More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct.Most of which had nothing to do with humans, obviously.
Many seem concerned that humans are responsible for the extinction of nearly 500 species since 1900. Some others seem very worried that man-mad global warming might wipe out some particular species, like Polar Bears. I don't have a particular fondness of polar bears, but even if I did I think I'd be able to accept the reality that species come and go all the time.
But what about the rate of extinctions? Aren't humans wiping out species way faster than usual? If we value biodiversity, then this would be awful.
It seems like the answer is yes and no. Humans create a lot of extinctions, but human beings are also responsible for the creation of many new varieties of life.
We have created scores of entirely new creatures, such as the hundreds of breeds of domestic cats and dogs living alongside us. We have intentionally and unwittingly transported all sorts of organisms — bacteria, ants, rodents, cattle, crops, garden plants, and roadside weeds — across the globe, to places they could never have reached on their own. We have formed numerous new environmental niches in our cities and suburbs, which many hardy critters have used to their advantage. And we have even spurred the hybridization of wild species, resulting in new chimeras, such as the Italian sparrow, yellow-flowered Yorkwort, and apple flies.So forgive me if I don't care that much about Polar Bears.
