New World monkeys do not show genital swelling during ovulation as female Old World monkeys do. Instead, a lack of female aggression towards males can serve as a signal of ovulation. Scent glands on its chest, anus, and genitals are also rubbed on surfaces which leave chemical signals about the reproductive state of the female.[27] The pygmy marmoset also performs visual displays such as strutting, back-arching, and piloerection when it feels threatened or to show dominance.[28]