Martin Taylor, who led the study at the Institute of Genetics and Molecular Medicine at the University of Edinburgh, said: "As a species, humans are wonderfully inventive - we are socially and technologically evolving all the time. But this research shows that we are innovating at a genetic level too.
"This new molecule sprang from nowhere at a time when our species was undergoing dramatic changes: living longer, walking upright, learning how to use tools and how to communicate. We're now hopeful that we will find more new genes that help show what makes us human."
The gene is highly active in two areas of the brain, controlling decision-making and language abilities, with the study suggesting it could have a role in the advanced brain functions that make us human.
It is known that most differences between species occur as a result of changes to existing genes, or the duplication and deletion of genes.
But, according to scientists, this gene emerged fully functional out of non-coding genetic material, previously termed "junk DNA", in a brief interval of evolutionary time. They said that, until now, it has been difficult to see this process in action.