Evolution could explain the placebo effect: Human immune system has developed on-off mechanism to save energy

By Anthony Bond

PUBLISHED:11:52 EST, 8  September 2012| UPDATED:11:52 EST, 8 September 2012

Scientists have discovered a possible  evolutionary explanation for the placebo effect with new evidence suggesting the  immune system has an on-off switch to save energy.

People who suffer from a weak infection often  recover whether they take a medicinal drug or a simple sugar pill – which  suggests humans can heal themselves.

But this has begged the question why people  need to wait for the placebo before the recovery process from an infection  begins.

Breakthrough: Scientists have discovered a possible evolutionary explanation for the placebo effect with new evidence - using Siberian hamsters, pictured, suggesting the immune system has an on-off switch to save energyBreakthrough: Scientists have discovered a possible  evolutionary explanation for the placebo effect with new evidence – using  Siberian hamsters, pictured, suggesting the immune system has an on-off switch  to save energy

According to the New Scientist, researchers  have now found that something similar to the placebo effect occurs in animals,  after studying Siberian hamsters.

If lights above the hamsters laboratory cages  mimicked winter, they found the hamsters would not fight the  infection.

However, if the lighting was changed to  replicate summer conditions, the hamsters mounted a full immune  response.

Similar to this, people who think they are  taking medicine to treat an illness, but are actually receiving a placebo, can  see a response from their immune system twice that than people who take no  pills.

Success: Peter Trimmer, pictured, a biologist at the University of Bristol has designed a computer model which supports previously released evidenceSuccess: Peter Trimmer, pictured, a biologist at the  University of Bristol has designed a computer model which supports previously  released evidence

The evidence shows that intervention causes a  mental response which kicks the immune system into action.

According to Peter Trimmer, a biologist at  the University of Bristol, there is an explanation for this.

He suggests that the immune system uses up  lots of energy when it is in action. So an animal’s energy reserves cold be  severely depleted if the immune system launches a long response to an illness.

If the infection is not likely to causes  death, it could be better to wait and see that fighting the illness will not put  the animal in other dangers.

Evidence from a computer model designed by Mr  Trimmer and his colleagues now supports this evidence.

It found those animals which live in more  challenging environments were food was harder to find,  they lived longer if they put up with infections rather than launch a response  from their immune system.

However, for those animals living in much  more favourable conditions, it was better for them to launch a response from  their immune systems so they return to health quicker.

This is because in better conditions they  have more access to food which provides energy to sustain an immune  response

Read more: http://www.dailymail.co.uk/sciencetech/article-2200277/Evolution-explain-placebo-effect-Human-immune-developed-mechanism-save-energy.html#ixzz25wuTSTk5