The researchers focus on one of these proteins that presents a single amino acid change in essentially all modern humans compared to Neanderthals, the protein transketolase-like 1 (TKTL1).

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. In fact, both, modern humans and Neanderthals, feature a brain, and notably a neocortex, of similar size, but whether this similar neocortex size implies a similar number of neurons remains unclear. The biological significance of these differences for the development of the modern human brain is largely unknown. 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 Neanderthals and Denisovans. 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 Neanderthals. 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. 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 Neanderthal variant, increases one type of brain progenitor cells, called basal radial glia, in the modern human brain. Researchers now show that the modern human variant of the protein TKTL1, which differs by only a single amino acid from the Neanderthal variant, increases one type of brain progenitor cells, called basal radial glia, in the modern human brain. However, while both Neanderthals and modern humans develop brains of similar size, very little is known about whether modern human and Neanderthal brains may have differed in terms of their neuron production during development. The increase in brain size, and in neuron production during brain development, are considered to be major factors for the increased cognitive abilities that occurred during human evolution. Comparisons with our closest relatives, the Neanderthals, therefore provide fascinating insights. 1 2 Modern humans generate more brain neurons than Neanderthals Date: SeptemSource: Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) Summary: The question of what makes modern humans unique has long been a driving force for researchers.

Number of neurons in the brain