Daddy doomed? With fewer little swimmers, cloning could be the future
It's something else to worry about. On top of global warming, drought and flooding, a hole in the ozone layer, a rise in burglaries, the ash tree disease and the fact we're all broke, it now appears our very existence is under threat.
Sperm counts are falling, meaning our ability to have children is lessening by the day.
A French study has found that the reproductive health of the average male is in sharp decline.
Researchers from the Institut de Veille Sanitaire, St Maurice, used data from 126 fertility clinics and found the concentration of sperm per millilitre of semen declined from 73.6 million in 1989 to 49.9 million in 2005.
It doesn't mean the average man is becoming infertile. There are just fewer swimmers in the pool.
But does it mean that men will become redundant in the reproductive process? Will children be bred, and not born?
The findings come on top of numerous other research projects which have found sperm counts declining across the globe.
There's lots of theories why – use of herbicides and pesticides. Oestrogen in the water from so many women taking the pill. Less exercise, smoking and drinking, and wearing tight pants.
Professor of Reproductive Health at the University of Edinburgh, Richard Sharpe, described the research as "hugely impressive", saying it was "time for action" to find out what's causing the problem.
But what's the problem? The global population is booming, more than doubling in the last half century. It hit seven billion last year, says the UN, up from three billion in 1959.
By 2083, some 10 billion are expected to share the Earth. A few misfiring Frenchmen won't stop that.
Besides, fewer people means less pressure on resources, resulting in less global warming. Can fewer children be a bad thing?
Sometimes. The problem is the children are being born in the 'wrong' countries.
Belgium, Bulgaria, Italy and the Russian Federation are all named by the UN as having 'below replacement' fertility rates.
That means that if people stopped migrating to those countries, the population would steadily fall as the birth rate declined.
Ireland was on the list in the mid-1990s, but now has the highest birth rate in the EU.
The ESRI, a think-tank says we are 'close' to the level required for the long-term replacement of the population.
But close isn't enough. If our men aren't up to the job, how are we going to get those workers? Are males about to become extinct – is human cloning the answer to our low birth-rate?
Reproductive cloning takes DNA from the donor, and transfers it into an egg which has had its nucleus, and therefore most of its own genetic material, removed.
Sperm is not involved, meaning no need for the man.
It's not a new idea. Film and literature have long portrayed cloning as a reality.
Need a kidney? Use your clone (Kazuo Ishiguro's 2005 novel Never Let Me Go). There's neither war nor want in Aldous Huxley's Brave New World (1932) where the global population is capped at two billion and children are 'decanted' and raised in 'hatcheries'.
It's already been done with animals. The first cloned being was Dolly the sheep, born in 1997 at the Roslin Institute in Edinburgh, Scotland.
But although some therapeutic cloning is permitted – using DNA to create stem cells to grow replacement organs or help create treatments for Parkinson's or Alzheimer's – reproductive cloning is illegal in most countries. There hasn't been any confirmed human clone created to date.
It's probably a good thing, as horror stories abound of clones with birth defects.
Dolly was cloned after more than 250 attempts. She died at six – about half her expected life expectancy – and developed premature arthritis and a lung disease found in older animals.
But don't fret. The science of cloning isn't proven, and probably won't be for some time, meaning men will be needed for the foreseeable future.