We cooperate with other people because of our ability to look forward and backward in time.

I give you bananas today, so you will give me mushrooms tomorrow.

Last time we crossed the beach a crocodile attacked us, and Jason pushed a kid over to get away. We tell our family to be careful at the beach, and around Jason.

The elders rest in the grove of fruit trees in the summer. We should build a wall and a ditch there, to make it safe while the adults hunt.

We tell stories that increase our survival fitness. Are humans unique in this ability?

Bears, snakes, and sharks follow scent trails; so do social hunters like wolves. Reading a scent trail or chasing prey might involve looking backwards in time and projecting forward, over a scale of hours and days. A leopard perches in a tree above a trail, waiting to pounce. A pack of wolves beds down near a herd, waiting until morning to trigger the ambush.

Squirrels bury food for winter. They seem to be planning ahead on a seasonal scale. But it doesn’t lead to cooperation. They aren’t talking to their family about where they buried their nuts. If they think another squirrel is watching, they pretend to bury food to fool the onlooker.

Mice were put in a maze and challenged to find food. When they fell asleep later, their brains replayed the same neuron activation sequences that fired when they were actually going through the maze. Were they dreaming about the puzzle solution?

When dogs “run” and whimper while sleeping, we imagine that in their dreams they’re chasing a rabbit or playing in a field. It seems plausible that episodic replay in dreams would be a prerequisite to mental time travel while awake. Dreams are like fuzzy stories.

Social insects like ants and bees build community shelters, trails, food storage, and nurseries for the next generation. They coordinate through pheromones and body language. Their organization seems to emerge from rigid, specialized behavior patterns. An ability to form expectations about the future or draw lessons from the past doesn’t seem necessary to explain what they do. They are collectively sophisticated, but individually their intelligence is weak.

Ground-nesting birds will settle an area as a group.

But there are no shared structural projects, like latrines or wind breaks. Each bird might perceive something like, “My neighbor’s nest is uphill from mine so poop is going to flow towards me unless I raise the side of my nest.”. This looks like coordination if you squint, but it doesn’t look like evidence for an ability to communicate about the past and future.

Several species, including wasps, are able to recognize individual faces. Two primate species, macaques and capuchins, have shown they understand how favors work, which depends on facial recognition. Macaques trade grooming for sex. They know who owes them a favor. Capuchin monkeys were taught to trade grapes for money, and understood that the money could be traded for more grapes in the future. Once they learned the exchange rate of present grapes for money for future grapes, they would protest when the human researchers withheld future grapes or gave less than they expected. We share a predisposition for getting pissed off when someone reneges on a deal.

Mental time travel is our super power.