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June 26, 2007
Humans Have Spread Globally, and Evolved Locally
From a Few Genes, Life’s Myriad Shapes
Evolution Is ...
NATURAL SELECTION 1858
Charles Darwin and Alfred Russell Wallace both independently arrived at the theory of evolution by natural selection. They first presented their ideas together in 1858. In 1859 Darwin published his monumental work, “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.”
PRINCIPLES OF HEREDITY 1866
Gregor Mendel published his research on peas, laying the foundation for the study of genetics. The work, which would not be recognized until the turn of the century, revealed how traits are passed from generation to generation, providing a crucial missing piece of the workings of evolution.
THE MODERN SYNTHESIS 1940s
A number of scientists, including Theodosius Dobzhansky, left, brought together the young field of genetics, the historical view of paleontology, and the theory of evolution by natural selection to come up with a unified view of the evolutionary process. The modern synthesis has since served as the basic framework for all of evolutionary biology.
STRUCTURE OF DNA 1953
On April 25, 1953, James Watson and Francis Crick published “A Structure for Deoxyribose Nucleic Acid” in Nature. Their discovery changed the science of biology at least as much as Darwin and Wallace’s theory of natural selection. From that discovery have come the sequencing of entire genomes, including that of humans, and the molecular biology revolution, which provided powerful tools for all of biology — evolutionary biology included.
CONTINENTAL DRIFT 1960s
In 1915, Alfred Wegener published the theory of continental drift, which suggested that over time the continents had moved, an idea that finally gained acceptance in the 1960s. The theory offered new explanations for how the diversity of life came to colonize earth’s various land masses.
EXTINCTION THEORY 1980
Luis Alvarez, a physicist, his son, Walter Alvarez, a geologist, and other scientists discovered that an asteroid hit the earth 65 million years ago, right at the time of a mass extinction that included the dinosaurs. Such mass extinctions cause evolutionary upheavals.
LESSONS OF THE EYE 1995
Walter Gehring and colleagues showed that the Pax-6 gene was acting as the master switch turning on the development of eyes in animals as different as flies and humans. It was one of the earliest and most striking indications that evolution proceeded much more by tinkering with ancient genes and much less by outright invention than had ever been guessed.