Imagine the forests of Chilean Patagonia: wet and cold, dense with monkey puzzle trees and other hardy conifers. Now imagine it with dinosaurs walking around. And on fire. This is what Antarctica was like 75 million years ago during the Cretaceous period, an era known by researchers as a “super
Sean O’Keefe, the NASA administrator who named the telescope in 2002, said in an email that Webb was “a champion of education, technology, science, aeronautics and human exploration.” “Arguably, were it not for James Webb’s determination to fulfill the most audacious vision of his time, our capacity to explore today
The authors of the new paper intentionally chose to invite only active practitioners of ancient DNA research, according to Kendra Sirak, a paleogeneticist at Harvard Medical School and one of the authors. They also emphasize that these guidelines come from a particular group of scholars in the ancient DNA community.
Upending centuries of medical dogma, a team of South African researchers has found that breathing may be a bigger contributor to the spread of tuberculosis than coughing, the signature symptom. As much as 90 percent of TB bacteria released from an infected person may be carried in tiny droplets, called
The death of former Secretary of State Colin Powell on Monday from complications of Covid-19 has provided fuel for vaccine skeptics and opponents, who immediately seized on the news that Mr. Powell had been vaccinated to stoke doubts about the effectiveness of the vaccines. But Mr. Powell’s immune system had
After a brutal summer surge, driven by the highly contagious Delta variant, the coronavirus is again in retreat. The United States is recording roughly 90,000 new infections a day, down more than 40 percent since August. Hospitalizations and deaths are falling, too. The crisis is not over everywhere — the