Los humanos tenemos una mayor inteligencia gracias a la indefensión de nuestros bebés

Una nueva idea se abre paso para explicar la enorme diferencia de inteligencia que existe entre los humanos y otras especies. Esta nueva teoría la han desarrollado dos investigadores de la Universidad de Rochester, en Nueva York. Steven Piantadosi y Celeste Kidd sugieren que los seres humanos pueden haber llegado a ser tan inteligentes gracias a otra característica evolutivamente extraña: a saber, que sus bebés son tan impotentes e indefensos.

THE ECONOMIST.- Compared with other animals, says Dr Kidd, some of whose young can stand up and move around within minutes of being born, human infants take a year to learn even to walk, and need constant supervision for many years afterwards. That helplessness is thought to be one consequence of intelligence—or, at least, of brain size. In order to keep their heads small enough to make live birth possible, human children must be born at an earlier stage of development than other animals. But Dr Piantadosi and Dr Kidd, both of whom study child development, wondered if it might be a cause as well as a consequence of intelligence as well.

Their idea is that helpless babies require intelligent parents to look after them. But to get big-brained parents you must start with big-headed—and therefore helpless—babies. The result is a feedback loop, in which the pressure for clever parents requires ever-more incompetent infants, requiring ever-brighter parents to ensure they survive childhood.

It is an elegant idea. The self-reinforcing nature of the process would explain why intelligence is so strikingly overdeveloped in humans compared even with chimpanzees. It also offers an answer to another evolutionary puzzle, namely why high intelligence developed first in primates, a newish branch of the mammals, a group that is itself relatively young. Animals that lay eggs rather than experiencing pregnancy do not face the trade-off between head size at birth and infant competence that drives the entire process.

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