More from Haidt & Graham (2009) on how two-foundation people appeared:
Wealth, mobility, technology, education, and cultural diversity – all of these factors weaken the historical interdependence of people within a longstanding community, and free individuals to construct lives for themselves guided by their own preferences. As that happens, the relative importance of the five foundations shifts. Moral foundations theory says that people in all cultures are born with the capacity to cultivate virtues based on all five foundations. Furthermore, people in all cultures do cultivate virtues based on the first two foundations: Harm/care and Fairness/reciprocity (See Brown, 1991, and Hauser, 2006, on moral universals) . But as a society becomes more modern and more individualistic, the first two foundations become ever more important in daily life and in moral and political philosophy, while the last three become less important.
More from Haidt & Graham (2009) on how two-foundation people appeared: