This file includes the original data of the ‘Human rating of female fecundity’ experiment. ‘observerID” refers to the 77 participants of the study, ‘order’ refers to the order in which they rated the duos of females, ‘duoIDwithin’ is the ID of each female duo within replicates, and ‘correct’ is the outcome of whether the high-fecundity female was correctly identified by the observer (0=no, 1=yes).