Modern humans generate more brain neurons than Neandertals

September 12, 2022

A collaborative research effort by NOMIS Awardee Svante Pääbo and colleagues shows that the modern human has more neocortex to work with than the ancient Neandertal did. Their findings were published in Science.

Due to the change of a single amino acid, brain evolution has proceeded differently

Microscopy picture of a dividing basal radial glial cell, a progenitor cell type that generates neurons during brain development. Modern human TKTL1, but not Neandertal TKTL1, increases basal radial glia and neuron abundance. (Photo © Pinson et al., Science 2022 / MPI-CBG)

While both Neandertals and modern humans develop brains of similar size, very little is known about whether modern human and Neandertal brains may have differed in terms of their neuron production during development. Researchers from the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden now show that the modern human variant of the protein TKTL1, which differs by only a single amino acid from the Neandertal variant, increases one type of brain progenitor cells, called basal radial glia, in the modern human brain.

Basal radial glial cells generate the majority of the neurons in the developing neocortex, a part of the brain that is crucial for many cognitive abilities. As TKTL1 activity is particularly high in the frontal lobe of the fetal human brain, the researchers conclude that this single human-specific amino acid substitution in TKTL1 underlies a greater neuron production in the developing frontal lobe of the neocortex in modern humans than Neandertals.

Only a small number of proteins have differences in the sequence of their amino acids – the building blocks of proteins – between modern humans and our extinct relatives, the Neandertals and Denisovans. The biological significance of these differences for the development of the modern human brain is largely unknown. In fact, both, modern humans and Neandertals, feature a brain, and notably a neocortex, of similar size, but whether this similar neocortex size implies a similar number of neurons remains unclear.

Svante Pääbo

The latest study of the research group of Wieland Huttner, one of the founding directors of the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden, carried out in collaboration with Svante Pääbo, director at the Max Planck Institute for Evolutionary Anthropology in Leipzig, and Pauline Wimberger of the University Hospital Dresden and their colleagues, addresses just this question.

Continue reading this Max-Planck-Institute release

Read the Science publication: Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neanderthals