The first chair, Raymond Pearl, was a population biologist and statistician and a student of Karl Pearson. He believed that there existed mathematical laws of population growth that rivaled the laws of planetary motion. He used the logistic curve to (under)-predict the steady state populations of several European countries and the US. Pearl, a leading intellectual of his day, was founding editor of the journals Human Biology and Quarterly Review of Biology; he was an early advocate of birth control when that position was not socially acceptable and he was a friend and weekly dinner partner of Baltimore's famous reporter and social critic, H. L. Mencken.
Pearl considered himself more a biologist than mathematician and therefore recruited Lowell Reed to the Department. Reed became the department's second chair in 1926.(photo courtesy of Johns Hopkins Medical Archives)