John Graunt (1620-1674) is considered by many historians to have founded the science of demography, the statistical study of human populations. He analyzed the vital statistics of the citizens of London and wrote a book regarding those figures that greatly influenced the demographers of his day and those in the centuries that followed. Graunt was honored for his work by being made a charter member of England's Royal Society, which was composed of prominent scientists.

John Graunt was born in London, England, on April 24, 1620, to Henry Graunt, a storekeeper in Hampshire, and his wife, Mary. The eldest of seven or eight children, Graunt attended school until adolescence. At age sixteen he became an apprentice to his father, who was employed as a draper (a dealer in clothing and dry goods). In February 1641, Graunt married Mary Scott, with whom he had one son and three daughters.

As his career prospered, Graunt held several different positions in the Freedom of the Drapers' Company. He also became involved in politics and served in various jobs for the city of London, including a term as a member of London's common council. By the age of 30 Graunt had attained such influence that he was able to procure the professorship of music at Gresham College for his friend, Sir William Petty. Petty, a physician, later invented the horse-propelled military tank and was appointed surveyor general of Ireland. Like Graunt, Petty also engaged in early demographic work.

Book Based on Mortality Records

Despite his lack of formal education, Graunt became interested in mortality statistics. He got the idea to write the book that was to make him famous from having thought a great deal about the Bills of Mortality (lists of the dead) that had been published in England beginning in the late sixteenth century. His book was titled Natural and Political Observations mentioned in a following index, and made upon the Bills of Mortality With reference to the Government, Religion, Trade, Growth, Ayre, diseases, and the several Changes of the said City. The Bills of Mortality were the vital statistics about the citizens of London collected over a 70-year period. In his book, hereinafter referred to as Observations, Graunt explained that the accounts were kept as the number of deaths rose from the plague, a catastrophic illness whose germs were carried by fleas that lived as parasites on rats. In the year 1625 alone, one-fourth of England's population died, many from the plague.

According to Graunt, the recording of the London statistics "first began in the year 1592, being a time of great Mortality; and after some disuse, were resumed again in the year 1603, after the great Plague then happening likewise. These bills were Printed and Published, not only every week on Thursday, but also a general [account] of the whole Year was given in, upon the Thursday before Christmas Day. Graunt studied the statistics compiled in the Bills of Mortality, along with christening records from churches and data from an area of rural England. A practical man, he decided that these carefully collected facts could be analyzed and the results put into book form. On February 5, 1662, Graunt's newly-printed 90-page work, Observations, was distributed to the members in attendance at a meeting of England's Royal Society.

Critique of Graunt's Data Analysis

Graunt had grouped together similar facts from the 70 years of records displayed in the Bills, and noted the comparisons of findings for different population groups. From his studies he drew a number of interesting and important conclusions. Graunt modestly described his own work as "to have reduced several great confused volumes [of Bills of Mortality] into a few [easy to understand] Tables, and abridged such Observations as naturally flowed from them, into a few succinct Paragraphs, without any long series of [wordy] Deductions."

In an article on Graunt in the Dictionary of Scientific Biography, Frank N. Egerton, III pointed out that Graunt's deduction of various characteristics of populations from the data he analyzed, "indicate a good understanding of the kinds of questions that are significant for demography." But pointing out some deficiencies in Graunt's work, Egerton also wrote, "Usually [Graunt] explained his steps in solving problems, but he seldom included the actual calculations; and sometimes he omitted important information. Furthermore, his indirect approach sometimes went beyond the reliable use of his data, and the accuracy of some of his answers was difficult to evaluate."

Egerton nevertheless commended Graunt for realizing the shortcomings of his data, and pointed out that Graunt sometimes "set an excellent example by seeking verification of his estimates by different indirect methods." In addition, Egerton observed, Graunt "introduced the use of statistical samples [though he] did not pursue this subject far enough to determine the sizes of samples or means of selection needed for insuring accuracy. [Graunt] also realized that demographic procedures could be used to make projections concerning both past and future populations."

In a 1996 article in the British medical journal Lancet, Kenneth J. Rothman pointed out some of Graunt's major achievements as a pioneer demographer: Graunt was the first to publish the fact that more boys than girls are born but that the mortality rate is greater for males, resulting in the population's being almost evenly divided between males and females. Graunt reported the first time-trends for many diseases; he offered the first well reasoned estimate of London's population; he used evidence from medical records to refute the idea that plague spreads by contagion and that it occurs early during the reign of a new king; he showed that doctors have twice as many female as male patients, but that males die earlier than females; he produced early hard evidence about the frequencies of various causes of death.

