Natural selection makes some relatives selfish, others altruistic

March 2, 2011

( -- Cain and Abel certainly displayed it and the three daughters of King Lear proved the point too - families contain a mixture of the selfish and those who put themselves out to help others.

Previous research has shown that these traits - selfishness and altruism - can be passed down through families. A new study from the University of Reading shows how determines the frequencies of selfishness and altruism in successive generations.

Studies in behavior genetics show that around 40% of the willingness to help others is inherited. Those who do not help others help themselves, and anti-social behavior is inherited too. Depending on the genotypes of their parents, children may all be , all altruistic or a mixture of both.

The Reading study, based on , suggests that the numbers of altruistic and selfish individuals in society are controlled by a law of diminishing returns. If there are only one or two altruists in a family, and their actions help others in the family sufficiently compared to the cost of the , then genes for altruism will do better than genes for selfishness, resulting in more altruists in the family tree. So eventually all individuals in the population may be altruistic. Alternatively, when there are many altruists natural selection may ensure that altruistic are less likely to be passed on.

This is because the extra altruists may not bring enough extra benefits to the family. For example, if someone needs shelter when injured or food when starving, the first individual to help may save their life. Latecomers may also attempt to help, but the additional benefit is less.

In other words, there are diminishing returns because there are limits to how much individuals can be helped. Altruists are selected when rare but selected against when common. The result is an evolutionary equilibrium with some individuals selfish and others altruistic.

The research was conducted by Professor Richard Sibly, of the School of Biological Studies, and Professor Robert Curnow, of the School of Mathematical and Physical Sciences.

Professor Sibly said: "Understanding how altruism evolved was of absorbing interest to Darwin and has continued to fascinate biologists ever since. Help comes in many forms, presumably with different genetic bases, for example, child rearing, provisioning during times of need, and defence of resources against competitors. Each and any of these may be subject to laws of diminishing returns. The form of the relationship between help received and number of helpers requires quantitative description. The expected mix of selfishness and can then be calculated using the new equations."

Explore further: The Greenbeards Have Blue Throats In The Evolution Of Altruistic Behavior

Related Stories

The economics of nice folks

June 19, 2008

A basic tenet of economics is that people always behave selfishly, or as the 18th century philosopher economist David Hume put it, "every man ought to be supposed to be a knave."

Acting selfish? Blame your mother

September 2, 2010

( -- The fact that our female ancestors dispersed more than our male ancestors can lead to conflicts within the brain that influence our social behaviour, new research reveals.

Recommended for you

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

Winter season reverses outcome of fruit fly reproduction

November 24, 2015

Male fruit flies could find their chances of fathering offspring radically reduced if they are last in the queue to mate with promiscuous females before winter arrives, according to new University of Liverpool research.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) Mar 05, 2011
So then it is OK that I was born with a trait of not believing in macro-evolution? This is saying that it is NOT any fault of mine? So that I am not seen as selfish, let me help by saying that Jesus Christ is the son of God, the world was created in 6, 24 hour days. Your attempts to prove otherwise are in vain. If only the writers of the article would read more than the story of Cain and Abel.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.