But there was no larger group to soak up their tensions, no forest into which to escape — and no food but dry leaves, no water but the ocean’s brine.

One featureless day it all came to a head.

Scrap threw yet another tantrum. She hurled herself around the raft, coming perilously close to the patiently waiting ocean, ripping at leaves and bark, making throaty cries. She had grown skinny, the flesh hanging off her tiny belly, her fur bedraggled.

This time, the males did not slap her away. Instead they watched her, all three of them, with a kind of calculation.

At last Patch retrieved Scrap. She clutched the infant to her chest and let her suckle, though there was no milk to be had.

Whiteblood moved toward Patch. Generally he approached her alone — but this time the bigger of the brothers, Crest, followed him, the spray of fur over his eyes gleaming in the harsh sun. With Whiteblood sitting alongside him, Crest began to groom Patch. Gradually his fingers worked their way toward her belly and genitals. It was a clear precursor to an attempt at mating.

Patch looked startled and pulled away, Scrap clinging to her belly. But Whiteblood stroked her back, soothing her, until she settled and let Crest approach her again. Though Crest continually cast nervous glances at him, Whiteblood did not intervene.

Slumped against the crook of a branch, Roamer stared at the males, baffled by their behavior in a way Noth could never have been. As the minds of the primates became steadily more elaborate, it was as if a sense of self was diffusing outward, from the solitary Purga to her increasingly social descendants. All this enabled the anthros to develop new, complex, subtle alliances and hierarchies — and to practice new deceptions. Noth had had a firm understanding of his own place in the hierarchies and alliances of his society. The anthros could go one step beyond this: Roamer understood her own rank as junior to Patch, but she also understood the relative ranking of others. She knew that a senior like Whiteblood should not be allowing Crest to behave like this, as if encouraging him to mate with “his” female.

At last Crest moved behind Patch and placed his hands on her hips. Patch gave in to the inevitable. Presenting her pink rump to Crest, she pulled the sleepy pup from her chest and held her out to Roamer.

But Whiteblood leapt forward. With the precision of the tree-dwelling primate he was, Whiteblood grabbed the infant from Patch’s hands. Then he scampered over to Left, carrying the infant by her scruff, quickly followed by a nervous Crest.

Patch seemed baffled by what had happened. She stared at Whiteblood, her rump still raised to her vanished suitor.

The males had formed a tight huddle, their furry backs making a wall. Roamer saw how Whiteblood cradled Scrap, almost as if nursing her.

The infant kicked her tiny legs and gurgled, gazing up at Whiteblood. Then Whiteblood put his hand over her scalp.

Suddenly Patch understood. She howled and hurled herself forward.

But the brothers turned to meet her. Both of these immature males outsized Patch. Though they were nervous about showing hostility to a senior female, they easily kept her at bay with slaps and hoots.

Whiteblood closed his hand. Roamer heard the crunch of bone — a sound like a potbelly biting into a crisp leaf. The infant kicked convulsively, and then was limp. Whiteblood looked down on the little body for a heartbeat, his expression complex as he stared at the olive-colored face, now twisted in final pain. And then the males fell on the tiny body. A bite at the neck and the head was soon severed; Whiteblood pulled the limbs this way and that until cartilage snapped and bones cracked. But it was not meat the males wanted most but blood, the blood that poured from the child’s severed neck. They drank greedily of the warm liquid, until their mouths and teeth were stained bright red.

Patch howled, displayed, rampaged around the raft tearing at branches and dying leaves, and beat at the males’ stolid backs. The raft shuddered and rocked, and Roamer clung to her branch nervously. But it made no difference.

Whiteblood had not lied, not really. Like Noth before him, he was unable to imagine what others were thinking, and therefore couldn’t plant false beliefs in their heads — not quite. But anthros were very smart socially, and they had a good problem-solving faculty when facing new challenges. Whiteblood, a kind of genius, had managed to put these facets of his intelligence together to come up with the ploy that had succeeded in stealing Scrap from her mother.

With a final hoarse cry, Patch threw herself against the mango trunk and pulled broken foliage around her in a kind of nest. And still the males fed, to the sound of slurping tongues and bones crunching between teeth.

Her head full of the stink of blood, Roamer made her way to the edge of the raft, where dead branches trailed in the water like fingers.

The murky ocean water was like a thin soup, full of life. The upper sunlit layers were thick with a rich algal plankton, a crowded microscopic ecology. The plankton was like a forest in the ocean, but a forest stripped of the superstructure of leaves, twigs, branches, and trunks, leaving only the tiny green chlorophyll-bearing cells of the forest canopy floating in their nutrient-rich bath. Though the ecological structure of the plankton had remained unchanged for half a billion years, the species within it had come and gone, falling prey to variation and extinction like any other; just as on land this ocean-spanning domain was like a long-running play whose actors changed repeatedly.

A jellyfish wafted by. A plankton-grazer itself, it was a translucent sac, pulsing with a slow, languid dilation and contraction. It was strewn with silvery fronds, tentacles that contained the stinging cells with which it would paralyze its planktonic food.

Compared to most animals the jellyfish was a crude creature. It had a simple radial symmetry, and lacked substance and tissue organization. It didn’t even have blood. But its form was very ancient. Once the ocean had been full of creatures more or less like the jellyfish. They had anchored themselves to the seafloor, turning the ocean into a forest of stinging tentacles. They did not need to be more active; they were untroubled by predators or grazers, as there had not been enough oxygen in the environment to fuel such dangerous monsters.

Roamer was baffled by the sea. To her water was something that came in ponds and rivers and cupped leaves, a fresh, salt-free stuff that you drank whenever you were safe enough to do so. Nothing in her experience or her innate neural programming had prepared her for suspension over a great inverted sky through which drifted such bizarre creatures as the jellyfish.

And she was thirsty, terribly thirsty. Her hand reached down, dipped into that murky soup, and lifted a palmful of water to her mouth. She had forgotten that she had done this not an hour ago, forgotten the bitterness of the brine.

The males had done feeding, she saw. They had fallen into a kind of stupor in the day’s continuing heat. Of Patch, all that could be seen was a single foot, toes curled, that protruded from her lonely nest.

Cautiously, Roamer made her way to the place where the infant had been slaughtered. Blood stained the branches, smeared by the licking of anthro tongues. Roamer picked through the leaves carefully. She found nothing of the infant save a scattering of thin fur — and one perfect little hand, severed at the wrist. She grabbed the hand and retreated to a corner of the raft, as far from the others as she could get.

The hand was limp, relaxed, as if it belonged to a sleeping infant. Briefly Roamer ran it over her chest and remembered how Scrap would pull at her fur.