A drop in testosterone levels around 50, 000 years ago led the the development of art and tools, researchers believe.
有研究人员认为，5万年前人体睾丸素水平的降低促进了人类艺术和工具领域的发展。
They say the drop, which led to a change in the shape of skulls, coincided with a blossoming in culture.
他们称，睾丸素的下降改变了人类的头骨形状，在此同时文化得到了繁荣发展。
The two could be linked, as humans developed a more co-operative outlook as levels dropped.
两者的联系在于睾丸素水平的下降让人类的面孔更利于合作。

Modern humans appear in the fossil record about 200, 000 years ago, but it was only about 50, 000 years ago that making art and advanced tools became widespread.
由化石推断，现代人类最早出现在大约20万年以前，但直到5万年前，人类才开始普遍地进行艺术创造与制造高级工具。
'The modern human behaviors of technological innovation, making art and rapid cultural exchange probably came at the same time that we developed a more cooperative temperament, ' said lead author Robert Cieri, a biology graduate student at the University of Utah who began this work as a senior at Duke University.
犹他州大学生物学研究生罗伯特·西里在杜克大学年本科四年级的时候就开始了这项研究工作，作为研究论文的主要作者，他说道，“现代人类的科技创新行为、艺术创造和频繁的文化交流很可能出现在我们性格更利于合作的同时。”
The study in the journal Current Anthropology, which is based on measurements of more than 1, 400 ancient and modern skulls, makes the argument that human society advanced when people started being nicer to each other, which entails having a little less testosterone in action.
《当代人类学》杂志上发表的这项研究测量了1400多个古代和现代人头骨，论证了当人类睾丸素水平下降，变得越来越友善的同时，人类社会也获得了进步。
Heavy brows were out, rounder heads were in, and those changes can be traced directly to testosterone levels acting on the skeleton, according to Duke anthropologist Steven Churchill, who supervised Cieri's work on a senior honors thesis that grew to become this 24-page journal article three years later.
杜克大学人类学家史蒂文·丘吉尔称，人类渐渐不再有粗壮的眉骨，头部变得更加圆润，这些变化与睾丸素水平直接相关。丘吉尔为西里的本科毕业论文导师，西里三年后在自己毕业论文的基础上发表了这次长达24页的论文。