A huge treasure trove of ancient DNA from animals including extinct woolly mammoths has been discovered in frozen squirrel faeces in Canada’s remote Yukon territory, scientists said on Tuesday. The DNA found deep inside sealed-off burrows is between 3,000 and 700,000 years old, offering a rare window into how life has changed over the millennia. As well as DNA from woolly mammoths – which the US company Colossal claims it is trying to “de-extinct” – genetic material was also found from wolves,...