During a 1906 meeting of the Royal Society of Edinburgh, Sir William Turner submitted part three of his research "Contributions to the Craniology of the People of the Empire of India." Included were the photographs of individual skulls from a group who the British Medical Journal said "made it their business to frequent the great highways of India and become friendly with travelers, with a view to setting upon them and strangling them."

Meet the original thugs.

The word "thug" traces its roots to the Hindi and Urdu word thag, which means thief or swindler, and which itself is derived from the Sanskrit verb (to conceal). The word would enter the English language in the 1800s during the British imperial rule of India.

The skulls examined by Turner in the craniology study once belonged to members of what was called the "Thuggee Cult." The thuggees were believed to be a professional organization of criminals and assassins who reportedly had strangled thousands of people on India's roadsides....