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Today's featured article

A silhouette of human evolution

The history of evolutionary thought has roots in antiquity. However, until the 18th century, Western biological thinking was dominated by essentialism, the belief that every species has essential characteristics that are fixed and unalterable. During the Enlightenment, naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinction further undermined the static view of nature. In the early 19th century, Jean-Baptiste Lamarck proposed his theory of the transmutation of species, the first fully formed scientific theory of evolution. In 1858, Charles Darwin and Alfred Russel Wallace published a new evolutionary theory, which was explained in detail in Darwin's On the Origin of Species. The theory was based on the idea of natural selection. The synthesis of natural selection with Mendelian genetics during the 1920s and 1930s founded the new discipline of population genetics. The gene-centered view of evolution rose to prominence in the 1960s, followed by the neutral theory of molecular evolution, sparking debates over adaptationism, the units of selection, and the relative importance of genetic drift versus natural selection. In the late 20th century, DNA sequencing led to molecular phylogenetics and the reorganization of the tree of life into the three-domain system. (more...)

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Portrait of Charles Darwin

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Today's featured picture

Charles Darwin in 1879

A portrait of naturalist Charles Darwin in his old age, from the Victorian photography studio Elliott & Fry. By his final years Darwin's fame had spread far and wide, as had his image—always with his iconic beard—in the form of carte de visite and cabinet card photographs. This portrait is from a photography session at Darwin's home, Down House, in 1879. It is one of the most widely distributed images of Darwin: it was issued by Elliott & Fry on heavy card stock around 1880 and subsequently reproduced on postcards, cigarette cards, commemorative stamps, and other memorabilia.

Photo credit: Elliott & Fry

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