Clinical research in ancient babylon: methodologic insights from the book of Daniel

Around 600 BC, Daniel of Judah conducted what is widely regarded as the earliest recorded clinical trial. His trial compared the health effects of a vegetarian diet with those of a royal Babylonian diet over a 10-day period. The strengths of his study include the use of a contemporaneous control group, use of an independent assessor of outcome, and striking brevity in the published report. Weaknesses include probable selection bias, ascertainment bias, and confounding by divine intervention. Although Daniel probably never achieved tenure, he did get "learning and skill in all letters and wisdom ... and understanding in all visions and dreams" (well before Freud). Despite the trial's dramatic findings, over 4 centuries elapsed before publication of Daniel's results. Daniel apparently perished, then published.