Jean-Jacques d'Ortous de Mairan
Encyclopedia
Jean-Jacques d'Ortous de Mairan (November 26, 1678 – February 20, 1771), a French geophysicist
, astronomer
and most notably, chronobiologist
, was born in the town of Béziers
on November 26, 1678. De Mairan lost his father, François d'Ortous, at age four and his mother twelve years later at age sixteen.
Over the course of his life, de Mairan was elected into numerous scientific societies and made key discoveries in a variety of fields including ancient texts and astronomy. His observations and experiments also inspired the beginning of what is now known as the study of biological circadian rhythm
s. At the age of 92, de Mairan died of pneumonia
in Paris on February 20, 1771.
from 1694–1697 with a focus in ancient Greek
. In 1698 he went to Paris to study mathematics
and physics
under the teachings of Nicolas Malebranche
. In 1702, he returned home to Béziers and began his life long study of several fields, most notably astronomy and plant rhythms. Furthermore, during his time in Béziers, he ate every day with Cardinal de Fleury; later, de Mairan founded his society under the protection of Cardinal de Fleury.
Eventually, de Mairan received official lodging in the Louvre where he remained pensionnaire until 1743 and served as secretary from 1741 to 1743. In 1746, he was reinstated as pensionnaire geometre, or full time boarding surveyor
. It is reported that the Prince of Conti
and other great lords heaped extravagant gifts upon him. He was also secretary to the Duke of Orléans.
.
He was intrigued by the daily opening and closing of the heliotrope
plant and performed a simple experiment where he exposed the plants to constant darkness and recorded the behavior. De Mairan's key conclusion was that the daily rhythmic opening and closing of the leaves persisted even in the absence of sunlight. However, de Mairan hesitated to conclude that heliotropes have internal clocks and hypothesized that other factors, such as temperature
and magnetic field
s, were responsible for the rhythmic behavior. He did not publish his results because he doubted his findings and the importance of their implications.
These results may have gone unnoticed had his colleague, Marchant, not published them for de Mairan. The published accounts of de Mairan's work stimulated further research in the field of chronobiology.
A video showing circadian rhythms in a cucumber plant in constant conditions, similar to what de Mairan observed, can be seen here.
In 1823, over a century later, the Swiss botanist Augustin Pyramus de Candolle expanded on de Mairan's early theory on the circadian nature of M. pudica by measuring the free running period
of plants in constant darkness, finding them to be 22–23 hours long. These results, when considered with the growing experimental evidence of circadian rhythms in many organisms, reinforced the idea that a circadian rhythm could be found in all living organisms, a belief widely held today among chronobiologists.
The circadian nature first described by de Mairan in plants is now evident in a variety of animal models from Drosophila
to the common laboratory mouse to humans. Even when describing his work with rhythmic eclosion times in his fly models or running activity of mice, founder of modern chronobiology, Colin Pittendrigh
, recognized the work of Jean-Jacques d'Ortous de Mairan. The circadian rhythmicity, which de Mairan first described in Mimosa leaf movements, is now recognized as a feature nearly ubiquitous across all phyla.
In 2011, researchers at the University of Tsukuba in Japan examined an ortholog of Gigantea
(GI), a key regulator of the flowering time in plants, to reveal key features of the flowering in plants. They isolated the GI ortholog PnGI from a short period (free running period less than 24 hr.) plant, Pharbitis (Ipomoea) nil. The mRNA expression of this ortholog showed diurnal rhythms that peaked at dusk under short and long day conditions; it also showed circadian rhythms under continuous light and continuous dark conditions. Their data also suggested that PnGI functioned as a suppressor of flowering through its down-regulation of PnFT1, a gene that induces the flower to bud given a single dusk signal.
as Associate Secretary of the Academie in 1743. De Mairan also served as the Academie's assistant director and later director intermittently between 1721 and 1760. Eventually, de Mairan was appointed editor of the Journal des sçavans
, a science periodical, by Chancellor d'Aguesseau
. Also, in 1735, de Mairan was elected a Fellow of the Royal Society and in 1769, a Foreign Member of the Royal Swedish Academy of Sciences
as well as to the Russian Academy (St. Petersburg) in 1718. De Mairan was also a member of the Royal Societies of London, Edinburgh, and Uppsala and the Institute of Bologna. With Jean Bouillet and Antoine Portalon, he founded his own scientific society in his hometown of Béziers around 1723.
