According to Thor Hanson’s Buzz, the relationship between bees and the human lineage goes back three million years, to a time when our ancestors shared the African savannah with a small, brownish, robin-sized bird—the first honeyguide. Honeyguides are very good at locating beehives, but they are unable to break into them to feed on the bee larvae and beeswax they eat. So they recruit humans to help, attracting them with a call and leading them to the hive. In return for the service, Africans leave a small gift of honey and wax: not enough that the bird is uninterested in locating another hive, but sufficient to make it feel that its efforts have been worthwhile. Honeyguides may have been critical to our evolution: today, honey contributes about 15 percent of the calories consumed by the Hadza people—Africa’s last hunter-gatherers—and because brains run on glucose, honey located by honeyguides may have helped increase our brain size, and thus intelligence.

Bees evolved from wasp ancestors around 100 million years ago. Most wasps are sleek carnivores, but bees are flower-loving, long-haired, and often social vegetarians (the branched hairs that cover their bodies trap pollen, which, along with nectar, is their principal source of food). Their shift to a vegetarian diet had a profound effect on the evolution of flowering plants. If we want to know what a world without bees looks like, Hanson writes, we should visit the bee-less island of Juan Fernández off the coast of Chile, where, despite varied vegetation, almost all flowers are small, white, and inconspicuous. But it is not just gloriously colored flowers that we owe to bees, for many of our crops rely on them for pollination. Both our world and our brains, it seems, have been profoundly shaped by bees.

There are around 20,000 bee species, classified into seven families. The most familiar are the apids, including bumblebees, carpenter bees, and honeybees. The most primitive bees, largely restricted to Australia, are classified into two families that only experts would recognize. Mining bees, which dig nest tunnels nearly ten feet deep and inhabit arid regions, represent another family; oil-collecting bees and a family including leafcutter bees and mason bees make up two more. Sweat bees comprise the final group. In addition to collecting pollen and nectar from flowers, they drink mammals’ sweat for its moisture and salts: as thousands of tiny bee tongues lick deep inside a person’s ears, nose, and other sensitive parts, they can inflict maddening torture; if brushed away they deliver a sting like an electric shock.

Around one fifth of all bee species are parasites on…