Louis Dollo

Belgian paleontologist
Louis Antoine Marie Joseph Dollo (Lille, 7 December 1857 – Brussels, 19 April 1931) was a Belgian palaeontologist, known for his work on dinosaurs. He also posited that evolution is not reversible, known as Dollo's law. Together with the Austrian Othenio Abel, Dollo established the principles of paleobiology.

Louis Dollo was born in Lille, Nord Pas de Calais, a scion of an old Breton family. He studied at the École centrale de Lille, with geologist Jules Gosselet and zoologist Alfred Giard, both of whom influenced the young Dollo. In 1877, he graduated with a degree in engineering. After his graduation, he worked in the mining industry for five years, but simultaneously developed a passion for paleontology. In 1879, he moved to Brussels.

For three years, starting in 1878, he supervised the excavation of the famous, multiple Iguanodon find at Bernissart, Belgium. He devoted himself to their study as a scientific passion, initially concurrently with his engineering career. In 1882 he became an assistant naturalist at the Royal Belgian Institute of Natural Sciences. Dollo was given membership in the Société des sciences de Lille and the Geological Society of London. From 1882 to 1885, while he was head of the vertebrate fossil section of the Royal Institute, Dollo worked on reconstructing the skeletons of the iguanodons, as it was necessary to display them on their hind legs. The first one was assembled in the interior of an unused church that Dollo was using as a workshop. Twelve of those skeletons have been the principal attraction of the Museum of Natural Sciences at the Royal Institute. Dollo collaborated with his former professor Alfred Giard and the Université Lille Nord de France.

Around 1890, he formulated a hypothesis on the irreversible nature of evolution, known later as "Dollo's law". According to his hypothesis, a structure or organ lost during the course of evolution would not reappear in that organism. This hypothesis was largely accepted until Michael F. Whiting's 2003 discovery that certain insects that had lost their wings regained them millions of years later. However, it was redeemed on the molecular level in 2009 as a result of a study on glucocorticoid receptors.

Dollo continued his work with fossils, in addition to studies of dinosaurs and their ecology. He was among the first to see fossil animals as part of an ecosystem. Because of that, he was instrumental in the development of paleobiology, and he kept up an extensive correspondence with Othenio Abel, another famous early paleobiologist. He taught paleontology at the Free University of Brussels, beginning in 1909, and in 1912 received the Murchison Medal. Recently, the stochastic Dollo model is being used to analyze matrix of cognates statistically. In linguistics, this model permits a newly coined cognate to arise only once on a tree language.