Can brain size increase your chance of survival? According to a recent research based on thecrania of 291 existing mammals and 50 similar ones whose owners went extinct during the LateQuaternary, having a smaller brain predisposed the relevant species __18__ extinction,. Theresearchers’ conclusion may sound intuitive: Big-brained animal adapts or gets out of the way. Butthere’s much more to the story. It’s not a given that a big brain __19__ evolutionary advantage.Big brains actually come at a cost because of the amount of energy they consume. Also, big-brainedanimals tend to live longer and have fewer offspring __20__ they make more of an investment oftime and effort—this can diminish survival probability under pressure. __21__ , species withbigger brains would theoretically be more flexible in their behavior and more competent to cope withthe rapidly changing conditions in the Late Quaternary. In other words, the conditions selected forthe smartest of the pack. This theory is supported by evidence that among birds and mammals today,relatively large brains have been found to improve __22__ in novel conditions and when theanimal is threatened, thanks to behavioral flexibility. It seems that brain size does matter.
【題組】18.
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