CHILDREN with a genetic disorder which prompts them to be over-friendly with strangers are providing clues to the origins of sociability.

While those with Williams syndrome (WS) find it easy to walk up to perfect strangers and make eye contact, they struggle to form lasting relationships. So Julie Korenberg of the University of Utah in Salt Lake City and her

colleagues wondered if people with WS might shed light on how sociability developed.

The team identified a girl with WS who, unusually, wasn’t overly friendly to strangers but was good at forming lasting relationships. They compared her genome with that of people who had typical WS symptoms and found that while she has the GTF2I gene, which most people have, the others lack

Scary associations wiped for good?

THE fear surrounding a horrible memory could be wiped for good by a blood pressure drug.

Previous studies found that propranolol reduces stress in people recalling traumatic events. To see if the effect persists, Merel Kindt at the University of Amsterdam, the Netherlands, taught students to associate a picture of a spider with an electric shock, to the point that they would be startled by the picture even in the absence of a shock. But those who took propranolol before seeing the picture alone could not be conditioned to fear it.

All students then underwent deconditioning until none were startled by the image. Later, shocks alone “reawakened” the fear of the picture in those who had not taken propranolol, but those who had taken it seemed immune. The drug seems to block the fear association for good (Nature Neuroscience, DOI: 10.1038/nn.2271).

Smashed Milky Way still reeling 2 billion years later

OUR galaxy may still be reeling from a massive collision

with another galaxy 2 billion years ago.

Some groups of stars near our solar system move

with unusually high velocities compared with others in the

galactic disc. Ivan Minchev of the University of Strasbourg,

France, says their pattern and velocity can be explained if

they were thrown by the shock of a past smash.

Minchev developed a computer simulation of the

distribution of velocities of billions of stars. This is far

more than have been modelled previously, says co-author

Alice Quillen of the University of Rochester in New York.

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Rare syndrome sheds light on sociability it . This suggests that the gene may play a role in governing normal social behaviour (American

Journal of Medical Genetics, DOI: 10.1002/ajmg.a.32652).

The next step is to find out whether GTF2I , which regulates other genes, helps determine brain function or controls the production of hormones that modulate trust and empathy. However, the team cautions that this may not be the only gene responsible for social behaviour.

A pattern of “ripples” emerged in Minchev’s

enormous starscape, with bands of stars travelling at

the same high velocity. He suggests these stars were

jolted by a shock wave from another galaxy merging with

ours – an event that other observations already point to.

This smash caused pulsations of energy in the galactic

disc akin to waves in a pond, says Minchev.

The model fits closest with actual measurements

if the collision happened about 2 billion years ago. The

work has been submitted to Monthly Notices of the Royal

Astronomical Society (www.arxiv.org/abs/0902.1531).

Minchev’s model contributes to a key debate in

astronomy about the origin of these streams of fast-

moving stars, says Benoit Famey of the Free University

of Brussels in Belgium.

PRIMITIVE deep-sea fish may have viewed the world much as we do. The elephant shark, which evolved about 450 million years ago, is the oldest vertebrate to have “the colour vision system we know as humans”, says David Hunt at University College London.

Until now, ancestors of modern sharks from 374 million years ago were the oldest known creatures to have both rods to see in dim light and cones, for bright light .

Now Hunt’s team has found that the elephant shark, Callorhinchus

milii, has rod pigments. It also has two copies of the long-wavelength cone pigment gene, a duplication which may have given them trichromatic vision like primates (Genome Research, DOI: 10.1101/gr.084509.108).

Sharks see the deep sea in colour

14 | NewScientist | 21 February 2009