RWANDA

I’M CLOSING IN ON THEM. After two hours’ trekking up Mount Karisimbi—in a bamboo forest so thick as to turn the daylight jade, past shoulder-high grasses and through stinging nettles—I stop at the sight of night-black fur breaching the vegetation.

Our guides stalk nearer, machetes in hand, pushing aside shivering bushes. A scowling brow juts from foliage: a silverback gorilla glaring imperiously. His bulk is staggering, the gorilla’s head a pyramidal black helmet spreading necklessly into kettlebell shoulders, like a marble-muscled Mr. Universe whose power food is a diet of little more than leaves.

He rips up the undergrowth for lunch, clearing our view and revealing a female at his back and a baby nestled behind hers. Other members of this family (the dominant male leads a harem of eight females plus nine offspring) materialize from the thickets, converging around their boss. With the confidence of the mighty, he sprawls for a snooze, arms and legs splayed, his vast dome of a chest rising and sinking. His brood snuggles in, forming a woolly nest; babies peep out, their liquid brown eyes contemplating us, furless great apes in multicolored jackets and chunky hiking boots, our faces lost behind digital cameras.

After a rush of snapshots, the eight trekkers in my group settle, mesmerized by the wonder of being here, at this remote frontier of northwestern Rwanda, near the center of Africa, halfway up a volcano, halfway around the world, with wild gorillas almost near enough to stroke. Up close, they transfix you. Perhaps it’s their similarity to us—those familiar hands, the expressions—that prompts you to nervously attempt eye contact, as if asking, What precisely the difference between your kind and ours? Each trek includes an hour in