Attractive women have higher expectations, the research suggested
Attractive women may have the competitive edge by letting their temper flare more, research suggests.
Researchers found women who rated themselves as pretty displayed a war-like streak when fighting battles to get their own way.
The University of California interviewed 156 female students to gauge their temperament and how they handled conflict.
The findings appear in Proceedings of the National Academy of Sciences.
In the study, the women who believed they were good looking were more likely to respond angrily in disputes than those who rated themselves as less attractive.
Attractive women also had higher expectations of what they deserved.
Survival of the fittest
These were strategies that appeared to work because the same women were better at resolving situations in their favour.
When the researchers, led by Dr Aaron Sell, scrutinised the findings further, they found how attractive other people rated the women also tallied.
And so did hair colour - with blondes rated as more attractive than brunettes and redheads.
The researchers believe the findings have an evolutionary basis, ensuring that the "fittest" people mate and have offspring.
In men, they found a similar link but with physical strength rather than attractiveness per se.
Consultant psychologist Ingrid Collins, of The London Medical Centre, said the latest findings were interesting but should be interpreted with caution.
"This is a small study on a very limited sample group so it is not possible to generalise."
19 January 2010: This story has been revised after Dr Sell made clear to the BBC that his research had set out to test the link between temperament and attractiveness, rather than hair colour, for which he said the link was weaker.