Birds evolved from dinosaurs 150 million years ago, a slow but thorough transformation. Their bodies gained aerodynamic feathers, their digits fused into wings, and they acquired a beak used to gather food.

We can see some details of this evolutionary marvel in the fossil record. Yet even the most exquisitely preserved fossil can’t tell us which pieces of DNA had to change in order to turn ground-running dinosaurs into modern birds.

Some researchers are now trying to pinpoint those genetic changes with experiments on chicken embryos. If the scientists succeed, they should eventually be able to reverse the evolution of birds — and then they may be able to engineer animals more at home in “Jurassic Park” than in a henhouse.

Continue reading “Reverse Engineering Birds’ Beaks Into Dinosaur Bones” →

Unlike bacteria, humans have big, complex cells, packed with nuclei containing DNA and mitochondria that produce energy. All so-called eukaryotes share our cellular complexity: animals, plants, fungi, even single-celled protozoans like amoebae.

Scientists estimate that the first eukaryotes evolved about 2 billion years ago, in one of the greatest transitions in the history of life. But there is little evidence of this momentous event, no missing link that helps researchers trace the evolution of life from simple microbes to eukaryotes.

Continue reading “Under the Sea, a Missing Link in the Evolution of Complex Cells” →

Climate change could drive to extinction as many as one in six animal and plant species, according to a new analysis.

In a study published Thursday in the journal Science, Mark Urban, an ecologist at the University of Connecticut, also found that as the planet warms in the future, species will disappear at an accelerating rate.

“We have the choice,” he said in an interview. “The world can decide where on that curve they want the future Earth to be.”

Continue reading “Study Finds Climate Change as Threat to 1 in 6 Species” →

Our genomes are riddled with the detritus of ancient viruses. They infected our hominid ancestors tens of millions of years ago, inserting their genes into the DNA of their hosts.

Today, we carry about 100,000 genetic remnants of this invasion. So-called endogenous retroviruses make up 8 percent of the human genome.

Mostly, these genetic fragments are generally nothing more than molecular fossils. Over thousands of generations, they have mutated so much that they cannot replicate in our cells. And our cells keep the viral DNA muzzled to minimize the harm it might cause.

Continue reading “Ancient Viruses, Once Foes, May Now Serve as Friends” →

In 1998, Dr. Philip A. Starr started putting electrodes in people’s brains.

A neurosurgeon at the University of California, San Francisco, Dr. Starr was treating people with Parkinson’s disease, which slowly destroys essential bits of brain tissue, robbing people of control of their bodies. At first, drugs had given his patients some relief, but now they needed more help.

After the surgery, Dr. Starr closed up his patients’ skulls and switched on the electrodes, releasing a steady buzz of electric pulses in their brains. For many patients, the effect was immediate.

Continue reading “Clues to How an Electric Treatment for Parkinson’s Works” →