<P> Furthermore, emerging adulthood occurs only within societies that allow for occupational shifts, with emerging adults often experiencing frequent job changes before settling on particular job by the age of 30 . Arnett also argues that emerging adulthood happens in cultures that allow for a period of time between adolescence and marriage, the marker of adulthood . Such marital and occupational instability found among emerging adults can be attributed to the strong sense of individualization found in cultures that allow for this stage of development; in individualized cultures, traditional familial and institutional constraints have become less pronounced than in previous times or in unindustrialized / developing cultures, allowing for more personal freedom in life decisions . However, emerging adulthood even occurs in industrialized nations that do not value individualization, as is the case in some Asian countries discussed below . </P> <P> Up until the latter portion of the 20th century in OECD countries, and contemporarily in developing countries around the word, young people made the transition from adolescence to young adulthood around or by the age of 22, when they settled into long - lasting, obligation - filled familial and occupational roles . Therefore, in societies where this trend still prevails, emerging adulthood does not exist as a widespread stage of development . </P> <P> Among OECD countries, there is a general "one size fits all" model in regards to emerging adulthood, having all undergone the same demographic changes that resulted in this new stage of development between adolescence and young adulthood . However, the shape emerging adulthood takes can even vary between different OECD countries, and researchers have only recently begun exploring such cross-national differences . For instance, researchers have determined that Europe is the area where emerging adulthood lasts the longest, with high levels of government assistance and median marriage ages nearing 30, compared to the U.S. where the median marriage age is 27 . </P> <P> Emerging adult communities in East Asia may be most dissimilar from their European and American counterparts, for while they share the benefits of affluent societies with strong education and welfare systems, they do not share as strong a sense of individualization . Historically and currently, East Asian cultures have emphasized collectivism more so than those in the West . For instance, while Asian emerging adults similarly engage in individualistic identity exploration and personal development, they do so within more constrictive boundaries set by familial obligation . For example, European and American emerging adults consistently list financial independence as a key marker of adulthood, while Asian emerging adults consistently list capable of supporting parents financially as a marker with equal weight . Furthermore, while casual dating and premarital sex has become normative in the West, in Asia parents still discourage such practices, where they remain "rare and forbidden". In fact, about 75% of emerging adults in the U.S. and Europe report having had premarital sexual relations by the age of 20, whereas less than 20% in Japan and South Korea reported the same . </P>

In terms of biosocial development the beginning of adulthood