After mother’s milk, the first significant source of sweetness in human experience must have been fruits. Some warm-climate fruits like the date can approach a sugar content of 60%, and even temperate fruits become very sweet when they dry out. But the most concentrated natural source of sweetness is honey, the stored food of certain species of bees, which reaches 80% sugars. It’s clear from a remarkable painting in the Spider Cave of Valencia that humans have gone out of their way to collect honey for at least 10,000 years. The “domestication” of bees probably goes back 4,000 years, judging by Egyptian hieroglyphs that show clay hives.