Here are some of the most interesting research papers to have appeared in top science journals last week. (Subscribe to Science For All, our weekly newsletter, where we aim to take the jargon out of science and put the fun in. Fossil plant studyPublished in PNASAbout 14,500 to 5,000 years ago, North Africa was green with vegetation and the period is known as the Green Sahara or African Humid Period. Now, a study of pollen and leaf waxes extracted from sediments have shown that there were two monsoon systems. "We found that even one-hour earlier sleep timing is associated with significantly lower risk of depression."

Source: The North Africa Journal June 02, 2021 11:15 UTC