Some anthropologists believe that the genetic homogeneity evident in the world`s people is the result of a "population bottleneck" -at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.
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A at some time in the past our ancestors suffered an event, greatly reducing their numbers
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Bthat at some time in the past our ancestors suffered an event that greatly reduced their numbers
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Cthat some time in the past our ancestors suffered an event so that their numbers were greatly reduced,
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D some time in the past our ancestors suffered an event from which their numbers were greatly reduced
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Esome time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,
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