In exchange for freedom of inquiry, scientists are obliged to explain their work.

The passion to explore is at the heart of being human.

For all its material advantages, the sedentary life has left us edgy, unfulfilled, even after 400 generations in villages and cities, we haven't forgotten: The open road still softly calls like a nearly forgotten song of childhood.

Human history can be viewed as a slowly dawning awareness that we are members of a larger group.

And you are made of a hundred trillion cells. We are, each of us, a multitude.

There are many other (besides testosterone) behaviour-eliciting hormones fundamental for humen well-being, including estrogen and progesterone in females. The fact that complex behavioural patterns can be triggered by a tiny concentration of moleculas coursing through the bloodstream, and that different animals of the same species generate different amounts of these hormones, is something worth thinking about when it's time to judge such matters as free will, individual responsibility, and law and order.

Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us - then, habits of thought familiar from ages past reach for the controls.