The colleague with whom I teach astronomy likes to challenge our students with the question, "Are we any smarter than the ancient Greeks were?" We surely have a great deal more knowledge—especially about technology, medicine and the natural world—than Plato, Aristotle or Aristarchus had, but few of us equal them in brain power or logical reasoning. Nor have we surpassed Jesus in moral reasoning. Two or three millennia are not long enough for natural selection and variation noticeably to augment brain capacity. It took 2 million years to double the cranial volume of homo habilis to that of modern homo sapiens.
Owen Gingerich is research professor of astronomy and the history of science at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and author of The Book Nobody Read: Chasing the Revolutions of Nicolaus Copernicus (Walker).