Sex is biologically expensive, so why did evolution keep it? Harvard scientists put the question to yeast

Harvard researchers studying yeast have found evidence that sexual reproduction can provide an evolutionary advantage, particularly when environments change. Across 960 generations, sexually reproducing yeast populations became fitter than asexual populations and performed better under shifts in temperature, salinity, acidity and phosphate levels. Scientists suggest sexual reproduction helps reshuffle genes, separating beneficial mutations from harmful genetic “baggage” that can accumulate through asexual reproduction. The findings offer new experimental insight into why sex persists despite its evolutionary costs.