A planetary census puts humans in their place

BILLIONS of years ago a star began to die. In the process, it created something new: 65,500 billion tonnes of carbon that would later be incorporated into the nascent planet Earth. That carbon is still there, and nowadays a fair chunk of it makes up the bodies of living beings. A new study, published this week by Yinon Bar-On and others from the Weizmann Institute of Science, in Israel, provides a comprehensive estimate of how the Earth's carbon stock is distributed among its inhabitants. By est...