[6] Pedigree charts published in scientific papers use an earlier anthropological convention of a square □ for male and a circle ○ for female.
[7] Before a shape distinction was adopted, all individuals had been represented by a circle in Morgan's 1871 System of Consanguinity and Affinity of Human Family, where gender is encoded in the abbreviations for the kin relation (e.g. M for 'mother' and F for 'father').
The modern gender symbols used for public toilets, 🚹︎ for male and 🚺︎ for female, are pictograms created for the British Rail system in the mid-1960s.
For example, schoolhouse outhouses in the 19th-century United States had ventilation holes in their doors that were shaped like a starburst Sun ✴ or like a crescent Moon ☾, respectively, to indicate whether the toilet was for use by boys or girls.
In themed locations, such as bars and tourist attractions, a thematic image or figurine of a man and woman or boy and girl may be used.
[3] In mainland China, silhouettes of heads in profile may be used as gender pictograms,[citation needed] generally alongside the Chinese characters for male (男) and female (女).
[12] Some contemporary designs for restroom signage in public spaces are shifting away from symbols that demonstrate gender as binary as a way to be more inclusive.