Research has since been carried out to see whether the conclusions of the rat experiment can be applied to humans. In 1993 Bob Jacobs, a neuroscientist working at the University of California, performed autopsies on elderly people, some of whom had been university graduates and some of whom had left school early. He found that the brains of those who were more highly educated had had up to 40 per cent more connections in their brains than the others. Although education can be seen as the human equivalent of the rats’ enriched environment, Jacobs also discovered that those graduates who had continued to learn, to read and to question their environment had more brain connections than those who had become mentally sluggish in later life. This was the case whatever the original level of education the person had.