Its called adaptation. Species need to adapt for different habitats. For example, the leg bones of a horse and a human are of the exact same structure, only over time, they have adapted and became enlongated. To answer the 'how,' it would be due only to subtle changes over many years. Species are still changing today.
As they adapt to their environment, they slowly change over time. They are said to Evolve.
Theory is they change slowly over time as they adapt and the ones that can't die out.
Evolution is a change in species over time.
Species not always change over time such sponges :D
velocity
Evolution is the change in species over long periods of time.
A gradual change in life-forms over time is organic evolution.
Living organisms slowly modify the evironment
Adaptation is when a species is able to change over time to new changes in their environment.
Slowly they are changing into Graphite.
To change over time refers to alterations in a thing or a person that happen slowly. The changes may be positive or negative.
Evolution