Eco-photos of the week: July 5-11

The Soay live on the remote island of Hirta in the North Atlantic, where brutal winters normally kill off the smaller, leaner lambs in favor of their heftier kin — natural selection in action. But the average female sheep there has shrunk by about three ounces per year since 1985. A study published by the journal Science offers an intriguing theory why: climate change. At the same time the sheep have been shrinking, Hirta has been getting warmer — fall lasts longer and spring comes earlier, meaning those little lambs have a better shot at surviving and passing on their diminutive genes. (Text from The Daily Briefing)