Do Your Genes Determine How Long You’ll Live?基因决定寿命？

伊娃·哈姆鲁德 译/邓梦寒

The average life expectancy in many developed countries is around 80 years old. Some individuals have famously lived for much longer—the oldest person who ever lived was 122 years old！

Whilst death is inevitable， longevity varies drastically between individuals. What is the secret to a long life？ Is our longevity already encoded in our DNA or is it determined by our lifestyle？

We asked 11 experts in ageing， cell biology and genetics： “Is longevity primarily determined by genetics？” Here’s what we found out.

Longevity in comparison to what？

Experts had two different interpretations of the question：

1） “Is the longevity of humans as compared to other species primarily determined by genetics？”

2） “Is the longevity of some individual humans as compared to other humans primarily determined by genetics？”

Genetics determines cross-species lifespans

Different animal species have very different lifespans. The Greenland shark is able to live to be 400 years old， whilst some species of mayfly only live for 5 minutes. The reason for these differences is genetics.

Professor David Gems， an expert in ageing from University College London， says， “The question could mean： are the upper limits of longevity in humans as a species primarily determined by genetics， in which case the answer is ‘near certain’. For example， the maximum lifespan of human beings is approximately twice that of our closest relatives among the higher primates， such as chimpanzees and gorillas.”

Lifestyle is more important than genes across humans

Dr Gems says， “If one takes [the question] to mean： are the differences in lifespan between individual people primarily determined by genetics， then the answer is ‘extremely unlikely’.” Most of the experts agreed with Dr Gems. Whilst genetics plays a role in longevity， it is not the primary determining factor.

Professor Dame Janet Thornton， an expert in anti-ageing and cell biology and previous director of the European Bioinformatics Institute says that “genetics accounts for less than 30 percent of the effect—but it is true that longevity tends to run in families—i.e. some families have many very old people.”

It can be difficult to determine if the existence of families with many very old people is due to genetics or environment， as often family members adopt similar diets and lifestyles. Studying the DNA of these long-lived people could tell us more.

Professor Ken Parkinson， an expert in anti-aging and oncology from Queen Mary University London says， “Many groups are trying to understand this by sequencing the DNA of centenarians and supercentenarians and performing genome-wide analysis.”

The lifestyle effect on longevity is clearly apparent when we look at how average life spans have increased over hundreds of years due to increased accessibility of clean water， food and medical care.

Counter-intuitively， it has been shown that restricting calorie intake could be linked to longevity in humans. Another lifestyle factor is exercise. Even light exercise for 15 minutes a day has been shown to increase life expectancy by around 3 years.

Individual longevity between humans is affected by genetics， but not primarily. Professor Lorna Harries， an expert in genetics and cell biology from Exeter University summarizes that “genetics can set you up for a long life， but you then need to do the right things to realize that.”

The takeaway

Differences in longevity between humans is not primarily determined by genetics. Regular exercise and a healthy diet may be the “secret” to longevity.

許多发达国家的人口平均寿命为80岁左右。有些人因活得特久而出名——有史以来最长寿的人活了122岁！

死亡不可避免，但寿命差异巨大。长寿的秘诀是什么？寿命已编入我们的DNA中，还是由我们的生活方式所决定呢？

就“寿命是否主要由基因决定？”这一问题，我们咨询了老龄化、细胞生物学和基因学领域的11位专家，总结如下。

寿命长短的比较对象是什么？

专家针对这个问题按两种不同情况做了解释：

1）“人与其他物种相比，寿命长短主要由基因决定吗？”

2）“人与人相比，寿命长短主要由基因决定吗？”

基因决定不同物种的寿命

不同的动物物种寿命差异极大。格陵兰睡鲨可以活400年，而有些种类的蜉蝣只能活5分钟。这些差别由基因决定。

英国伦敦大学学院的老龄化专家戴维·格姆斯教授说：“这个问题可能相当于：人类作为一个物种，其寿命上限是否主要由基因决定——这一问题的答案是：‘几乎可以肯定’。举个例子，与高等灵长类动物中人类的近亲（如黑猩猩和大猩猩）相比，人类的最长寿命大概是它们的两倍。”

人与人相比，生活方式比基因更重要

格姆斯博士说：“如果有人认为[这个问题]的意思是：人与人之间寿命长短不同是否主要由基因决定，那么答案是‘极不可能’。”大多数专家赞同格姆斯博士的观点。尽管基因与寿命有关，但不是主要的决定因素。

抗衰老和细胞生物学专家、欧洲生物信息研究所前所长、女爵士珍妮特·桑顿教授说，“ 基因的作用占了不到30%——但是长寿确实往往跟家族有关，例如有些家族有很多长寿的人”。

家族拥有很多长寿者是由基因还是环境因素决定的，这一点可能很难确定，因为家庭成员的饮食和生活方式通常都相似。研究这些长寿者的DNA或许会有更多发现。

伦敦玛丽女王大学的抗衰老和肿瘤学专家肯·帕金森教授说：“ 许多研究团队正试图通过对百岁老人和超百岁老人的DNA进行测序并开展全基因组分析来了解这一点。”

数百年来，由于净水、食物和医疗服务的普及，人类平均寿命延长，生活方式对寿命的影响由此显而易见。

令人意外的是，有研究表明，限制卡路里摄入可能也与人类长寿相关。另一个跟生活方式有关的因素是运动。已有研究显示，即使每天轻度运动15分钟，也可以增加大约3年的寿命。

基因会影响人类个体寿命长短，但并非主要因素。埃克塞特大学基因学和细胞生物学专家洛娜·哈里斯教授总结说，“基因可能为你打下了长寿的基础，但你还需要做正确的事才能达到长寿的目标”。

要点

基因并不是决定人与人之间寿命不同的主要因素。经常锻炼和健康饮食或许才是长寿的“秘诀”。                             □