Our ancestors would not have lasted long if they had assumed that a rustle in the grass was caused by wind when there was even a small chance it was a lion.

• 当周围有一条狮子，甚至这仅是很小的意外时，如果我们的祖先就认为，在草丛中沙沙声是由刮风所引起的，那么他们就不会长期持续地活下去了。