, light
, sound
, motion
, the shape of the Earth
, and the aurora
".
The following is an abbreviated list of publications (with their English translations) organized by Dr. Robert A. Hatch at the University of Florida:
He also published mathematical works.
Geophysics
Geophysics is the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and...
, astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
and most notably, chronobiologist
Chronobiology
Chronobiology is a field of biology that examines periodic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος , and biology, which pertains to the study, or science,...
, was born in the town of Béziers
Béziers
Béziers is a town in Languedoc in southern France. It is a sub-prefecture of the Hérault department. Béziers hosts the famous Feria de Béziers, centred around bullfighting, every August. A million visitors are attracted to the five-day event...
on November 26, 1678. De Mairan lost his father, François d'Ortous, at age four and his mother twelve years later at age sixteen.
Over the course of his life, de Mairan was elected into numerous scientific societies and made key discoveries in a variety of fields including ancient texts and astronomy. His observations and experiments also inspired the beginning of what is now known as the study of biological circadian rhythm
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
s. At the age of 92, de Mairan died of pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
in Paris on February 20, 1771.
Life and education
De Mairan attended college in ToulouseToulouse
Toulouse is a city in the Haute-Garonne department in southwestern FranceIt lies on the banks of the River Garonne, 590 km away from Paris and half-way between the Atlantic Ocean and the Mediterranean Sea...
from 1694–1697 with a focus in ancient Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
. In 1698 he went to Paris to study mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
and physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
under the teachings of Nicolas Malebranche
Nicolas Malebranche
Nicolas Malebranche ; was a French Oratorian and rationalist philosopher. In his works, he sought to synthesize the thought of St. Augustine and Descartes, in order to demonstrate the active role of God in every aspect of the world...
. In 1702, he returned home to Béziers and began his life long study of several fields, most notably astronomy and plant rhythms. Furthermore, during his time in Béziers, he ate every day with Cardinal de Fleury; later, de Mairan founded his society under the protection of Cardinal de Fleury.
Eventually, de Mairan received official lodging in the Louvre where he remained pensionnaire until 1743 and served as secretary from 1741 to 1743. In 1746, he was reinstated as pensionnaire geometre, or full time boarding surveyor
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...
. It is reported that the Prince of Conti
Prince of Conti
The title of Prince of Conti was a French noble title, assumed by a cadet branch of the house of Bourbon-Condé. It was taken from Conty, a small town of northern France, c. 35 km southwest of Amiens, which came into the Condé family by the marriage of Louis of Bourbon, first prince of Condé,...
and other great lords heaped extravagant gifts upon him. He was also secretary to the Duke of Orléans.
Observations and notable experiments
- In 1719, De Mairan discussed the varying obliquity of light that causes cold in winter and heat in summer. He postulated that the sun's heating effect was related to the square of the sineSineIn mathematics, the sine function is a function of an angle. In a right triangle, sine gives the ratio of the length of the side opposite to an angle to the length of the hypotenuse.Sine is usually listed first amongst the trigonometric functions....
of its elevation. He neglected the effects of atmosphere, admitting that he did not know how much the sun's heat would be absorbed by it. Two and a half years later, he presented a paper to the Academie Royale des Sciences in Paris: "Problem: the ratio of two degrees or quantities of sunlight seen through the atmosphere at two different known angular elevations being given, to find what part of the absolute light of the sun is intercepted by the atmosphere at any desired elevation." In this paper, de Mairan made a hypothesis based on mere observations, supposing that the ratio had been measured, even though it had not. The significance of de Mairan's work, although incorrect, led his protégé, Pierre BouguerPierre BouguerPierre Bouguer was a French mathematician, geophysicist, geodesist, and astronomer. He is also known as "the father of naval architecture"....
