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科学美国人60秒:北极熊进化-托福听力下载

2017-01-20 14:01:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：北极熊进化

　　科学美国人60秒中英文翻译：北极熊进化

　　科学美国人60秒英文文本

　　A triple bacon cheeseburger seems like a heart attack on a plate.

　　So how can polar bears thrive on their version, seal blubber?

　　Turns out they've stocked up on genes that let them clear fats from their blood.

　　That's according to a study in the journal Cell.

　　Polar bears are well adapted to life on the sea ice.

　　Up to half their body weight's fat, which gives them extra insulation and buoyancy, and provides them with a ready source of energy.

　　But how can an animal so fat also be so fit?

　　Researchers compared the genomes of polar bears with those of brown bears, and found that polar bears have accumulated genetic changes that boost their heart health and fat metabolism.

　　One gene in particular, called ApoB, helps move cholesterol out of the blood—where it causes problems in humans—and into cells.

　　These genomic changes happened quickly, evolutionarily speaking.

　　Polar bears and brown bears diverged from a common ancestor less than half a million years ago.

　　But if that seems super speedy, the ability to digest lactose didn't spread through human populations until we domesticated cows, just 10,000 years ago.

　　A moooving testament to the power of natural selection.

　　中文翻译请点击下一页

本文关键字: 科学美国人60秒 科学60秒下载 托福听力

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