2022-03-21 16:07:03 来源:参考消息网 责任编辑:黄晋一
核心提示:从向日葵到海星,对称似乎在生物界无处不在。但这是为什么呢?难道进化天然偏爱对称?一支国际研究团队认为的确如此。

参考消息网3月21日报道

Endless Forms Most Beautiful:Why Evolution Favors Symmetry

无尽的形态最美:为何进化偏爱对称

From sunflowers to starfish, symmetry appears everywhere in biology. This isn't just true for body plans –the molecular machines keeping our cells alive are also strikingly symmetric. But why? Does evolution have a built-in preference for symmetry?

An international team of researchers believe so, and have combined ideas from biology, computer science and mathematics to explain why. As they report in PNAS, symmetric and other simple structures emerge so commonly because evolution has an overwhelming preference for simple “algorithms” – that is, simple instruction sets or recipes for producing a given structure.

“Imagine having to tell a friend how to tile a floor using as few words as possible,” says Iain Johnston, a professor at the University of Bergen and author on the study. “You wouldn't say: put diamonds here, long rectangles here, wide rectangles here. You'd say something like: put square tiles everywhere. And that simple, easy recipe gives a highly symmetric outcome.”

The team used computational modeling to explore how this preference comes about in biology. They showed that many more possible genomes describe simple algorithms than more complex ones. As evolution searches over possible genomes, simple algorithms are more likely to be discovered – as are, in turn, the more symmetric structures that they produce. The scientists then connected this evolutionary picture to a deep result from the theoretical discipline of algorithmic information theory.

“These intuitions can be formalized in the field of algorithmic information theory, which provides quantitative predictions for the bias towards descriptive simplicity”, says Ard Louis, professor at the University of Oxford and corresponding author on the study.

The study's key theoretical idea can be illustrated by a twist on a famous thought experiment in evolutionary biology, which pictures a room full of monkeys trying to write a book by typing randomly on a keyboard. Imagine the monkeys are instead trying to write a recipe. Each is far more likely to randomly hit the letters required to spell out a short, simple recipe than a long,complicated one. If we then follow any recipes the monkeys have produced – our metaphor for producing biological structures from genetic information – we will produce simple outcomes much more often than complicated ones.

The scientists show that a wide range of biological structures and systems, from proteins to RNA and signaling networks, adopt algorithmically simple structures with probabilities as predicted by this theory. Going forward, they plan to investigate the predictions that their theory makes for biases in larger-scale developmental processes.

从向日葵到海星,对称似乎在生物界无处不在。不仅身体轮廓如此,让我们的细胞保持生机的分子机器也惊人地对称。但这是为什么呢?难道进化天然偏爱对称?

参考消息网3月21日报道

Endless Forms Most Beautiful:Why Evolution Favors Symmetry

无尽的形态最美:为何进化偏爱对称

From sunflowers to starfish, symmetry appears everywhere in biology. This isn't just true for body plans –the molecular machines keeping our cells alive are also strikingly symmetric. But why? Does evolution have a built-in preference for symmetry?

An international team of researchers believe so, and have combined ideas from biology, computer science and mathematics to explain why. As they report in PNAS, symmetric and other simple structures emerge so commonly because evolution has an overwhelming preference for simple “algorithms” – that is, simple instruction sets or recipes for producing a given structure.

“Imagine having to tell a friend how to tile a floor using as few words as possible,” says Iain Johnston, a professor at the University of Bergen and author on the study. “You wouldn't say: put diamonds here, long rectangles here, wide rectangles here. You'd say something like: put square tiles everywhere. And that simple, easy recipe gives a highly symmetric outcome.”

The team used computational modeling to explore how this preference comes about in biology. They showed that many more possible genomes describe simple algorithms than more complex ones. As evolution searches over possible genomes, simple algorithms are more likely to be discovered – as are, in turn, the more symmetric structures that they produce. The scientists then connected this evolutionary picture to a deep result from the theoretical discipline of algorithmic information theory.

“These intuitions can be formalized in the field of algorithmic information theory, which provides quantitative predictions for the bias towards descriptive simplicity”, says Ard Louis, professor at the University of Oxford and corresponding author on the study.

The study's key theoretical idea can be illustrated by a twist on a famous thought experiment in evolutionary biology, which pictures a room full of monkeys trying to write a book by typing randomly on a keyboard. Imagine the monkeys are instead trying to write a recipe. Each is far more likely to randomly hit the letters required to spell out a short, simple recipe than a long,complicated one. If we then follow any recipes the monkeys have produced – our metaphor for producing biological structures from genetic information – we will produce simple outcomes much more often than complicated ones.

The scientists show that a wide range of biological structures and systems, from proteins to RNA and signaling networks, adopt algorithmically simple structures with probabilities as predicted by this theory. Going forward, they plan to investigate the predictions that their theory makes for biases in larger-scale developmental processes.

从向日葵到海星,对称似乎在生物界无处不在。不仅身体轮廓如此,让我们的细胞保持生机的分子机器也惊人地对称。但这是为什么呢?难道进化天然偏爱对称?

一支国际研究团队认为的确如此,研究人员综合运用生物学、计算机科学和数学知识解释了背后的原因。他们在美国《国家科学院学报》上说,对称结构和其他简单结构之所以如此常见,是因为进化极为偏爱简单的“算法”,也就是形成特定结构的指令集(或者说制作方法)。

卑尔根大学教授、论文作者伊恩·约翰斯顿说:“想象一下,假如你得用最简单的话告诉朋友怎样铺地砖。你不会说:把菱形的铺这儿,长条形的铺这儿,短条形的铺这儿。你会这样说:所有地方都铺正方形的。这句简单易懂的指令就会带来高度对称的结果。”

研究团队利用计算机建模来探索这种偏好在生物界是如何产生的。他们发现,描述简单算法的潜在基因组要比描述复杂算法的潜在基因组多得多。在进化寻找潜在基因组的过程中,简单的算法更有可能被发现,它们产生的对称结构也就更有可能被发现。接着,科学家将这幅进化图与算法信息论这一理论学科的深层结果联系起来。

牛津大学教授、该研究的通讯作者阿尔德·路易斯说:“这些直觉感知可以在算法信息论领域得以形式化。算法信息论对描述简单性偏好做出定量预测。”

这项研究的关键理论观点可以通过稍稍改变进化生物学的一个著名思想实验来说明。这项实验是,房间里一群猴子在键盘上随意敲击来写书。想象一下,如果这些猴子不是写书而是写指令呢。每只猴子随意敲击字母拼写出简短指令的可能性要远远大于拼写复杂的长指令。接着,如果我们按照这些猴子所写的指令去做——我们借此比喻从遗传信息产生生物结构,那么我们得到简单结果的频率要比复杂结果高得多。

这些科学家指出,从蛋白质到核糖核酸和信号网络,多种多样的生物结构和系统都采用了算法简单的结构,其概率与这种理论所预测的一致。未来,他们计划探究其理论对更大规模发展过程中各种偏好做出的预测。(刘白云译自3月14日美国《欧亚评论》网站)

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