Why are human beings, who look so different from each other in terms of size, colour and looks said to be of the same species?

Why are human beings, who look so different from each other in terms o

1.	Why are human beings, who look so different from each other in terms of size, colour and looks said to be of the same species?
Answer» Why are human beings, who look so different from each other in terms of size, colour and looks said to be of the same species?