During a woman’s menstrual cycle, she is more biased against men of different ethnicities and social groups than her own, if she finds them physically threatening.
Men of a different ethnicity or social group, when perceived as physically intimidating, have a negative impression on women. But when a man is of the same ethnicity or social group they have a positive impression, even if they are also physically intimidating, says researchers from Michigan State University.
The prejudice may be a biological development, designed to protect against sexual coercion by male “invaders”, which has been a problem throughout history.
Read more at Michigan State University