The asking of which feature is special to modern people has been a hot topic for scientists. Comparative analysis with our close extinct relatives, the Neandertals, however, gives thrilling findings.
The growing size of neurone generation during the growth of a central nervous system is counted to be the key points for the enhanced cognitive skills that formed during the lengthy processes of change by which people originated from apelike ancestors. Even so, whilst both people of XXI century and Neandertals feature brains of almost the same sizes, little detail is available about if they may vary in respect of their neurone generation. Scientists now showcase that the variation of the Transketolase-like-1 prοtein (TKTL-1) in people living today, which contrasts by only one building block of prοtein from the extinct relative variation, makes the generation of brain prοgenitor cells – descendants of stem cellular units, also named radial glial cells (RG), more intensive in the brains of persons of XXI century.
A group of scientists from MPΙ-CBG in Germany now suggest that the nowadays variation of the TKTL-1, which diverges by only one building block of prοtein from the Neandertalian one, boosts the amount of RG in brains of people living today. RG cells create the lion`s share of the nerve cells in the growing set of layers of the mammalian cerebral cortex that is in charge of many brain-based skills. Given the fact that TKTL-1 exercise is generally high in the front part of the embryo brain, the scientists came to the conclusion that this sole aminoacid replacement in TKTL-1 contributes to better neurone generation in the growing front part of the neocοrtex in people living today than ancestors.
Only a few prοteins feature dissimilarities in the sequences of their aminoacids when comparing modern people and representatives from prehistoric eras. The big importance of these distinctive features for the current growing aspect of the brain is undiscovered yet. To bring some clarity to the point, the German scientists from MPI-CBG carried out a study. They focused on one of these prοteins that presented a sole aminoacid dissimilarity in all nowadays people contrary to Neandertals, the prοtein TKTL-1. Notably, in XXI cent. people, TKTL-1 has an arginine at the sequencing structure under consideration, while in Neandertal TKTL-1 it is the precursor to many proteins, lysine. Specifically, the degree of TKTL-1 is uttermost in the descendants of stem cells of the frontal brain part.
For study purposes, scientists put either the Homo sapient or the Neandertal variation of TKTL-1 into the neocοrtex of mice embryo. They saw that RG cells, deemed to be the key points for a larger brain, enlarged with the variation of TKTL-1 of humans. Hence, the mice embryo with the present-time TKTL-1 had more brain cells.
Following obtained results from the experiment with mice, the scientists learned the importance of these factors on humans. The findings showed that with the Neandertal-type of aminoacid in TKTL-1, less amount of RG cells were generated compared to the nowadays type and, as a result, also less amount of brain cells.
This study showcases that the generation of neurones in the neocοrtex during embryo growth is higher in people living today than it was in Neandertal people, especially in the front brain part. It temps to state that this spurred brain-based skills.