All 'homosapiens' have originated from a common ancestor and yet they show tremendous variation in size, colour and appearance.  Explain in brief. 

Although, all Homo sapiens share a common ancestor they are widespread geographically. The phenomenon of genetic drift, geographical isolation and natural selection have diversified the species. They have evolved as different races at varied places exposed to different climatic conditions and environment making them highly variable. There has always been a vast diversity observed with respect to human body and its features. This diversity led to the grouping of human beings into races. The human races were classified into black, yellow and brown on the basis of their skin colour. However, they are still not reproductively isolated and hence, belong to a common species.