In the heart of the Serengeti, a lone zebra foal named Dika was born with a stark white forelock and a tremor in her hind legs. Her mother, a vigilant plains zebra named Saba, nudged her relentlessly. To a casual observer, it was just a mother encouraging her baby to stand. But to Dr. Elara Venn, a veterinary scientist studying the herd from a camouflaged rover, it was a masterpiece of applied ethology.