Why nature gave us sex

<body leftmargin="0" bgcolor="#000060" text="#FFFFFF" link="#FFFF00" vlink="#FF9900"> <b> <p class="MsoNormal"><font face="Arial" size="5">Why nature gave us sex</font></p> </b> <p class="MsoNormal"><font face="Arial" size="1">Posted April 9, 2005<br> Courtesy Nature<br> and World Science Staff<br> </font> <b> <font size="2" face="Arial"><br> Why do we bother with sex? Although it seems obvious to us, it’s a longstanding puzzle to biologists why nature favors this mechanism of reproduction, at least for most advanced organisms.<br> <br> Sex is time-consuming, exhausting, even dangerous. The genetic jumbling involved means that favorable combinations of genes are forever at risk of being broken up. Also, the fact that sexual organisms must pair up to create each offspring makes them reproduce half as fast as competing creatures who can reproduce without sex.<br> <br> Nineteenth-century scientists proposed that sex is sustainable because it allows faster evolution, but no one had ever proved them right. </font></b> </p> <p class="MsoNormal"><b><font face="Arial" size="2">But new evidence backs up the theory, researchers say.<br> <br> When the going gets tough, yeast that have sex are much better at adapting to conditions than their non-sexy counterparts, a new study has found. The study, by Matthew R. Goddard of the University of Auckland, New Zealand, and colleagues, was published in last week’s issue of the research journal <i>Nature</i>. <br> <br> The researchers created a mutant strain of yeast that cannot divide into sexual spores. In stress-free conditions, the mutant strain performed as well as normal yeast. But at higher, more stressful temperatures, the sexually reproducing yeast showed a far better increase in growth rate than the mutants as the experiment progressed.<br> <br> This hints that sex does indeed come in handy when it comes to survival of the fittest, as the genetic shuffling may allow a greater chance that a useful suite of genes will come together. <br> <br> But the study fails to answer all the conundrums of mammalian sex, such as why females let males get away with making such small, cheap sex cells, the researchers said. “We are still far from a definitive answer to the question of why sexual reproduction is so common,” wrote Rolf F. Hoekstra of Wageningen University, The Netherlands, in a commentary in the journal. </font></b> </p> </body>