Revealed: The EXACT number of friends you need to be successful - and why having too many can be just as bad as having none

 A behavioural psychologist has revealed the exact number of friends you need to be successful - and why having too many can be just as bad as having none.

British anthropologist and 'mathematician of relationships' Robin Dunbar believes we can only maintain a certain number of human connections at any one time.

In his latest book, Friends: Understanding the Power of our Most Important Relationships, the 73-year-old dissects scientific research into human groups to determine that 150 is the 'magic number' needed for success.

Mr Dunbar discovered that historically, 150 was the preferred grouping found in factories, small villages and and military units, where everyone knows each other's names and skills and are willing to help each other when needed.

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British anthropologist and 'mathematician of relationships' Robin Dunbar believes we can only maintain a certain number of human connections at any one time (stock image)

In modern times, Mr Dunbar says this number chiefly consist of 'regular' friends, who we see at weddings and school reunions where we promise to meet up more often, the Australian reported.

Within the 150 figure, Mr Dunbar suggests we have five 'intimate' friends - who would donate a kidney to you - and anywhere from 12 to 15 'supportive' friends, who would be distraught if you died.

He also claims we have 50 'good' friends, who would be invited to a birthday party but not to an intimate dinner at your house.

Mr Dunbar's theory is based on the idea that we only have a certain amount of 'emotional capital' or energy to invest in others, which is why the majority of people have roughly the same amount of friends.

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Robin Dunbar (pictured) discovered that 150 was the preferred grouping historically found in factories, small villages and and military units

Trying to maintain too many social circles will result in burnout because we stretch ourselves too thin, his theory suggests.

Mr Dunbar's research into human interaction has been used to determine the ideal number of participants for everyday activities from dinner parties to walking groups.

Four is the perfect number of guests to invite for dinner if you want to have a meaningful conversation where everyone gets involved, but six should be invited if you want the discussion to cover a broader range of subjects.

His theory claims 10 is the ideal membership for a book club to encourage diverse and lively debate, while holiday groups should consist of no more than eight to avoid arguments and headaches over restaurant bookings.