How should we judge the success of an animal? Philip S. Ward, a biologist at the University of California, Davis, offers what could be called the Picnic Test. “Have a picnic anywhere in the world,” he suggests. “Who would pick up the crumbs?”

Unless you happen to lay down your picnic blanket in Greenland, Antarctica, or a few remote islands in the Pacific, the answer will be ants. Ants have spread to just about every corner of earth’s dry land, colonizing virtually every imaginable ecosystem. By one rough estimate, there are 10,000 trillion ants on earth at any moment. In one study in a Brazilian rain forest, scientists discovered that the total mass of the ants that lived there was about four times greater than that of all the mammals, reptiles and amphibians combined.

Continue reading “Key to Ants’ Evolution May Have Started With a Wasp” →

We point to things without giving much thought to what a sophisticated act it really is. By simply extending a finger, we can let other people know we want to draw their attention to an object, and indicate which object it is.

As sophisticated as pointing may be, however, babies usually learn to do it by their first birthday. “If you don’t get that they’re drawing your attention to an object, they’ll get cross,” said Richard W. Byrne, a biologist at the University of St Andrews.

When scientists test other species, they find that pointing is a rare gift in the animal kingdom. Even our closest relatives, like chimpanzees, don’t seem to get the point of pointing.

Continue reading “Elephants Get the Point of Pointing, Study Shows” →

To Donald E. Canfield, there’s something astonishing in every breath we take. “People take oxygen for granted because it’s just there and we breathe it all the time,” said Dr. Canfield, a geochemist at the University of Southern Denmark. “But we have the only planet we know of anywhere that has oxygen on it.”

What’s even more astonishing is that the earth started out with an oxygen-free atmosphere. It took billions of years before there was enough of it to keep animals like us alive.

Although scientists have been struggling for decades to reconstruct the rise of oxygen, they’re still making fundamental discoveries.

Continue reading “The Mystery of Earth’s Oxygen” →

In 1987, the government of Thailand launched a huge, unplanned experiment. They built a dam across the Khlong Saeng river, creating a 60-square-mile reservoir. As the Chiew Larn reservoir rose, it drowned the river valley, transforming 150 forested hilltops into islands, each with its own isolated menagerie of wildlife.

Conservation biologists have long known that fragmenting wilderness can put species at risk of extinction. But it’s been hard to gauge how long it takes for those species to disappear. Chiew Larn has given biologists the opportunity to measure the speed of mammal extinctions. “It’s a rare thing to come by in ecological studies,” said Luke Gibson, a biologist at the National University of Singapore.

Continue reading “In Fragmented Forests, Rapid Mammal Extinctions” →

The name Myllokunmingia may not ring a bell, but it is worth knowing. This 520-million-year-old creature was the size of a guppy, with a tiny swordfish-like fin running high over its back. The fossils it has left behind preserve traces of a skull.

Humans have a skull, too. This and a number of other traits we share with Myllokunmingia reveal it to be one of the oldest, most primitive vertebrates yet found. It is, in other words, a hint of where we came from.

Myllokunmingia emerged during one of the most important phases in the history of life, an evolutionary boom known as the Cambrian explosion (named for the geological period when it took place).

Continue reading “New Approach to Explaining Evolution’s Big Bang” →