Saharan desert ants of the genus Cataglyphis have to travel long distances to discover food in their impoverished, sandy environment. How they find their way home once they have done so is a mystery. Ants in more temperate climates often lay down chemical trails, but Cataglyphis, apparently, does not. Like honeybees and ancient mariners, they can navigate by the sun, so they know the general direction in which to travel. But, also like ancient mariners (who knew their latitude, but not their longitude), such solar reckoning cannot tell them when to stop.

　　撒哈拉沙漠的箭蚁不得不在贫瘠的沙质环境中长途跋涉寻找食物。它们找完食物后如何返回蚁巢却一直是个谜。温和气候环境下的蚂蚁往往会在路途中留下化学记号，可箭蚁显然不会。它们跟蜜蜂和古代海员一样，可以通过日照导航，从而知道出行的大致方向。但是也跟古代海员一样（他们只会辨认纬度不会辨认经度），这种根据太阳测算位置的方法无法告知它们该在何时结束行程。