Factors of human evolution : 

(i) One of the earliest defining human traits, bipedalism-the ability to walk on two legs-evolved over 4 million years ago. Other important human characteristics- such as a large and complex brain, the ability to make and use tools, and the capacity for language developed more recently. Many advanced traitsincluding complex symbolic expressions, art and elaborate cultural diversity emerged mainly during the past 100,000 years. 

(ii) Early humans first migrated out of Africa into Asia probably between 2 million and 1.8 million years ago. They entered Europe somewhat later, between 1.5 million and 1 million years. Species of modern humans populated many parts of the world much later. For instance, people first came to Australia probably within the past 60,000 years and to America within the past 30,000 years or so. The beginnings of agriculture and the rise of the first civilizations occurred within the past 12,000 years. 

(iii) The process of evolution involves a series of natural changes that causes species (populations of different organisms) to arise, adapt to the environment, and become extinct. All species or organisms have originated through the process of biological evolution. In animals that reproduce sexually, including humans, the term species refers to a group whose adult members regularly interbreed, resulting in fertile offspring that is, offspring themselves are capable of reproducing. Scientists classify each species with a unique, two-part scientific name. In this system, modern humans are classified as Homo Sapiens. 

(iv) Evolution occurs when there is change in the genetic material- the chemical molecule, DNA - which is inherited from the parents, and especially in the proportions of different genes in a population. Genes represent the segments of DNA that provide the chemical code for producing proteins. Information contained in the DNA can change by a process known as mutation. 

(v) The way particular genes are expressed - that is, how they influence the body or behavior of an organism can also change. Genes affect how the body and behavior of an organism develop during its life, and this is why genetically inherited characteristics can influence the likelihood of an organism’s survival and reproduction.