THE MALAGASY baobab tree, whose thick trunks and tiny branches dot Madagascar’s panorama, shouldn’t, by rights, have survived to the current day. Scientists imagine that its giant seeds had been as soon as dispersed by the enormous tortoises and gorilla-size large lemurs that roamed the island. When these species went extinct over one thousand years in the past owing to human exercise, the baobab tree ought to have vanished too. It didn’t. Seheno Andriantsaralaza on the College of Antananarivo in Madagascar and Onja Razafindratsima on the College of California, Berkeley, now suppose they might know the rationale why.