1. A species is a group of organisms that are capable of interbreeding to produce fertile offspring. Skin colour, looks, and size are all variety of features present in human beings.
2. These features are generally environmentally controlled. Various human races are formed based on these features.
3. However, there is no biological basis for this concept of race. Therefore, all human beings are a single species as humans of different colour, sizes and looks are capable of reproduction and can produce fertile offspring.