Levene enrolled at Columbia University and in his spare time conducted biochemical research, publishing papers on the chemical structure of sugars. In 1896 he was appointed as an Associate in the Pathological Institute of the New York State Hospitals, but he had to take time off to recuperate from tuberculosis.
This graph shows the median age of the resident population of the United States from 1960 to 2015. In 2015, the median age of the United States population was approximately 37.7 years.
US Population to Hit 324 Million in 2016, 400 Million in 2050. The U.S. population is aging, and is moving away from one which is largely descended from people who came from Europe and more toward people from Central America, Mexico, and Asia. And, the rate at which the U.S population is growing has stagnated. There will be 323,996,000 Americans in 2016, barely up from 321,369,000 last year and slightly less than 326,626,000 in 2017. The U.S. population will not reach over 400,000,000 until 2051, when the Census forecasts it will reach 400,124,000.