Daily Archives: 5 July 2014

July 5, 1904 (a Tuesday)

Evolutionary biologist Ernst Mayr.

On this date, the American biologist Ernst Mayr was born in Germany. He began bird watching as a young boy, and by the age of ten, he could recognize all of the local bird species by call as well as sight. Mayr was known for his work in avian taxonomy, population genetics, and evolution. He led development of what has become known as the “modern synthesis,” the establishment of Darwin’s theory of evolution on a firm foundation of experimental genetics and population statistics. In 1940, Mayr proposed the concept of a species as a group of populations that are reproductively isolated from other such groups, the definition most widely used by biologists today.

Mayr was productive throughout his life and lived to a ripe old age but could never fully explain his longevity. “There is no history of it among my ancestors and both my parents died of cancer,” he said. “Probably it results from exercising every day, living a healthy life and having an active mind. My mind is still in very good shape; I have never let it rest. I’ve always had a tremendous breadth of interest; I’ve always wanted to know everything and read everything.” He died on February 3, 2005.

July 5, 1687

Newton's *Philosophiæ Naturalis Principia Mathematica*

On this date, the Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) by Isaac Newton was published.  This three-volume work contains the statement of Newton’s laws of motion forming the foundation of classical mechanics, as well as his law of universal gravitation and a derivation of Kepler’s laws for the motion of the planets (which were first obtained empirically).   The Principia is widely regarded as one of the most important scientific works ever written.  It is in a supplement to the Principia, entitled General Scholium, that Newton expressed his famous “Hypotheses non fingo” (“I feign no hypotheses” or “I make no guesses”).