February 14/17, 1766 (Friday-Monday)

Title page of An Essay on the Principle of Population

Sometime on these dates, the English demographer and political economist Thomas Robert Malthus was born at Dorking, a place just south of London.

Malthus entered Jesus College, Cambridge, in 1784 and was ordained a minister of the Church of England in 1788. He earned his M.A. in 1791. He is best known for his An Essay on the Principle of Population, which was first published in 1798 and was read by Charles Darwin forty years later. This important essay first identified the geometric role of natural population increase in outrunning subsistence food supplies, prompting Darwin to explore the actual patterns of evolution.

September 7, 1936 (a Monday)

Benjamin, the last known Thylacine (1933)

On this date, the last known Thylacine, commonly known as the Tasmanian Tiger or Tasmanian Wolf, died in captivity at Hobart Zoo, Tasmania, as a result of neglect. The animal, named Benjamin, was locked out of its sheltered sleeping quarters and exposed to freezing temperatures at night.

The Thylacine was the largest known carnivorous marsupial mammal of modern times. Like the tigers and wolves of the Northern Hemisphere, the Thylacine was an apex predator. As a marsupial, it was not closely related to these placental mammals, but because of convergent evolution it displayed the same general form and adaptations. Its closest living relative is thought to have been either the Tasmanian Devil or Numbat. Interestingly, the Thylacine was one of only two marsupials to have a pouch in both sexes (the other being the Water Opossum). The male Thylacine had a pouch that acted as a protective sheath, protecting the male’s external reproductive organs while running through thick brush.

Thylacinus in Washington D.C. National Zoo, c. 1906.

Virtually wiped out in the wild due to constant hunting (they were thought to be a threat to sheep and other small farm animals) and the encroachment of humans on their already limited habitat, the Thylacine was finally recognized as being in danger of becoming extinct in 1936, but much too late. There have been no confirmed sightings in over 70 years.  It was the last extant member of its genus, Thylacinus, although several related species have been found in the fossil record dating back to the early Miocene.

September 3, 1907 (a Tuesday)

Loren Corey Eiseley

On this date, the highly respected anthropologist, ecologist, science writer, and poet Loren Corey Eiseley was born. He published books of essays, biography, and general science in the 1950s, ’60s, and ’70s.

Eiseley is best known for the poetic essay style, called the “hidden essay”. He used this to explain complex scientific ideas, such as human evolution, to the general public. He is also known for his writings about humanity’s relationship with the natural world. These helped inspire the environmental movement.

Eiseley’s first book, The Immense Journey: An Imaginative Naturalist Explores the Mysteries of Man and Nature (1946), a collection of writings about the history of humanity, established him as a writer with the unique ability to combine science and humanism. In the essay from it entitled “The Snout”, he wrote:

The door to the past is a strange door. It swings open and things pass through it, but they pass in one direction only. No man can return across that threshold, though he can look down still and see the green light waver in the water weeds.

Eiseley’s book, Darwin’s Century (1958), focuses on the development of the theory of evolution and was awarded the Phi Beta Kappa Science prize in 1959. His other books include The Unexpected Universe (1969), The Night Country (1971), the memoir All The Strange Hours: The Excavation of a Life (1975), and Darwin and the Mysterious Mr. X: New Light on the Evolutionists (1979).

When Loren Eiseley was 3 his father held him up to watch Halley’s Comet blaze across the sky and told his son to look for its return in 75 years. But Loren Eiseley did not live that long. He died July 9, 1977, having used his brief seventy years to leave behind a heritage that continues to enrich the lives of all who come to know his work.