Salon: The sixth mass extinction is nearly upon us. Species on Earth are dying out at a rate one thousand times greater than they were before humans began altering the environment. By the end of this century, scientists warn, anywhere from 20 to 50 percent of the species on Earth could be lost forever.
And among those who might not make it out the other side, says science writer Michael Tennesen, are humans.
It`s to be expected: No species lasts forever, and in our relatively short existence, humanity...