There is no doubt that humans are the smartest creatures on the planet. But for the longest time it has been unclear just how exactly we made the jump from simple creatures to ones capable of mathematics, ethical debate and invention.
But now scientists may have begun to unravel the mystery, discovering that three similar genes may be behind the boost.
Coding for the expansion of our brains by increasing the potential for creating neuronal cells, it may be that these three genes hold the key to human intelligence.
Genes For ‘Clever’ Are A Mistake.
Publishing in Cell, Pierre Vanderhaeghen and his team investigated the role of the NOTCH2NL gene. This is just one of a family of genes responsible for modulating the development of organisms, but has appeared in four similar forms in humans.
By reconstructing the story of the gene over time, the team noticed something interesting.
Around 14 million years ago a part of the gene was copied by mistake, and remained silent for millions of years. Later another mutation and insertion rendered it functional, eventually leading to a total of four versions. Three work, and the last remains quiet within our DNA.
So what does the gene do? Aside from promote brain cell maintenance, it seems the trio also increase the potential for new brain cells to be created. When Vanderhaeghen inserted the genes into a growth culture including human brain cells, they created new stem cells.
These stem cells can differentiate (change) into new brain cells.
Furthermore, a certain protein expressed by the gene stops further change, meaning that new neuronal cells can replicate over and over.
Basically, the duplication of the gene seems to lead to a greater number of brain cells, and with that, intelligence.
Neuronal Cells, Evolution and Cleverness
When studying ‘intelligence’ humans have made a lot of mistakes. First we considered a ‘larger’ brain likely ‘more intelligent’, but when you consider an elephant you can see this doesn’t quite work.
It seems that the two best predictors of intelligence are ‘surface area’ of the brain and ‘number of connections’ between the cells.
Basically, by increasing the surface area of the brain there is more room for brain cells, and by forming efficient and numerous connections between them these cells can work more effectively.
This is the case in the human brain, which due to its many rolls and crevices boasts a relatively huge surface area.
This new data sheds some light on why our brains may have developed this way, with the NOTCH2NL genes fundamental in both producing surplus neutrons and modulating their abilities.
But the odd thing is that this kind of ‘mistake’ is fundamental to evolution.
When a species reproduces it passes its genes, the coding material for the production of the species, down the line. Although the mechanisms for replication of the molecule are pretty good, mistakes are made. These are called ‘mutations‘.
Most are harmless, and have no clear effect on the new organism. But sometimes they confer some benefit, increasing the organisms, and thus the species’, chance of reproducing again.
Explained in the context of evolution, these mutations are defined as ‘individual variation‘, and this is one of the central tenets of evolutionary theory. In the case of the NOTCH2NL gene, it seems the mutation means greater intelligence.
More research is needed to explain intelligence fully, but it seems we have caught a lucky break.
- Find out how robots are being used to grow new cells for research.
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The opinions expressed in this article are those of Dr Janaway alone and may not represent those of his affiliates. Featured image courtesy of Pixabay.