Infradian Rythms

Question 1

Supporting evidence for the role of pheromones as an exogenous zeitgeber in the control
of the menstrual cycle

Answer 1

Supporting evidence for the role of pheromones as an exogenous zeitgeber in the control
of the menstrual cycle is provided by Russell et al. (1980) Daily samples of sweat were collected from one group of women by placing cotton pads under the armpits of donors for 24 hours. The sweat was then rubbed on the upper lips of other women. Over a number of months, each recipient’s menstrual cycle became synchronised with their donor. This suggests that pheromones in sweat can act as an exogenous zeitgeber that entrains the infradian rhythm of the menstrual cycle. These findings lack validity…

Question 2

…However, there is conflicting evidence for the synchronisation of menstrual cycle due to
pheromones.

Answer 2

Schank (2006) found with Chinese university students that there is no evidence beyond chance that women synchronise their cycles. The perception of synchrony is therefore
due to the inevitable variation of menstrual cycles which leads to menstrual cycles coinciding
and there is no actual effect of pheromones on synchronisation.

Question 3

Research into the menstrual cycle suggests the infradian rhythm is deterministic, which has
legal implications

Answer 3

Research into the menstrual cycle suggests the infradian rhythm is deterministic, which has legal implications. There is irrefutable scientific evidence that the female menstrual cycle is controlled by hormones (endogenous pacemakers) to prepare the body for pregnancy. A consequence of the menstrual cycle is pre-menstrual syndrome (PMS). The aggressive tendencies of women undergoing PMS has been used as a legal defence, as it has been argued that PMS can strongly influence biological processes and therefore individuals should not be held responsible for their actions. This has moral implications as it suggests that women do not have complete free will or control over their own behaviour.