It was once thought that only humans could pass the mark test. Then chimpanzees did, followed by dolphins and elephants. These successes challenged the notions that humans were alone on one side of a cognitive divide. Many researchers think the notion of a divide is itself mistaken. Instead, they propose a gradual spectrum of cognitive powers, a spectrum crudely measured by mirrors.I do have to say that stuff like this is why I'd never do science in animal models... at least not primates.
Indeed, macaques — including those in Populin’s study — have repeatedly failed the mark test. But after Rajala called attention to their strange behaviors, the researchers paid closer attention. The highly social monkeys only rarely tried to interact with the reflections. They used mirrors to study otherwise-hidden parts of their bodies, such as their genitals and the implants in their heads. Mark tests not withstanding, they seemed quite self-aware.
“I think that these findings show that self-awareness is not an all-or-nothing phenomenon,” said Lori Marino, an Emory University evolutionary neurobiologist who was not involved in the study. “There may be much more of a continuum in self-awareness than we thought before,”
According to Emory University primatologist Frans de Waal, the new findings fit with his work on capuchin monkeys who don’t quite recognize themselves in mirrors, but don’t treat the reflections as belonging to strangers. “As a result, we proposed a gradual scale of self awareness. The piece of intriguing information presented here may support this view,” he said.