进化导致女性择偶要求降低

译/邹梦芸 审订/赵刚

进化导致女性择偶要求降低

译/邹梦芸 审订/赵刚

Evolution and Bad Boyfriends

Throughout history and in societies all over the world， parents have tried to in fl uence the love lives of their children—with mixed success1mixed success有成有败。. Parents and children frequently don’t see eye to eye2see eye to eye意见一致。on what makes a suitable partner， as studies across cultures have con fi rmed.

[2] Whenever a pattern of human behavior is widespread， there is reason to suspect that it might have something to do with our evolutionary history.(Think of the fear of snakes， or the incest taboo.) You think your daughter’s boyfriend isn’t good enough? It may be evolution’s fault.

[3] But how could evolution have led to such an awkward situation as parent-child conflict over mates? In a recent paper in the journal Evolution and Human Behavior， we and two colleagues， the biologist Franjo Weissing and the social psychologist Bram Buunk， showed how it could work.

[4] When thinking about mate choice，the natural starting point is the theory of sexual selection. This theory， which focuses not on the struggle for existence but on the competition to attract sexual partners， has been hugely successful in explaining the diverse courtship behaviors and mating patterns in the animal kingdom， from the peacock’s flamboyant tail to the chirping calls of male crickets.

[5] Modern mathematical versions of this theory show how female mating preferences and male characteristics will evolve together. But when you try to apply the theory to humans， you hit a snag3hit a snag碰壁，遇到意外的困难。. In humans， there is an extra preference involved—that of the parents.

[6] At first sight， it might seem surprising that parents and their children should evolve to have any con fl ict at all.After all， they share many of the same genes， and both have an evolutionary interest in having those genes persist through the generations. Shouldn’t the preferences of parents and their children be perfectly aligned?

[7] Well， no—not completely. Parents each pass on half of their genes to each of their children， so from a genetic point of view， all children are equally valuable to them. It is in parents’evolutionary interests to distribute their resources—money， support， etc.— in such a way that leads to as many surviving grandchildren as possible，regardless of which of their children provide them.

[8] Children， by contrast， have a stronger genetic interest in their own reproduction than in that of their siblings， so each child should try to secure more than his or her fair share of parental resources. It is this con fl ict over parental resources that can lead to a con fl ict over mate choice.

[9] In our study， we built a computer model to simulate the evolutionary process. We generated a large virtual population4of males and females， the males all differing genetically in their ability to invest resources in raising children. The females had a genetically determined preference for5this male quality， which meant that females with a strong preference were more likely to end up with6a male who invested more.

[10] The males and females that paired up7in our model then mated and produced offspring， who inherited (with a small chance of mutation) the investing qualities and mating preferences of their parents. We ran our model over thousands of generations， observing which genetic traits thrived and which didn’t.

[11] Evolutionary biologists had built this kind of model before to understand mating preferences in other animals，but we added some new ingredients.First， we allowed a female’s parents to interfere with8interfere with干涉，干预。her choice of a male.Second， we allowed parents to distribute their resources among their children.

[12] We found that over time9over time随着时间的推移。， parents in our model evolved to invest more resources in daughters who chose mates with few resources. This unequal investment was in the parents’ best interests， because a daughter with an unsupportive partner would pro fi t more from extra help than her more fortunate sisters (the principle of diminishing returns on investment). By helping their needier daughters， parents maximized their total number of surviving grandchildren.

[13] But this unequal investment created an incentive for daughters to “exploit”their parents’ generosity by choosing a partner who was less supportive. A daughter who was less picky than her sisters would accept a less helpful partner，but since her parents picked up the slack she ended up with a similar amount of support， while sparing herself the costs of holding out for the perfect man.

[14] As a result， the choosiness of females gradually declined over evolutionary time. To counterbalance this， the parental preference for caring sons-in-law increased. Hence the con fl ict.

[15] We’re not suggesting that the person you choose as a partner comes down entirely to your genes. Cultural factors， personal development and chance events presumably have a far greater influence. But given the prevalence of mate-choice conflict， it seems likely that evolution has played an important role. ■

纵观人类历史，不论在哪种社会中，父母都会试图对子女的爱情生活施加影响，结果有成有败。对于选择什么样的伴侣，父母与子女往往看法不一，跨文化研究已证实了这一点。

[2]只要人类的某种行为模式得以广泛传播，就有理由怀疑其可能与人类的进化史相关。（想想人类对蛇的恐惧或乱伦禁忌吧。）你对女儿的男友不够满意吗？这可能得归咎于进化。

