Madeleine Simonne Charnier (15 June 1919—9 July 2002) was a French
zoologist
Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...
. She is known for having first described
temperature-dependent sex determination
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. It is observed in reptiles and teleost fish, ...
in 1966.
Biography
Charnier's mother was a mathematics professor.
Charnier received her license in science around 1935 at the Faculty of Sciences in Paris. She moved to Africa around 1945 to join her brother: first to Kaolack, Senegal, then to Cotonou, Dahomey (now
Benin
Benin, officially the Republic of Benin, is a country in West Africa. It was formerly known as Dahomey. It is bordered by Togo to the west, Nigeria to the east, Burkina Faso to the north-west, and Niger to the north-east. The majority of its po ...
), then to
Dakar, Senegal
Dakar ( ; ; ) is the capital and largest city of Senegal. The department of Dakar has a population of 1,278,469, and the population of the Dakar metropolitan area was at 4.0 million in 2023.
Dakar is situated on the Cap-Vert peninsula, the w ...
at the end of the 1940s. In 1953, she divorced her husband, Marcel Robert. That year, she was hired at the university library of University of Dakar.
From 1955, Charnier worked at the faculty of medicine in
parasitology
Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...
hematology
Hematology (American and British English spelling differences#ae and oe, spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to bloo ...
. There, she published her first scientific article on the common agama, which would become her preferred species to research for the next ten years (Charnier and Dutarte 1956).
In 1958, she left the faculty of medicine for the Faculty of Sciences at the University of Dakar. She completed her training in science to join the zoology department of Professor C. Boisson, a specialist in ciliated and opaline
protozoa
Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...
. Charnier also met Claudine and Xavier Mattéi, who were researching the
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
*Morphology (archaeology), study of the shapes or forms of artifacts
*Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
of
spermatozoa
A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
. She was appointed
assistant professor
Assistant professor is an academic rank just below the rank of an associate professor used in universities or colleges, mainly in the United States, Canada, Japan, and South Korea.
Overview
This position is generally taken after earning a doct ...
. It was during this period that she published five articles on the
embryonic development
In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermat ...
of the common agama (Charnier 1963;1965;1966b;a;1967), including her article describing temperature-dependent sex determination on this species in 1966. Charnier observed that eggs incubated at a cool temperature produced female hatchlings, while those incubated at a warm temperature produced males, and posited that the sex of the hatchlings was influenced by the temperature. This discovery was not widely recognized internationally for several years as it was published in French. It has now been referenced more than 230 times, making it one of the most cited zoology articles from the 1960s.
Charnier left Senegal in 1968 and abandoned her work on the agama, which was the subject of her
thesis
A thesis (: theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144: D ...
which she did not defend. Once in France, she worked with Professor Jean Cachon in
Villefranche-sur-Mer
Villefranche-sur-Mer (, ; ; ) is a resort town in the Alpes-Maritimes department in the Provence-Alpes-Côte d'Azur region on the French Riviera and is located southwest of the Principality of Monaco, which is just west of the French-Italian ...
. Charnier published another scientific article on the ultrastructural morphology of a siphonophorean parasite (Cachon et al. 1972).
Charnier retired in 1984 in
Nice
Nice ( ; ) is a city in and the prefecture of the Alpes-Maritimes department in France. The Nice agglomeration extends far beyond the administrative city limits, with a population of nearly one million
Legacy
Charnier's work on temperature-dependent sex determination opened the door investigating the role of
estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...
in determining sex and the implications of
global warming
Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
on reptiles, as well as to a large number of works on this subject which have implications in the fields of
developmental biology
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and di ...
,
evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
, and
ecology
Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...
.
Bibliography
*Cachon, J., M. Cachon, and M. Charnier. 1972. Ultrastructure du bodonidé ''Trypanophis grobbeni'' Poche, parasite des siphonophores. Protistologica 8:223-236.
*Charnier, M. 1963. Action de l'hormone mâle (hexahydrobenzoate de testostérone) sur les femelles dAgama agama'', Saurien. Agamidae. Comptes Rendus des Séances de la Société de Biologie, Paris 157:1470-1472.
*Charnier, M. 1965. Le cycle sexuel chez le lézard male ''Agama agama'' (Reptilia, Lacertilien) dans la région de Dakar. Annales de la Faculté des Sciences de Dakar 18:33-59.
*Charnier, M. 1966a. Action d'une hormone femelle sur le tractus genital des mâles adultes du lézard ''Agama agama'' (Lacertilian, Agamidae). Comptes Rendus des Séances de la Société de Biologie 159:1822-1825.
*Charnier, M. 1966b. Action de la température sur la sex-ratio chez l'embryon dAgama agama'' (Agamidae, Lacertilien). Comptes Rendus des Séances de la Société de Biologie, Paris 160:620-622 scanned version of the article *Charnier, M. 1967. Le développement embryonnaire de l'appareil genital du lézard ''Agama agama''. Annales de la Faculté des Sciences, Université de Dakar 20:23-32.
*Charnier, M., and J. P. Dutarte. 1956. Changement histophysiologique de la thyroïde des lézards de la région de Dakar durant la période préhibernatoire. Comptes Rendus des Séances de la Société de Biologie, Paris 150:1387-1388.