You feel very vulnerable — very, very vulnerable — in that every crack of a grasstalk nearby, you think there’s a lion attached to that, where it might be a mouse. So every hair on your body is standing upright, every sense of survival is crying out to you that you better be alert, and your twitch muscles are already halfway twitched, so you can imagine what it’s like to be a zebra.  Our defense mechanisms don’t allow us to do this all the time. That’s why it’s so extreme. But zebras and other prey animals are not like that all the time. They’re in a fairly relaxed state going into it, and then they have these action moments, and then they forget very quickly. It’s their only mechanism, otherwise they wouldn’t cope. In the same way as combat soldiers can’t stay on high alert all the time, because you just wouldn’t cope.