Researchers transferred a gene linked to brain development, called MCPH1, into rhesus monkey embryos.
Once they were born, the monkeys were found to have better memories, reaction times and processing abilities than their untouched peers.
“This was the first attempt to understand the evolution of human cognition using a transgenic monkey model,” said Bing Su, a geneticist at Kunming Institute of Zoology in China.
The research was conducted by Dr Su’s team at the Kunming Institute of Zoology, in collaboration with the Chinese Academy of Sciences and University of North Carolina in the US.
“Our findings demonstrated that nonhuman primates (excluding ape species) have the potential to provide important – and potentially unique – insights into basic questions of what actually makes human unique,” the authors wrote in the study.
The authors explained that the rhesus monkey had been chosen because it is genetically closer to humans than rodents – which are normally used in testing – but still distant enough to reduce ethical concerns.
Other scientists and animal activists criticised the experiment.
“You just go to the Planet of the Apes immediately in the popular imagination,” Jacqueline Glover, a University of Colorado bioethicist MIT Technology Review.
“To humanise them is to cause harm. Where would they live and what would they do? Do not create a being that can’t have a meaningful life in any context,” she added.
Animal rights group PETA described the study as “vile”.
“Macaque monkeys are highly intelligent fellow primates who form intricate social relationships, experience every emotion humans do and can suffer just as much as we can.
“In this vile study, female monkeys were cut open and artificially fertilised – and many pregnancies failed,” Anna Van Der Zalm, of PETA UK, told Tech Times.
The research is published in the Bejing-based journal National Science Review.