A genetic link between dinosaurs and humans has been found by scientists at Aberdeen University. The researchers say this could provide clues to developing a treatment for depression.
The team found that the component in human DNA, which activates depression, was also present in dinosaurs and would have helped determine their moods.
Using revolutionary technology, the scientists identified the genetic "switches" they believe turn off and on genes that control our behaviour and moods.
According to the team, the switches, also known as "enhancers", have not changed in human genes for hundreds of millions of years.
To make the link between humans and dinosaurs, the researchers examined the DNA structures of other species of animals and birds.
They believe that these enhancers may hold the key to understanding the causes of depression and shed light on why some people develop the illness while others, with a similar genetic make-up, do not.
Though the enhancers are found in every animal alive today, their position has remained unknown until now.
"It appears the switch that drives the gene (which causes depression] seems to have controlled feelings of fear and anxiety in our ancestors 300 million years ago," the Scotsman quoted Dr Alasdair MacKenzie, senior lecturer at Aberdeen University, who is leading the study, as saying.
"The difference is that, originally, it was part of our survival system. The pathology of this gene now is people suffer these same feelings of fear and anxiety when they don't need them," he added.
Dr MacKenzie explained that the cells containing these genes are present in the amygdala, located deep within the human brain, the primary role of which is in the processing and recall of emotional reactions.
He added that the breakthrough was in focusing on the switches that drive the genes rather than the genes themselves.
He compared it to "moving from looking at a car to examining its engine" and said the distances between the switch and the part of the brain they affected were "as surprising as having a light bulb in London with the switch for controlling it in Liverpool".
Researchers will now join forces with Liverpool University and King's College London to launch a 1 million pound research programme in the hope of finding a cure for the debilitating condition.
They will work with people who have depression to inspect their DNA and look for common changes in their genetic switches.
This could eventually lead to drug treatments, which will target the cause of depression and not just its symptoms.