科学美国人60秒 由于基因变异，城市天鹅可能会容忍人类（在线收听）

Animals that live in the city are usually less wary of humans than their rural counterparts. Most people think the boldness comes from experience: since the majority of humans are rather harmless, the critters learn to go about their business without fear. But the truth turns out to be far more interesting, at least for Australian swans. Turns out the city birds are genetically different from their country counterparts.

与城市动物相比，生活在农村的动物更易惧怕人类。多数人认为勇敢源于经验：由于大部分人类不会伤害动物，因此动物们可以无所畏惧的从事自己的活动。但是对于澳大利亚的天鹅来说，结果更为有趣。结果表明，城市天鹅和农村的天鹅基因不同。

Australian researchers looked at two groups of swans. One population lived on a pond in the center of Melbourne. The second hung out just 30 kilometers away in a more bucolic setting, surrounded by far fewer humans. The researchers measured what they call each bird’s “flight initiation distance”: basically, how close could a human get before the swan would fly away?

澳大利亚的研究人员调查了两组天鹅。其中一组生活在墨尔本市中心的池塘里。而第二组则生活在30公里外，人烟稀少的乡村景色中。研究人员测量了每只天鹅的“飞行起始距离”：即，在天鹅起飞时，人类可靠近的距离。

“We found that the flight initiation distance for the swans at the urban environment was only 13 meters, and on average at the non-urban environment it was 96 meters. So that’s like an 83 meter difference, a really big difference in how wary these swans are at the two habitats.” Victoria University ecologist Wouter van Dongen.

“我们发现，在城市生活的天鹅其飞行起始距离只有13米，而在非城市环境中天鹅的平均飞行起始距离为96米。这83米的差距也揭示了这些天鹅对两处不同栖息地谨慎程度。”瑞士维多利亚大学的生态学家Wouter van Dongen说到。

The researchers also took blood samples from some of the swans to analyze their DNA. And almost 90 percent of urban swans had the same variant of a gene for dopamine transport, while just 60 percent of rural birds had that version. And those swans were less wary of humans than were the swans with the rarer genotypes.

研究人员也从天鹅的身上采集了血液样本分析其DNA。其中，几乎90%的城市天鹅有多巴胺转运体变体，而农村天鹅此数据仅为60%。拥有此变体的天鹅更不惧怕人类。

Dopamine influences a lot of brain function, so the gene variation could be behind the difference in swan attitudes. The study is in the journal BMC Evolutionary Biology.

多巴胺会影响大脑的活动，因此，此基因的变体是天鹅对人类态度差异的实质原因。该研究结果发表在《BMC进化生物学》杂志上。

Since swans can easily fly wherever they want, the researchers think that the bolder birds don’t mind setting up shop in the city, while the more timid swans prefer the quieter country life. And that’s something that wildlife managers should keep in mind.

因为天鹅可以飞向自己喜爱的地方，研究人员认为胆子大天鹅并不介意在城市安家，而那些胆小的天鹅则更喜欢宁静的乡村生活。而野生动物管理者需要谨记此点。

"With release programs, often you breed up a small population of whatever animal and then you release them into the wild…and so one potential application of our research is to select individuals that are better able to cope with human disturbance, those that are less wary of humans, and release them into those areas that are more likely to experience human disturbance."

随着越来越多回归大自然的项目，你可以将自己喂养的小动物放回大自然——因此，我们研究的潜在的目的是选择应对人类干扰力强的物种。选择对人类畏惧小的动物，然后将它们释放到更易体验人类干扰的领域。