Researchers from the University of New South Wales, Australia took photographs of 10 men when they were clean shaven, at 5 and 10 days without shaving and with a full beard.
They then asked 351 women and 177 heterosexual men to evaluate what they thought of the men in various phases of beard growth.
Each face was rated for attractiveness, masculinity, health and potential parenting ability.
Women chose men with a heavy 10-day beard as the most attractive and both women and heterosexual men chose men with full beards as the best with perceived parenting skills.
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According to the researchers, "a threshold of density and distribution may be necessary for beards to function as an attractive signal."
Researchers also tested women who were on contraceptive pills and determined that women who were highly fertile and ovulating increased their score of men's masculinity rating compared to women not ovulating.
However, the phase of fertility that women were in had no effect on their impression of a man's attractiveness.
Researchers concluded that full beard implied less aggressiveness.