According to the biblical story of the Tower of Babel, the people of the earth once spoke a common language. Filled with their own self-importance, they decided to build a tower in Babylonia reaching into the heavens. But God, displeased at their hubris, caused them to speak in different tongues. No longer able to communicate in harmony, the people of the tower dispersed across the face of the earth, leading to the formation of nations, each harbouring its own language.The original language from which all others sprung was Hebrew, the language of the Old Testament. This story was the basis of scholarly research in the 18th century. For instance, James Parsons, an English physician and antiquary, argued in The Remains of Japhet (1767) that many European languages were descended from a form of Hebrew he called Japhetian (Japhet being a son of Noah).Against this backdrop, in 1783 William Jones, a 37-year-old English lawyer, who had received a knighthood that year for his work in languages and orientalism (the scholarly study of the people of Asia), sailed to Calcutta, in Bengal, India to take up the post of judge. Jones had received a grounding in the classical languages Latin and Greek during his education at Harrow School. He was also familiar with many European languages, including the Celtic language Welsh and the Romance languages French, Italian, Spanish and Portuguese (so called because they developed from colloquial forms of Latin after the decline of the Roman Empire). At Oxford University in the 1760s, Jones undertook an extensive study of Persian, later publishing his influential Grammar of the Persian Language (1771).In Bengal, then under the control of the British East India Company, he embarked upon intensive study of Sanskrit, a classical Indian language spoken from roughly 1500 BCE to 1300 CE. Sanskrit is the language of the vedas, the Hindu sacred texts, and as such continued to exert an influence on Indian culture. By studying Sanskrit, Jones hoped to gain a better understanding of Indian laws and customs, so that he could carry out his governance work in a fair and culturally sensitive way. He soon developed an appreciation for the language, calling it ‘more perfect than the Greek, more copious than the Latin and more exquisitely refined than either’1. Jones noticed that Sanskrit shared many cognates with its European counterparts Greek and Latin. A cognate (from Latin ‘born together’) is a word that has a very similar or identical sound and meaning across a group of languages. For instance, Sanskrit दश (dáśa) corresponds to Ancient Greek δέκα (déka) and Latin decem, as well as Welsh deg and Classical Persian ده (dah), all of which mean ‘ten’2. Cognates generally arise from among a language’s most primitive vocabulary (for example, numerals or body parts), since, as Jones identified, such words are less susceptible to change and replacement over the millennia of their use. If two or more languages possess a large number of cognates, this suggests that, in a sense, they may be considered related.The concept of linguistic relatedness had a parallel in 18th-century ideas about taxonomy, the scientific classification of organisms3. In 1735, the Swedish botanist Carl Linnaeus had suggested that plants and animals could be grouped into hierarchical family trees, a revolutionary theory at the time. Thus, the domestic dog, canis familiaris, is a member of the genus canis, together with the wolf, canis lupus, and the golden jackal, canis aureus. Linnaeus also observed that these classifications were not immutable. Organisms can diverge from each other to the point where they no longer fall under the same species, but are instead categorised as taxonomic siblings; or they can become extinct. This is also true of languages. For instance, Cornish, a language spoken in Cornwall, England, is a sibling of Welsh, sharing the common ancestor Brittonic. Cornish became extinct in the late 18th century with the death of the last surviving native speaker (although it was artificially revived in the early 20th century). On 2 February 1786 at the third annual meeting of the Asiatic Society in Calcutta (which he had founded two years earlier to further research into Indian culture) Jones made a startling proposal. Based on his linguistic study of Sanskrit, Greek and Latin, he theorised that all three languages had ‘sprung from some common source, which, perhaps, no longer exists’4. He also suggested that Celtic and Persian may have shared this common source.Jones’s remarkable insight paved the way for further investigation into the commonalities between Sanskrit, Persian, Celtic, Romance and the classical languages, which became known as the Indo-European language family (a term subsequently invented by the English physicist Thomas Young in 1813). Their parent language — the ‘common source’ — was called Proto Indo-European. In the 19th century, a group of German linguists (known as the Neogrammarians) began a reconstruction of Proto Indo-European by comparing cognates across the Indo-European language family and identifying regular patterns (a technique called the comparative method). For each cognate, they were able to create a hypothetical word representing the original Proto Indo-European form, providing a view into an ancient past. This was also the birth of the field of study now known as comparative linguistics — a field directly attributable to Jones demonstrating that the Indo-European languages shared a common origin.Jones’s hypothesis also marked a decisive separation of linguistics from religion. Notably, he did not identify Hebrew as his ‘common source’; instead, he recognised that Hebrew differed greatly from the Indo-European languages and placed it in a separate Semitic language family together with Arabic and Amharic (a classification still adopted by linguists today)5. In doing so, he rejected mythical explanations of linguistic diversity, such as the Tower of Babel story, and initiated the study of linguistics as a science.