User:TanishaT/Cooperative breeding

Cooperative Breeding

Lead and Subsequent Information from original article

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Mammals

Across all mammalian species, less than 1% exhibit cooperative breeding strategies. Phylogenetic analysis shows evidence of fourteen discrete evolutionary transitions to cooperative breeding within the class Mammalia. These lineages are nine genera of rodents (Cryptomys, Heterocephalus, Microtus, Meriones, Rhabdomys, Castor, Atherurus and two in Peromyscus), four genera in Carnivora (Alopex, Canis, Lycaon, and in mongooses), and one genera of primates (Callitrichidae). Cooperative breeding in mammals is not limited to these stated lineages, rather they are significant evolutionary events that provide the framework for understanding the origins and evolutionary pressures of cooperative breeding. All of these evolutionary transitions have occurred in lineages that had a socially monogamous or solitary breeding system, suggesting that strong kinship ties are an essential factor the evolutionary history of cooperative breeding. Additionally, polytocy, or the birth of multiple offspring per birthing episode, is a highly correlated evolutionary determinant of cooperative breeding in mammals. These two factors, social monogamy and polytocy, are not evolutionary associated, suggesting that they independent mechanisms leading to the evolution of cooperative breeding in mammals. The global distribution of mammals with cooperative breeding systems is widespread across various climatic regions, but evidence shows that the initial transitions to cooperative breeding are associated to species in regions of high aridity.

Canids (from original article)

New Addition: Cooperative breeding increases the rate of reproduction in females and decreases the litter size.

Primates

In most non-human primates, the reproductive success and survival of offspring is highly dependent to the mother's ability to produce food resources. Therefore, one component of cooperative breeding is the delegation of offspring holding, which allows the mother to forage without the added costs of holding her offspring. Additionally, in primate species with cooperative breeding systems, females have shorter interbirth intervals. Female grey mouse lemurs (Microcebus murinus) form social groups and cooperatively breed with closely related female kin. The females benefit from sharing limited nesting spaces and increased nest defense but do not exhibit food provisioning behaviors as they are solitary foragers.

Humans

Direct expression of cooperative breeding includes facultative parental care, including alloparenting, and extended post-menopausal lifespan in females, which forms the basis of the Grandmother Hypothesis. Cooperative breeding in humans is theorized as the optimal solution to high energetic costs of survival due to nature of human diet, which involved high-quality foods often in need of processing and cooking. Additionally, food provisioning in cooperate breeding societies may explain the relatively short period of weaning in humans, typically two to three years, when compared to non-human apes who wean their offspring for upwards of six years.

Human offspring do not fall neatly into the dichotomous categorization of precocial versus altricial, and instead Portmann proposes they are "secondarily altricial" at birth due to the underdevelopment of neurological and cognitive capabilities. Therefore, human offspring are highly dependent on caregiver investment, a necessity that serves as the precursor for theories on the development of pair-bonding, alloparenting, and cooperative breeding. The evolution of cooperative breeding in early Homo species also promoted other pro-social behaviors such as social learning, increased social tolerance, and shared intentionality especially in food acquisition. Additionally, pro-social behaviors in cooperative breeding in humans had a by-product effect of enhancing cognitive capabilities, especially in social tasks involving coordination.

Human mother's tend to have overlapping, dependent offspring due to shorter interbirth intervals, high fertility rates, and low infant mortality rates, thus imposing high energetic costs. Unlike other species with cooperative breeding systems, human female "helpers" do not incur the cost of reproductive suppression at the benefit of a single, dominant breeding mother. Instead, cooperative breeding is highly prevalent among grandparents, and juveniles, who are generally not competing for mating opportunities. This intergenerational flow of resources supports the theory of mutualism as an evolutionary pathway to cooperative breeding in humans.