early modern period. The germ theory of disease was not widely accepted until the 1880s, in the late modern period. Modern scientific dentistry was founded by Pierre Fauchard. The smallpox vaccine was invented in the 1770s and popularized by Edward Jenner in the 1790s, though it was unclear at the time how it worked. Carl Linnaeus published the first modern taxonomy in 1735, replacing Aristotle's Great Chain of Being. Binomial nomenclature was used in publications by Gaspard Bauhin as early as 1622, and by Linnaeus in 1753. The ancient theory of spontaneous generation remained dominant throughout the early modern period, but the history of evolutionary thought includes some who questioned the strictest form of this dogma. The idea of partial common descent was famously promoted by Georges-Louis Leclerc, Comte de Buffon. Evolution was not fully articulated and accepted until the 19th century. Modern geology began to take shape mainly in the 18th and 19th centuries. Early on, Nicolas Steno proposed the law of superposition in 1669, and various writers in the history of geology began to question the notion derived from the Christian Bible that the Earth was only about 6,000 years old and relatively unchanged over time. Steno and James Hutton are often considered founders of the modern field. The study of fossils and rock types became systematic. Early developments in the history of electromagnetism during this era include gradual teasing out of the relationships between electricity, magnetism, and lightning; development of the electrostatic generator and Leyden jar for storage; and the discoveries of ferromagnetism, "electrics" and "non-electrics" (conductors and insulators). The now-obsolete fluid theory of electricity was developed to explain electrical phenomena in terms of "vitreous" and "resinous" fluids (later recognized as positive and negative electrical charges). Electrochemistry was born with the discovery of voltaic electricity (which would provide a power source for later experimentation) and pyroelectricity. Around 1784, Coulomb's law mathematically described the strength of electrical attraction. The discovery that electricity could cause muscles to contracted was termed "Galvanic electricity". In the new social sciences: Historical linguistics emerged in the late 18th century as a field after the discovery of the common origin what are now called Indo-European languages by philologist William Jones. The fields of anthropology and paleoanthropology emerged in the 18th century, but much of early modern anthropology is now considered scientific racism. The 1776 multi-book publication The Wealth of Nations by Adam Smith is