The accepted timeframe for the beginnings of life on Earth is now being questioned, after scientists found a key indicator to the earliest life forms in diamonds from Jack Hills in Western Australia. The 4.2 billion-year-old diamonds found trapped inside the Jack Hills zircon crystals are the oldest-known samples of Earth’s carbon. The team’s discovery of very high concentrations of carbon 12, or “light carbon” within these crystals is remarkable as it is a feature usually associated with organic life.