Prehistoric humans never threw spears at Tyrannosaurus rex but really did hunt mammoths and mastodons.
史前人类从未向雷克斯暴龙扔过长矛，但确实猎杀过猛犸象和乳齿象。
It will never be known how and when this numeration ability developed, but it is certain that numeration was well developed by the time humans had formed even semi-permanent settlements.
我们永远也不会知道这种计算能力是何时、如何发展起来的，但可以肯定的是，在人类形成半永久定居点的时候，这种计数法已经发展得很好了。
But we never know how well it's going to hold up with humans.
但我们从来不知道，这项结果用在人类身上，好使不好使。
But, to his lasting frustration, he never unravelled the mystery of what triggers Labour in humans.
但是让他一直沮丧的是，他无法解释引发人类生产的谜底。
But until now, scientists had never demonstrated the technique in primates - a move essential for developing therapeutic USES for the technology in humans.
但直到现在，科学家们仍无法解释这一技术在灵长类动物脑中的应用——实际上这是开发这项技术用于人类的必不可少的一步。
But you will never know if they work unless you study them in humans, so this is an important first step.
但是如果你不在人类身上应用这些研究你将永远不知道它们是否能获得成功，所以这是很重要的第一步。
"We can never really know if animals are giving consent, but they do often engage in forms of behaviour which suggest they'd rather not encounter humans," he said.
“我们永远不能真正了解动物是否表示同意，但它们确实经常做出种种行为暗示它们宁愿没遇到人类，”他说。
But important as it is, researchers have never understood the mechanism by which humans index the happenings of everyday life.
尽管这个很重要，研究人员却从未发现人类大脑编排日常事务的机理。
We may not get it totally right collectively-in fact, humans almost never get anything entirely right-but we can get closer as we assemble new data and nuances.
也许我们不会完全正确的得到它，事实上人们从来没有完全正确的得到任何东西。但我们能够在收集这些事实和细微的差别之后离真相更近。
As humans, we outgrow the need for constant maternal care. But we can never outgrow our reliance on Mother Earth.
生而为人，我们长大以后就不再需要母亲的持续呵护，却永远不能摆脱对地球母亲的依赖。
As humans, we outgrow the need for constant maternal care. But we can never outgrow our reliance on Mother Earth.
生而为人，我们长大以后就不再需要母亲的持续呵护，却永远不能摆脱对地球母亲的依赖。
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