Gene (n.) Tiny, without mercy, and in charge.
If aliens visited Earth and looked for the ruling lifeform, they would conclude that the real bosses of the planet were genes, which had established a ruthless empire that ran the entire planet simply as a factory to produce more genes. They would try to establish a dialogue with the little buggers and then realize that there was no way to communicate. They would then classify the planet as "useless" and cover it with asphalt and use it as a parking lot. Human protests would be treated much as the barks of dogs: annoying.