Neanderthals also had to face an internal enemy: their own chromosomes

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Taking time to get things right seems to work even when we’re talking about cells replicating. And this seems to be one of the changes that occurred in the evolutionary step between our closest relatives, the Neanderthals, and ourselves, the modern humans.

A hundred amino acids.
Understand the details that separate us biologically from the species closest to us, the homo neanderthalensis, is key to understanding human evolution and our space within the order of species. Over the years, scientists have identified changes in a hundred amino acids between these species.

Little is known about how these amino acid changes in the cells of both species translate into changes on a larger scale. A new job has studied some of these changes, specifically six amino acids that vary in three proteins.

These changes, as the team found, affect how stem cells transmit information to neurons that will later form the neocortex, a part of the brain shared by different mammalian species. These changes played an important role in the distribution of chromosomes in the cells created from these stem cells.

The first "Gallery" art from Europe was in Spain and the artists were the Neanderthals

Mice and organoids.
To understand the role of these amino acid changes, the researchers conducted two tests. In the first they introduced these changes in mice. The configuration of this group of amino acids in these rodents is identical to that of Neanderthalsso the researchers had an easy time making these changes and making them similar to modern humans.

Thus, they verified the significance of these six changes. The alteration implied that the process of cell replication slowed down but also implied fewer errors in the distribution of chromosomes during the process.

The researchers performed a second analysis. In this phase they went the other way: they took human brain organoids (a group of cells created to function as a miniature copy of brain tissue) and altered their cells to reverse changes in all six amino acids. The result was precisely the opposite: a greater number of errors in the cell replication process.

Evolutionary step forward.
These changes are a clear advantage for humans. According to explains Felipe Mora-Bermúdezfirst author of the study, “having errors in the number of chromosomes is usually not a good idea for cells, as can be seen in disorders such as trisomies and cancer.”

Víctor Borrell Franco, from the Institute of Neurosciences of Alicante, who did not participate in the research coincides with Mora Bermudez: “These findings confirm for the first time the hypotheses that proposed superior brain development in modern man compared to Neanderthals”

Subtle differences.
Both species have similar brain sizes, so the evolutionary advantage of modern humans could not have its origin in this factor. The new research points in another direction by targeting cell replication. “[Las] The differences are not in the number of neurons born, but in the quality control of this process, which has much greater impact on the function of the adult brain”, concludes Borrell Franco.

Evolution and survival.
The analysis involves small steps to resolve some of the many questions we still have regarding the evolution of human beings as homo sapiens and anatomically modern humans. First, it tells us the implications of six of the more than 100 amino acid changes that separate our cells from those of Neanderthals.

Secondly, it may give us information that will one day resolve the question of why evolution favored sapiens as the only human species that ended up surviving the passage of time, as well as what were the factors that led to the extinction of the sapiens. Neanderthals, who ruled Europe not many millennia ago.

Image | Neanderthal-Museum, Mettmann

Taking time to get things right seems to work even when we’re talking about cells replicating. And this seems to…

Taking time to get things right seems to work even when we’re talking about cells replicating. And this seems to…

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