On 10 July 2013 someone posted a YouTube video. Three days later it had 5 million hits. Here is the link:

http://www.youtube.com/watch?v=uD6wdrVFc0g

The one minute clip shows an amazing life-or-death race. It was shot by some Krueger Park tourists on safari in South Africa. Routinely and sternly, visitors to the park are told to stay in their vehicles at all times. But tourists being tourists, you know the rest of the story. The video shows cars parked along the access road with all their windows and doors wide open, and people hanging out every which way in order to get a better view.

In this case what everyone was gawking at was a herd of gazelles being chased down by two amazingly speedy cheetahs. Suddenly the whole chase changed course and headed into the roadway. Predator and prey …