Rhitu Chatterjee

The number of people dying by suicide in the United States has risen by about 30 percent in the past two decades. And while the majority of suicide-related deaths today are among boys and men, a study published Thursday by the National Center for Health Statistics finds that the number of girls and women taking their own lives is rising.

Loneliness isn't just a fleeting feeling, leaving us sad for a few hours to a few days. Research in recent years suggests that for many people, loneliness is more like a chronic ache, affecting their daily lives and sense of well-being.

Now a nationwide survey by the health insurer Cigna underscores that. It finds that loneliness is widespread in America, with nearly 50 percent of respondents reporting that they feel alone or left out always or sometimes.

The head of the Environmental Protection Agency, Scott Pruitt, has proposed a new rule that restricts scientific research that can be used by the agency for its regulatory decisions.

The proposed rule only allows the use of studies that make all data publicly available for anyone to analyze. Pruitt proposed the new rule as a way to make the agency's decision-making more "transparent, objective and measurable."

Our ancestors in Kenya's Southern Rift Valley made some pretty innovative tools. And they made them far earlier than previously thought.

The oldest innovations were axes designed to be held in the palm of the hand. They were shaped like a tear drop, with a rounded end and a pointed eye. The edges were wavy and sharp. And they look as if they were great at chopping down branches — or chopping up the carcass of a large animal.

Archaeologists in Israel have discovered the oldest fossil of a modern human outside Africa. The fossil suggests that humans first migrated out of the continent much earlier than previously believed.