Why some people are more attractive than others

Mar 28, 2007

Paradox of evolutionary theory, often cited by creationists, is explained at last. Researchers believe they have solved a mystery that has puzzled evolutionary scientists for years ... if 'good' genes spread through the population, why are individuals so different?

The so-called 'lek paradox', that sexually-selecting species like humans should have much less individuality than is the case, has been seized upon by creationists as an argument that Darwin's theories are fundamentally flawed.

The problem with current evolutionary theory is that if females select the most attractive mates, the genes responsible for attractive features should spread quickly through a population, resulting in males becoming equally attractive, to the point where sexual selection could no longer take place.

However, new research by Professor Marion Petrie and Dr Gilbert Roberts at Newcastle University, England, suggests that sexual selection can in fact cause greater genetic diversity by a mechanism not previously understood.

Professor Petrie theorised that since genetic mutations can occur anywhere in the genome, some will affect the 'DNA repair kit' possessed by all cells. As a result, some individuals have less efficient repair kits, resulting in greater variation in their DNA as damage does unrepaired.

Although unrepaired DNA is generally harmful - causing tissue to degenerate or develop cancers - it is useful in some parts of the genome, such as those parts resposible for disease defence where variation can help in the resistance to disease. It has long been known that greater variation of DNA in the disease defending regions makes it more likely that an individual can resist attacks by bacteria and viruses.

Using a computer model to map the spread of genes in a population, Professor Petrie demonstrated that the tendency towards reduction in genetic diversity caused by sexual selection is outweighed by the maintenance in greater genetic diversity generated by mutations affecting DNA repair.

The research is published today (28 March 2007) in the academic journal, Heredity, part of the Nature Publishing Group.

Professor Petrie, of the Evolution and Behaviour Research Group in the School of Biology at Newcastle University, said: 'We started this research ten years ago and our model has now produced a good fit with what we observe in terms of genetic variation, which leads us to believe that our theory is correct.' 'We find that sexual selection can promote genetic diversity despite expectations to the contrary.'

In 2005, Professor Petrie and colleagues demonstrated that men with greater genetic diversity in disease defence regions of the genome — and therefore better prospects of passing disease resistance to their offspring — had a number of physical features which women found attractive. The research involved testing men for genetic diversity and showing photographs of them to women, who allocated scores for attractiveness. These scores were found to correlate strongly to genetic diversity.

Source: University of Newcastle upon Tyne

Explore further: Saved from Sandy: Shorebird efforts are declared a success

Related Stories

Beautiful, but blacklisted

May 07, 2015

If you have this beautiful flower in your garden, you should uproot it before the seed pods explode, releasing thousands of seeds. It spreads like the black plague.

See flower cells in 3-D—no electron microscopy required

Apr 30, 2015

Scientists require high-resolution imaging of plant cells to study everything from fungal infections to reproduction in maize. These images are captured with scanning electron microscopy (SEM), where an electron ...

A new crustacean species found in Galicia

Apr 01, 2015

One reason that tourists are attracted to Galicia is for its food. The town of O Grove (Pontevedra) is well known for its Seafood Festival and the Spider Crab Festival. A group of researchers from the University ...

Recommended for you

Birds 'weigh' peanuts and choose heavier ones

May 23, 2015

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

Q&A: Why are antibiotics used in livestock?

May 22, 2015

Wal-Mart, the world's biggest retailer, is the latest company to ask its suppliers to curb the use of antibiotics in farm animals. Here's a rundown of what's driving the decision: ...

User comments : 0

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.