Well, for a long time, scientists thought that birds lost their teeth to make their bodies lighter.

好吧，很长一段时间以来，科学家们都认为鸟类失去牙齿是为了让它们的身体更轻。

So this is your body attempting to rush the job of digestion so that it can allow for a fight and make your body lighter, and more aerodynamic which makes fleeing easier.

所以这就是你的身体试图加速消化工作，这样它就可以允许你去战斗，让你的身体更轻，更符合空气动力学，让逃跑更容易。

You want your body, the part that's moving to weigh at least as much as the foot and when your body's lighter it's basically this collision this energy transfer is very inefficient and you don't jump very high.

你希望你的身体，移动的部分至少与脚一样重，当你的身体较轻时，基本上是这种碰撞，这种能量传递非常低效，你不会跳得很高。