It isn't size that counts
It's the question that drives fear into the hearts of most men: does size
really matter? Is bigger always better?
good DNA and strong swimming ability. Volume also helps, so human men redeem themselves thanks to the fact they produce 60million of the little blighters per ejaculation compared with the fruit fly's paltry 1,000.
Still, only one sperm will reach its goal so it's a case of quality over
quantity. 'No one knows why so much is produced,' says Holt. 'Sorne species
mate with many partners so it's a bit like a
lottery: the more tickets
you have, the higher your chance of winning. Even so, if the DNA is no
good, then it doesn't matter how much there is.' Despite a high production
rate, it looks like spermatology is yet another biological fact men can feel
insecure about. 'Humans have bad sperm,' says Holt 'They have lots of abnormally
shaped sperm and a lot of the DNA is damaged. Having said that, the female
is very efficient and won't let the bad sperm get anywhere near the egg.'
Yet another example of the female of the species outdoing the males.
· Spermatology, an exhibition at London Zoo, runs from now until August 2005.
Bad for Boys
Modern life is making men sterile. First it was laptops then, last week it was mobile phones, with a report saying men who carried them in pockets lowered their sperm count by as much as 15per cent. But don't give technology too bad a rap, says JAMIE WALTERS. There are many influences that take far more lead out of your pencil. So read on before you ditch your phone.
Sperm enjoy good nosh and need a number of nutrients for optimum
Tap water makes a surprise entry here. 'The water supply contains a number of gender-bending chemicals these days,' says Prof George Lewith, a complementary medicine expert from Westminster University. 'For instance, oestrogen - which enters the water system through women's urine [and is on the increase thanks to the widespread use of the contraceptive pill). As only bacteria gets filtered out during the cleaning process, this hormone remains and is probably having an effect on male fertility.'
What about booze? At moderate levels, there's no problem. But drink beyond the recommended 21 units a week and, according to DR stuart, the body will be stripped of key nutrients,particularly folic acid and zinc, both important for sperm
No surprises this makes the list. Sperm don't like toxins m general and cigarette smoke is packed full of them. 'Smoking appears to have a negative effect on sperm count and mops up a lot of the micronutrients and antioxidants needed for healthy effective sperm,' says Prof Lewith. Dr Downing goes a step further, saying: 'Heavy metals such as cadmium have the effect of reducing sperm count and tobacco contains relatively high levels of this. The leaves also tend to be treated with pesticides and this reduces the health and number of your sperm.'
It's another shock inclusion but we're not saying it's bad for you.
Some research has shown, however, that exercise can be bad for fertility when done at excessive levels. 'Scientists are not sure why but heavy exercise seems to lead to a drop in sperm count,' says Prof Lewith. So don't go overboard on the weights when you're at the gym. Equally, make sure you wear unrestrictive clothing. 'Jockey shorts or any tight underwear will keep your testicles at too high a temperature [sperm like a cooler environment than the rest of your body), and can do damage,' says Lewith. 'Also, don't have too many hot baths as this will have a similar effect.' So communal baths after sport: no. Showers: yes.
They're not big, they're not clever and sperm won't thank you for taking them. Much like alcohol, they can have the effect of stripping your body of essential nutrients - at least the stimulants do. 'The likes of cocaine, amphetamines and even caffeine increase the amount of adrenaline in the system and cause the body to flush out various micronutrients,' says Dr Downing. 'This depletes your body of the nutrition it needs too keep sperm healthy. If you're on heroin, you tend not to eat so become nutrient-deficient that way. Meanwhile, marijuana smoked with tobacco will give you many of the same problems as cigarettes.' So remember kids, just say no.
** His Brain, Her Brain
On a gray day in mid-January, Lawrence Summers, the president of Harvard University, suggested that innate differences in the build of the male and female brain might be one factor underlying the relative scarcity of women in science. His remarks reignited a debate that has been smoldering for a century, ever since some scientists sizing up the brains of both sexes began using their main finding--that female brains tend to be smaller--to bolster the view that women are intellectually inferior to men.