(CNN) Scientists in China have engineered monkeys to have a human autism gene in the hope that they can find a treatment for the condition, according to the scientific journal, Nature.
A team of researchers at the Institute of Neuroscience in Shanghai created the special test-tube monkeys by giving them copies of the MECP2 gene thought to be linked to autism in humans.
They say the macaques, the second generation to have the gene, showed asocial behavior at 11 months.
"This work demonstrated the feasibility and reliability of using genetically engineered non-human primates to study brain disorders," a statement from the institute read.
According to Nature, autism has a vast array of symptoms and types and researchers think that at least 100 genes play a part.
Until now animal studies of autism have relied on lab mice -- far removed from humans in terms of genes and behavior.
Alysson Muotri, who researches stem cells, autism and Rett's syndrome at the University of California, San Diego told Nature that the macaques are "superior" to existing mouse models because monkeys more clearly show autism-like behavior.
However, he urged caution: "It remains to be seen if the model can actually generate novel insights into the human condition," he says.
China has been at the forefront of research into genetically engineered animals.
Last year, scientists in China said they had created dogs twice as strong as they would be naturally and the animals could help fight or prevent Parkinson's disease.
The Beijing Genomic Institute BGI, caused controversy in 2015 when they genetically engineered "micro-pigs" to sell as pets.
But scientists warn that while advancements in genetic engineering are creating a wealth of new opportunities in medical science, it raises difficult ethical dilemmas.
Penny Hawkins, head of Research Animals Department at the Royal Society for the Prevention of Cruelty to Animals, told CNN last year:
"The creation of genetically engineered animals can involve painful, invasive procedures on animals; including the removal of eggs and hormone treatment.
"Genetic alteration is never predictable and can result in oversized embryos, resulting in painful births. It can leave the animals severely affected in a way which is impractical for life. The process also very wasteful."