16 | NewScientist | 12 June 2010

COSMIC strings – imperfections in space-time – may be to blame for two unusual bursts of gamma rays in the early universe.

Gamma-ray bursts come in two types. Long-lived, high-intensity bursts are thought to originate from collapsing stars, while shorter, dimmer ones are emitted when neutron stars merge with one another or with black holes.

In 2008 and 2009 two unusual

bursts were seen, both short-lived but with the brightness of long bursts. Both occurred within a billion years of the big bang.

K. S. Cheng of the University of Hong Kong and colleagues say the culprit could be cosmic strings – defects in space-time, like streaks in clear plastic, that formed as the early universe cooled.

If a loop of string oscillated in the magnetic fields that pervaded

Biblical bee-keepers picked best bees

THE Bible didn’t dub it “a land flowing with milk and honey” for nothing. Not only are the oldest known beehives in the world in Israel, bee-keepers of the time selected the best bees for the job.

Ancient Egyptian paintings depict bee-keeping, but hives were not found in the Middle East until 2005, when Amihai Mazar of the Hebrew University of Jerusalem excavated 30 clay cylinders just like the hives in the paintings, in the ancient town of Tel Rehov.

The remains of bees were found in two of the hives, but instead of being the local subspecies of the western honeybee, we now know they hailed from what is now Turkey (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1003265107). Importing bees would have been a shrewd business decision: Turkish bees produce up to eight times as much honey as Syrian bees, and are less aggressive.

Bulldog bats ‘honk’ when they meet a stranger

ULTRASOUND doesn’t just help bats fly in the dark and locate their dinner, it also serves as a social broadcast. The discovery places bats in the select group of mammals that use ultrasound to communicate – along with whales, dolphins and some squirrels.

Ultrasonic bat calls can differ between species, colonies and even individuals. So Silke Voigt-Heucke of the Free University of Berlin in Germany decided to investigate the significance, if any, of different types of calls, to see if bats could identify calls from other species, for example. She played pre-recorded calls to lesser

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Gamma rays unleashed by wobbly string the early universe, it would induce a current within the string, the team’s calculations suggest (arxiv.org/abs/1005.3427). Parts of the string then emit low-frequency radio waves that accelerate the surrounding plasma into generating a burst of gamma rays.

Nial Tanvir of the University of Leicester, UK, whose group discovered the 2009 burst, finds the idea interesting but thinks an unknown property of the first stars is a more likely explanation.

bulldog bats, some made by individuals from the same species and some from different species, and then watched how they responded.

The bats responded to all the calls with social behaviours like nodding and yawning, regardless of whether they were from bats of the same colony or a different species. However, they showed more of the behaviour when the call came from a bat of the same species but a different colony (Animal Behaviour, DOI: 10.1016/j.anbehav.2010.03.025). Voigt-Heucke says this suggests that the bats use ultrasound as a way of broadcasting their identity to strangers.

She also identified an entirely new ultrasonic call, made in response to strange individuals of the same species, which she has dubbed the “honk”.

AN ANCIENT foot bone is forcing a rethink of when our ancestors first reached the islands off south-east Asia. The find on Luzon, the largest and northernmost major island in the Philippines, suggests humans got there at least 67,000 years ago, tens of thousands of years earlier than thought.

“It seems coherent for us to think that in south-east Asia and Australia, humans had seafaring capabilities by 60,000 to 70,000 years ago,” says expedition member Florent Detroit of the National Museum for Natural History in Paris, France.

The size of the bone falls within the ranges of Homo habilis and Homo floresiensis (Journal of Human Evolution, DOI: 10.1016/j.jhevol.2010.04.008).

Seafaring ancestor found in Philippines

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