In more than 1,500 animal species, from crickets and sea urchins to bottlenose dolphins and bonobos, scientists have observed sexual encounters between members of the same sex.

Some researchers have proposed that this behavior has existed since the dawn of the animal kingdom. But the authors of a new study of thousands of mammalian species paint a different picture, arguing that same-sex sexual behavior evolved when mammals started living in social groups. Although the behavior does not produce offspring to carry on the animals’ genes, it could offer other evolutionary advantages, such as smoothing over conflicts, the researchers proposed.

In the 1970s, soft-shell clams started mysteriously dying off in Maine and the Chesapeake Bay. Years later, scientists identified the culprit: a bizarre form of cancer that spread like an epidemic.

When people get cancer, it typically arises when some of their own cells gain mutations and multiply out of control. But the clams were being invaded by free-floating cells that came from other clams. The alien cancer cell multiplied inside its new victim, and then some of its descendant cells escaped to attack other clams.

Continue reading “Bizarre Cancer Has Been Spreading Among Shellfish for Centuries, Studies Find” →

It’s been about 250 million years since reptile-like animals evolved into mammals. Now a team of scientists is predicting that mammals may have only another 250 million years left.

The researchers built a virtual simulation of our future world, similar to the models that have projected human-caused global warming over the next century. Using data on the movement of the continents across the planet, as well as fluctuations in the chemical makeup of atmosphere, the new study projected much further into the future.

Continue reading “Mammals’ Time on Earth Is Half Over, Scientists Predict” →

Nearly half a million years ago, humans in Africa were assembling wood into large structures, according to a study published Wednesday that describes notched and tapered logs buried under sand in Zambia.

The discovery drastically pushes back the historical record of structural woodworking. Before, the oldest known examples of this craft were 9,000-year-old platforms on the edge of a British lake.

Ancient wood products are extremely rare because the organic material typically degrades over thousands of years, said Annemieke Milks, an archaeologist at the University of Reading who was not involved in the new study, which appeared in the journal Nature. “It almost never preserves,” she said.

Continue reading “Ancient Logs Offer Earliest Example of Human Woodworking” →

No place on the planet has escaped the influence of Homo sapiens, from the rainforests cleared for farms to microplastic-laced deep oceans to climate-altered jet streams. Last November, the world population reached 8 billion.

But as omnipresent as humans may be today, a team of scientists now claims that our species came very close to never appearing at all.