Women tend to post sexy selfies online more in environments with greater economic inequality, rather than where they might be oppressed because of their gender.
The findings, published in the journal Proceedings of the National Academy of Sciences (PNAS), suggest that women take sexy selfies to compete with peers and climb the social ladder.
"The argument is usually that when you see sexualisation, you see disempowerment," said lead author Khandis Blake from University of New South Wales (UNSW) Sydney in Australia.
"What we found instead is that women are more likely to invest time and effort into posting sexy selfies online in places where economic inequality is rising, and not in places where men hold more societal power and gender inequality is rife," Blake added.
For the study, the team analysed tens of thousands of social media posts across 113 countries.
They tracked posts where people had taken selfies and then noted those that they were tagged sexy, hot or similar.
The researchers explained that income inequality increases competitiveness and status anxiety among people at all levels of the social hierarchy, making them sensitive to where they sit on the social ladder and wanting them to do better than others.
"That income inequality is a big predictor of sexy selfies suggests that sexy selfies are a marker of social climbing among women that tracks economic incentives in the local environment," Blake said.
"Rightly or wrongly, in today's environment, looking sexy can generate large returns, economically, socially, and personally," she added.
The researchers then found the exact same pattern in real-world spending in other appearance-enhancing areas.
"So, when a young woman adjusts her bikini provocatively with her phone at the ready, don't think of her as vacuous or as a victim.
Think of her as a strategic player in a complex social and evolutionary game. She's out to maximise her lot in life, just like everyone," Blake said.