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1 .This is Scientific American 60-Second Science. I'm Cynthia Graber. Got a minute?
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2 .Plants thrive all over the planet, despite the fact that many animals love to snack on them.
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3 .Various hypotheses account for all those plants.
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4 .One is that predators kill enough plant-eating animals to give vegetation a chance.
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5 .Another is that plants develop physical and chemical means to defend themselves.
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6 .Now researchers have teased out some of these factors in an East African savannah.
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7 .The impala an African antelope eats grasses and trees and is itself eaten by wild dogs and leopards.
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8 .Impala often munch on a tree called the acacia.
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9 .Some acacia have thorns, and some don't.
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10 .The researchers found that the impala perhaps not surprisingly prefer thorn-free acacia.
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11 .Also, the animals avoid woody areas where predators are more likely to hide.
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12 .And as a result, the thorn-free, vulnerable acacia are more plentiful in woody areas with plenty of predators.
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13 .But the thorny acacia are more numerous on the open savannah, where they need to defend themselves.
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14 .The study is in the journal Science.
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15 .The researchers say their findings show that both plant defenses and carnivorous predators help plants thrive.
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16 .They also say that when humans influence in part by eliminating large predators, we disrupt longstanding, complex systems.
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17 .And that we should really try to better understand such systems, and our effects on them.
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18 .Thanks for the minute, for Scientific American 60-Second Science. I'm Cynthia Graber.
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