Gorillas learn to play fair by playing tag

There's more to an innocent game of tag than meets the eye. When gorillas play the playground favourite, it teaches them a valuable life lesson about unfairness, social boundaries and retaliation. That, at least, is the conclusion of the first study to observe the primates' reactions to inequity outside a controlled laboratory setting.

Young gorillas often engage in play fights that resemble what children do in a game of tag: one youngster will run up to another and hit it, then run away. The other gorilla then gives chase and hits the first one back (see video, above).

Marina Davila-Ross of the University of Portsmouth, UK, and colleagues studied video footage of six groups of gorillas in zoos. Twenty-one juveniles – both males and females – were observed chasing one another in a total of 86 games.

They found that the gorilla that did the hitting almost always moved to run away before its victim started moving. The researchers argue that this means the hitter is expecting retaliation and has therefore learned something about acceptable social behaviour.

It was a different story, however, when the gorillas played the game more gently, grabbing each other rather than hitting. Then the "grabber" was not the first to run – perhaps because the gorillas saw the gentler act as less aggressive. "Apes use play to explore the ramifications of unfair social situations," says Davila-Ross.

Heart of darkness could explain sun mysteries

IS DARK matter lurking at the centre of our bright sun? Yes, say two research groups who believe the elusive stuff is cooling the solar core.

The insight doesn't significantly affect the sun's overall temperature. Rather, a core chilled by dark matter would help explain the way heat is distributed and transported within the sun, a process that is poorly understood.

Dark matter doesn't interact with light and so is invisible. The only evidence for its existence is its gravitational effects on other objects, including galaxies. These effects suggest dark matter makes up about 80 per cent of the total mass of the universe.

The idea that it might lurk at the heart of the sun goes back to the 1980s, when astronomers found that the number of ghostly subatomic neutrinos leaving the sun was only about a third of what computer simulations suggested it should be. Dark matter could have explained the low yield because it would absorb energy, reducing the rate of the fusion reactions that produce neutrinos.

However, the problem was solved another way when it was found that neutrinos oscillate between three kinds, only one of which was being detected on Earth. As a result, the idea of solar dark matter was dropped.

Now it is being resurrected in the light of recent searches for dark matter, which have put limits on the mass of the particles that it is made of and shown that it interacts only very weakly with ordinary matter. These led Stephen West of Royal Holloway, University of London, and his colleagues to explore what would happen if particles that fell within these limits exist in the sun.

Their simulations show that gravity would pull such dark particles to the centre of the sun, where they would absorb heat. Some of these dark matter particles would then carry this heat from the core to the surface, decreasing the core temperature

Let there be night, for wildlife's sake

IT IS time to take back the night for wildlife. That was the rallying call from a landmark session on light pollution at the Society for Conservation Biology .

The disruptive effects on animals of our penchant for bright lights has rarely impinged on public consciousness. Notable exceptions are when turtle hatchlings head inland to the bright lights of a beach resort instead of the safety of the moonlit sea, or birds collide en masse with brightly lit buildings.

It is rapidly becoming clear, though, that light pollution subtly interferes with the growth, behaviour and survival of many nocturnal species - not just those that hit the headlines.

The threats posed by the humble street lamp do not rival the wholesale destruction of tropical forests and other habitats, or indeed the threat of climate change. But participants in the session at the Edmonton meeting agreed that planners should spare a thought for wildlife when installing lighting. "We've taken away the night," warns Travis Longcore of the University of Southern California in Los Angeles, who chaired the session.

For instance, Emma Stone of the University of Bristol, UK, has shown that high-pressure sodium street lights can divert lesser horseshoe bats from their usual routes between roosts and foraging grounds. Such diversion may be energetically costly - all the more of a worry as the bats in the study were pregnant.

Fluorescent felines

The fluorescent cat on the left, whose skin glows in ultraviolet light, is one of two created at Gyeongsang National University in Jinju City, South Korea, in 2007.

The gene for the fluorescent protein was added to skin cells, which were then cloned by transferring their nucleus to empty eggs.

The cats were a practice run; using fluorescent proteins make it very obvious when animals have been successfully modified.