How ants find their way

Path finders: Humans can use higher cognitive functions to combine information from a range of sources when they’re trying to find their way, but how do insects achieve this? (Photo: Getty Images.) Just over 80 years ago, a young biologist in Leiden, in the Netherlands, handed in a PhD thesis that was only 29 pages long and had been written up in a mad hurry, as the author was keen to join a special expedition to Greenland, conducted in celebration of the International Polar Year 1932–33. And yet, this slim thesis, published in a German scientific journal in the same year (Zeitschrift für vergleichende Physiologie (1932) 16, 305–334) is still being quoted in the scientific literature today. The student had conducted what one might call mischievous field experiments. He created landmarks around the nest entries of a wasp species known as bee-wolf (Philantus triangulum), such as a ring of pine cones placed on the ground. But once the wasps had grown used to this, he moved the pine cones a few metres away from the nest and observed returning wasps heading straight to the middle of the cone cycle, but frustrated in their expectation of finding their nest entry there. This mischief-making led to a long and distinguished scientific career, which eventually earned Niko Tinbergen a Nobel Prize (for Physiology and Medicine in 1973), and it highlighted one of the mechanisms by which insects find their way. Even though Tinbergen’s pine cones elegantly and conclusively proved the use of landmarks in insect homing, it turned out to be just one navigation aid of several at their disposal.