Being at the bottom of the social-economic spectrum could raise the risk of heart disease, diabetes, and mental health problems, according to a new study which strips the negative behaviors associated with poorer groups.

"We know smoking, eating unhealthily and not exercising are bad for you - that puts the onus on the individual that it's their fault," said Duke University researcher Dr. Noah Snyder-Mackler.  "Our message brings a positive counter to that - there are these other aspects of low status that are outside of the control of individuals that have negative effects on health."

The researchers from Duke University came to this conclusion by observing 45 captive rhesus monkeys.  One-by-one, they were divided into nine new groups of five.  The newest member of each group almost always ended up at the bottom of the social order; that caused it to become "chronically stressed".  These monkeys received less grooming and more harassment from the others.

"All the evidence is showing the findings are terrifically applicable to humans," Professor Graham Rook from University College London told the BBC.  "It is something governments just don't understand; they think people at the bottom have got cars, have got TVs, so compared with people in India they're enormously wealthy.  But that really isn't the point, they feel they are at the bottom of the heap."

For example, the wealth gap in the US is directly mirrored by life expectancy between rich and poor - it's more than a decade for women and 15 years for men.  

Dr Snyder-Mackler said, "Status is always relative, but if we could flatten the slope so the differences between the highest and lowest weren't as much, or find ways to focus attention on lower social environments so they are not as 'crappy' we could mediate some of those consequences."