【卫报】灵长类觅食水果可能是其大脑进化的关键丨第64期

A western lowland gorilla. According to the study, primates that eat fruit have about 25% more brain tissue than leaf-eaters of the same body weight.

一只来自西部低地的大猩猩。研究表明，同等体重下，以水果为食的灵长类动物脑组织比以叶类为食的灵长类动物的重25%。

Foraging for fruit may have driven the evolution of large brains in primates, according to research attempting to unpick the mystery of our cerebral heftiness.

一项试图解开大脑进化之谜的研究发现，觅食水果可能催化了灵长类动物大脑的进化。

• Forage：vi. 搜寻粮草；搜寻

• Cerebral：a. 大脑的，脑的

• Heftiness：n. 健壮、大量

The finding appears to be a blow to a long-held theory that humans and other primates evolved big brains largely as a result of social pressures, with extra brain power needed to navigate and engage in complex social interactions. Instead the researchers say it supports the view that the evolution of larger brains is driven by diet.

这一发现似乎颠覆了长久以来人们对大脑发展的认识。既往认为，人类和其他灵长类的大脑进化主要由社会压力导致，额外的脑力用以掌控和从事复杂的社会互动。与此相反，新研究结果表明，饮食对大脑的进化起促进作用。

• as a result of：ad. 因此，由于；作为……的结果

"All of these things are co-evolving: brains are getting bigger, sociality is becoming more complex, diet quality is becoming better, but it is maybe a shift in that focus on what might have been relatively more important, or more consistent throughout [primate] evolution," said Alex DeCasien, co-author of the research from New York University.

“万物都在持续不断地共同发展：脑容量增加，社会关系复杂化，饮食质量提升。但是这可能是因为在（灵长类）演化过程中，关注点的转变趋势为更重要或持久的方向的缘故。”来自纽约大学的亚历克斯·德卡西恩，本研究论文的合著者提到。

Writing in the journal Nature Ecology & Evolution, DeCasien and colleagues describe how they analysed the differences in brain size between more than 140 non-human primate species to unpick whether larger brains were linked to diet or to social factors. These factors included group size, mating habits and social system - for example, whether a species was solitary or lived in a system where males are surrounded by a harem of females.

在《自然生态与进化》一杂志中，德卡西恩和他的同事们阐述了他们如何分析了超过140多种非人类灵长类动物物种大脑体积的区别，揭示其到底与饮食还是与社会因素有关。这些社会因素包括群体规模，交配习惯及社会体系等，例如，一个物种的生活结构是独居亦或一雄多雌。

• Harem：n. 为一个雄性动物所控制的许多雌性动物

After taking into account factors such as body size and the position of species on the evolutionary tree, the team found no evidence that greater sociality is linked to bigger brain size.

在考虑了这些因素（体型与及物种在进化树的位置）后，该团队发现，并没有迹象表明更大范围的社会性与更大的大脑体积相关。

Instead, they found that big brains appear to be linked to diet. According to the study, primates that eat fruit have about 25% more brain tissue than leaf-eaters of the same body weight. Omnivores were also found to have larger brains than leaf-eaters, although there was no difference when compared to fruit eaters.

相反，他们发现，大脑的尺寸与饮食有关。根据该研究发现，食用水果的灵长类拥有比以相同体重以树叶为生的灵长类多25%的大脑组织。而杂食类动物的大脑也比叶类为食的灵长类大脑要大，尽管与食用水果的灵长类相比没有明显差别。

DeCasien says the results support the idea that fruit-eating provides more energy than leaf-eating, aiding brain growth. "[Fruit] is higher quality, it is more nutrient dense, it requires less digesting time, than the leaves," she said.

