Female mammals that suckle another’s young have more offspring

By Christa Lest.

When nursing mothers are supported in other ways, such as being provided abundant food or parenting help, the benefits are even greater.

According to the findings, shared nursing benefits the entire community.

We are in a world of sharing now, where everyone wins.

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During World War II, women helped feed other women's babies in Italy, she says.

At New York University, Cerrito and her colleague Jeffrey Spear created models to assess the effects of different kinds of parental help on the reproductive performance of wild and domesticated mammals.

They used previously published data to represent all orders of placental mammals. They looked at offspring weight, relative to maternal mass, and litter sizes. They looked for published evidence of shared parenting and shared nursing. They considered the effects of domestication, which means mothers receive shelter and food.

Both domestication and shared parenting had a positive effect on litter size and offspring weight. Over the course of a year, domesticated species produced more offspring weight than wild species.

Read more: Female vampire bats groom each other and share their food

The greatest effect was related to shared nursing. Over the course of a year, the offspring of species in which this behavior is seen produced, are 83.1% greater in weight than the offspring of species where infants are fed by their mothers alone.

For both domestication and shared nursing, the increase in offspring weight is usually translated as a bigger child.

According to the findings, even domesticated females can reach the maximum amount of milk they can produce because of the high amount of energy required for milk production.

Milk must be metabolised by a female before it can be fed to an infant.

The findings show that sharing milk helps maximize reproductive output in mammals.

I was pleasantly surprised. He says it was surprising that the effect was greater than domestication.

The findings of this study are somewhat surprising for Heldstab. Heldstab had previously found no reproductive benefits of milk-sharing.

The scientists assumed that in species that allonursing, the infants still go to their mothers more than 80 percent of the time.

She says that the new study challenges that theory and brings allonursing back into play. Depending on how much milk is shared in individual species and cases, she encourages more research to tease out the effects.

There is a journal reference in the PNAS.

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