[3]然而，进化是如何导致这种尴尬的呢？父母与子女为什么会就后者的择偶问题发生冲突？最近，我们和两位同事——生物学家弗拉尼奥·韦斯和社会心理学家布拉姆·布恩克——在《进化与人类行为》这本刊物上发表了一篇论文，对这一现象进行了分析。

[4]谈到择偶，自然要从性伙伴选择理论开始。该理论研究的不是动物为生存而进行的斗争，而是它们为吸引性伙伴而展开的竞争，极为成功地解释了动物界形形色色的求偶行为与交配模式，包括雄性孔雀华丽的尾巴以及雄性蟋蟀唧唧的鸣叫声。

[5]性别选择理论有多种现代数学版本，展示了雌性择偶偏好与雄性特征如何共同进化，相互适应。但若想将该理论应用于人类，则会遇到意外的困难，因为人类择偶还涉及另一个因素，那就是父母的偏好。

[6]乍看起来，经过漫长的进化，父母与子女竟然还会存在冲突让人惊讶。毕竟他们拥有许多相同基因，而且都希望这些基因能世世代代传承下去。如此来看，父母与子女在后者择偶问题上的偏好难道不该完美契合吗？

[7]然而，事实并非如此，或并非完全如此。每个孩子都遗传了父母各一半的基因。因此，从基因的视角来看，每个孩子对父母来说都同等重要。父母将其所拥有的资源（如金钱、援助等）以某种方式进行分配，以期子女们能够生养众多，从进化的角度而言，这符合父母的利益。父母并不在乎孩子是由哪个子女生养的。

[8]相较而言，从基因的角度来看，子女更关注的是其自身的繁衍，而非兄弟姐妹的繁衍，所以每个子女都会试图从父母那里获得更多的资源。正是这种在父母资源分配上的冲突，导致了父母和子女在择偶问题上的分歧。

[9]本研究中，我们建立了一种计算机模型来模拟这一进化过程，生成了一个大型两性实际种群。该种群中所有男性投入资源养育孩子的能力存在基因上的差异，而女性则在基因上极为偏好男性的这一能力，这就意味着这些女性更有可能选择对养育孩子投入资源更多的男性。

[10]然后，模型中经过配对的两性进行交配并繁衍后代，后代则继承了父母的资源投入与择偶偏好的特征(基因突变的几率很小)。我们使用该模型研究了成千上万代的繁衍，观察哪些基因特质会健康发展，哪些会衰退。

[11]为了理解其他动物的择偶偏好，进化生物学家早前已建立过这种模型，但我们此次增加了一些新的成分。首先，我们允许女方的父母对女儿的配偶选择进行干预。其次，我们允许父母在子女间进行资源分配。

[12]研究发现，随着时间的推移，模型中的父母会逐渐对配偶拥有的资源较少的女儿增加投入。这种不均等的投入对父母最为有利，因为与其他条件较好的姐妹相比，父母的额外投入会使得不到配偶支持的女儿获益更多（这就是所谓的投资收益递减原则）。通过帮助更为贫困的女儿，父母可使孙辈的存活数量达到最大化。

[13]但父母投资不均，会激励女儿们选择条件较差的配偶，以“利用”父母的慷慨投入。姐妹中不太挑剔的那个会接受资源较少的伴侣，但由于父母会给予更多帮助，她最终获得了与其他姐妹相近的支持，而且还省去了选择完美配偶的支出。

[14]结果，女性在进化过程中逐渐变得不再挑剔。为了达到平衡，父母则愈来愈偏好选择对女儿更为体贴的女婿。冲突也因此而生。

[15]我们并不是说配偶选择完全取决于基因。文化因素、个人发展及偶发事件等也许影响更大。但鉴于父母与子女择偶冲突盛行，进化可能发挥了重要作用。 □

（译者单位：华东师范大学翻译系）

Most Famous Dogs in History (3)Canine Rescue Team, 9/11

Within 15 minutes of the attack on the World Trade Center on September 11， 2001， a trained search and rescue(SAR) dog named Appollo was onsite with his handler， Peter Davis of the New York City Police Department.In the following hours and days， over 350 SAR dogs and their handlers came to the Twin Towers site， and to the Pentagon， to search for survivors and to fi nd bodies.

“The SAR dogs worked with their handlers up to 16 grueling hours a day，” says Animal Planet， “and it became evident that the dogs were nearly as distraught as the human rescuers when there were so few survivors to be found. For the human rescue workers， the lack of survivors made the attacks feel ever more horrific and tragic. For the dogs trained to fi nd survivors， though， it felt like a personal failure.”