Alfonso XIII (Alfonso León Fernando María Jaime Isidro Pascual Antonio de Borbón y Austria-Lorena; 17 May 1886 – 28 February 1941) was King of Spain from 1886 until 1931. His mother, Maria Christina of Austria, was appointed regent during his minority. In 1902, on attaining his 16th year, the King assumed control of the state.

Alfonso was born in Madrid, posthumously born son of Alfonso XII of Spain, and became King of Spain upon his birth. The French newspaper Le Figaro described the young king as "the happiest and best-loved of all the rulers of the earth".

When he came of age in 1902, the week of his majority was marked by festivities, bullfights, balls and receptions throughout Spain.

During his reign, Spain lost its last colonies in the Americas (Cuba and Puerto Rico) and the Philippines; fought and, after several setbacks, won a war in Morocco; witnessed the start of the Spanish Generation of 1927, and endured the dictatorship of Miguel Primo de Rivera. During the First World War, because of his family connections with both sides and the division of popular opinion, Spain remained neutral. The King ran an office for captives from the Royal Palace, which leveraged the Spanish diplomatic and military network abroad to intercede for thousands of prisoners-of-war, receiving and answering letters from Europe. However, he became gravely ill during the 1918 flu pandemic and, since Spain was neutral and thus under no wartime censorship restrictions, his illness and subsequent recovery were covered worldwide, giving the false impression (in the absence of real news from anywhere else) that Spain was the most-affected area. This ultimately led to the pandemic getting the nickname "the Spanish Flu."

Charles Robert Darwin, FRS (12 February 1809 – 19 April 1882) was an English naturalist. He established that all species of life have descended over time from common ancestors, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.

Darwin published his theory with compelling evidence for evolution in his 1859 book On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species. By the 1870s the scientific community and much of the general public had accepted evolution as a fact. However, many favoured competing explanations and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.

Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. Studies at the University of Cambridge encouraged his passion for natural science. His five-year voyage on HMS Beagle established him as an eminent geologist whose observations and theories supported Charles Lyell's uniformitarian ideas, and publication of his journal of the voyage made him famous as a popular author.