Pierre Belon was one of the first and most important naturalists to rely on his own exploration in order to further his research. He is considered the originator of comparative anatomy due to his systematic analysis of similarities between the skeletal systems of humans and birds. Likewise, his discussion of dolphin embryos signifies the emergence of modern embryology.
Pierre Belon was born in Soutiere, a small village near Le Mans, France, in 1517. He came from an obscure family and, before 1535, was apprenticed to René des Prez, who was the apothecary of Guillame du Prat, the bishop of Clermont. Later, Belon became the protégé of René du Bellay, the bishop of Le Mans. Because of this alliance, Belon was able to begin his study of botany at the University of Wittenberg in 1540. In 1542 Belon went to Paris. There du Prat recommended him as an apothecary to François, the cardinal of Tournon, who was, throughout Belon's life, his most significant patron. Later, in 1542, Belon journeyed to Geneva, presumably because of a diplomatic mission for the cardinal. There he was imprisoned for six months following a violent altercation with two young Calvinists.
Between 1546-1548 Belon embarked on a series of diplomatic missions to Constantinople and the Middle East. On this extended tour he identified and described places, objects, animals, and plants mentioned by ancient writers. While Belon was engaged primarily on diplomatic missions, he recorded a detailed account of scientific curiosities that he discovered on his travels in Les Observations de plusieurs singularitez et choses mémorables (Observations of Several Curiosities and Memorable Things). The itinerary described by Belon was frequently followed by travelers interested in scientific discoveries for several centuries following its publication. Belon's account of his travels was so significant because of his detailed depiction of items of primarily scientific interest. In this sense, Belon established a pilgrimage route that was not exclusively religious.
The period between 1551-1555 formed a new stage in Belon's life. In this period he composed his principal works. L'Histoire Naturelle des Etranges Poissons Marins (The Natural History of Strange Marine Fish), published in 1551, contains descriptions and illustrations of fish and cetaceans, such as porpoises and whales, which Belon had dissected. Furthermore, this work established a classification system for marine fish. This classificatory system was based largely on Aristotle's (384-322 BC) animal classifications, and included both cetaceans and hippopotami under "fishes." However, in this work, Belon recognized that the milk glands of cetaceans were mammalian in type. Likewise, he noted that these creatures were air-breathing mammals, even though they lived underwater.
His last work, L'Histoire de la Nature des Oyseaux (The Natural History of Birds) was completed in 1555. This was the most significant of his works and brought him the greatest fame. In fact, it was so significant that King Henry II accepted Belon's dedication of the text to the crown. This dedication was significant because it was accompanied by the promise of a royal pension. Belon was also commissioned by the king to develop a botanical garden used to acclimate exotic plants to the French climate. However, Belon's payment was anything but prompt. A bit displeased by his unsuccessful attempts to collect his royal subsidy, Belon traveled to Switzerland and Italy and explored more of France in 1556. Upon returning, he received the money and, in 1558, obtained his medical license. Belon practiced medicine until 1564, when he was murdered in what was almost certainly a politically motivated crime.