Only Our Closest Relatives?

An article in Science Daily on altruistic behavior in plants, of all things, quotes a Harvard evolutionary biology professor named William Friedman:

"One of the most fundamental laws of nature is that if you are going to be an altruist, give it up to your closest relatives," said Friedman. "Altruism only evolves if the benefactor is a close relative of the beneficiary."

Either Friedman doesn't consider altruism in humans to be a product of evolution, which would be an odd stance for an evolutionary biologist to take, or he's never heard of Mother Teresa.