GENES critical to the evolutionary expansion of brains have been discovered :

''How the humans got his brain, is probably the most important ''Just So'' story that Rudyard Kipling never wrote. Kipling did not ignore people in his quirky take on evolution

Two of his tales describe the inventions of alphabet and the invention of letter writing.

But he took for granted the human brains behind the these inventions, which are  three times the size of those of humanity's closest living relatives, the apes, and are thus as characteristic of people as trunks are of elephants or humps are of camels.

Last year, saw the publication of  of two studies which, added together, form an important paragraph in the story of  the human brain.

Both concern a version of the gene called NOTCH2, which has been known for sometime to be involved in embryonic development. Both point to an event in the past which changed the activity of this gene in the evolutionary line that leads to modern people.

And both are  supported by experiments which suggest that the change in question is crucial to the emergence of the big brains which distinguish human beings from all other animal species.

The two studies, which were carried out independently, are published in Cell. One was a team lead by  David Haussler, a bioinformatician at the University of California, Santa Cruz.

The other was directed by  Perre vanderhaeghen, a developmental biologist at the  Free University of Brussels, in Belgium.

Dr. Haussler stumbled on his discovery while comparing the development of the brain's cortex in human beings and in macques, a type of monkey.

He and his colleagues found in humans what appeared to be several previously undiscovered versions of NOTCH2, alongside the established one.

The new genes, which they refer to as NOTCH2NL genes, but they seemed to be inactive.

The difference between apes and humans is that in the human line one of these NOTCH2NLS  has now become active, and has multiplied to create three versions, known as A, B and C.

Critically, this A, B, and C pattern is replicated in the DNA of two extinct species of human, Neanderthals and Denisovans.

By looking at the minor differences between various  NOTCH-related genes to the three human species and the two great apes, the researchers were able to estimate when the active NOTCH2NL arose :
3 million to  4 million years ago.

That is when, according to the fossil record. the craniums of mankind's ancestors started expanding.

The Honor and Serving of the latest Global Operational  Research  on Humans, Evolution and Brains continues, to part 2. The World Students Society thanks The Economist.


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