Secrets of the Sleeping Beauties of the Animal Kingdom

In Siberian permafrost, in the Arctic, in Chile’s nearly rainless Atacama Desert, and in the dark forests of Poland, organisms have been found that appear lifeless yet will revive and become fully functional when propitious environmental conditions arise. The question these discoveries evoke is not merely how life endures in harsh, inhospitable-to-life places, but what, exactly, it retains while doing so.

Hibernating squirrel in a snowy nest

Source: ChatGPT 5.2

Consider the bdelloid rotifer, a microscopic animal invisible to the naked eye and seemingly indifferent to the usual limits of survival. In a laboratory in Pushchino, Russia, researchers revived rotifers that had been frozen in Siberian permafrost for more than 24,000 years. During that interval, the animals existed in cryptobiosis, a reversible state of suspended animation. “This is the hardest proof so far,” Stas Malavin, one of the researchers, remarked, “that multicellular animals can withstand tens of thousands of years in a state of almost completely arrested metabolism.”

Cryptobiosis is not death, though it resembles it closely enough to make the distinction difficult. Growth stops. Repair ceases. There is no signaling, no transcription, and no detectable metabolism. Biological processes halt, and life retreats to something like a shadow of the real thing.
The organism remains poised, asleep, waiting for Prince Charming to kiss her and bring her water, energy (warmth), and oxygen. When that happens, no matter how much time has passed, the organism awakens and carries on as before.

Along the western coast of South America lies the Atacama Desert, so dry that rain may not arrive for decades. Beneath its soil, scientists have found bacteria that showed no visible activity for years revive and reproduce when moisture finally appears. While earlier studies uncovered dying organisms at the surface and residual DNA, this was the first documented instance of a long-term, viable form of life existing in the desert. “We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains,” commented Dirk Schulze-Makuch, the lead investigator.

Continuing our travels, I take you back to the Arctic, where we find the eponymously named Arctic ground squirrel. Every September in Alaska and Siberia, these squirrels retreat into burrows more than a metre beneath the tundra, curl up in nests built from grass, lichen, and caribou hair, and begin to hibernate. Their core body temperatures plummet, dipping below the freezing point of water. Their neurons shrink, and thousands, if not millions, of vital connections between brain cells wither. Extensive pruning occurs in areas necessary for long-term memory, such as the hippocampus.

And yet, months later, when the squirrels emerge, they behave as though nothing essential has gone wrong. They reliably perform tasks learned before hibernation set in. This offers a persuasive demonstration that memory can endure even under conditions approaching biological suspension.

Researchers at the Polish Academy of Sciences, in Białowieża, set out to test whether bats retain what they have learned prior to hibernation. The experiment was straightforward. Bats were trained to locate food in one of three arms of a maze. Then they were allowed to hibernate. When they emerged months later, they navigated the maze with the same accuracy as before, matching the performance of control bats that had not hibernated.

The squirrel and bat studies provide us with provable evidence that these animals retained known capacities they acquired before they went into a dormant state.

Conventional neuroscience rests on the assumption that memory, identity, and consciousness require ongoing neural activity. According to this view, when electrical signaling ceases, memory dissolves; when metabolism stops, life ends; and when the brain is inactive, the organism becomes a blank slate. Yet the study of cryptobiotic organisms, as well as of the organisms mentioned here, contradicts this premise. These organisms return to their pre-dormant state once the right conditions materialize. This suggests they could not do so unless they “remembered” their past configurations. For this to occur, the organism’s past, its developmental history, adaptive strategies, and future potential must be embedded somatically, conserved in cellular organization, and epigenetic configurations. What that tells us is that these tiny animals carry information necessary for their survival in their bodies, not in neurons or a brain.

The old metaphor of memory being stored like documents in file folders in the brain has been steadily eroding. A growing number of scientists are proposing that memory is distributed throughout the body. No single neuron “contains” a memory any more than a single word contains a language. Instead, memory is encoded in patterns of relationships between cells, tissues, and organs.

Our bodies are perfectly capable of healing wounds or broken bones or even replacing a complex structure such as the liver. For healing to occur, cells, tissues, and organs need to know what, when, and how to accomplish this. Without the ability to “remember” the body’s own structure, healing and regeneration of body tissues would not be possible. Repair of damaged tissues or organs is not top down but bottom up, not controlled by the brain but organized locally by the affected cells or assemblies of cells in body tissues and organs.

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Sleeping Beauty creatures reveal that life is defined by the persistence of embodied information. The organism is a living archive capable of suspension, conservation, and renewal. This lends biological plausibility to the concept of cellular memory and supports my long-held belief that all our experiences, from conception on and perhaps even going back to those of our parents, are somatically archived.

Life can take many forms. It may burn brightly, like a candle, or linger as smoldering embers beneath a blanket of ash, apparently asleep. Waiting for Prince Charming.

A version of this post, "What Animals Teach Us About Life and Memory," appears in The Globe and Mail.