Alison Jolly

Six million years ago, Kenya’s Mombasa beach. You and I forage in the leaf litter of the coastal forest. Every few seconds we pop insects into our mouths. We squat on our haunches, shuffling forward as we feed. You lift a rotting log with one hand and pry out juicy grubs with your other forefinger. I munch a mushroom, then strip a spiny ground herb to yield a mouthful of sweet white...

“A better theory is that drugs are a short circuit to the pleasure centres. Pleasure is usually a reward for behaviour patterns that are good for survival and reproduction. By taking a psychoactive drug, animals (and people) skip the hard work of getting food, getting resources or getting laid, and get the pleasure pay-off directly. Because psychoactive chemicals are rare in the wild and come in small doses, the casualty rate in spaced-out animals hasn’t been high enough for it to be a factor in selection.”

I woke up a little bit jealous of Wendy. She told me yesterday that a baby lemur had jumped right into her lap. It was Triangle’s baby, a precocious extrovert. Triangle, named for her high-peaked white brow, is the troop’s alpha animal; her infant is fearless. The troop was taking a siesta on the forest floor of the Berenty reserve. The hot afternoon sun filtered down through...

Asked​ whether any single word would serve as a prescription for all one’s life, Confucius proposed ‘Reciprocity’. Jesus said it in a few more words: ‘Do unto others as you would have them do unto you.’ They weren’t the first. A ‘black-haired, big-jawed, knuckle-walking species, that ate seasonally available soft, ripe rainforest fruits’...

Sarah Hrdy is tough-minded about a tender subject. Motherhood, she says, is a minefield. Mothers love babies passionately – but not unconditionally. We have evolved as adept sociobiologists, able to calculate love. On the other side of the relationship, baby love is unconditional, indeed desperate. Babies want it all, every scrap of attention they can command, at least up to the point where the mother would be so exhausted that her failure would rebound on the baby itself. Babies cannot be physical tyrants, at their body size, so they resort to psychological tyranny: they are irresistible.