Earlier issues of our Journal were dedicated to physics, space, India, ageing…This one is dedicated to Man, with articles
by Yves COPPENS on the origins and evolution of Mankind, and Jean-Pierre CHANGEUX the title of whose paper is
«From the Molecule to Conscience ». Both are members of the French Academy of sciences and well-known internationally
in their respective fields.
Yves COPPENS is one of the co-discoverers, in 1974, of Lucy that well known pre-human girl born about 3.2 million years
ago. The joints of her limbs suggest that she could climb trees as well as she could walk, since her species Australopithecus
afarensis lived in wooded regions. A contemporary species, Australopithecus anamensis, which lived in more open spaces,
was exclusively biped. Between 3 and 2 million years ago, the Earth grew warmer and less humid. Trees and plants rarefied.
Pre-human species adapted and became Man. His teeth adapted, adding meat to his hitherto exclusively vegetarian
diet. Standing upright, his brain cavity increased and with it his central nervous system, developing his ability to think and
reflect : the first chipped stones appear at this stage, i.e. tools made with other tools. His respiratory system evolves (a possible
effect of climate change) inducing a shift of the position of the larynx, a pre-condition of articulate language.
Man starts to migrate. From his African birthplace he spreads to the Mediterranean, then to the Sinai, the Near East
and the Caucasus and thence to the Far East : 2 million years old tools are to be found in China. He spreads westwards
too, where Homo erectus (Neanderthalis) evolved, cut off from the rest of the world by the movement of glaciers which
isolated Europe. How did Neanderthal Man disappear and did he cross breed with Homo sapiens ? Yves COPPENS
reminds us that when « two mammal species live in the same ecological niche, even with a shared culture, they compete,
even passively, and ultimately one of the two will prevail ». As to cross breeding, geneticists’ conclusion is that « if
there is some Neanderthal in us, there cannot be very much » !
Yves COPPENS’ concluding remarks are that evolution is an ongoing process, as our hand demonstrates : « Among primates,
the opposability of the thumb and the other digits, combining skill and power, appeared at least 50 million years
ago and never ceased to improve… To-day we have an increasing range of keyboards and tactile screens to manipulate.
We are no less good at holding and catching but the use of our fingers is developing in a most amazing way. The
intelligence of our finger-tips, among the younger generations, is already « informing » zones of our brains that were
formerly used for other purposes ».
Jean-Pierre CHANGEUX, in the course of his career, studied fundamental molecular biology and allosteric interactions
then moved on to the communication between nerve cells via a neuromediator, acetylcholine, and the isolation of its
receptor. He went on to address the issue of the impact of the environment on the connectivity of our brain cells ending
with the question of what constitutes conscience.
His earliest research on the enzyme molecule led to his 1964 Ph.D thesis on « The Allosteric Properties of L-Threonine
Desaminase », then to the Monod-Wyman-Changeux Concerted Model, whose findings X-ray crystallography would
fully substantiate in the following decades.
In 1967 he moved on to a new research field, the chemistry of our nervous system’s receptors, working on the electric
eel (Gymnotus electricus), first at Columbia University, then at the Pasteur Institute. The article on the isolation of the
acetylcholine receptor appeared in 1970 in the Proceedings of the National Academy of Sciences. In it he showed that
the receptor protein supports two distinct sites, a catalytic site and a regulatory one, and that these two sites interact
with one another through a change in the shape of the molecule. Here too, thanks to the progress of electronic microscopy
it has become possible since 1999 to observe the atomic structure of this receptor protein, prepared from the electric
organ of Electrophorus .All these findings confirm that « we have here an explanatory mechanism which operates
from the bacterium to our central nervous system » the transduction of a signal by the allosteric mechanism (identified
in his thesis as early as 1964),which exhibits a high degree of generality.
Jean-Pierre CHANGEUX goes on to analyze the impact of the environment on the development of the synaptic network : 50%
of the brain’s circuitry develops after birth. When comparing the brain of an illiterate person with that of a literate child
Jean-Pierre CHANGEUX interprets the developed circuitry of the latter in terms of an « epigenetic appropriation through
reading and writing. Such circuits are not genetically determined ; they are imprinted in our brain through post-natal
epigenetic experience ». His observations on different states of consciousness (being asleep or awake, under anesthesia,
in a coma…) and on the content of subjective experience (to anticipate a future event, recollect a past one..) enables
conscious activity to be caracterized : it is what one can record. It is the neurones with long axons ensuring the overall
integration of signals coming from all parts of the brain, which support our mind’s activities and thoughts. « The sheer
volume of the white substance i.e. the long distance circuitry of the brain is what really differentiates Man from the other
species ». However, « our brains contain molecules that are 3 to 4 billion years old » and « what was acquired in the
bacterial era has been maintained and genetically perpetuated right into the era of Homo sapiens ».
Jean-Pierre CHANGEUX ends his presentation with a plea for much more multi-disciplinarity as a pre-condition of the
advancement of knowledge, and for the improved tuition of foreign languages starting at an early age, so that everyone
may better communicate in a global world.
In this global environment and at the request of the President of CNRS, the CNRS Alumni Association aims at re-establishing,
and reinforcing, its links with former members of CNRS overseas. We are pleased to announce that the
«Chinese chapter of CNRS Alumni abroad» was set up in May, in Beijing and in Shanghai, with Professor ZHAN
Wenlong, Vice President of the Chinese Academy of Science, as its President. He is a nuclear physicist and was a CNRS
researcher at GANIL. We are proud to have him as an External Member of our Board of Directors.
From China we move to the United States, with the lecture delivered by Hélène HARTER on the day of President OBAMA’s
investiture. She stresses how much this great democracy respects its traditions and its two centuries’ old Constitution, while
at the same time displaying its ability permanently to renew itself both in terms of ideas and with respect to the choice of
its elected representatives and leaders. Respecting too, the diversity of its population and ultimately its motto : E pluribus
unum. A source of inspiration for the European Union.
Edmond Arthur LISLE
President, CNRS Alumni Association