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La Lettre
© B.Eymann - Académie des sciences
Jean-Pierre Changeux
Member of the Académie des Sciences, International Faculty at
the University of California, San Diego, Honorary Professor at the
Collège de France and Institut Pasteur
Descartes wrote about 1632 the
Treatise on Man
,
which would only be published after his death, in 1664,
two years before the first session of the Académie des
Sciences was held. Although unfinished, this prophetic
text anticipates, despite the inaccuracies, 350 years of
research on the discovery of human beings and their
brains. From the elementary structures of man’s body –
muscles, nerves “small and big pipes”, and so on – he attempted to establish a causal link between
the anatomy of this “machine” and its physiological functions, one level after the other, up to the
“reasonable soul”, with “its principal seat in the brain”.
Here is the end of Descartes’ treatise: “
In this machine (...) it is not necessary to conceive of (...) any other
principle of movement or life, other than its blood and its spirits which are agitated by the heat of the fire
that burns continuously in its heart, and which is of the same nature as those fires that occur in inanimate
bodies.
” This proposition will be the backbone of my presentation on the successive steps by which our
knowledge on human beings has progressed, from the chemistry of life to the higher functions of the brain.
Step 1: the chemistry of life
In 1661, the Irish Boyle, as a follower to Descartes’ mechanistic philosophy, tried to explain the properties
of matter from atoms he called "corpuscles
"
. He also observed that pumping air from a closed vase
extinguishes the flame of a candle and kills the animals placed inside it.
Lavoisier, the founder of modern chemistry, was interested in combustion. He demonstrated at theAcadémie
des Sciences, on 26 April 1775, that the combustion of charcoal released "fixed" air, which resulted from
On the path to discovering
human beings and their brains