CRYSTALS found in comets could be the remnants of stellar burps.

We know that half the dust inside comets is crystalline, but where did it come from? The dust in the gas cloud that formed comets and the rest of the solar system is thought to consist of amorphous glass-like grains instead.

In January 2008, Attila Juhász of the Max Planck Institute for Astronomy in Heidelberg,

Germany, and colleagues, studied the infrared light given off before and after an outburst of the young star EX Lupi, which allowed them to infer the chemical composition of the dust surrounding the star.

Before the outburst, the spectrum closely matched that of glassy dust, but afterwards it was almost identical to the spectrum of crystal-rich comets, suggesting that eruptions of young stars can

Incestuous moths scrimp on sperm

INCEST may not be taboo among amorous insects but male moths invest less in the family members they mate with. They ejaculate less sperm when copulating with their sisters to avoid wasting it on inbred offspring.

Nina Wedell and Zenobia Lewis from the University of Exeter in the UK paired males from 14 Indian meal moth families with either a sister or an unrelated mate, then shock-froze the females and counted the sperm in their bodies. Sisters received 54 per cent less sperm than non-related females, on average (Animal Behaviour, DOI: 10.1016/j.anbehav.2009.03.013 ).

This is the first time males have been found to apportion sperm according to relatedness. “We know that producing sperm is tiring so it is prudent for them to tailor their ejaculate to get the largest return for their investment,” says Wedell.

European settlers turned up the heat on Australia’s big dry

DEFORESTATION by European settlers may be to blame

for making Australia’s drought longer, hotter and dryer

than it would be otherwise.

The “big dry” , Australia’s 11-year drought, has been

blamed on greenhouse gases and natural variability. To

see if deforestation played a part, Clive McAlpine of the

University of Queensland in Brisbane and colleagues

used a climate model to simulate Australian conditions

from the 1950s to 2003. They then compared the impact

of today’s fragmented vegetation, obtained from satellite

images, with that of 1788, prior to European settlement.

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Did stars leave message in comet dust? turn dust particles into crystals. Comets zipping around today’s solar system may be carrying crystals that act as “messengers” of past outbursts from our sun, says the team (Nature, DOI:10.1038/nature08004).

The study offers “a plausible explanation for how the first crystalline stuff was made”, says Phil Bland of Imperial College London, which will help to determine the starting composition of the solar system.

Over much of south-east Australia, where the drought

has hit hardest, less that 10 per cent of the original

vegetation remains. The team’s model showed that this

land clearance has increased the length of droughts in

the area by one to two weeks per year. In years of

extreme drought, the loss of vegetation caused the

number of days above 35 °C to increase by six to 18 days,

and the number of dry days to increase by five to 15 days

(Geophysical Research Letters, in press).

“Land clearing may be having a similar impact on

the drought as greenhouse gases,” says McAlpine.

Reforestation could minimise future droughts, he adds.

“It’s a nice piece of work,” says Andy Pitman of the

University of New South Wales in Sydney, but he adds

that the modelling needs to be confirmed.

PIG embryos may be better as a source of organs than fully developed pigs.

To test the idea, Yair Reisner at the Weizmann Institute in Rehovot, Israel, and colleagues, gave two diabetic monkeys pancreases from pig embryos. The organs made insulin, grew to the right size and were infiltrated by monkey blood vessels (Proceedings of the

National Academy of Sciences, DOI: 10.1073/pnas.0812253106).

Embryos have evolved to dodge attack from the maternal immune system, so embryonic organs might stand a better chance of surviving in their new host than adult ones. It is not yet clear whether they do in fact evade attack, because the monkeys were given immunosuppressant drugs.

Transplant organs from unborn pigs

16 | NewScientist | 16 May 2009