As biological research races forward, ethical quandaries are piling up. In a report published Tuesday in the journal eLife, researchers at Harvard Medical School said it was time to ponder a startling new prospect: synthetic embryos.

In recent years, scientists have moved beyond in vitro fertilization. They are starting to assemble stem cells that can organize themselves into embryolike structures.

Soon, experts predict, they will learn how to engineer these cells into new kinds of tissues and organs. Eventually, they may take on features of a mature human being.

Continue reading “A New Form of Stem-Cell Engineering Raises Ethical Questions” →

Human skeletons and archaeological remains in Australia can be traced back nearly 50,000 years before the trail disappears. Before then, apparently, Australia was free of humans.

So how did people get there, and when? Where did humans first arrive on the continent, and how did they spread across the entire landmass?

Answers to some of these questions are stored in the DNA of Aboriginal Australians. A genetic study of 111 Aboriginal Australians, published on Wednesday, offers an interesting — and, in some respects, unexpected — view of their remarkable story.

Continue reading “How Did Aboriginal Australians Arrive on the Continent? DNA Helps Solve a Mystery” →

They are microscopic artwork: tiny tubes and long filaments, strange squiggles etched into some of the most ancient rocks known.

On Wednesday, researchers reported that these may be the oldest fossils ever discovered, the remains of bacteria thriving on Earth not long, geologically speaking, after the very birth of the planet. If so, they offer evidence that life here got off to a very early start.

But many experts in the field were skeptical of the new study — or downright unconvinced.

Continue reading “Scientists Say Canadian Bacteria Fossils May Be Earth’s Oldest” →

Every continent save Antarctica is ringed by vast stretches of seagrass, underwater prairies that together cover an area roughly equal to California.

Seagrass meadows, among the most endangered ecosystems on Earth, play an outsize role in the health of the oceans. They shelter important fish species, filter pollutants from seawater, and lock up huge amounts of atmosphere-warming carbon.

The plants also fight disease, it turns out.

Continue reading “Disappearing Seagrass Protects Against Pathogens, Even Climate Change, Scientists Find” →

Over the years, scientists have come up with a lot of ideas about why we sleep.

Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators.

A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day.

Continue reading “The Purpose of Sleep? To Forget, Scientists Say” →