Got a great relationship? You may want to thank your prehistoric grandmother
拥有美妙的关系?你可能想感谢你远古的祖母

I went to a cross-cultural wedding last weekend. The guests travelled across continents to be there, spoke mutually incomprehensible languages and came from different traditions. However, they all shared a common understanding of the relationship between the bride and the groom. Pair bonds are, after all, universal in human societies, despite being rare in other mammals. And we don’t exactly know why.

上周末我参加了一场跨文化的婚礼。源自不同的文化传统、说着彼此都听不懂的语言的婚礼嘉宾们穿越各大洲来到这里。虽然如此,对新郎和新娘的关系,他们却有着共识。在其他哺乳动物中罕见的配偶式结对,却实实在在地在全人类社会中普遍存在。而我们却不太清楚这是为什么。

Before the wedding breakfast, I chatted with a relaxed couple who had left their kids with their grandparents for the day. This is not unusual; UK grandparents babysit on average 76 times a year – and we often take it for granted. But now a new study finally gives grandparents the credit they deserve by arguing that long-term relationships actually evolved thanks to grandmothers helping out with kids in prehistoric times.

婚礼早餐之前,我与一对十分放松闲适的夫妇聊了会。那天他俩把孩子交给了他们的祖父母照看。这种做法应该不在少数;在英国,祖父母们每年平均照顾孙辈76次——而我们常常也觉得这是理所当然的。但是,现在一项新研究终于承认了爷爷奶奶们应得的功劳,研究认为,长期夫妻关系的进化产生,实际上多亏了远古时代祖母们对孩子们的照看。

The greatness of grandparents
祖父母的伟大之处

The question of why humans form pair bonds – the biological term for the strong affinity that develops between partners (often a male-female pair but not always) – is in fact one of the biggest puzzles in evolutionary anthropology. Humans are apes, yet our closest living relatives – chimpanzees and bonobos – have no such long-term relationships between male-female pairs.

人类为何会形成配偶式结对——生物学术语,指伴侣之间(常常是雌雄配对,但并不全然如此)发展出的强亲和关系——事实上是进化人类学上的最大谜题之一。人类是一种猿,可我们的现存近亲——黑猩猩和倭黑猩猩——的雌雄伴侣之间却不存在这种长期关系。

In the late 1990s, anthropologists put forward the “grandmother hypothesis” to explain why human females stop reproducing at a similar age to other great apes, but live markedly longer lives. Chimpanzees live into their 30s or 40s, but human females often live decades beyond their child-bearing years.

1990年代末,人类学家提出了“祖母假说”,以解释为何人类女性停止生育的年龄与其他大猿相仿,却明显更加长寿。黑猩猩可以活到30多或40多岁,人类女性却能在育龄后再活数十年。

The grandmother hypothesis was based on observations of the Hadza people, in Tanzania. Hadza people live by hunting and gathering food, like our ancestors, although, they are of course modern people.

祖母假说基于对坦桑尼亚哈扎族人的观察而提出。尽管哈扎族人象我们祖先一样,靠狩猎和采集食物而生,但他们当然也是现代人。

Older Hadza women dig up tubers to feed youngsters who aren’t strong enough to it themselves. The grandmother hypothesis suggests that this help allows daughters to have their next baby sooner than they would otherwise. Over time, grandmothers who lived longer and helped more had more grandchildren, who shared their genes for longer life and care of their grandchildren. Thus, these genes became increasingly common in the population and human lifespan increased.

年老的哈扎族妇女靠挖掘植物块茎来喂养不够强壮、不能自食其力的年幼者。祖母假说认为,这种帮助让女儿们能更快地孕育下一个宝宝,否则间隔时间会更久。随着时间推移,更长寿并能提供更多帮助的祖母们就拥有了更多的孙辈,这些孙辈会共享她们的长寿基因并再去照顾自己的孙辈。这样一来,这些基因在人口中变得越来越普遍,人类寿命就此增加了。

The evolution of partnership
伴侣关系的演变

The new study, published in the Proceedings of the National Academy of Sciences, has used computer simulations to link this hypothesis to the evolution of pair-bonding in humans. The authors argue that long-term romantic relationships evolved due to a combination of people living longer and men remaining fertile longer than women. This situation led to a surplus of older men competing for younger, fertile women.

发表在《美国国家科学院院刊》上的一项新研究,用计算机模拟将这一假说与人类固定配偶关系的进化联系了起来。作者们认为,长期浪漫关系之所以进化出来,是因为人类越来越长寿,并且男性保有生殖能力的时间比女性更长。这种状况使得有更多相对较老的男性为年轻的育龄女性而相互竞争。

In fact, the study shows that the ratio of fertile males to fertile females in humans is twice as big as it is in chimpanzees, making humans very unusual mammals. This excess of males makes us more like birds. And birds are well-known for their pair-bonds.

事实上,这项研究显示,人类的育龄男女比,要比黑猩猩群体中的同一比例大两倍,这让人类成为十分不同寻常的哺乳动物。男性过多,使得我们更像鸟类,而鸟类的配偶关系是众所周知的。

Where many males compete for relatively few females, a male who develops a strong bond with one female will have more surviving offspring than males who seek numerous partners. The authors suggest that this created increasing incentives for men to “guard” their mate against rival males.

在数量更多的男性为相对较少的女性而彼此竞争时,与那些寻求众多伴侣的男性相比,同某一女性发展出强结合的男性将会拥有更多的成活后代。作者们认为,这就造成了很大的激励,促使男性去“守卫”他们的伴侣,赶走竞争对手。

While mate-guarding is not necessarily the same thing as pair-bonding, the authors argue that both involve a trade-off between paying attention to the current partner and seeking a new one. Of course, although the study concentrates on male strategy, females are not passive in this scenario – it takes two to bond.

当然,守卫伴侣与配偶关系未必是同一回事,作者们认为,两者有共同点,即都涉及在专心于当前伴侣和寻找新伴侣之间的权衡取舍。当然,尽管这项研究集中于男性的策略,女性在这一情景中也不是被动的——配偶结合需要两个人。

So, to put the wedding celebrations into their evolutionary context, perhaps it was the caring grandparents who led to the special relationship that we celebrated. A toast to the bride and groom … and one to their parents.

因此,把婚礼庆典放到进化论中来说,也许是因为那些曾经照看孙子的爷爷奶奶们,才造就了今天我们来庆祝的这种特殊关系吧。来吧,让我们为新娘和新郎干一杯……也为新人的父母干一杯。

翻译:淡蓝 (lilacinrain@gmail.com)
校对:沈沉(@你在何地-sxy)
编辑:辉格@whigzhou

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