Can animals have wealth inequality?

Wealth inequality has followed human societies around the world for millennia. But is it exclusive to humans?

A review in Proceedings of the Royal Society B: Biological Sciences proposes studying the wealth inequality of animal societies. This framing, argue the researchers, could allow for new insights into animal behaviour.

The idea first occurred to co-authors Eli Strauss, from the Max Planck Institute of Animal Behaviour, Germany, and Daizaburo Shizuka, from the University of Nebraska-Lincoln, US, when they started to look at economics and sociological research on wealth inequality.

“Reading these fascinating sociology and economics papers, it struck me that this work shares a common goal with my work in animal behaviour, which is that we both want to understand how inequality arises and affects outcomes for individuals and groups,” says Strauss.

There is plenty of research on animal societies, resources and social power. But the researchers think that pulling these themes together under wealth inequality gives them a new way to look at the field.

“As we read, we wondered how the scholarship on the causes and consequences of inequality in humans could help biologists like us better understand animal societies,” says Shizuka.

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Read more: The science of animal sentience

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There’s an obvious fly in the ointment here: animals don’t have money. But then, neither did many human societies, and that hasn’t stopped wealth inequality analyses there.

“These societies show varying degrees of wealth inequality, but wealth isn’t limited to bills and coins,” says Strauss.

Instead, food and resource security, and influence or social relationships, can be used to determine the wealth of an individual. And plenty of animal groups have those.

So what can we learn from this? The researchers think that it can lead to a more comprehensive understanding of ecology.

“The structure of a society has a lot of different influences on all individuals that live within it,” says Shizuka.

“The biology of animal societies includes these types of dynamics, and we can’t understand the evolution of social animals without recognising this feedback between the individual and the society.”

But the researchers caution that animal wealth inequality isn’t identical to that found in human societies.

“We can look to other species to understand the general evolutionary processes that produce all animals, ourselves included,” says Strauss,

“But the question of what makes an ethical human society is fundamentally a moral question where the social lives of animals can’t guide us. This is something we need to figure out on our own.”