Early trauma cuts life short for squirrels, but this can be reversed

Life in the wilds of the Yukon is a relentless test of survival. For the red squirrels that inhabit this territory, danger lurks around every corner – freezing temperatures, scarce resources, and hungry predators. So how do squirrels manage the traumas?

Why do some squirrels live longer, healthier lives than others? Scientists are discovering fascinating answers that even have implications for our understanding of human stress and resilience.

Early traumas, shorter squirrel lives

Lauren Petrullo, a researcher at the University of Arizona, is deeply involved in studying the survival factors of red squirrels. Her recent study highlights a significant finding: young red squirrels that encounter numerous traumas during their first year typically experience a reduction in their adult lifespan.

Specifically, in the challenging conditions of the Yukon, such early life stress leads to an average lifespan reduction of at least 14 percent. This research underscores the critical impact of early developmental conditions on the longevity of these animals.

“The ecosystem red squirrels inhabit in this region is unique. Every three to seven years, their favorite food – seed from cones of white spruce trees – is produced in superabundance during what we call a food boom,” Petrullo said.

“We found that these booms, even though rare, can interrupt the biological embedding of early-life adversity. If a squirrel had a harsh first year of life, if they were lucky enough to experience a food boom in their second year of life, they lived just as long – if not longer – in spite of early-life adversity.” 

What is a food boom?

A food boom is a sudden and significant increase in the availability of food resources within an animal’s environment. There are multiple causes behind food booms. Some food sources experience cyclical booms and busts. For example, trees that produce nuts or seeds might only have huge yields every few years.

Additionally, favorable weather conditions can lead to increased plant growth, insect populations, or other food sources for animals. The removal of a predator or the introduction of a new prey species can disrupt the balance and make more food available for some animals.

Food boom benefits

Even with a rough beginning, plentiful food sources can repair damage caused by early-life stress in animals. The research shows that squirrels who had difficult early lives, and later experienced a surge in food availability, had lifespans comparable to (or even exceeding) squirrels who never had to experience hardship.

This implies that the benefits of a food boom extend beyond simple nutrition. A possible explanation is that abundant food favorably alters the animal’s surroundings by decreasing the need for competition and ultimately improving chances of survival.

Study significance

“Our findings in red squirrels echo what we know about how early-life adversity can shorten adult lifespan in humans and other primates,” said Petrullo.

The main takeaway from this research is the concept of resilience. Similar to squirrels, individuals vary in their ability to cope with the lingering effects of early life trauma. The study proposes that later positive experiences are significant in determining the extent to which early stress affects an individual.

Squirrels are often subjects in laboratory studies due to their physiological similarities to humans. However, Lauren Petrullo emphasizes the value of studying these animals in their natural surroundings. This approach provides a clearer view of how stress, resilience, and environmental factors interact dynamically outside the controlled conditions of a lab.

Climate change: A new challenge to squirrel trauma

The survival strategies of red squirrels, particularly their reliance on periodic food booms, have developed to thrive within a specific climatic context. Unfortunately, the escalating issue of global warming poses a significant threat to these patterns.

Rising temperatures have the potential to disrupt the timing and abundance of these crucial food booms. If these natural events become less frequent or less predictable, squirrels that encounter significant challenges early in life may find themselves even more vulnerable to the adverse effects of their harsh environments. This could result in increased mortality rates and impact the overall population stability of the species.

“As food boom patterns begin to change, the pathways that connect early-life experiences and lifespan may change as well, potentially offering important insight into how animals may adapt to increasingly challenging environments,” said Petrullo.

This research isn’t just about squirrels and their trauma. It’s a captivating story about survival, where even in harsh conditions, there’s always hope. Just like a lucky food boom can alter a squirrel’s fate, our own paths might hold life-changing opportunities.

As scientists continue to study these resilient creatures, we may not only discover the secrets to their success, but also gain valuable insights to enhance our own well-being.

The study is published in the journal Proceedings of the Royal Society B Biological Sciences.

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