@Logicus,
In some scientific inquiry, just knowing how is enough to satisfy most people.
Scientists understand that evolution is in play in most natural phenomenon that we can "observe."
There are things about our environment that will never be answered as to "why."
For those seeking the why's of our universe, they would need to have the abilities to measure beyond the existence of earth's 4.55 billion years. Nothing begats nothing except guesses and more guesses.
How far did you want to go with the "why?"
Scientists have already concluded (from evidence they found) that we are decended from the ape family.