A first-of-its-kind analysis of the self-esteem of almost 1 million men and women from 48 countries around the world has confirmed that internationally men feel higher self worth than women, and that both genders demonstrate gains in self-esteem as they get older.

And most interestingly, it appears that the gap between men and women's self esteem is more pronounced in Western nations than in less developed countries.

"During the past two decades, a large number of studies on age and gender differences in self-esteem have found that men have higher self-esteem than women and that both men and women show age-graded increases in self-esteem," said Wiebke Bleidorn, a psychologist at the University of California, Davis. "However, one issue potentially undermines this conclusion: Virtually all previous studies have only examined samples from Western, educated, industrialised, rich and democratic countries."

To ascertain whether the self-esteem gap was universal across cultures outside the Western world, the researchers analysed data from the Gosling-Potter Internet Personality Project, a survey that collected responses from more than 985,000 men and women aged between 16 and 45 in 48 countries.

The findings, which are published in the Journal of Personality and Social Psychology, indicate that while the gender gap in self-esteem levels is for the most part universal across different cultures, it's not always equally severe.

"Specifically, individualistic, prosperous, egalitarian, developed nations with higher gender equality had larger gender gaps in self-esteem than collectivist, poorer, developing nations with greater gender inequality," said Bleidorn. "This is likely the result of specific cultural influences that guide self-esteem development in men and women."

In particular, Asian countries, such as Thailand, Indonesia, China, and India, stood out for having a smaller gap.

But what are these specific cultural influences that seem to make the gap in self-esteem between the genders differ between nations? According to the researchers, several factors could come into play.

"[One] explanation of the larger gender differences in many Western societies concerns the cultural emphasis of girls' and women's physical appearance," the researchers write. "[N]umerous studies have shown that girls' attitudes about their appearance become more negative during adolescence… This decline in girl's perceived physical attractiveness is supposed to have particularly negative effects on self-esteem when cultural pressures regarding women's physical appearance are high."

Further, in developed countries with a lower adolescent birthrate and a later age of marriage, the researchers found that while the absolute gender gap may be larger, it becomes less pronounced with age.

"In countries with less traditional gender roles and smaller gender- based gaps in economic participation, education, political empowerment, and health … women are more likely to have access to status positions and instrumental roles, to experience a sense of mastery, and to receive appreciation and social support," the researchers write. "As a consequence, women from countries with greater gender equality might show relatively stronger age-graded increases in self-esteem as they traverse early and middle adulthood."

In any case, the finding that the self-esteem gap is not itself a "Western idiosyncrasy" is important, and further studies exploring how cultural factors impact this seemingly universal gap in how we feel about ourselves could lead to understanding how to boost our notions of self worth.

"This remarkable degree of similarity implies that gender and age differences in self-esteem are partly driven by universal mechanisms; these can either be universal biological mechanisms such as hormonal influences or universal cultural mechanisms such as universal gender roles," said Bleidorn. "This new research refines our understanding of how cultural forces may shape self-esteem, which, when worked out more fully, can help inform self-esteem theory and design interventions to promote or protect self-esteem."