T. H. Morgan discovers white eye and consequently sex linkage in Drosophila. Drosophila genetics begins.

A few years after the find of some isolated teeth from the same species, British paleontologist Clive Forster Cooper finds better specimens of what will later be identified as Paraceratherium in an area that will later be part of Pakistan. A century later, Paraceratherium will still hold the title of the biggest land mammal yet discovered.

While digging the foundation for an imposing home, two laborers, Mercer and Crittenden, discover the remains of a cremation from the Iron Age, including a Neolithic axe and a fossil echinoid.

A chance discovery turns up the astonishingly well-preserved Clacton Spear. Made of yew and over 400,000 years old, it's one of the world's oldest wooden artifacts.

T. H. Morgan proposes that the genes for white eyes, yellow body, and miniature wings in Drosophila are linked together on the X chromosome.

A hand axe, possibly 200,000 years old and of Neanderthal design, is found in Norfolk, England. The axe has been fashioned to give prominence to a fossil bivalve.

Charles Dawson discovers the Piltdown skull in southern England. Excavations of faked fossils will continue for years.

Alfred Wegener proposes the theory of continental drift. His ideas will be almost completely ignored until the late 1960s.

A. H. Sturtevant, an undergraduate working with Morgan at Columbia, provides the experimental basis for the linkage concept in Drosophila and produces the first GENETIC MAP.

Geologist-physicist Arthur Holmes concludes that the breakdown of radioactive isotopes in igneous rocks can be used to determine when the rocks solidified. The ability to determine the absolute ages of rocks will enable scientists to better date fossils.

Calvin Blackman Bridges reports nondisjunction of sex chromosomes as PROOF of the chromosome theory of heredity.

Charles Doolittle Walcott identifies fossil bacteria in Cryptozoon-like structures (stromatolites).

Peyrony finds the remains of Neanderthal baby in southwestern France. Because no one knows the bones are Neanderthal, they are not examined closely and are later believed lost. They will be rediscovered and described nearly 90 years later.

Calvin Bridges identifies strains of mutant fruit flies with extra pairs of wings. Decades later, these strains will help biologists understand Hox genes that control the head-to-toe anatomy of widely varying animals.

Frederick Twort discovers a virus capable of infecting and destroying bacteria.

Thomas Hunt Morgan, Alfred Henry Sturtevant, Calvin Blackman Bridges, and Hermann Joseph Muller publish The Mechanism of Mendelian Heredity. This monograph provides the first systematic description of the actual mechanisms that control inheritance as evidenced in the Mendelian model. Here, for the first time, the gene is made real.

Two duckbill dinosaur fossils, with extremely rare skin impressions, sink to the bottom of the Atlantic when the ship carrying them to London — the SS Mount Temple — is stopped by the German military vessel, the SMS Möwe. The German ship takes the passengers prisoner and then sinks the Mount Temple.

Stone tools discovered at Bir el Ater in eastern Algeria include triangular objects that might have been arrowheads or spear points. The tools will be dubbed Aterian, but their age will be underestimated for decades.

British polymath D'Arcy Wentworth Thompson publishes On Growth and Form arguing that the forms Darwinian natural selection can produce through evolution are constrained by physical and mathematical laws, and that organic structures often emulate inorganic natural structures. His analysis led the way for the scientific explanation of morphogenesis, the process by which patterns and body structures are formed in plants and animals. Thompson's description of the mathematical beauty of nature and the mathematical basis of the forms of animals stimulated thinkers as diverse as Julian Huxley, Conrad Hal Waddington, Alan Turing, Claude Lévi-Strauss, Eduardo Paolozzi, Le Corbusier, and Mies van der Rohe.

C. B. Bridges discovers the first chromosome deficiency in Drosophila.

Felix Hubert D'Herelle, independently of Frederick Twort, discovers a virus capable of infecting and destroying bacteria, which he calls a BACTERIOPHAGE.

First reported connection between smoking and lung cancer.

Thomas Hunt Morgan and coworkers publish The Physical Basis of Heredity, a book-length summary of the rapidly growing findings in genetics.

C. B. Bridges discovers chromosomal duplications in Drosophila.

T. H. Morgan calls attention to the equality in Drosophila melanogaster between the number of linkage groups and the haploid number of chromosomes.

Swedish geologist Johann Andersson discovers a major "dragon bone works" in northern China. Otto Zdansky also examines the works several years later, discovering that the fossils are referred to as dragons even though the workers recognize them as more pedestrian species such as horses and deer.