The agency sends warning letters to makers of products that claim to prevent or treat Alzheimer’s and other diseases, and announces changes to its enforcement practices.
If the structures identified in a 2.1-billion-year-old rock are really signs of burrowing organisms, it would push back the earliest known mobile organisms by 1.5 billion years.
Donald Trump announced a plan to drastically cut HIV transmission by 2030, but some scientists and nonprofits aren’t sure the administration will follow through.