25 September 2010 | NewScientist | 5

AT WHAT age should children be held criminally liable for their actions? It depends where they live. In England and Wales, children under 10 are not considered capable of committing a crime and cannot be tried, no matter what they might have done. In Scotland the age is 8, though it will soon to be raised to 12. Some US states consider 7-year-olds to be criminally responsible, others set a minimum age of 15. In Belgium, the cut-off point is 18.

The age of criminal responsibility is quite literally all over the place. So what are we to make of claims that a 5-minute brain scan can determine a child’s level of brain development, and hence whether they are mature enough to understand the consequences of their actions?

Given the seemingly random nature of the age of responsibility,

the idea has some appeal. Nobody wants to see child criminals who knew what they were doing get off because they are below some arbitrary age. Nor should children being tried for acts that they don’t understand are wrong.

Yet on closer examination it raises myriad problems.

Neuroscience has discovered much about brain development, but as yet no studies have looked into the relationship between brain development and behaviour. So it’s not yet clear how to convert developmental maturity into a measure of behavioural maturity.

And that is not all. Many legal scholars regard neuroscience with suspicion because it diminishes individual responsibility – the “my brain made me do it” defence. The prospect of lawyers trying to dazzle juries with brain scans “proving” that their client isn’t mature enough to face charges is not an appealing one.

Indeed, in the US defence lawyers have successfully argued that their young clients are still developing mentally and hence can’t be held responsible for their actions.

What the research does do is highlight the arbitrary nature of the age of criminal responsibility, and the absurdity of setting a cut-off point. If it leads to a more nuanced understanding of brain maturity that can be factored into the legal system, justice will have been served. n

Mental maturity on trial

EDITORIAL

Brain scans may mire the already muddy waters of criminal responsibility

FOR many years, any mention of the sun’s influence on climate has been greeted with suspicion.

People who believe human activity has no effect on the climate staked a claim on the sun’s role, declaring it responsible for the long-term warming trend in global temperatures. Climate scientists were often uneasy about discussing it, fearful that

any concession would be misunderstood by the public and seen as an admission that climate sceptics are right.

No one has ever denied that the sun has an effect on climate. But the consensus view has always been that variations in the sun’s activity, such as the 11-year sunspot cycle, have insignificant effects. While this remains true, the latest

findings show that the sun might be significant on a more regional scale. It seems changes in solar activity can have consequences ranging from higher rainfall in the tropics to extreme weather events in the north (see page 10).

We now know we should take the influence of our local star into account. But its effects are far more subtle and complex than those who flatly deny human influence on climate change would have us believe. n

The sun has its place

“Many legal scholars regard neuroscience with suspicion because it diminishes responsibility”

LOCATIONSUKLacon House, 84 Theobald’s Road, London WC1X 8NS Tel +44 (0) 20 7611 1200 Fax +44 (0) 20 7611 1250

AUSTrALIATower 2, 475 Victoria Avenue, Chatswood, NSW 2067Tel +61 2 9422 2666 Fax +61 2 9422 2633

USA225 Wyman Street, Waltham, MA 02451Tel +1 781 734 8770 Fax +1 720 356 9217

201 Mission Street, 26th Floor, San Francisco, CA 94105Tel +1 415 908 3348 Fax +1 415 704 3125

TO SUBSCrIBeUK and InternationalTel +44 (0) 8456 731 731 ns.subs@quadrantsubs.com The price of a New Scientist annual subscription is UK £137, Europe €211, USA $154, Canada C$182, Rest of World $267. Postmaster: Send address changes to New Scientist, PO Box 3806, Chesterfield, MO 63006-9953, USA.

CONTACTSeditorial Tel +44 (0) 20 7611 1202news@newscientist.comfeatures@newscientist.comopinion@newscientist.com

Picture desk Tel +44 (0) 20 7611 1268

Who’s who newscientist.com/people

Contact us newscientist.com/contact

enquiries Tel +44 (0) 20 7611 1202

Display Advertising Tel +44 (0) 20 7611 1291displayads@newscientist.com

recruitment Advertising UK Tel +44 (0) 20 8652 4444recruitment.services@rbi.co.uk

Permission for reuse syndication@newscientist.com

Media enquiriesTel +44 (0) 20 7611 1202

MarketingTel +44 (0) 20 7611 1299

Back Issues & MerchandiseTel +44 (0) 1733 385170

SyndicationTribune Media Services InternationalTel +44 (0) 20 7588 7588

UK Newsagents Tel +44 (0) 20 3148 3333Newstrade distributed by Marketforce UK Ltd, The Blue Fin Building, 110 Southwark St, London SE1 OSU Tel: + 44 (0) 20 8148 3333

© 2010 Reed Business Information Ltd, England

New Scientist is published weekly by Reed Business Information Ltd. ISSN 0262 4079.

Registered at the Post Office as a newspaper and printed in England by Polestar (Colchester)

THE pursuit of happiness may be your right, but the chances are that complete success will elude you – which is probably all for the best.

Psychologists studying this

intangible quality are starting to realise that happiness does more than simply make us feel good: it also appears to improve our powers of problem-solving and to make us calmer and more resilient too (see page 44).

But ask people who live comfortable, healthy lives to rate their happiness on a scale up to 10,

and scores seldom exceed 8. Why not more? The answer may be that we have evolved to avoid the downside of excessive happiness: gullibility, carelessness and a reduced ability to argue persuasively. The optimum level appears to be around 7, showing once again that you can have too much of a good thing. n

Aim for cloud seven, not nine

100925_R_UK_Editorial.indd 5 21/9/10 17:12:50