Evolution is not usually thought of as an arms race. But the term, evolutionary arms race, is a prominent facet of evolution theory. In the case of the Giraffe and the Acacia tree, it’s a story of defences, counter-defences and counter-counter-defences.
Giraffes first appeared on this planet around 5-23 million years ago (mya), in the early to middle phase of the Miocene. The Giraffidae family has two extant species – the long-necked Giraffe, and its shorter-necked cousin, the Okapi.
To understand why the giraffe is the way it is, we must turn to one of its favourite foods – the leaves and twigs of the Acacia Tree. In particular, the Southern African species of Vachellia Erioloba – also known as the “Giraffe Thorn.” Its branches are dotted with razor sharp thorns, resembling barbed wire.
Why would a plant need such thorns? To keep herbivores at bay, one would imagine. But this is simply the first line of defence – one that giraffes breached early on. The giraffe’s tongue is a blackish, purple whip – 50 centimetres (cm) in length. It’s capable of weaving through and past Acacia’s spiky thorns, to grasp the leaves it so desires.
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