Professor Sam McNaughton
Vegetarians are sometimes mocked by their meat-eating peers who claim that ‘even carrots scream’ when they are being eaten. Now there is increasing evidence to suggest that this is not as far-fetched as once imagined, with studies showing that plants can recognise an attack, identify their herbivorous attacker, step up their defences against specific attack and even communicate warning to neighbouring plants that herbivore attack is imminent. The ongoing development by plants of sophisticated defence mechanisms and the adaptations of herbivores to these ramped up defences, may even be an important driver of the evolutionary process.
In 1983, the ecologist, Professor Sam McNaughton published a study which showed that grasses in the Serengeti plains take up silicon to synthesise sharp silica crystals within their foliage to deter grazing herbivores by rendering the plants non-palatable and hard to digest, and that the plants on the most heavily grazed areas had the highest content of silica crystals. It is thought that the abrasive effects of plant silicas led to the evolution of ‘hypsodont dentition’, with increased areas of hard enamel on the teeth of some herbivores, and extension of enamel below the gum line, to resist the abrasive damage done by grazing on plants containing high levels of silica. Digestive mechanisms have also evolved and this constant evolutionary battle between herbivores and plants may drive some aspects of evolution.
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March 2017
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