Who first discovered color blindness?

Dalton, the man who found color blindness

1844 On July 26th, a 78-year-old man trudged into his laboratory. It's a quarter to nine. From 2 1 year-old to today, for 57 years, he has recorded the meteorological data of the day at the same time every night. I saw him pick up the pen with trembling hands, write down the readings of barometer and temperature, and write "light rain" in the last column of the form. When he got up and left, he found that the date had not been written, so he sat down again. After that, he never got up again.

John dalton (1766- 1844), an old man who finished his last scientific practice with the handwriting of life, was a British chemist and physicist, and was also the first person to systematically study color blindness.

A meteorologist from a poor background

1On September 6th, 766, john dalton was born in Eaglefield, a backcountry in northern England. His father is a poor farmer who makes a living by knitting wool. In addition to doing housework, my mother also helps my father farm. Due to the meager income and six children to support, the family's economy is quite tight. Although his family was poor, when Dalton was six years old, his parents managed to get him into the church primary school in his village. Dalton's academic performance in school is not outstanding, but he is diligent, thoughtful and tenacious, and will never give up until he solves the problem. Whenever a student complains bitterly about the teaching problems left by the teacher, Dalton sits there alone and thinks hard. Even if the teacher sometimes wants to remind him, he refuses without looking up. It often gets dark when you sit down. The classroom was empty, only little Dalton was alone in the dim candlelight. In this regard, his teacher, Mr. Fletcher, praised: "Among Quaker children, no one can compare with John in terms of maturity."

Dalton was forced to drop out of school because he couldn't pay the tuition. At the age of 12, he began to teach in a private school and was hired to do farm work, which provoked the burden of life prematurely. In spite of adversity, he insisted on self-study and never slackened off. Elihu Robinson is a local knowledgeable Quaker and a natural science enthusiast. He appreciates Dalton very much and would rather give up his rest time to teach Dalton mathematics, physics and other knowledge in the evening.

Robinson likes to observe the weather and makes all kinds of exquisite instruments. Under Robinson's enthusiastic guidance, Dalton began meteorological observation and came up with the idea of forecasting the weather for sailors and farmers.

178 1 year, 15-year-old Dalton went out to make a living and came to Kendall town. I worked as a teaching assistant in my cousin's boarding school, where I worked for 12 years. After work, he is eager to learn, whether it is mathematics, natural science, philosophy or literature. He read more books in this 12 year than in the next 50 years, which shows that he is diligent in self-study.

While reading extensively, he did not give up his meteorological observation work. He hung Robinson's parting gift-barometer on the wall, installed a rain gauge on the campus, and filled his indoor table with all kinds of glass instruments. Most of these instruments are played by himself. Extensive reading and meteorological observation have made Dalton deeply feel that there are too many mysteries in nature, and too much knowledge, like-minded friends and teachers are needed to know them and make use of them.

One day, Dalton heard that there was a knowledgeable Mr. John Huo nearby, so he went to visit. He froze when he grasped the hand of the experimenter praised by the local people-Mr. Huo was blind.

Hogg seemed to sense Dalton's doubts. He stood up and walked to a big table. The table is full of all kinds of instruments and test tubes, but it is in good order. I saw him take the necessary utensils without any difficulty, fill the container, do not spill or bump, and be skillful and accurate in every movement. From Hoff, Dalton once again deeply felt the importance of perseverance. He once introduced Fu Hao as follows: "Fu Hao was blinded by smallpox when he was about two years old. Perhaps it can be said that after being deprived of the most precious senses, he created an extremely surprising model, combining genius with perseverance. He is proficient in Latin, Greek and French, and is familiar with various departments of mathematics, astronomy, chemistry and medicine. It is particularly surprising that he can solve difficult and profound problems only by relying on his mind. With his sense of touch, taste and smell, he can distinguish almost every plant within twenty miles of where he lives. If I have made any new or important contributions to science, it is first because I can get his guidance and his example in philosophical research. "

It is under the encouragement and guidance of such a blind scholar that Dalton not only learned mathematics, natural science, philosophy, Greek, Latin and French, but also learned to keep a meteorological diary and began to systematically observe nature scientifically. Dalton wrote a meteorological diary for 57 years from 1787, and all the observation records exceeded 200,000.

1793, Dalton published his first academic monograph "Collection of Meteorological Observations", preliminarily summarized his observation results, and analyzed the formation of clouds, evaporation process and the distribution of atmospheric precipitation, from which we can see Dalton's unique views on many subsequent discoveries. Since then, this 27-year-old young teacher has attracted the attention of the scientific community.

