Thunberg was born and grew up in Jönköping, Sweden. At the age of 18, he entered Uppsala University where he was taught by Carl Linnaeus, regarded as the "father of modern taxonomy". Thunberg graduated in 1767 after 6 years of studying. To deepen his knowledge in botany, medicine and natural history, he was encouraged by Linnaeus in 1770 to travel to Paris and Amsterdam. In Amsterdam and Leiden Thunberg met the Dutch botanist and physician Johannes Burman and his son Nicolaas Burman, who himself had been a disciple of Linnaeus.