Herbert McLean Evans (September 23, 1882 – March 6, 1971) was an American anatomist and

embryologist Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos ...

best known for co-discovering

Vitamin E Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vi ...

Education

He was born in

Modesto, California Modesto () is the county seat and largest city of Stanislaus County, California, United States. With a population of 218,464 at the 2020 census, it is the 19th largest city in the state of California and forms part of the Sacramento-Stockton- ...

. In 1908, he obtained his medical degree from

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consi ...

Career

Evans became associate professor of anatomy at Johns Hopkins University. Evans moved back to California in 1915 and was made professor of anatomy at the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant un ...

, and held that position until his death. His medical research at Berkeley addressed problems relating to human

nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...

endocrinology Endocrinology (from '' endocrine'' + '' -ology'') is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones. It is also concerned with the integration of developmental event ...

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embr ...

, and

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures v ...

. In 1918, his research into the number of human

chromosomes A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

led him to believe the number to be 48, when most people assumed the number to be much higher. It was only later discovered that the correct figure was 46. Evans had much greater success however with

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

s extracted from the anterior lobe of the

pituitary gland In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The h ...

. He isolated

Human Growth Hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in ...

, which is essential for human growth and development. In 1922 along with Katharine Scott Bishop, during feeding experiments on rats, he co-discovered

which is needed for human reproduction. Evans became director of the Institute of Experimental Biology at Berkeley in 1931. With

Gladys Anderson Emerson Gladys Ludwina Anderson Emerson (July 1, 1903 – January 18, 1984) was an American historian, biochemist and nutritionist who researched the impact of vitamins on the body. She was the first person to isolate Vitamin E in a pure form, and won th ...

, he reported the isolation of the pure Vitamin E from wheat germ in 1937. He also determined the formula C₂₉H₅₀O₂. Evans was also instrumental in developing

reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are ...

s research with Miriam Elizabeth Simpson and Choh Hao Li, by studying the

oestrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrou ...

cycle of rats. Evans is also credited with developing

Evans blue Evans Blue is a Canadian rock band from Toronto, founded in 2005. They have sold over one million albums worldwide, including five studio albums and one live album. History Origins (2005) Evans Blue came together in early 2005. Five musi ...

, a method which determines

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

volume in humans and animals. Evans took a strong interest in the history of science and was an active collector of rare books in the field. His collection was later acquired by the

Harry Ransom Center The Harry Ransom Center (until 1983 the Humanities Research Center) is an archive, library and museum at the University of Texas at Austin, specializing in the collection of literary and cultural artifacts from the Americas and Europe for the pur ...

at the

University of Texas at Austin The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,07 ...

. He died in

Berkeley, California Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and E ...

, aged 88.

Quotation

*"No single feature of man's past equals in importance his attempt to understand the forces of Nature and himself."

Bibliography

*Evans, H. McLean (1904) ''A New Cestraciont Spine from the Lower Triassic of Idaho''. The University Press: Berkeley, California. *Evans, H. McLean and Scott, Katharine J. (1921) ''On the Differential Reaction to Vital Dyes Exhibited by the Two Groups of Connective-tissue Cells''. Carnegie Institution of Washington. *Evans, H. McLean and Long, Joseph A. (1922) ''The oestrous cycle in the rat and its associated phenomena''. Univ. of California Press: Berkeley, California. *Evans, H. McLean and Cole, Harold H. (1931) ''An Introduction to the Study of the Oestrous Cycle in the Dog''. University of California Press: Berkeley, California. *Evans, H. McLean and Swezy, Olive (1931) ''Ovogenesis and the Normal Follicular Cycle in Adult Mammalia''. University of California Press: Berkeley, California. *Evans, H. McLean and Becks, Hermann (1953) ''Atlas of the Skeletal Development of the Rat (Long-Evans strain): normal and hypophysectomized''. American Institute of Dental Medicine: San Francisco. *Evans, H. McLean, ed. (1959) ''Men and Moments in the History of Science''. University of Washington Press: Seattle.

References

External links

National Academy of Sciences Biographical Memoir
{{DEFAULTSORT:Evans, Herbert Mclean 1882 births 1971 deaths American anatomists American geneticists Johns Hopkins University alumni University of California, Berkeley faculty Foreign Members of the Royal Society Members of the Royal Swedish Academy of Sciences Vitamin researchers