Plate Nº 14 · recorded October 10, 2026
Neuroscience & MindReported finding
Human Microglia Take Up to 8 Years to Mature, Study Finds
Human microglia take 4–8 years to mature — roughly 100 times longer than in mice — a delay linked to the human-specific gene SRGAP2, a new Neuron study finds.
By Nathan Brooks3 min read637 words
In brief
- Human microglia take four to eight years to mature, compared with about three weeks in mice.
- Human-specific copies of SRGAP2 are nearly 10 times more abundant in microglia than in neurons.
- Microglia make up 5 to 10 percent of brain cells and help prune and refine synapses during development.
- The study was published in Neuron, Volume 114, Issue 15, on August 31, 2026 (DOI: 10.1016/j.neuron.2026.07.007).
- Lead author Carlos Diaz-Salazar carried out the work in Franck Polleux's lab at Columbia's Zuckerman Institute.
Human microglia — the brain's most abundant immune cells — take four to eight years to fully mature, compared with roughly three weeks in mice, Columbia University researchers reported on August 31, 2026.
The study, published in the journal Neuron, ties that unusually long timeline to SRGAP2, a gene that duplicated only in the human lineage. The researchers say the delay could help explain the wiring that underlies human cognition.
"This slow development may help human microglia influence the human brain in ways that enable our powerful cognitive abilities," said lead author Carlos Diaz-Salazar, PhD, who carried out the work in the lab of Franck Polleux, PhD, at Columbia's Zuckerman Institute.
What is SRGAP2?
SRGAP2 belongs to a small set of human-specific duplicated genes. Earlier work from Polleux's lab showed that human copies of SRGAP2 slow the maturation of synapses — junctions where neurons exchange signals. The result is a denser network of connections, a feature that distinguishes human neurons from those of other mammals.
In the new work, the team asked whether the same gene also shapes other brain cells. They found something unexpected: human-specific SRGAP2 copies appeared roughly 10 times more often in microglia than in neurons.
"So the question was, 'Why on Earth is this gene so active in microglia?'" Polleux recalled.
Why do microglia matter?
Microglia make up 5 to 10 percent of brain cells. Scientists once saw them mostly as cleanup crews that fight infection and clear debris. Work over the past two decades has revealed a wider role:
- They prune excess synapses during development.
- They reinforce the connections neurons keep.
- They fine-tune how strongly neurons respond to one another.
In other words, microglia help sculpt the circuits the brain uses to process information.
How does SRGAP2 change microglial development?
Using mouse models and cultured human cells, the researchers showed that human-specific SRGAP2 copies dramatically slow microglial maturation. Mouse microglia mature in about three weeks; human microglia need years.
"This gene helps control the developmental tempo of neurons, and nature has also selected it to control the development of microglia that are so crucial to neuron development, so they are in sync during development," said Diaz-Salazar, who now works at the Hospital del Mar Medical Research Institute in Barcelona.
Shared timing may matter. If neurons and microglia matured on different schedules, microglia could prune synapses before neurons were ready — or after the window for rewiring had closed.
What does this mean for human brain evolution?
Biologists have long noted that the human brain develops over an unusually long window compared with other mammals. They call this extended schedule neoteny and link it to advanced cognition. Diaz-Salazar's results suggest SRGAP2 helps coordinate that pace across multiple cell types, not just neurons.
The team now plans to test how the gene drives neoteny in microglia and other brain cells, and whether disruptions contribute to disease.
"Because scientists have recently found that microglia are involved in neurodevelopmental disorders and neurodegenerative diseases, our findings get us a step closer to understanding what makes human microglia special in the context of brain diseases," Polleux said.
What are the limits of the study?
The work relies on mouse models and cultured human cells, not direct observation of developing human brains. Researchers cannot yet measure microglial maturation in living children across the four-to-eight-year window, so the timeline rests on cellular markers rather than brain scans. The team also focused on one gene; other human-specific genes likely contribute.
The Polleux lab has studied SRGAP2 for more than 15 years. Co-authors on the paper include JaeYeon Kim, Marine Krzisch, Juyoun Yoo, Patricia R. Nano, Aparna Bhaduri, Rudolf Jaenisch, and Mercedes Paredes. The study appears in Neuron, Volume 114, Issue 15. DOI: 10.1016/j.neuron.2026.07.007.
via zuckermaninstitute.columbia.edu (Original)
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