According to Professor Win Vandebergh and his colleagues at the University of Brussels, the cytoskeletal proteins that evolved to help the tree frog Hyla cinera cling to wet surfaces in its niche environment also passed down to mammals and eventually to us.
Chris Wick, from the Environment Agency, said landfill sites generated gas when waste broke down but 2012 had been exceptionally wet and it was believed heavy rain had increased the gas produced.