User:Silence/Introduction to evolution
From Wikipedia, the free encyclopedia
Evolution is the change in groups of living things over time. Living things (organisms) have children (offspring) which differ from their parents in minor random ways. Many of these differences, called traits, can be passed down to future generations of offspring during reproduction. Evolution is the process of these inheritable differences becoming more common or rare within large groups (populations) of organisms.
Evolution occurs in two different ways. The first way is random — when a population's traits change by chance. The second way is called selection. Selection happens when a trait helps an organism to have more offspring, such as by keeping the organism from dying early. This helpful trait will tend to become more common in the population, because organisms with the trait produce more offspring — who may inherit the same trait.
Selection and random change can cause more and more differences to accumulate in a population, eventually resulting in new species. Every living thing is distantly related — every organism is part of an enormous family tree. This means that all differences between species have arisen through this gradual process of change, as different populations have evolved in different ways.