cons

• in Aschoff and weaver and siffre artificial light was not deprived only natural
• mcclintock- 38% didnt, debates over humans can smell pheremones, small sample size
• Schank (2004)

  Infradian and ultradian rhythms - limitation of evolutionary theory:If too many females cycled together, would produce competition for highest quality males; avoidance of synchrony would appear to be better adaptation for real life menstrual cycle.
• Trevathan (et al. 1993)Explain thisInfradian and ultradian rhythms - limtation:Stern and McClintock's research has not be replicated; no evidence for menstrual synchrony.
• Miles (et al. 1977)

  Exogenous zeitgebers - limitation:Reported case of man who was blind from birth, with a circadian rhythm of 24.9hrs; unable to adjust despite social cues.