"So very seldom do people at that moment make the decision to donate their child's brain tissue for research, and in the absence of brain tissue for research, it goes very slowly," he said.

“因此，在这种情况下很少人会将孩子的大脑捐献用于研究，并且由于缺少可研究的大脑，这项研究进展的十分慢，”他说。

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That is to say, when humans evolved without a particular switch, the absence of that switch allowed the brain to grow further.

也就是说，人类在进化中丢弃了这个特殊的开关，而这个缺失的开关让大脑能发育更高级。

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Neurons in that brain region showed activity that signaled depth perception even in the absence of other cues.

这个部分的神经甚至在没有其他信号作用的时候（也就是说睁开一只眼的时候）依然显示出了感知深度的活动。

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They are also going to look at whether the presence or absence of amyloid plaques, a marker of Alzheimer's in the brain, predicts participants' cognitive status over the next five years.

CNN: STORY HIGHLIGHTS