Charles Darwin was born on February 12,1809, the second son of a physician in a small English country town (Fig. 1.2). From his boyhood on, he was an ardent naturalist, particularly passionate about beetles. At his father's wish, he studied medicine in Edinburgh for a while, but was so appalled, particularly by the operations, that he soon gave it up. The family then decided he should study for the ministry, and this seemed a perfectly natural education for a young naturalist, for nearly all leading naturalists of his time were ordained ministers. Although Darwin conscientiously did all the required reading in the classics and in theology, it was really natural history that he pursued with single-minded devotion. After obtaining his degree at Cambridge University (Christ College), he received through one of his teachers at Cambridge the invitation to join one of the Navy's survey ships, HMS Beagle, for a survey of the coasts of South America, particularly the harbors. The Beagle left England at the end of December 1831. On the five-year cruise of the Beagle, Darwin shared a cabin with the commander, Captain Robert Fitzroy. While the ship surveyed the coast of Patagonia in the east, the Strait of Magellan, and parts of the western coast and adjacent islands, Darwin had abundant opportunity to explore the mainland and the biota of the islands. Throughout the trip, he not only made significant collections of natural history specimens, but more importantly he asked endless questions about the history of the land and its fauna and flora. This was the foundation on which his evolutionary ideas grew.
After his return to England in October 1836, he devoted his time to the scientific study of his collections and to the publication of scientific reports, at first on some of his geological observations.
After a few years, he married his cousin Emma, the daughter of the famous potter Wedgwood, bought a house near London (Down House), and lived there until his death on April 19,1882, at the age of 73. It was at Down House that he wrote all of his major papers and books.
What made Darwin such a great scientist and intellectual innovator? He was a superb observer, endowed with an insatiable curiosity. He never took anything for granted but always asked why and how. Why is the fauna of islands so different from that of the nearest mainland? How do species originate? Why are the fossils of Patagonia basically so similar to Patagonia's living biota? Why does each island in an archipelago have its own endemic species and yet they are all much more similar to each other than to related species in more distant areas? It was this ability to observe interesting facts and to ask the appropriate questions about them that permitted him to make so many scientific discoveries and to develop so many highly original concepts.
Darwin also saw clearly that there are two aspects of evolution. One is the "upward" movement of a phyletic lineage, its gradual change from an ancestral to a derived condition. This is referred to as anagenesis. The other consists of the splitting of evolutionary lineages or, more broadly, of the origin of new branches (clades) of the phylogenetic tree. This process of the origin of biodiversity is called cladogenesis. It always begins with an event of speciation, but the new clade may become, in time, an important branch of the phylogenetic tree by diverging increasingly from the ancestral type.
The study of cladogenesis is one of the major concerns of macroevolutionary research. Anagenesis and cladogenesis are largely independent processes (Mayr 1991). Already in the 1860s knowledgeable biologists and geologists accepted that evolution was a fact, but Darwin's explanations of the how and why of evolution faced protracted opposition.
E.Mayer
The study of cladogenesis is one of the major concerns of macroevolutionary research. Anagenesis and cladogenesis are largely independent processes (Mayr 1991). Already in the 1860s knowledgeable biologists and geologists accepted that evolution was a fact, but Darwin's explanations of the how and why of evolution faced protracted opposition.
E.Mayer
