Bbc Inside Science

Y Chromosome We learn from a young age that if a fertilised egg carries XX chromosomes it will be a girl, but with XY it will be a boy. This male Y sex chromosome has lost many genes along its evolution over the past 180 million years and now only about 20 genes remain. Now two new studies in Nature journal have given clues into how the Y chromosome evolved into its current state by looking at the genetic make up of 15 species the team built an archaeological record of all the mutations that occurred over time - to trace the timing of how the Y originated.... Professor Henrik Kaessmann from the University of Lausanne in Switzerland explains that the genes that remain play a more important role than previously believed.Everest Avalanche Last week the biggest single loss-of-life event occurred on Everest: a huge avalanche killed 16 Sherpa guides. All were so-called "icefall doctors", possibly the riskiest job of all, which involves finding a route through the broken mass of icefall, and then securing ladders a