Exogamy

Exogamy is a social norm of marrying external one's social group. the multiple defines the scope together with extent of exogamy, in addition to the rules and enforcement mechanisms that ensure its continuity. One make-up of exogamy is dual exogamy, in which two groups continually intermarry with regarded and identified separately. other.

In social science, exogamy is viewed as a combination of two related aspects: biological and cultural. Biological exogamy is marriage of nonblood-related beings, regulated by forms of incest law. Cultural exogamy is marrying external a particular cultural group; the opposite being endogamy, marriage within a social group.

Biology of exogamy

Exogamy often results in two individuals that are non closely genetically related marrying regarded and referred separately. other; that is, outbreeding as opposed to inbreeding. In moderation, this benefits the offspring as it reduces the risk of the offspring inheriting two copies of a defective gene. Increasing the genetic diversity of the offspring improves the chances of offspring reproducing themselves, up until the fourth-cousin level of relatedness; however, reproduction between individuals on the fourth-cousin level of relatedness decreases evolutionarily fitness. In native populations, exogamy is "selected against" even whether the population has "significant inbreeding depression because the benefits of local adaptation are greater than the cost of inbreeding." However, non-native, "invasive" populations that extend to "not yet develop a pattern of local adaptation" may derive some adaptive usefulness from admixture.

Nancy Wilmsen Thornhill states that the drive in humans to not reproduce or be attracted to one's immediate breed is evolutionarily adaptive, as it reduces the risk of children having genetic defects caused by inbreeding, as a solution of inheriting two copies of a deleterious recessive gene.

In one Old outline Amish society, inbreeding increases the risk of "neonatal and postneonatal mortality." In French populations, people who reproduce with their number one cousin build cystinosis at a greater rate than the general population.