Where stem cells come from?

yes the words are placed in front

i think i can answer even without the example. over time with environmental changes, sometimes a group of animals will adapt to better survive. take a moth for example. if the trees the moths use to camouflage themselves from predators, started to die or change colors themselves, the moths may, overtime of course, change color too. its just adapting to its surroundings. hope i was of any : )

answerearly selection theory;