We
at Science Careers see little ethical equivalence between the chattel slavery practiced in the United States before 1865 and employment in an
academic institution, but there is a coincidental
connection: Seven years (the approximate length of the average biomedical Ph.D.) plus 5 years (the maximum allowable time for a postdoc supported by the National Institutes of Health, and the length of many postdocs these days) equals 12 years.