Leap seconds have helped keep clocks synchronized with Earth’s rotation, but their time is now over – here’s why
300 glaciers have disappeared from the American West since the mid‑20th century – the survivors have a few things in common
Read More 4 minute read History 1.5 million-year-old bone tools discovered in Tanzania rewrite the history of human evolution Jackson K. Njau, Indiana University The ancestors of humans started making tools about 3.3 million years ago. First… byJackson NjauMay 6, 2025