Researchers already know that women live longer than men in all parts of the world.

研究人员早已知道，在世界各地，女性的寿命都比男性长。

Scientists have largely linked the difference in life expectancy between the sexes to biological survival factors.

科学家们在很大程度上将男女预期寿命差异与生物生存因素联系起来。

Now, a new study of wild mammals has found great differences in length of life and aging in many species of mammals.

现在，一项关于野生哺乳动物的新研究发现，许多哺乳动物在寿命和衰老方面存在巨大差异。

The researchers found that, in humans, women live almost 8 percent longer than men.

研究人员发现，在人类中，女性的寿命差不多比男性长8%。

But among wild mammals, females in 60 percent of the studied species live, on average, 18.6 percent longer.

但在野生哺乳动物中，60%的所研究物种，其雌性平均寿命比雄性长18.6%。

The percentages are very different for different groups of mammals.

对不同哺乳动物群体来说，雌性寿命长于雄性寿命的百分比差异很大。

Jean-François Lemaître led the study.

让-弗朗索瓦·勒梅特领导了这项研究。

He is from the University Lyon 1 in France.

他来自法国里昂第一大学。

He and his research team collected information on age-related deaths for 134 groups of 101 wild species of mammals.

他和他的研究小组收集了101种野生哺乳动物物种的134个种群的年龄相关死亡信息。

Lemaître said, "It was surprising to observe that this gender gap in lifespan often exceeds the one observed in humans,

勒梅特说：“令人惊讶的是，哺乳动物寿命上的性别差异经常超过人类，

and is, at the same time, extremely variable across species.”

同时其在物种之间差异极大。”

Tamás Székely, from the University of Bath, was one of the writers of the study.

巴斯大学的塔玛斯·塞凯利是这项研究的作者之一。

He told VOA that female lions in the wild live at least 50 percent longer than male lions.

他告诉美国之音，野生雌狮的寿命至少比雄狮长50%。

"We previously thought this was mostly due to sexual selection," he said.

他说：“我们之前认为这主要是由于雌雄淘汰。”

"However our data do not support this."

“然而，我们的数据并不支持这一点。”

Scientists say the risk of death does not increase more quickly in males than in females across species.

科学家说，在不同物种中，雄性的死亡风险并不比雌性增长得快。

They say there must be other more complex reasons.

他们称肯定还有其他更复杂的原因。

These include things such as environmental conditions in which the animals live,

这些因素包括动物生存的环境条件

sex-specific growth, survival and reproduction through the history of the species.

以及物种进化史上的性别特异性生长、生存和繁殖。

Székely suggests that one reason for the differences between the sexes is that

塞凯利认为，造成性别差异的一个原因是，

"female survival increases when males provide some or all of the parental care."

“当雄性提供部分或全部抚育时，雌性的存活率会增加。”

He added that "giving birth and caring for young becomes a significant health cost for females,

他补充说：“对女性来说，生育和照顾孩子要付出巨大的健康成本，

and so this cost is reduced if both parents work together to bring up their offspring."

因此，如果父母双方共同抚养子女，这一成本就会降低。”

Scientists plan to compare the data on wild mammals with the data on mammals kept in zoos.

科学家们计划将野生哺乳动物的数据与饲养在动物园里的哺乳动物的数据进行比较。

They want to measure how much biological differences between the sexes affect life expectancy.

他们想要衡量两性间的生物学差异对预期寿命的影响程度。

In zoos, animals do not have to fight with predators or fight for food and mates.

在动物园里，动物不必与捕食者搏斗，也不必为食物和配偶而战。

Scientists hope the findings will give them a better understanding of what affects length of life in humans.

科学家希望这些发现能让他们更好地了解影响人类寿命的因素。

In the past 200 years, the average life expectancy of humans has more than doubled.

在过去的200年中，人类的平均预期寿命已经增加了一倍多。

The main reasons for the increase are improved living conditions and developments in the field of medicine.

增加的主要原因是生活条件的改善和医学领域的发展。

However, women continue to live longer than men.

然而，女性的寿命仍然比男性长。

This suggests biological differences also play a part.

这表明生物学差异也起作用。

The U.S. Centers for Disease Control says the average American man will live to age 76.

美国疾病控制中心表示，美国男性的平均寿命为76岁。

The average woman in America will live to age 81.

美国女性的平均寿命为81岁。

Women can also expect to be healthier than men in their older years.

女性在老年阶段也会比男性更健康。

Experts said this is because of a combination of biological and social differences.

专家表示，这是生物学差异和社会差异综合作用的结果。

A hormone in men called testosterone is connected to a decrease in their immune system and risk of heart-related diseases as they age.

随着年龄的增长，男性体内一种叫做睾丸素的激素会抑制自身免疫系统并降低患心脏相关疾病的风险。

It is also connected to risky behavior, such as smoking, drinking and unhealthy eating habits.

它还与吸烟、饮酒和不健康的饮食习惯等危险行为相关。

Men are also less likely than women to follow suggestions and warnings from a doctor.

与女性相比，男性也较少可能听从医生的建议和警告。

And research shows that men are more likely to take life-threatening risks and to die in car accidents or gun fights.

研究表明，男性更有可能冒生命危险，死于车祸或枪战。

I'm Jonathan Evans.

乔纳森·埃文斯为您播报。