介绍： This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
Immigrants to the U.S. might lose touch with certain customs and traditions back home. But here's something else they lose: their microbes. "When they came to the U.S. almost immediately they began losing their native microbes." Dan...

介绍： This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
Immigrants to the U.S. might lose touch with certain customs and traditions back home. But here's something else they lose: their microbes. "When they came to the U.S. almost immediately they began losing their native microbes." Dan Knights, a computational biologist at the University of Minnesota. "And over time the balance shifted to the point where they were dominated by the U.S. associated microbes."
He's referring to first- and second-generation immigrant women, from the Hmong and Karen ethnic minorities in southeast Asia. His team sequenced the DNA found in their feces. And they saw that there was an immediate decline in the number and diversity of gut microbes among the immigrants, compared to their counterparts still living back home. And the decline continued over time.

If you're thinking, well, maybe the women just switched up their diets — started eating more hamburgers, more bacon and eggs? Dietary surveys don't bear that out. The women weren't changing their diets nearly fast enough to explain the drop in diversity.

这里是科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。
移民美国者可能会与丢失家乡的某些习俗和传统。但同时失去的还有一样东西：他们体内的微生物。“移民来到美国后，他们体内的原有微生物就会马上开始流失。”明尼苏达州大学的计算生物学家丹·奈特说到。“随着时间的推移，他们体内的平衡状态会转变为由美国相关微生物主导。”
他指的是来自东南亚苗族和克伦族等少数民族的第一和第二代女性移民。他的团队对这些移民粪便中的DNA进行了测序。他们发现，与生活在故乡时相比，这些移民在进入美国后，其肠道微生物的数量和多样性立即下降。而且随着时间的推移，这种下降趋势会一直持续下去。
如果你认为，也许这些女性只是改变了她们的饮食——开始食用更多的汉堡、培根和鸡蛋。可饮食调查结果并不支持这种想法。这些女性改变饮食的速度，不足以解释肠道菌群多样性下降的原因。