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” →

In the early 1920s, farmers in New Jersey noticed their potatoes were shriveling, their leaves becoming deformed. The plants were sick with an illness that came to be known as potato spindle tuber disease. But it took almost five decades for someone to find the cause.

In 1971, Theodor O. Diener, a plant pathologist at the Department of Agriculture, discovered that the culprit is an inconceivably tiny pathogen — one-80th the size of a virus. Dr. Diener called it a viroid.

Since Dr. Diener’s initial discovery, scientists have identified nearly three dozen species of viroids that attack crops from tomatoes to coconuts, as well as flowers such as dahlias and chrysanthemums.

Continue reading “A Tiny Emissary From the Ancient Past” →