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Article History

Received: 14 January 2018

Accepted: 15 April 2018

First Online: 25 April 2018

Ethics approval and consent to participate

: The research is conducted under the supervision of Research Ethics Committee of the University of Tokyo, Japan. For human samples, this study was approved by the Ethics Committee of Faculty of Science, The University of Tokyo (No. 20–05).All the human samples were collected previously for other studies with broad consent; verbal informed consent had been obtained from the human subjects prior to the survey. The samples are anonymous and no personal or medical information were used in this study. The 37 chimpanzee samples were originally obtained from Japanese zoos and institutions and are currently stored at Unit of Human Genetics and Biology, School of Science, the University of Tokyo. For the animal material sampling, we strictly adhered to the Guidelines for Proper Conduct of Animal Experiments (Science Council of Japan) and Fundamental Guidelines for Proper Conduct of Animal Experiment and Related Activities in Academic Research Institutions (Ministry of Education, Culture, Sports, Science and Technology). Four additional chimpanzee samples used for ddPCR that are obtained from Coriell Cell repository.

: The authors declare that they have no competing interests.

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