It's the lesson Scrooge learned the hard way - and now a study has revealed the moral behind Dickens' classic A Christmas Carol may be true after all.

这是斯克鲁奇历经苦难才学到的东西，如今一项研究揭示，狄更斯的经典作品《圣诞颂歌》背后的寓意也许是正确的。

New research has revealed the do-gooders amongst us live longer than the meaner, less charitable people.

The figures also showed people who volunteer to help others have an increased lifespan（寿命） than those who do it for personal satisfaction.

Scientists studied a random¹ group of 10,317 college students from their graduation in 1957 until the present day.

In 2004, respondents reported whether they had volunteered within the past ten years and how regularly.

Researchers found that four years later 4.3 percent of 2,384 non-volunteers were dead.

A similar number - four percent - of volunteers with more self-orientated motives² were also dead.

However, only 1.6 percent of those volunteers whose motivations were more focused on others were dead four years later.

The study's lead author Dr Sara Konrath, of the University of Michigan, said: 'This could mean people who volunteer with other people as their main motivation may be buffered³（缓冲，减轻） from potential stressors associated with volunteering, such as time constraints⁴ and lack of pay.

'We recommend that people pay attention to their reasons for volunteering, and try to focus on how their behaviour can positively⁵ impact others.

'It does not appear that volunteering for self-serving reasons does actual harm, and it can still do your community good.'