Human brain organoids (left) become significantly larger than those of gorilla (milieu) and chimpanzee (right.) Philosophers, evolutionists, ethologists, geneticists, biologists… all proposed elements of response, without putting an end to the debate. And if we looked at the side of brain development, at the embryogenesis?
By setting the focal point on this point, a British team discovered an essential key that opened the way to the extra-north expansion of our brain. In plain terms, they no longer give birth to two identical girls cells by multiplying exponentially. They start to divide in an asymmetrical way: one of the girls’ cells remains a progenitor cell, while the other engages in the specialization path in neuron.
And the connection to the unpublished development of our encephalus? Here it is: in the human embryo, this moment of flipping is later than in the embryos of the other great monkeys. “Thanks to this delay, progenitor cells have more time to divide themselves before the start of the process of differentiation in neurons.
They will therefore give more neurons,” says Professor jürgen knoblich of the Austrian Academy of Sciences. The basic ingredients of these models: nerve cells derived from human stem cells – cells capable of self-renewing to infinity and being guided, under certain conditions, to a specialization in either of the types of cells of our various organs. But to make “take the sauce” of these minicerveaux, you have to simmer them in a gel that mimics the matrix where embryonic cells rest.
Suddenly, these cells self-organize to memorize in space the architecture and functions of a young embryonic brain.