Change is good

 What is evolution?

First proposed by Charles Darwin in 1859 book (ON THE ORIGIN OF SPECIES). The theory of evolution explains how all plants ,animals including humans slowly change to improve their chances of survival.

All life forms are subject to the forces of "natural selection" in which nature favors changes that help a species survive and reproduce. These helpful adaptions are passed onto next generations. If you go back far enough into earths history that is from all life forms - from great white sharks to cherry tress all evolved from the same ancestor.

If human evolved from apes then why do chimpanzees and other apes still exist? 

Humans didn't evolve from modern chimpanzees. We all share a common ancestor which lived 6 million years ago. The branch that gave rise to humans go into one direction while other that gave rise to today's chimpanzees went into other. Also just because particular group of animals evolve into new species doesn't mean the original species has to be extinct. The process of evolution follows a branching path rather than a series of dead end and new beginning.

What are the oldest living things on earth?

Field of moss-2000 years old.

Farmers oak tree in California -13,000 years old.

Quaking aspen trees-80,000 years old.

But the leader of longetivity is BATCH OF BACTERIA discovered in frozen group of Siberia. Scientist estimate it has been growing from a half million years making these microbes earth's seniors citizen.