Science briefs: Incoming humans may have doomed Neanderthals

We may have doomed the Neanderthals

Neanderthals went extinct about 40,000 years ago. We're not exactly sure what led to their demise, but climate change and competition over prey from Homo sapiens may have played roles.

Another thing that may have helped kill off the Neanderthals in Europe? Infectious diseases, carried by humans who left Africa and made their way to Europe.

That's according to researchers at Cambridge and Oxford Brookes universities who analyzed ancient DNA and pathogen genomes. They published their findings in the American Journal of Physical Anthropology.

"Humans migrating out of Africa would have been a significant reservoir of tropical diseases," said lead author Charlotte Houldcroft of Cambridge. "For the Neanderthal population of Eurasia, adapted to that geographical infectious disease environment, exposure to new pathogens carried out of Africa may have been catastrophic."

Dinosaurs were in decline long before the Chicxulub asteroid finished them off.

Sixty-five million years ago, a massive asteroid slammed into Earth, causing tsunamis, earthquakes, fires, a global winter and the end of the age of the dinosaurs.

New research suggests the answer is probably not. Instead, scientists have found evidence that dinosaurs were in the midst of a long, slow decline that began millions of years before the asteroid struck.

In a study published in the Proceedings of the National Academy of Sciences, researchers report that at least 40 million years before the Chicxulub asteroid landed in Mexico, dinosaur species were going extinct at a higher rate than new ones were coming into existence. With less species — and less variation in habitat requirements and ecological niches — dinosaurs would be more susceptible to environmental changes, the authors write.

Only a keen-eyed observer can spot the rare yellow-eyed penguin in the impenetrable forest hills that hug New Zealand's South Island beaches.

Incredibly shy, the yellow-eyed penguin is truly odd. Measuring just over 2 feet tall, with striking yellow eyes and a yellow band across its head, it is the rarest species of penguin. It is also severely endangered.

On average, only 18 of 100 penguin chicks survive their first year at sea. A decade ago, the population was estimated at 6,000. Today, conservationists reckon that only 2,000 yellow-eyed penguins are alive.