Reproductive compensation was originally a theory to explain why recessive genetic disorders may persist in a population

Population

A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...

. It was proposed in 1967 as an explanation for the maintenance of Rh negative blood groups. Reproductive compensation refers to the tendency of parents, seeking a given family size, to replace offspring that are lost to genetic disorders. It may also refer to the effects of increased maternal or parental investment in caring for disadvantaged offspring, seeking to compensate for genetic disadvantage. It is a theory that suggests that behavioral as well as physiological factors may play a role in the level of recessive genetic disorders in a population.

According to Andrew Overall of the University of Edinburgh

University of Edinburgh

The University of Edinburgh, founded in 1583, is a public research university located in Edinburgh, the capital of Scotland, and a UNESCO World Heritage Site. The university is deeply embedded in the fabric of the city, with many of the buildings in the historic Old Town belonging to the university...

, “Reproductive compensation may be particularly significant where economic or social factors mean that families are small compared to the maximum reproductive rate. Within small families, diseased infants may be more likely to be replaced. As a consequence, parents with otherwise reduced fertility have a greater influence on the frequency of recessive alleles in future generations.”

Ian Hastings has argued that reproductive technologies such as embryo sex selection

Sex selection

Sex selection is the attempt to control the sex of the offspring to achieve a desired sex. It can be accomplished in several ways, both pre- and post-implantation of an embryo, as well as at birth...

, preimplantation genetic diagnosis

Preimplantation genetic diagnosis

In medicine and genetics pre-implantation genetic diagnosis refers to procedures that are performed on embryos prior to implantation, sometimes even on oocytes prior to fertilization. PGD is considered another way to prenatal diagnosis...

 with in vitro fertilization, and selective termination of pregnancy may increase the frequency of genetic disorders through reproductive compensation.

More recently the reproductive compensation hypothesis has been generalized to include, not only recessive genetic disorders, but in a more general sense, the effects of parental compensation when mate selection or breeding take place under constraints. According to Patricia Adair Gowaty

Patricia Adair Gowaty

Patricia Adair Gowaty is an American evolutionary biologist. She received her B.A. in biology at Tulane University and her PhD in zoology at Clemson University in 1980. She is currently a Distinguished Professor at the University of California, Los Angeles....

, “The reproductive compensation hypothesis says that individuals constrained by ecological or social forces to reproduce with partners they do not prefer compensate for likely offspring viability deficits.” In human societies, such constraints include and manipulation of female mating options, forced copulation

Rape

Rape is a type of sexual assault usually involving sexual intercourse, which is initiated by one or more persons against another person without that person's consent. The act may be carried out by physical force, coercion, abuse of authority or with a person who is incapable of valid consent. The...

, arranged marriages, and the trading of copulation for access to resources

Prostitution

Prostitution is the act or practice of providing sexual services to another person in return for payment. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including a "john". Prostitution is one of...

.

Whereas heterozygote advantage

Heterozygote advantage

A heterozygote advantage describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. The specific case of heterozygote advantage is due to a single locus known as overdominance...

 can explain the persistence of high carrier rates of lethal alleles

Lethal alleles

Alleles that cause an organism to die only when present in homozygous condition are called lethal alleles. The gene involved is considered an essential gene....

 in certain regions (e.g. sickle-cell disease

Sickle-cell disease

Sickle-cell disease , or sickle-cell anaemia or drepanocytosis, is an autosomal recessive genetic blood disorder with overdominance, characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various...

 in Central and West Africa), Johan Koeslag and Stephen Schach have suggested that reproductive compensation might explain why different communities have high carrier rates for differing lethal alleles, despite living in similar or sometimes the same environment. Examples are Tay-Sachs disease

Tay-Sachs disease

Tay–Sachs disease is an autosomal recessive genetic disorder...

 amongst Ashkenazi Jews, cystic fibrosis

Cystic fibrosis

Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...

 amongst people of West European origin, and phenylketonuria

Phenylketonuria

Phenylketonuria is an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene for the hepatic enzyme phenylalanine hydroxylase , rendering it nonfunctional. This enzyme is necessary to metabolize the amino acid phenylalanine to the amino acid tyrosine...

among persons from Ireland.