This year, Dalton was hired as a lecturer by the new college founded by Manchester Literature and Philosophy Society, teaching mathematics and natural science. The college has excellent conditions, but the teaching burden is heavy and the laboratory is lacking. Before long, Dalton realized that the heavy teacher's work hindered his exploration and research of natural science. Six years later, he resolutely resigned as a lecturer, spent little time teaching privately, lived a poor life, and spent most of his time doing experiments, reading papers and other academic activities. "Sleep at midnight and get up at dawn" is Dalton's motto. It is with this strong dedication and deep love for natural science that he struggled on the road of scientific research and exploration for 26 years and finally ushered in his glorious heyday.

An outstanding physical chemist

Dalton has extraordinary ability of analysis, synthesis and generalization. He started with observing meteorology, then studied the composition of air, the diffusion and partial pressure of mixed gas, summed up the law of partial pressure of gas, and concluded that air is composed of different particles, which confirmed the objective existence of atoms. Taking this as a starting point, he turned his scientific research from meteorology and physics to chemistry through chemical experiments, and developed his scientific research from qualitative stage to quantitative stage, and gradually established scientific atomism through strict logical deduction.

180 1 June, Dalton read a series of papers: the composition of mixed gas, the force of water vapor, and the evaporation and expansion of gas when heated. These four papers show that the ubiquitous atmosphere is composed of countless particles or ultimate particles of four main substances: oxygen, nitrogen, carbon dioxide and water vapor.

So, how does mixing happen? Soon, Dalton published an article entitled "The Trend of Elastic Flow Diffusion" to explain this problem. Gas mixtures are formed because gases diffuse with each other. So what are the characteristics of this mixed gas? Dalton designed an experiment for this. Through experiments, he came to the conclusion that the pressure of the mixed gas is equal to the sum of the partial pressures when each component gas occupies the container alone under the same conditions. This is the famous Dalton's law of partial pressure.

Faced with the law of partial pressure, Dalton began to rethink the inference and clearly described the existence of atoms for the first time. Then the understanding of atoms advanced from qualitative to quantitative-Dalton discovered the law of multiple relationship. The discovery of the law of multiples became an important cornerstone of his atomism.

In order to establish a scientific view of atomism, Dalton devoted himself to the experimental work with great enthusiasm in order to obtain the relative mass of matter and deduce the relative mass of the final particle or atom of matter. He measured the atomic relative mass of different elements, and also investigated a lot of experimental data of other chemists, and wrote the first table of relative atoms, and concluded that the lightest element is hydrogen, and it is more reasonable to set the atomic weight of hydrogen as 1. 1803 10 2 1 At the Manchester Society of Literature and Philosophy, Dalton gave a report entitled "About the Absorption of Gases by Water and Other Liquids", in which he expounded his scientific atomism for the first time and read out his first atomic scale.

Dalton's new ideas have aroused widespread concern in the scientific community, especially in the chemical community. Although the atomic weight determined by him has a great numerical error compared with the general atomic weight now, because he regards the equivalent of some atoms as atomic weight, after all, people began to build their understanding of the basic level of material structure-atomic weight on the basis of science. It is precisely because Dalton first introduced the discovery of atomic weight into chemistry that chemistry really embarked on the stage of quantitative development.

Dalton's atomism caused a great sensation not only in Britain, but also in the whole European scientific community, and was widely valued and respected. 18 16, Dalton was elected as a member of the Communication Academy of French Academy of Sciences. 18 17 was elected president of Manchester literature and philosophy society and served until his death. 1822, Dalton became a member of the Royal Society at the suggestion of David. 1826, the British government awarded Dalton the Gold Medal. In the following years, Dalton was awarded various honorary titles and a doctorate in law from Oxford University.

How did Dalton, who enjoys a high reputation, face these problems? His close friend, Dr. willaim henley, described it this way: "Mr. Dalton has never and never wanted to get any reward or reward from the government." I dare say that he has never pursued these things. "He pursues science and is a contribution to mankind. As early as 1788, Dalton said when he was engaged in meteorological research: "If we can predict the weather conditions, it will bring great benefits to farmers, seafarers and all mankind, then a person who contributes to this goal can't be regarded as wasting energy or life in any case. "It is in pursuit of this goal that Dalton was poor, thrifty and diligent all his life, living a single life and never getting married." I have no time to have a girlfriend and fall in love. As Roscoe, a historian of science, said, "Genius rarely achieves anything without persistent efforts. And Dalton is a man with this perseverance. "

He found himself color blind.

