News that a nurse in full protective gear had become infected with the Ebola virus raised some disturbing questions on Monday. Has the virus evolved into some kind of super-pathogen? Might it mutate into something even more terrifying in the months to come?

Evolutionary biologists who study viruses generally agree on the answers to those two questions: no, and probably not.

The Ebola viruses buffeting West Africa today are not fundamentally different from those in previous outbreaks, they say. And it is highly unlikely that natural selection will give the viruses the ability to spread more easily, particularly by becoming airborne.

Continue reading “Scientists Rein In Fears of Ebola, a Virus Whose Mysteries Tend to Invite Speculation” →

Invasive species are both a fact of life and a scientific puzzle. Humans transport animals and plants thousands of miles from where they first evolved — sometimes accidentally, sometimes intentionally. Many of those species die off in their new homes. Some barely eke out an existence.

But some become ecological nightmares. In the Northeast, emerald ash borers are destroying ash trees, while Japanese barberry is blanketing forest floors, outcompeting native plants. Scientists aren’t certain why species like these are proving superior so far from home.

Continue reading “Turning to Darwin to Solve the Mystery of Invasive Species” →

As much as we may try to deny it, Earth’s cycle of day and night rules our lives.

When the sun sets, the encroaching darkness sets off a chain of molecular events spreading from our eyes to our pineal gland, which oozes a hormone called melatonin into the brain. When the melatonin latches onto neurons, it alters their electrical rhythm, nudging the brain into the realm of sleep.

At dawn, sunlight snuffs out the melatonin, forcing the brain back to its wakeful pattern again.

Continue reading “The Evolution of Sleep: 700 Million Years of Melatonin” →