Free Stripping Down Science by Chris Smith, Dr Christorpher Smith Page B

t-shirts that had been worn by four non-pill-using women for three nights at points straddling the time when ovulation occurs in the middle of their cycles.
    The men were also asked to smell a second set of t-shirts that had been worn by the same women, also for three nights, but this time towards the ends of their cycles (days 20 to 22), when fertility is low. A set of unworn t-shirts were also included as controls, and the women were asked, for the duration of the study, to use only neutral-smelling soaps and to avoid wearing perfumes or consuming foods with strong odours, like garlic or onions.
    Before and after the men smelled the shirts, saliva samples were collected from each of them to measure their testosterone levels. They were also asked how ‘pleasant’ they found the shirt odour to be in each case. The results revealed that the men were rating the smells of the shirts worn around the time of ovulation (days 13 to 15) as much more pleasant. Moreover, the average post-sniff testosterone level was also significantly higher than when the men smelled control shirts or shirts worn by the women towards the endsof their cycles. So something in the shirts was peaking the men’s sexual interests and provoking a libido-boosting burst of testosterone when the women were ovulating and most likely to conceive. Women, it seems, chemically augment their allure at certain times of the month.
    This fits with the findings of Geoffrey Miller’s lap dancer study (see previous chapter), in which scientists showed that lap dancers earn over 200% more in tips during their most fertile days. At the time of this earlier study, it wasn’t clear whether the fiscal boost was just because the lap dancers were making themselves look more appealing or had sexier-sounding voices when they were at their most fertile. Now it looks like it was at least partly down to smell.
    From an evolutionary standpoint, the results are exactly what we would expect: women exude some sort of pheromonal smell signal to broadcast their fertility to men who, in turn, as Miller and Maner put it, manifest ‘mating-related behaviour’. By which, presumably, they mean a sudden inability to speak coherently coupled with the urge to drink too much, turn up the stereo to ‘11’ and perform outlandish macho displays and skateboard stunts. And that’s just the over-60s …

Most people assume, correctly, that flowers look the way they do to attract insects that pollinate them. But that’s not the whole story. Scientists have now discovered that plants have another ‘trick up their leaves’ to make themselves irresistible to even the most choosy insect – solar power.
    Cambridge University’s Beverley Glover and her colleagues 34 recently set up some fake flowers filled with a sugar solution, which they kept at different temperatures. Unleashing a team of bumblebees on their floral offerings, they watched as the insects visited the flowers to drink the surrogate ‘nectar’. Very quickly, it became obvious that the bees were concentrating on the flowers with the warmest nectar. Just in case it was something to do with the colour of the fake flowers, the scientists also tried a different colour combination – and got the same result.
    This proved that bees like their nectar hot, irrespective of the colour of the cup it’s served in. But can flowers dish up hot beverages? ‘Yes,’ say the scientists, who have found that the surfaces ofover 80% of flowers are covered with tiny conical-shaped cells which behave like microscopic lenses. These focus sunlight, warming up the flower and its nectar by several degrees. As the sun moves across the sky, the flower head moves too, keeping a fix on the sun like the dish of a radar tracking station.
    But why would bees be interested in a warm drink anyway? Well, flight is an energy-hungry business, and by drinking hotter nectar the bee keeps warm for