Social status in some mammals is passed to offspring through the epigenome

Spotted hyenas are fascinating creatures with complex social statuses and hierarchy.

In the wild plains of Tanzania, scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) have made a remarkable discovery: a hyena’s rank within its clan leaves a lasting mark on its epigenome.

What is epigenetics?

Your DNA comprises an intricate blueprint that dictates the construction, maintenance, and functioning of your entire body.

The sequence of nucleotides — adenine (A), thymine (T), cytosine (C), and guanine (G) — encodes this blueprint within your genetic material.

However, not every segment of this genetic code is active at all times. The selective activation and deactivation of genes is crucial for the body’s adaptation to its environment, developmental stages, and various physiological needs.

Epigenetics is the scientific study of the biological mechanisms that switch genes on and off. These mechanisms do not alter the underlying DNA sequence but instead modify the accessibility of genes to the cellular machinery responsible for gene expression.

DNA methylation

One of the primary mechanisms of epigenetic regulation is the addition or removal of methyl groups to the DNA molecule, particularly at the cytosine bases.

This process, known as DNA methylation, can either suppress or enhance gene activity depending on the location and context of the methylation event.

Understanding spotted hyenas

Spotted hyenas (Crocuta crocuta) offer a fascinating glimpse into the intricate world of animal social structures.

Their unique matriarchal society, where females reign supreme, provides a rich backdrop for exploring how social rank shapes the lives of individuals within the clan.

In spotted hyena society, female dominance sets the structure, unlike in most mammals. Females are typically larger and more aggressive than males.

The highest-ranking female, the matriarch, leads the clan, directing them to food sources and making crucial survival decisions.

This power structure permeates all aspects of hyena life, from access to food to opportunities for mating.

Hyenas social status

In spotted hyena clans, social status is passed down through the maternal line. Cubs, male or female, inherit their mother’s rank. This has far-reaching consequences.

The offspring of female hyenas with high-ranking social status enjoy a privileged life with priority access to food. They get the choicest parts of a kill, while lower-ranking members must wait and often receive less nutritious leftovers.

Hyena social status advantage

“Additionally, the effects of social status on life history trajectories and health are typically passed across generations,” said Dr. Heribert Hofer, founder of the Serengeti hyena project.

Cubs of high-ranking mothers receive more than just better food; they benefit from increased protection and social support within the clan.

This boosts their chances of survival and future reproductive success, essentially perpetuating an elite class within the hyena society.

Hyena epigenetic code and social status

The team of researchers led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) had a clever idea. Instead of invasive sampling, they collected fresh droppings from wild hyenas.

These samples contained traces of DNA from cells lining the gut, and with cutting-edge techniques, they analyzed the chemical “sticky notes” – the epigenetic marks.

What they found was astounding. High-ranking and low-ranking female hyenas, both adults and cubs, had distinctly different patterns in their DNA methylation.

Social stress

The scientists found that genes related to energy regulation, immunity, and cell communication contributed to many of the epigenetic changes.

The experts believe that low-ranking hyenas, who have to work harder to find food, might show epigenetic adaptations to handle more physical exertion. It’s like their bodies are adjusting to their tougher lifestyle.

The potential impact on immune function suggests that even a hyena’s place in society can influence its ability to fight disease.

The study opens up a new window into understanding the “social stress” faced by wild animals, and how that stress gets embedded in their biology.

Linking hyena social status, genes, and life

In mammals, social behavior and social status can substantially influence the survival, reproductive performance and health of individuals.

This research in hyenas has incredible implications. It shows how social structures in the animal world aren’t just a matter of who gets the biggest piece of meat.

These social dynamics can have long-lasting biological consequences. While further research is needed, it might even point towards similar mechanisms at play in humans.

The next time you see footage of a snarling, squabbling hyena clan, remember – they’re not just fighting over scraps. Their DNA carries the echoes of their social world, and that world has shaped their health and survival potential.

The study reminds us that the effects of our environment go far deeper than we sometimes realize.

The study is published in the journal Communications Biology.

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