Final answer:
The cultural advantage of plural marriages in some societies is predominantly due to the economic and reproductive benefits seen in small-scale farming economies where children contribute to labor. Polygyny, practiced by wealthier and older men, may decrease with modern influences. Cultural values often present contradictions between ideals and practices.
Step-by-step explanation:
The most common cultural advantage explaining why plural marriages have value for some societies comes from economic and reproductive benefits. In cultures with small-scale farming economies, plural marriages can result in more children who contribute to farming labor, making it an advantageous arrangement. In these societies, polygamy is often a practical response to the need for additional labor and is more prevalent where children are a significant aspect of food production. However, more factors such as religious ideologies, social status, and population growth also play a role in the existence and acceptance of polygamy.
While polygyny is common in certain cultures, often due to the economic benefits, it tends to be practiced by a minority of men, generally those who are older and of higher status. As societies modernize and become influenced by urbanization, mass media, and education, the practice tends to decrease.
The value systems within a culture can be complex and sometimes contradictory. For instance, while monogamy is valued in Western cultures, instances of infidelity occur, and while cultural diversity is prized, inequality and discrimination persist. These inconsistencies reflect the ongoing struggle to align cultural values with actual practices.