ABSTRACT Based on the assumptions that human food is available for dogs and isotope diet–tissue differences are similar in dogs and humans, the ‘canine surrogacy approach’ (CSA) has been used to infer patterns of ancient populations. The goal of this study was to test the CSA in urban (Brasília and Piracicaba) and in rural (Ubatuba and Maraã) areas. The hair C and N isotope ratios of modern dogs were compared with those of human fingernails from different regions of Brazil. Our CSA results showed a correlation between dog and human isotopes values: in rural areas δ15N of humans and dogs was not statistically different; contrarily, in urban centres, δ15N of humans was approximately 1 ‰ higher (p < 0.01) than δ15N of dogs; humans had lower δ13C values (p < 0.01) than dogs in Brasília, Piracicaba and Ubatuba. In Maraã, there was not any significant difference between dogs and humans. We concluded that CSA is still valid as a first approach in modern societies. However, isotopic differences found suggest that in modern societies processed dog food is increasingly disconnecting human and dog, jeopardising the use of CSA in the future if the trend of increasing processed dog food consumption continues to occur.

中文翻译：

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“犬类代孕方法”（CSA）对巴西以市场为导向和以生计为导向的社区中的狗和人类仍然有效吗？

摘要基于人类食物可用于狗和同位素饮食 - 狗和人类的组织差异相似的假设，“犬代孕方法”（CSA）已被用于推断古代种群的模式。本研究的目标是在城市（巴西利亚和皮拉西卡巴）和农村（乌巴图巴和马拉昂）地区测试 CSA。将现代狗的头发 C 和 N 同位素比率与来自巴西不同地区的人类指甲的比率进行了比较。我们的 CSA 结果显示了狗和人类同位素值之间的相关性：在农村地区，人和狗的 δ15N 没有统计学差异；相反，在城市中心，人类的 δ15N 比狗的 δ15N 高约 1 ‰ (p < 0.01)；在巴西利亚、皮拉西卡巴和乌巴图巴，人类的 δ13C 值（p < 0.01）低于狗。在马拉昂，狗和人之间没有任何显着差异。我们得出结论，CSA 作为现代社会的第一种方法仍然有效。然而，发现的同位素差异表明，在现代社会中，加工狗粮越来越使人和狗脱节，如果加工狗粮消费量增加的趋势继续发生，将来会危及 CSA 的使用。