After ovulation, women are not only at their most fertile, they are more adept at spotting snakes, too. Useful if you're in the Outback, not so useful in Britain.
Japanese primatologists from Kyoto University, claim that when women are in the ‘luteal phase’ of their menstrual cycle (after ovulation), their fear reflexes are stronger, meaning they’re better at detecting snakes and other potentially dangerous things.
Researchers came to their conclusion after running a series of tests on 60 healthy women of childbearing age during three different stages of their menstrual cycle.
They wanted to investigate whether fluctuating mood, cognition and social behaviour influenced a woman’s fear factor.
The female participants were tested on how quickly they responded to spotting a snake in photographs. Those who detected them the fastest were at the post-ovulation stage of their menstrual cycle.
The ‘luteal cycle’ (or premenstrual stage) begins just after ovulation, the time a woman is at her most fertile. This causes fluctuating estradiol and progesterone hormones that influence the amygdala, the brain region responsible for feelings of fear and anxiety.
Scientists believe that women are quicker at detecting danger just before their period as its nature’s way of heightening a woman’s sense of fear to keep them safe for pregnancy, or make them feel protective towards their baby if they are already pregnant.
"It could contribute to women's ability to increase their vigilance towards biologically relevant threatening stimuli around themselves during this period of possible pregnancy,” researchers said in the paper, published in the Scientific Reports.
Other strange ways women are affected by their menstrual cycle:
Menstruating makes women think more like men
During a woman’s period, her levels of oestrogen dip and testosterone increase. This means her behaviour, voice and mannerisms are subconsciously more 'male' than usual.
Stress influences regularity of periods
A woman’s brain responds to nerve-racking events by releasing stress hormones that can interfere with those regulating her cycle, resulting in irregular periods or shorter cycles
Periods increase libido
Many women find their libido goes through the roof when on their period. This is because the levels of progesterone are low during menstruation (these are usually blamed for dampening libido) resulting in a higher sex drive.