德卡西恩认为，这个结论支持水果提供的能量要大于叶类，有助于大脑生长的理念。“（水果）的质量叫叶片更高，营养更丰富，消化需要的时间更短。”她说道。

• Dense：a. 稠密的；浓厚的

• Digesting：a. 消化的；吸收的

At the same time, DeCasien adds, foraging for fruit could be a driver for large brains since finding fruit in a forest, logging its location, knowing how to get into the fruit, and remembering when it is likely to be ripe, all take brain power. "That is much more demanding than eating leaves which are relatively abundant all around you," said DeCasien. "That might allow, afterwards, then an increase in how complex your social interactions are."

同时，德卡西恩补充，在森林中寻找水果也许会刺激脑容量变大，记下水果在什么地方，知道如何能得到水果，并且记住水果什么时候会成熟，这些都是费脑力的过程。“这比吃叶类植物更为费力，毕竟叶类植物的数量较之更为充足，”德卡西恩说道，“随之而来的是，社会互动的复杂化可能因此而增加。”

• foraging for：搜查

While the study looked only at non-human primates, experts believe that its findings could shed light on why our own species is endowed with a large brain.

尽管这一研究只针对非人灵长类动物，但专家们认为这也许从侧面解释了为什么我们人类物种天生具有较大的大脑。

• be endowed with：被赋予；天生具有

"[We are the only primate that] is able to get lots of calories from meat really easily from cooking it and making it more digestible," said Chris Venditti, an evolutionary biologist at the University of Reading who was not involved in the research. "So if diet is really that important it could be that that was important in our own brain evolution - that transition to being able to process food and eat meat and take on even more energy which gives us even more opportunity to grow larger brains. "

“（我们是唯一）能够轻而易举地从烹煮肉类中得到大量卡路里并使其更容易消化的灵长类。”来自英国雷丁大学，并未参与该研究的进化生物学家克里斯·温蒂迪提到，“期待您的翻译，将您的理解留言在文章下方留言处，第二天将会有长难句解析。”

But, Venditti warns, the latest study has its drawbacks, not least that measures of group size might not reflect the degree to which individuals interact with each other, and that the team only looked at the overall relative brain size of different species, rather than the size of the neocortex - the area primarily involved in complex cognitive processes such as perception, reasoning and thought.

不过，温蒂迪担忧，最新的研究也有其缺陷，尤其是群体规模的尺度可能并不反应个体之间彼此互动的程度，同时，该团队仅关注不同物种整体的大脑相对体积，而非新皮层的体积，而这一区域主要参与复杂的认知过程，比如感知，推理和思考能力。

• Perception：n. 知觉；感觉；看法

• cognitive process：认知过程

"Different brain regions can evolve independently of each other," said Venditti. "If you look at the specific brain region involved in cognition itself it might be that there could be a relationship between [group size and brain size]."

“不同的大脑区域可以彼此独立地进化，” 温蒂迪说，“如果你观察认知所涉及的特定脑区，那可能（与种群数量、大脑大小）有关系。”

 Robin Dunbar, professor of evolutionary psychology at the University of Oxford agrees, pointing out that neuroimaging studies have shown a link between the size of components of the neocortex and group size in humans and monkeys.

罗宾·邓巴斯坦福大学的进化心理学专家同意这一点，他指出，神经影像研究表明在人类和猴子中，新（大脑）皮质构成的体积与群体规模之间存在关联。

What's more, he says, it is a mistake to assume that social group size and diet are two alternative explanations for the evolution of big brains, pointing out that one is a cause and the other a constraint.

他还说，假定社会群体规模和饮食是对大脑进化的两种交替性解释，这是错误的，并指出两者中一个是原因，而另一个是其制约因素。

"You cannot evolve a large brain to handle anything, social or otherwise, unless you change your diet to allow greater nutrient acquisition so as to grow a larger brain," he said. "But that is not an explanation for why large brains evolved."

“你不可能进化得到用一个大脑处理任何事情，包括社会关系或其他事项，除非你改变饮食得到更大的营养获取来成长一个更大的大脑。”他说，“不过这也不能成为大脑进化的解释。”

翻译丨妖精、Sasha

审核丨SUNNY

编辑丨Ternence

注：以上所有图片均来源于网络