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1 .This is Scientific American 60-Second Science. I'm Dina Fine Maron. Got a minute?
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2 .Women have a biological cap on their reproductive years.
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3 .And from an evolutionary standpoint researchers have long wondered why human female longevity extends well past fertility.
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4 .Other than humans, only short-finned pilot whales and killer whales live three or more decades after menopause, some even reaching their 90s.
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5 .Male whales, which are far less likely to be followed by group-mates than are females, seldom survive past 50.
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6 .Now a study of killer whales offers some clues about why evolution may have selected for such long life:
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7 .older females have accrued what the study authors call "repositories of ecological knowledge," that can help their entire group survive.
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8 .The researchers examined more than 750 hours of killer whale video.
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9 .They saw that older, wizened females were the individuals most likely to lead younger whales to salmon feeding grounds, especially during lean times.
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10 .The study is in the journal Current Biology.
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11 .The work provides the first evidence that the advantage conferred via the knowledge held by elderly female whales may be behind the adaptation for their post-fertility longevity.
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12 .In humans, an analogous explanation for post-menopausal longevity is part of what's called "the grandmother effect," the constellation of attributes that make older women especially valuable to the community.
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13 .Whale grandmas appear to be highly valuable, too.
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14 .Thanks for the minute, for Scientific American 60-Second Science. I'm Dina Fine Maron.
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