different because our modern facial features evolved much later than that. The bipedal adaptation then evolved into upright walk that is how we walk today. Paul Rincon, a science reporter in BBC News, reports that scientists have found in Western Europe, and specifically in Spain, the most ancient remains of human. He reports, “A jawbone and teeth discovered at the famous Atapuerca site in northern Spain have been dated between 1.1 and 1.2 million years old.” Borgus, the city of Spain, is well known for having many antique limestone caves that contain fossils of early hominids and other tools that show the occupations of early humans. As far as United States is concerned, most Americans believe that humans did not evolve over a period of time. However, there is a designer God who designed the mechanism of humans and created them magically. There are two parts of human biological evolution: Anagenesis and Cladogenesis. Anagenesis Also called phyletic evolution, ancestry of organisms changes generation after generation. Kesner and Olton describe anagenesis as progress of the humankind in evolutionary context (15). Continuous natural selection results in the modification of forms and organs so that they perfectly adapt to the new environments and habitats. Cladogenesis Another name for it is lineage splitting which means that new species come into existence with the passage of time which results in diversity. While modification in a phylogenetic lineage is occurring, branching of forms also occurs at the same time which causes them to expand on the face of the earth. Natural Selection Considered as one of the most fundamental processes that results in evolution, natural selection was a concept put forth by Charles Darwin in 1859 in his book On the Origin of Species. According to this concept, organisms (or traits) that are best suited to the environment are selected by nature to prevail due to which they are able to pass on their genetics on to the following generations. On the other hand, organisms (or traits) that are not best adapted in the environment tend to vanish away. Human evolution has also been influenced by this concept of natural selection. According to Darwin, as he states in the revised version of his book, another name for natural selection is survival of the fittest (Darwin 8).