Sunday, March 1, 2015

Veteran scientist #21, Anderson McKendrick

Lieutenant Colonel Anderson Gray McKendrick (1876-1943)

Indian Medical Service physician and researcher 1900-1920.  Epidemiologist, statistician, population ecologist.

A.G. McKendrick is today known for his accomplishments later in life, when he became a pioneer in the study of disease ecology.  Those discoveries built from a long medical and military career.

Born in Scotland, McKendrick graduated medical school in 1900 and joined the Indian Medical Service—the British Empire’s military medical branch in Asia—and soon left for India.

Meanwhile, in the Horn of Africa, the Italian and British governments had been scrambling to put all of Somaliland under European control.  In response, a local leader named Mohammad Abdullah Hassan raised an army, resisted the European powers, and set up an independent Dervish State.

In 1903 McKendrick and other Indian forces deployed to Somaliland as part of a British attempt to destroy Hassan, who they referred to as the “Mad Mullah.”  The expedition was largely a failure, and McKendrick returned to India in 1904.  As for Hassan and his Dervish State, they successfully resisted European control until well after World War I.

Back in India, McKendrick began to specialize in medical research, and studied public health and disease outbreaks in India.  He occasionally took leave from active duty to continue his education in Scotland, studying chemistry in 1907 and mathematics in 1913.

Working his way up the ranks to Lieutenant Colonel, in 1914 McKendrick became director of the Pasteur Institute—an epidemiology research center in northern India.  Then, after two decades of military service, McKendrick left India in 1920 and returned to Scotland as a researcher.  He became superintendent of a medical research lab and joined a mathematical society.

Building on 20 years of fieldwork, McKendrick set about combining his mathematical talent with his disease data from India and Scotland to produce a series of landmark scientific papers.

In 1926 he published Applications of Mathematics to Medical Problems, which marked our first attempt to model the spread of diseases.  By describing how individual members of a population interacted, and modeling those interactions with differential equations, McKendrick’s model predicted how diseases would spread (or fail to spread) through a population.

For his next big discovery he teamed up with another Scottish veteran scientist.  William Ogilvy Kormack was a mathematician and chemist who had served in the Royal Air Force.  Together, the two scientists developed a quantitative theory of the spread of diseases.

They published their ideas in a 1927 paper—A Contribution to the Mathematical Theory of Epidemics.  In it they laid out a model that used three basic equations—showing the proportions of susceptible, infected, and dead individuals in a population—and the ages of the individuals, to calculate whether, how fast, and for how long a disease would spread.  Known as Kormack-McKendrick Theory, it was the ancestor of epidemic models used today to combat diseases around the world.

For the rest of his career McKendrick continued to produce, refine and find new practical uses for his population ecology models, before dying in his home country of Scotland.

With the help of a military career, McKendrick went from being a humble physician to fighting wars in East Africa, to combating diseases in India, and finally to modeling life-and-death phenomena with abstract equations, earning his place in scientific history.

MacTutor History of Mathematics. http://www-history.mcs.st-and.ac.uk/Biographies/McKendrick.html

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