Scientists age-dated a cache of stone-tipped throwing spears unearthed from Ethiopia's Gademotta Formation at 280,000 years old. This find appears to pierce the conventional story of human evolution—a narrative about modern man evolving from some pre-human type only 200,000 years ago. How will this date discrepancy be resolved?

Scientists recently ran experiments to determine what happens when excess nucleotides are present during DNA replication.¹ In normally functioning living things, each newly formed cell receives all the freshly minted DNA it needs. But DNA copying (replication) requires manufacturing a new chromosome based on the template of an existing one—a complicated task.