Darwin Day, 12 February

Darwin Day falls on the twelfth of February, the birthday of Charles Darwin, born in 1809, the same calendar date as Abraham Lincoln, a coincidence noted often enough in Darwin Day commentary to have become part of how the day is discussed. Unlike other modern observance days, Darwin Day has no ancient textual basis and no claim to religious revelation behind it. Its observance instead developed from the late twentieth century onward, promoted particularly by organized secular humanist and freethought organizations as an occasion to celebrate science generally and Darwin's contribution to evolutionary biology specifically.

The day functions, for the organizations that promote it, as something close to a secular counterpart to a religious feast day, marked with public lectures, museum programming and educational events rather than any form of worship, and its inclusion among the observance days covered here reflects the same functional pattern found in avowedly non theistic movements more broadly. Groups including the American Humanist Association have lobbied for formal government recognition of the day in the United States without securing binding legislative adoption, so the observance remains a civil society tradition rather than an officially established one.