, to invent the photometerPhotometerIn its widest sense, a photometer is an instrument for measuring light intensity or optical properties of solutions or surfaces. Photometers are used to measure:*Illuminance*Irradiance*Light absorption*Scattering of light*Reflection of light*Fluorescence...
. - In 1729, de Mairan constructed an experiment showing the existence of a circadian rhythms in plants, presumably originating from an endogenous clock, or the rhythms internally generated by an organism (See 'Experiment on circadian rhythms in plants' below). See the shows in an interactive museum.
- In 1731, he also observed a nebulosity around a starStarA star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
near the Orion nebulaOrion NebulaThe Orion Nebula is a diffuse nebula situated south of Orion's Belt. It is one of the brightest nebulae, and is visible to the naked eye in the night sky. M42 is located at a distance of and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light...
. This was later designated M43 by Charles MessierCharles MessierCharles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects"...
.
Experiment on circadian rhythms in plants
In 1729, de Mairan performed an experiment that demonstrated the existence of circadian rhythms in plants, specifically the Mimosa pudicaMimosa pudica
Mimosa pudica , is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, re-opening minutes later...
.
He was intrigued by the daily opening and closing of the heliotrope
Heliotropism
Heliotropism is the diurnal motion of plant parts in response to the direction of the sun.It is found in some members of family Malvacea e.g Malva or Lavetara...
plant and performed a simple experiment where he exposed the plants to constant darkness and recorded the behavior. De Mairan's key conclusion was that the daily rhythmic opening and closing of the leaves persisted even in the absence of sunlight. However, de Mairan hesitated to conclude that heliotropes have internal clocks and hypothesized that other factors, such as temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
s, were responsible for the rhythmic behavior. He did not publish his results because he doubted his findings and the importance of their implications.
These results may have gone unnoticed had his colleague, Marchant, not published them for de Mairan. The published accounts of de Mairan's work stimulated further research in the field of chronobiology.
A video showing circadian rhythms in a cucumber plant in constant conditions, similar to what de Mairan observed, can be seen here.
de Mairan's experimental legacy
Despite Marchant's publication of de Mairan's work, which was clear evidence for intrinsic circadian oscillations, rhythms in plant movements were thought to be extrinsically controlled, by light and dark cycles, or magnetic and temperature oscillations, for more than thirty years. As more researchers confirmed and replicated de Mairan's result that plant rhythms persisted in constant darkness it became clear that the rhythms continued even while controlling for other possible influences, such as temperature.In 1823, over a century later, the Swiss botanist Augustin Pyramus de Candolle expanded on de Mairan's early theory on the circadian nature of M. pudica by measuring the free running period
Free-running sleep
Free-running sleep experiments can involve any organism which sleeps. Free-running sleep is sleep which is not adjusted, entrained, to the 24-hour cycle in nature nor to any artificial cycle. Such experiments are used in the study of circadian and other rhythms in biology...
of plants in constant darkness, finding them to be 22–23 hours long. These results, when considered with the growing experimental evidence of circadian rhythms in many organisms, reinforced the idea that a circadian rhythm could be found in all living organisms, a belief widely held today among chronobiologists.
The circadian nature first described by de Mairan in plants is now evident in a variety of animal models from Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
to the common laboratory mouse to humans. Even when describing his work with rhythmic eclosion times in his fly models or running activity of mice, founder of modern chronobiology, Colin Pittendrigh
Colin Pittendrigh
Colin Pittendrigh was a US-American biologist of English parentage. He is a co-founder of modern chronobiology along with Jürgen Aschoff and Erwin Bünning.-Life:...
