A human gene slows the maturation of the brain’s immune cells

Microglia are the local immune service. They not only catch infections, but also prune excess synapses while the brain is learning. In mice, these cells become mature in about three weeks. In humans, in 4–8 years. Such an extended schedule matches how slowly human neural networks are assembled.

The торможение is driven by human copies of the SRGAP2 gene. This gene once duplicated only in our lineage. Previously, it was mainly associated with neurons: extra copies slow synapse maturation and allow more connections to be preserved. Now it has been found that in microglia there are almost ten times more of these copies than in nerve cells. They synchronize two processes: neurons spend a long time building circuits, and microglia spend just as long deciding which of them to keep.

This is neoteny — a prolonged “childhood” of the brain. While the cells are not fully mature, the window for learning is broader. The authors suggest that such coordination may have enhanced human cognitive abilities compared to other mammals.

So far, the data have been obtained in mice and in human cells. You cannot directly derive the “reason for our intelligence” from a single gene. But the logic is elegant: unique human SRGAP2 duplicates slow down not only the wiring, but also those who trim that wiring.

Sources:

1. The Zuckerman Institute at Columbia University. "Scientists find a human-only gene that may help explain our brainpower." ScienceDaily (31 August 2026).
2. Diaz-Salazar C. et al. "Human-specific SRGAP2 paralogs synchronize neotenic microglial maturation and synaptic development." Neuron (2026). DOI: 10.1016/j.neuron.2026.07.007.