On Christmas Eve, Dalton bought his mother a pair of "brown-gray" socks as a Christmas present. Mother thought the socks were too bright when she saw them, so she said to Dalton, "How can I wear these cherry red socks you bought?" Dalton felt very strange: socks are obviously brown and gray, why does mother say they are cherry red? Dalton was puzzled, took the socks and asked his brother and the people around him. All the people who were asked said that the socks were cherry red except his brother. Dalton didn't let this little thing go easily. After careful analysis and comparison, he found that his and his brother's color vision was different from others. It turns out that my brother and I are both color blind. Although Dalton was neither a biologist nor a medical scientist, he became the first person to find color blindness and the first patient to be found to have color blindness. For this reason, he wrote a paper "On Color Blindness" and became the first person in the world to put forward the problem of color blindness. Later, in memory of him, people called color blindness Dalton's disease. Scientists have found that human color vision can be divided into normal color vision and color vision disorder. According to the tricolor theory, any color in visible light is composed of red, green and blue. In medicine, people who can recognize trichromatic blindness are called trichromatic blindness, and their color discrimination ability is completely normal, while people who can't recognize a certain color at all are called color blindness. In color-blind patients, if one primary color is unrecognizable, it is called dichroism, which is mainly manifested as red blindness and green blindness; If you can't distinguish the three primary colors, you are called color blindness. If someone's ability to recognize colors is relatively low, it is called color weakness. Among patients with weak color, mainly red and green are weak, and blue blindness and blue weakness are relatively rare. Therefore, color blindness disorders are mainly congenital color blindness (autosomal recessive inheritance) and congenital red-green color blindness and color weakness.

Dalton and his younger brother suffer from red-green color blindness, which is the most common human sex-linked genetic disease.

This disease is controlled by a recessive gene (B) located on the X chromosome. Y chromosome is too short to have this gene. Therefore, the red-green color blindness gene is passed on to future generations together with the X chromosome. According to the dominant-recessive relationship between gene B and gene B (that is, as long as there is normal gene B, normal gene B is dominant gene and color blindness gene B is recessive gene), the genotypes and phenotypes of human normal color vision and red-green color blindness can have the following five situations (see the table below):

How is human red-green color blindness inherited? It mainly has the following situations:

1. A woman with normal color vision (homozygote) married a male patient with red-green color blindness, and her offspring had normal color vision; Although the daughter is normal, she is the carrier of the red-green color blindness gene because she got the red-green color blindness gene from her father. In this case, the father's red-green color blindness gene is passed on to his daughter together with the X chromosome, but it will definitely not be passed on to his son.

2. If a female red-green color-blind gene carrier marries a normal male, in their offspring: the son is 1/2 normal, 1/2 red-green color-blind; My daughter is not color blind, but 1/2 is the carrier of red-green color blindness gene. In this case, the son's red-green color blindness gene must come from his mother.

3. If a female red-green color blindness gene carrier marries a male red-green color blindness patient. Among their descendants: 1/2 daughters are normal, but they are all carriers, 1/2 daughters are red-green color blind; Son 1/2 normal, 1/2 red-green color blindness; In this case, half of the daughter's red-green color blindness genes come from her mother and half from her father; And the son's red-green color blindness gene must come from his mother.

4. If a female patient with red-green color blindness marries a normal male, among her offspring; Daughters have normal phenotypes, but they are all carriers, and sons are all red-green color-blind patients. In this case, it was the mother who passed on the red-green color blindness gene and the X chromosome to her son.

Through the analysis of the above four marriage results, we can see that the male red-green color blindness gene is passed from mother to daughter. It can be seen that the red-green color blindness gene is passed from women to men. This genetic feature is called cross inheritance in genetics. Therefore, in families with hereditary diseases, it is often seen that the mother of a male patient behaves normally, while his grandfather is a patient with this disease.

In the investigation of red-green color blindness, it is often found that there are more male patients than female patients. According to statistics, the incidence of red-green color blindness in China is 7% for men and only 0.5% for women.

Sex-linked inheritance is very common in biology. In addition to the inheritance of red-green color blindness, the inheritance of human hemophilia, the inheritance of animal Drosophila expression, and the inheritance of certain traits of dioecious plants are all sex-linked genetic phenomena.

It is precisely because of his strong curiosity, sense of responsibility and perseverance that Dalton can find the problem of color blindness from his own physical defects, thus promoting the development of genetics, biology and medical research.