Every once in a while I speak with someone who is certain that humans were brought to earth by aliens. Their resolute convictions often stem from an assortment of personal observations. They speak of the impossible sophistication of the Nazca Lines in Peru, Stonehenge, the Great Pyramids and other striking sites. One person I recently met said that the diversity of the human species was clearly evidence of coming from another planet. “How else could people who began in one place, Africa, turn into four different races without being dropped off from a spaceship?”

But I look at humankind and see extraordinary diversity everywhere. Subtle differences among ourselves cannot be reduced to the four races I learned as a child in books. Biodiversity abounds in flora and fauna. We seem to fit in perfectly among the rest.

And I can never doubt the human intellect while astounding evidence of its capability is all around us.

No, I will stick to the less titillating prospect, that we are all products of evolution and luck.