Monkeys have special brain cells dedicated to keeping track of who owes who a favor in the grooming circle.
March 20, 2026
Original Paper
Dynamic tracking of social variables in simultaneous brain recordings of socially interacting monkeys
bioRxiv · 10.64898/2026.03.12.711496
The Takeaway
It was previously thought that social accounting happened in high-level executive regions of the brain. This study shows that a monkey's visual system is actually doing the math on social debt by tracking how much grooming they've given versus received.
From the abstract
Primates are deeply social, but the underlying neural basis has been elusive because brain activity is often recorded in artificially constrained conditions. Here, we recorded wireless neural activity simultaneously from two macaque monkeys interacting socially in a natural setting. Neural activity in each monkey encoded key social variables such as allogrooming state, partner identity and joint movements. Surprisingly, neurons in the high-level visual cortex of each monkey continuously tracked