Central nervous system (display 83)

With an average weight of 1.3 kg, the human brain occupies a volume of about 1,400 cm³ and represents approximately 2% of the total weight of an individual. This amazing organ is characterised by some 86 billion neurons, capable of generating at least 100 trillion connections. Because of its central role, it consumes 20% of the energy, 20% of the oxygen and receives 15% of the blood flow necessary for the functioning of our body. The constant supply of blood, and therefore of oxygen, is guaranteed by the circle of Willis, a system of arterial connections situated at the base of the brain. It also contributes to cerebral cooling. This system of connections is present in other mammals such as the gorilla, whose encephalic arteries are clearly visible in the preparation below.

The cortex is a particularly well-developed part of the human brain. With a surface area of about 2,000 cm², it ensures numerous important functions such as thought, memory, language, processing of information, reasoning, perception and consciousness. Certain zones of the cortex are associated with specific functions whereas more complex functions, such as memory and consciousness, appear to be more dispersed. 

For mammals, brain growth ceases well before body growth is complete. The development of the human brain reaches its greatest growth rate between the 3^rd and 7^th month of pregnancy. At this stage, around 250,000 new neurons are generated per minute.

The cranial endocasts of these three individuals - a Tasmanian, a young woman with a congenital brain malformation formerly described as an “Idiot”, and a dwarf known as “Bébé” - can be interpreted as relics of a controversial 19^th century ideology.

The cranial endocast of the Tasmanian, made from a skull collected by the naturalist Joseph Fortuné Eydoux (1802-1841) during the voyage of La Favorite in 1830, was used at the time as pseudoscientific proof of Tasmanian inferiority. 

The individual affected by primordial dwarfism was Nicolas Ferry (1741-1764), nicknamed “Bébé”. This famous dwarf served the Duke of Lorraine, Stanislas Leszczynski (1677-1766), who gave him his nickname and thus introduced the word into the French language. His brain is significantly smaller than a normal brain. 

The young woman's brain is also very small, but smoother. Its even surface and reduced size could indicate a case of microcephaly.

The cranial endocasts of Mr Ferry and the young woman were presented as examples of cerebral underdevelopment. The Tasmanian’s brain was also deemed deficient, but from an evolutionary standpoint. This flawed reasoning was based on 19^th century racial theories that considered Tasmanian culture as primitive and therefore inferior.

Born in Paris in 1892, Fernande Coupin (1892-1930) was exposed to the world of science from an early age thanks to her father Henri Coupin (1868-1937), a well-respected naturalist. She studied at the Paris Faculty of Sciences where she obtained degrees in both zoology and histology. After a period consecrated to the war effort, Mme Coupin joined first the Pasteur Institute and then the Sorbonne.

Her career at the Muséum began in 1922 as preparer of the Professorship of Comparative anatomy. She submitted her doctoral thesis in science two years later, while working with Professor Raoul Anthony (1874-1941). Coupin studied vertebrate nervous systems, focusing on the brain development of primates, including humans.