why am I different?

[claymore]

Why are n`t we all exact copies of each other ,what makes each and everyone of us unique? Other species of mammals such as dolphins , killer whales for example all look nearly identical.And I defy anyone to recognize one chicken out of a hundred.

[Tom Braider]

The answer to the first question is sex. You're a product of a "mixture" of the genes of your mother and father. They can mix in various ways and the different "combinations" result in different physical attributes. To an alien we probably would look all the same... As for other animals, you may not be able to tell one from another but they certainly can - and so can humans who take careful enough note of what they see. Ask a zoo keeper which giraffe is which; you may not be able to tell them apart but he/she will certainly be able to.

[sp1214]

But dont we in the west have problems differentiating a Chinese or Japanese person from one another?

[newtron]

I've been told by Native Americans that all white people look alike.

[wildwood]

Humans (primates) are visual animals and because of the way they need to live in groups in a hierachy it is helpful to be able to recognise each other so facial distinguishing features have evolved. We have forward facing eyes and excellent binocular vision.

Many other animals can not recognise each other by sight but use scent and gestures so do not need to look different.
Birds and fish are so reliant on visual signs that will even treat their mate as an enemy until the right signs are given.

Nature will always make small adjustments to an animal's genetic make up (mutations) to allow for evolution on a changing planet or else there would be no life on Earth left.