Taken in 1901, this image is the earliest known living histogram. Living histograms are visualisations constructed out of the data they are representing: humans. This photo is visualising the distribution of the height of men.
The photograph was taken to illustrate an idea in C. B. Davenport's article The Statistical Study of Evolution (1901). To take the image, Davenport placed forty University of Chicago students (read: 'men') into columns. Each column corresponds to students of a certain height class. For example, one column might contain students between 160cm and 170cm.
The image received a fuller analysis in Graphical Methods for Presenting Facts by Brinton (1914). However, some eagle-eyed historical OSINT from Robert W. Jernigan found that Brinton had misinterpreted the graph in his article. He assumed that the histogram had the tallest students at the right, as you would expect in a conventionally oriented histogram. However, Jernigan found that the picture was intended to be oriented in the opposite direction. Here, the picture is shown in the original, unconventional orientation with the taller students further left.