[Alex Murphy]

We’ve already figured out an effective way to warm up a planet: pump greenhouse gases into its atmosphere. [Chris McKay, a planetary scientist at NASA’s Ames Research Center in California] imagines a not-too-distant future in which we park machinery on Mars that converts carbon and fluorine in the Martian soil into insulating chlorofluorocarbons, and spews them into the planet’s puny atmosphere like a protein shake designed to bulk it up....The practice of making a dead world habitable is called terraforming. In science fiction, Earthlings terraform other planets in order to occupy them, usually after trashing Earth.

RIPLEY: That the atmosphere processor?
BURKE: Uh-hunh. One of thirty or so, all over the planet. They're completely automated. We manufacture them, by the way.

[dp0622]

This is all too deep for me. I still dont understand how the first cells turned into so many different animals and plants. First with dinosaurs, which must have come from single cell creatures, and then humans.
How the heck did the earth create two such different set of creatures?