In 1905, Levene was appointed as head of the biochemical laboratory at the Rockefeller Institute of Medical Research. He spent the rest of his career at this institute, and it was there that he identified the components of DNA.
It also takes anywhere from 18 to 24 months to get promoted to O-2 following entry to the Army, so the effective minimum age to join the Rangers for officers is around 23 to 24 years old. Officers can then continue to apply until they are promoted to O-5.
Management Level Statistics from the Vietnam War indicate the average age of the US GI was in their low 20's. However, actual on the ground observations & interviews tâ¦hru several years, and covering from the Mekong Delta to the DMZ (17th Parallel); the average age of the US Serviceman appeared to be age 19 or 20.