Researchers have recently focused on DNA sequences as a means for determining the evolutionary history of both viruses and their host organisms. To discover when mammals were first infected by them, a team of scientists scanned the genomes of all mammals. They searched for common DNA sequences that they interpret as having come from a retrovirus that entered mammals long ago.

Monarch butterflies have fascinated biologists for a long time. A 3,000-mile road trip in even the most comfortable car would prove daunting to many humans, but these beautiful insects can migrate that same distance every year from Canada to a specific grove of fir trees in Mexico each fall. The next generation of monarchs can then travel back to Canada in the spring.

A new species of chimaera found in Californian waters has been given a name. Chimaeras are bizarre cartilaginous fish with features that stand out among other fish. What also stands out is their lack of evolutionary change over supposed eons of evolutionary time.

Pandas face a difficult future, despite great efforts to preserve them. With their dwindling population, shrinking habitat, and weakening genetic strength, one evolutionist has suggested that these longstanding symbols of the World Wildlife Federation (WWF) should be allowed to die out.

Ardipithecus ramidus is an extinct primate whose fossilized remains were first found along the Awash River in Ethiopia about 15 years ago. Many fragments were collected, including shattered bones from a four-foot-tall female nicknamed "Ardi." She was chosen to represent her kind, apparently because of the comparative completeness of her remains.