Two recent studies suggest surprising but heartwarming keys to a longer life. You're more likely to rack up the years if you:

Expect the best. Of 100,000 women in the Women's Health Initiative study, those rated optimistic by special questionnaires were 14 percent less likely than pessimists to die during the study's first eight years. "Optimists are master copers," points out investigator Hilary Tindle, MD. "They have strong social networks and handle stress better, which could make a difference."

Care for a loved one. Despite the stress involved, men and women who put in the most time taking care of a spouse cut their own risk of dying by 36 percent over a seven-year period, researchers at the University of Michigan in Ann Arbor found. Aiding a loved one may release the "bonding" hormone oxytocin, countering cortisol, a stress hormone that can raise blood pressure and interfere with regulation of the immune system, the scientists speculate.

最近两个惊人但温心的研究发现了可能能增加寿命的秘诀：

乐观：在倡议妇女健康研究的10万妇女中，特别问卷评价乐观的在研究的八年内去逝的机率低于悲观者 40%. "乐观者具强力适应力，" 医学博士调查员希拉里葶荳指出。 "具有强大的社会人络，对压力具韧力，才造就其不同。"

爱心：尽管存在压力，无论是男性还是女性，推心照顾配偶的，能在在7年期间减低自己死亡风险 36%,美国密歇根大学安阿伯研究人员发现。帮助所爱的人时会释放 "接合"荷尔蒙催产素，打击皮质醇 -- 一种能使血压高昇和影响调节免疫系统的应激激素，科学家们推测。