Evolutionary basis of the menstrual cycle

• Menstrual synchrony , of the kind observed in the McClintock study is thought by many to have an evolutionary value
• for our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant around the same time
• this would mean that newborns could be collectively cared for within a social group increasing the chances of offspring survival
• The validity of the evolutionary perspective has been questioned by some
• Jeffrey Schank (2004) has argued that if there were too many females cycling together within a social group, this would produce competition for the highest quality males (and lowering the fitness of any potential offspring)
• from this point of view the avoidance of synchrony would appear to be the most adaptive evolutionary strategy and therefore naturally selected