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cover of episode All Of Life Has A Common Ancestor. What Was LUCA?

All Of Life Has A Common Ancestor. What Was LUCA?

2025/1/17
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Jonathan Lambert: 我研究了LUCA，也就是所有生命的最后共同祖先。它是一种已经灭绝的单细胞生物，存在于数十亿年前。通过追溯生命树上所有物种的进化路径，最终都会汇聚到LUCA这个共同的祖先。我们研究LUCA，是为了了解所有地球生命的起源。最近一项研究表明，LUCA可能比我们之前认为的更古老、更复杂。 我们知道LUCA存在，是因为所有生物都共享一些基本的生命机制，例如遗传密码和使用氨基酸构建蛋白质。这表明我们拥有共同的祖先。LUCA并非生命起源本身，而是我们通过研究现存生物能够追溯到的生命起源的最终点。理解LUCA的性质，可以帮助我们了解早期生命的进化过程。 研究人员通过比较不同生物体中共享的基因和蛋白质来推测LUCA的特征。然而，水平基因转移和基因丢失等因素会干扰研究，使结果变得复杂。为了减少干扰，一种方法是严格筛选，只关注那些显示出少量水平基因转移证据的基因。但过于严格的筛选可能会导致对LUCA图像的简化，忽略它可能拥有的许多蛋白质。 为了获得更准确的图像，研究人员采用了概率建模的方法。他们分析了来自细菌和古菌的近万个基因家族，并为每个基因分配了属于LUCA基因组的概率。这创建了一个更模糊但可能更准确的LUCA图像。研究表明，LUCA比之前认为的更加复杂，拥有更大的基因组和更丰富的蛋白质，甚至可能拥有类似CRISPR-Cas9的古老免疫系统，能够抵抗病毒。 LUCA可能生活在没有氧气的环境中，通过转化二氧化碳或氢气来获取能量。它可能生活在深海热液喷口附近，也可能生活在靠近海洋表面的地方。一些研究人员认为，LUCA可能生活在一个复杂的微生物生态系统中，并非独自存在。他们认为，像LUCA这样复杂的生物体不可能在孤立的环境中进化。 研究人员通过基因突变的速率来估算LUCA的生存年代，并利用碳定年化石校准他们的分子钟。他们估计LUCA生活在大约42亿年前。这个年代暗示早期生命进化可能比之前认为的更容易，也可能意味着其他星球上也更容易出现复杂生命。 Emily Kwong: 作为节目的主持人，我主要负责引导访谈，提出问题，并对Jonathan Lambert的观点进行总结和补充。我表达了对LUCA研究的兴趣和惊讶，并对一些关键信息进行了追问，例如水平基因转移对研究的影响，LUCA的复杂程度，以及LUCA生存年代的估计及其意义。我与Jonathan Lambert的对话，共同呈现了对LUCA研究的全面理解。

Deep Dive

Chapters
The episode introduces LUCA (Last Universal Common Ancestor), the common ancestor of all life on Earth. Scientists study LUCA to understand the origin of life and early evolution. Understanding LUCA's nature helps researchers learn about the end of the origin of life story.
  • LUCA is the last universal common ancestor of all life.
  • Studying LUCA helps understand the origin of life.
  • LUCA's characteristics provide insights into early evolution.

Shownotes Transcript

Imagine the tree of life. The tip of every branch represents one species, and if you follow any two branches back through time, you'll hit an intersection. If you keep going back in time, you'll eventually find the common ancestor for all of life. That ancestor is called LUCA, the last universal common ancestor, and there is no fossil record to tell us what it looked like. Luckily, we have Jonathan Lambert. He's a science correspondent for NPR and today he's talking all things LUCA: What we think this single-celled organism may have looked like, when it lived and why a recent study suggests it could be older and more complex than scientists thought. *Have other questions about ancient biology? Email us at [email protected]) — we'd love to hear from you!Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave).*Learn more about sponsor message choices: podcastchoices.com/adchoices)NPR Privacy Policy)