How to beat jet lag: don't eat, researchers suggest.

In addition to the light-driven circadian clock that regulates the body in response to changes in night and day, the mouse brain contains a second, separate clock that keeps track of mealtime, scientists say.

This clock, which resides in a different brain structure than the light-driven clock, probably takes over when food is scarce, changing the animals' behavior patterns so that they don't sleep through an opportunity to eat.

Sniffing out the identities of mice

New research shows how mammals use their sense of smell to detect complex signals in urine that convey information about gender, strain, and the social and reproductive status of individual animals. In mice, an organ in the nose called the vomeronasal organ detects chemicals that trigger behavioral responses and transmits the corresponding signals to the brain.

When sand dollar larvae sense mucus produced by nearby predator fish, they start cloning themselves, scientists have found. The clones are smaller than regular larvae, which may give them an advantage because they are more difficult for the fish to detect.

While larval cloning is well-documented in echinoderms, itʼs generally been thought of as a means to improve growth and reproduction, not as a defense against predators.

The study offers some insight into the evolution of modern human populations in small geographic areas as well as their initial spread throughout the world. For instance, the researchers were able to tease apart the genetic ancestries of eight different European groups and four groups in the Middle East. Their data set also supports an “out of Africa” model for the spread of the first modern humans, who colonized the rest of the world in stepping-stone fashion after leaving Africa. Genetic variation within populations accounts for most of human genetic diversity, the researchers confirm, but they also suggest that there is enough between-population variation to delineate and compare human populations on a fine scale.

The analysis of the rhesus macaque monkey shows that it shares about 93 percent of its DNA with chimps and humans, but that the three species have some significant differences among their genes.

The macaque monkey is widely used for laboratory studies. Researchers say their work will enhance medical research in a wide range of areas, including HIV and neuroscience.

It will also advance scientists' understanding of primate evolution, and how humans are genetically different from our primate relatives.