, recognized the work of Jean-Jacques d'Ortous de Mairan. The circadian rhythmicity, which de Mairan first described in Mimosa leaf movements, is now recognized as a feature nearly ubiquitous across all phyla.
In 2011, researchers at the University of Tsukuba in Japan examined an ortholog of Gigantea
Gigantea
Gigantea is a genus of brown alga with a single species Gigantea bulbosa....
(GI), a key regulator of the flowering time in plants, to reveal key features of the flowering in plants. They isolated the GI ortholog PnGI from a short period (free running period less than 24 hr.) plant, Pharbitis (Ipomoea) nil. The mRNA expression of this ortholog showed diurnal rhythms that peaked at dusk under short and long day conditions; it also showed circadian rhythms under continuous light and continuous dark conditions. Their data also suggested that PnGI functioned as a suppressor of flowering through its down-regulation of PnFT1, a gene that induces the flower to bud given a single dusk signal.
Scientific societies and recognition
In 1718, de Mairan was inducted into the Académie Royale des Sciences. The Cardinal and the Count of Maurepas selected Mairan to replace Bernard le Bovier de FontenelleBernard le Bovier de Fontenelle
Bernard Le Bovier de Fontenelle , also called Bernard Le Bouyer de Fontenelle, was a French author.Fontenelle was born in Rouen, France and died in Paris just one month before his 100th birthday. His mother was the sister of great French dramatists Pierre and Thomas Corneille...
as Associate Secretary of the Academie in 1743. De Mairan also served as the Academie's assistant director and later director intermittently between 1721 and 1760. Eventually, de Mairan was appointed editor of the Journal des sçavans
Journal des sçavans
The Journal des sçavans , founded by Denis de Sallo, was the earliest academic journal published in Europe, that from the beginning also carried a proportion of material that would not now be considered scientific, such as obituaries of famous men, church history, and legal reports...
, a science periodical, by Chancellor d'Aguesseau
Henri François d'Aguesseau
Henri François d'Aguesseau was Chancellor of France three times between 1717 and 1750.-Biography:He was born at Limoges, France, in a family of magistrates...
. Also, in 1735, de Mairan was elected a Fellow of the Royal Society and in 1769, a Foreign Member of the Royal Swedish Academy of Sciences
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences or Kungliga Vetenskapsakademien is one of the Royal Academies of Sweden. The Academy is an independent, non-governmental scientific organization which acts to promote the sciences, primarily the natural sciences and mathematics.The Academy was founded on 2...
as well as to the Russian Academy (St. Petersburg) in 1718. De Mairan was also a member of the Royal Societies of London, Edinburgh, and Uppsala and the Institute of Bologna. With Jean Bouillet and Antoine Portalon, he founded his own scientific society in his hometown of Béziers around 1723.
Key publications
Beyond astronomical and circadian observations, de Mairan actively worked in several other fields of physics including "heatHeat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
, light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
, sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
, motion
Motion (physics)
In physics, motion is a change in position of an object with respect to time. Change in action is the result of an unbalanced force. Motion is typically described in terms of velocity, acceleration, displacement and time . An object's velocity cannot change unless it is acted upon by a force, as...
, the shape of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, and the aurora
Aurora (astronomy)
An aurora is a natural light display in the sky particularly in the high latitude regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere...
".
The following is an abbreviated list of publications (with their English translations) organized by Dr. Robert A. Hatch at the University of Florida:
- Dissertation sur les variations du barometre (Bordeaux, 1715) (Essays on barometric variations)
- Dissertation sur la glace (Bordeaux, 1716) (Essay on the ice)
- Dissertation sur la cause de la lumiere des phosphores et des noctiluques (Bordeaux, 1717) (Dissertation on the cause of light phosphates and noctilucence or nightly light)
- Dissertation sur l'estimation et la mesure des forces motrices des corps (1728) (Essay on the estimation of the measures of forces on the body)
He also published mathematical works.
- Traité physique et historique de l'aurore boréale, (1733) (Physical and historical Treaty of the aurora borealis)