Work Had Wide Influence

The invention that some historians have called Graunt's most original was his creation of "life tables"-- a new way to present population and mortality statistics by calculating survivorship on a chart. Using this method Graunt was able to predict the number of persons who would survive to each successive age on his chart and the life expectancy of the groups from year to year. Development of the life tables has been hailed as marking the beginning of the science of demography. Such charts are said to have made an impact on the pioneer demographic work of other noted astronomers and scientists, including Edmund Halley (1656-1742), England's astronomer royal. The types of charts Graunt originated remain in use today.

The widspread acceptance of Graunt's work also led to his being acclaimed as the founder of the science of statistics, particularly the branch that deals with the analysis of population data. Yet Graunt never made a formal study of mathematics. Some historians have speculated that Graunt received more help with his book from his better-educated friend, William Petty (1623-1687), than is generally acknowledged. However, while Petty surely offered support to his friend and probably made some contribution to the book, most historians agree that Graunt wrote at least a major portion of the work.

Graunt's book on the Bills of Mortality had great influence throughout Europe. It has been noted that soon after its publication, France embarked on the most precise registering of births and deaths in all of Europe. The publication also caused Charles II of England to endorse Graunt's being made one of the early members of the then newly-established and prestigious Royal Society, a distinct honor for someone who was a businessman and not a professional scientist. Charles requested of the society "that if they found any more such tradesmen, they should be sure to admit them all, without any more ado."

Financial Problems and Religious Conversion

Graunt's Observations became popular reading in educated circles. On June 20, 1665, the Royal Society declared its support for the publishing of the third edition of the book, which appeared later that year. But the following year, 1666, was to bring personal disaster for Graunt. A great fire in London on September 2 destroyed his clothing firm, leaving him with financial problems that were to persist throughout the rest of his life.

During this period, Graunt converted from the Protestant faith that he had adopted as a young man to Roman Catholicism. Graunt had been brought up as a Puritan but had lived as an anti-Trinitarian for a number of years before his final conversion to Catholicism. Anti-Trinitarians rejected the notion that God is made up of three distinct beings, the Father, the Son, and the Holy Spirit.

Around the time that fire destroyed his fortune, Graunt became a manager at the New River Company, which was involved with furnishing London's water supply. Graunt's position there led to a rumor spread by enemies who despised his religious conversion. They accused Graunt of having played a role in starting the great fire of London, or at least of trying to interfere with water being transported to the city the night before the fire broke out. However, the accusation was disproved when an examination of the New River Company's books showed that Graunt had not become part of its management group until 21 days after the fire took place.

Lauded After Death

On April 18, 1674, after several years of working for the New River Company, Graunt died of jaundice, a disease of the liver. Among the mourners at his funeral were members of the London government and distinguished scientists, including Sir William Petty, who appeared grief-stricken at his friend's death. In addition to his famous book Observations, Graunt left behind another book titled Observations on the Advance of Excise, as well as a manuscript on religion.

In the centuries since his death, Graunt has been acknowledged by many historians and scientists for his important scientific contributions. In his 1741 work Divine Order in the Changes of the Human Race shown by its Birth, Death, and Propagation, German chaplain J. P. Sussmilch (1707-1767) praised Graunt as "a Columbus" for his discovery of the new field of demographics. In the opinion of Kenneth J. Rothman, writing in the British medical journal, The Lancet, "With [Graunt's book on the Bills of Mortality] he added more to human knowledge than most of us can reasonably aspire to in a full career."

Further Reading

• Autobiography of Science, edited by Forest Ray Moulton and Justus J. Schifferes, Doubleday and Co., Inc., 1960.
• Boorstin, Daniel J., The Discoverers: A History of Man's Search to Know His World and Himself, Random House, 1983.
• Dictionary of National Biography, edited by Sir Leslie Stephen and Sir Sidney Lee, Oxford University Press, 1963-64.
• Dictionary of Scientific Biography, edited by Charles Coulston Gillispie, Charles Scribner's Sons, 1972.
• "John Graunt," Encyclopedia Britannica, http://www.britannica.com (December 14, 2000).
• "John Graunt," http://es.rice.edu/ES/humsoc/Galileo/Catalog/FilesBAK1/graunt.html (December 14, 2000).
• "Lessons from John Graunt," Lancet, January 6, 1996, http://www.findarticles.com (December 14, 2000).