You, who are on the road must have a code that you can live by.
And so become yourself because the past is just a good bye.

CSN&Y, Teach Your Children

The latest findings highlight once again the extent to which obesity is a consequence of Homo sapiens carrying into an era of abundance, leisure and warmth the physiology that humans evolved in a world marked by barely enough food, constant physical activity and dangerous cold.

From a Washington Post article on brown fat.