What a 20 million-year-old monkey skull reveals about the evolution of human brains

一个两千万年前的猴子头骨，揭示了人类大脑的进化过程

A rare, palm-size, 20 million-year-old fossil skull from an extinct monkey that was discovered high in the Andes Mountains is helping researchers learn more about the evolution of the human brain.

在安第斯山脉高处发现的一具罕见的、手掌大小、距今2000万年的猴子头骨化石，帮助研究人员更多地了解人类大脑的进化过程。

The fossilized skull is the only known specimen of the extinct Chilecebus carrascoensis, a New World monkey that lived in what is now Chile and had a body mass of roughly a pound.

这具头骨化石是已知的唯一一种已灭绝的卡拉斯科红毛猴标本。红毛猴是一种新的世界猴，生活在现在的智利，体重约为1磅。

A study published Wednesday in the journal Science Advances, led by researchers from Manhattan’s American Museum of Natural History, the Chinese Academy of Sciences, and the University of California Santa Barbara, suggests that the brain “enlarged repeatedly and independently over the course of anthropoid history and was more complex in some early members [of anthropoid primates] than previously recognized.”

周三，由曼哈顿美国自然历史博物馆、中国科学院和加州大学圣巴巴拉分校的研究人员领导的一项发表在《科学进展》杂志上的研究表明，“大脑在类人猿的历史，在一些早期类人猿(类人猿灵长类)成员中，比以前认知的要复杂得多。”

“Human beings have exceptionally enlarged brains, but we know very little about how far back this key trait started to develop,” said lead author Xijun Ni, a research associate at the museum and a researcher at the Chinese Academy of Sciences.

“人类的大脑特别大，但我们对这一关键特征的发展历史知之甚少，”首席作者倪锡军说，他是博物馆的研究助理，也是中国科学院的研究员。

Xiaocong Guo/Xijun Ni

“This is in part because of the scarcity of well-preserved fossil skulls of much more ancient relatives.”

“这在一定程度上取决于保存完好的古代亲属头骨化石的匮乏。”

John Flynn, the museum’s Frick curator of fossil mammals, called Chilecebus “one of those rare and truly spectacular fossils, revealing new insights and surprising conclusions every time new analytical methods are applied to studying it.”

博物馆的化石哺乳动物弗里克馆长约翰·弗林(JohnFlynn)，称奇莱切布斯为“那些罕见的、真正壮观的化石之一，每当新的分析方法被应用于研究它时，都会揭示出新的见解和令人惊讶的结论。”

The use of high-resolution CT scanning and 3D digital reconstruction of the inside of Chilecebus’ skull gave the research team new understanding of the anatomy of its brain.

科学家们利用高分辨率的CT扫描和三维数字重建技术，对智利人颅骨内部进行重建，使研究小组对其大脑的解剖结构有了新的认识。