On our first full day in Tanzania, my two sons and I sat out on the terrace of our room at the Four Seasons Serengeti watching game ambling across the vast open plains. The long grasses, baked crisp by the sun, rustled in the breeze with a hollow rattle. Topi, gazelles, impalas and zebras strolled in single file past olive-green acacias towards a small watering hole about 40 feet from where we sat. Occasionally a foal would startle and everyone would break into a canter. Warthogs swatted their t...