Hibernation and Humans

Hibernation, a fascinating phenomenon observed in nature, has intrigued scientists for centuries. When temperatures plunge and food becomes scarce, various species—ranging from the minuscule dormouse to the mighty bear—enter a state of suspended animation to conserve energy. However, an intriguing question has emerged in recent times: Can humans hibernate? And if so, what would it mean for our species and the future of medical science?

The concept of human hibernation is not as far-fetched as it might initially appear. It’s premised on the biological adaptability humans have displayed throughout history and the advances in medical science. Some experts theorize that human hibernation could provide groundbreaking solutions in fields like space travel, medical surgery, and trauma care. However, it’s critical to understand that we are still at the very early stages of comprehending the complexities involved in translating animal hibernation to human beings.

Dr. Kelly Drew, a Professor at the University of Alaska Fairbanks’ Institute of Arctic Biology, has dedicated much of her career to studying hibernation in arctic ground squirrels. According to Drew, the possibility of inducing hibernation-like states in humans could revolutionize how we approach critical care medicine and long-duration space travel. Her team’s research has shown that a molecule called adenosine, which is present in all cells of the body, triggers hibernation in these squirrels (Source: University of Alaska Fairbanks, 2018).

Duke University’s medical center has also looked into this concept, exploring the potentials of therapeutic hypothermia. Their studies suggest that cooling the body can slow metabolism and provide a form of protection during trauma or surgeries (Source: Duke Health, 2019). While not true hibernation, the practice of inducing hypothermia shows promise in buying precious time for medical interventions.

In terms of space travel—an area where human hibernation could be exceptionally beneficial—NASA’s Innovative Advanced Concepts program is already exploring the potential of “torpor,” a hibernation-like state, to make long-duration space missions more viable (Source: NASA, 2019).

In literature, Mark Healy’s book “The Future of Human Space Flight” discusses human hibernation, proposing its utility for extended periods of space travel. The book argues that hibernation would reduce the spacecraft’s overall mass by lowering the requirements for food, water, and oxygen, thus significantly cutting the costs associated with long-distance space travel.

There are many mammals that hibernate or go into a hibernation-like state, but the details can vary widely among species. Here are a few examples:

  1. Bats: Bats are perhaps the most well-known hibernating mammals. Depending on the species and region, bats can hibernate for more than six months to avoid the winter when insect populations (their primary food source) are low.
  2. Ground Squirrels: Ground squirrels, such as the Arctic ground squirrel, can hibernate for seven to eight months a year. They do this to survive the harsh winter conditions when food is scarce.
  3. Dormice: These small rodents are known to hibernate for up to seven months in a year. Hibernation helps them conserve energy during the winter when food sources are limited.
  4. Hedgehogs: Hedgehogs hibernate during the winter months, which can last from a few weeks to six months, depending on the climate. They hibernate to conserve energy when their insect prey is less available.
  5. Woodchucks (or Groundhogs): Woodchucks typically hibernate from late October to February or March, which means they are in hibernation for about three to five months. They do this to survive the winter when the vegetation they eat is not available.
  6. Bears: While not true hibernators, bears enter a hibernation-like state known as torpor. They can spend up to seven months during the winter in this state, waking up occasionally. The main reason bears do this is food scarcity during the winter months.
  7. Fat-tailed Dwarf Lemurs: Native to Madagascar, these are the only primates known to hibernate. They can hibernate for up to seven months during the dry winter season when food and water are scarce.
  8. Eastern Chipmunks: These small rodents hibernate during the winter months, usually from around November until about April. They store food in their burrows and wake every few days to eat, drink, and defecate.
  9. Bumblebee Bats: Also known as Kitti’s hog-nosed bats, these bats are native to Thailand and Burma. They’re believed to hibernate, but the exact duration isn’t well-known due to their elusive nature and the difficulty of studying them in the wild.
  10. Alpine Marmots: These large rodents found in mountainous areas of central and southern Europe hibernate for up to nine months, one of the longest hibernation periods. This allows them to survive in environments where food is unavailable for most of the year due to snow cover.
  11. European Hedgehogs: They hibernate for approximately six months, from around October to April, depending on the weather conditions. They roll themselves into a ball for protection during their long sleep.
  12. Thirteen-lined Ground Squirrels: Found in North America, these squirrels hibernate for about eight months, from early fall to late spring. During hibernation, their body temperature can drop to match the outside temperature.
  13. Etruscan Shrews: While not full hibernation, these tiny mammals enter a state of torpor that can last for a few hours during the winter months to conserve energy.
  14. Pygmy Possums: These small marsupials found in Australia can hibernate for up to a week at a time in the winter, waking occasionally to eat.

It’s important to note that “hibernation” can mean slightly different things depending on the species. Some animals, like bears, go into a deep sleep but can be roused relatively easily, while others, like bats and ground squirrels, enter a deeper state of hibernation where their body temperature drops significantly, and waking them can be more difficult. All hibernation behaviors, however, serve the same purpose: to conserve energy and survive in a period when food is scarce.

The genetic similarity between humans and these animals varies quite a bit but we have a lot in common.

  1. Bats: Humans and bats both belong to the group Eutheria, which includes all placental mammals. Genetic similarity is estimated to be around 52%.
  2. Ground Squirrels: These animals are rodents, a group that is relatively distant from primates (which includes humans) on the tree of life. Genetic similarity is roughly 68%.
  3. Dormice: As rodents, dormice are also more distantly related to humans, with a genetic similarity around 68%.
  4. Hedgehogs: Hedgehogs are more distantly related to humans than some of the other animals on this list. Genetic similarity is approximately 49%.
  5. Woodchucks (or Groundhogs): As another rodent species, the genetic similarity between woodchucks and humans is also around 68%.
  6. Bears: Bears are part of the group Carnivora, which is more closely related to humans than rodents or bats. Genetic similarity is about 82%.
  7. Fat-tailed Dwarf Lemurs: As primates, lemurs are much more closely related to humans than any other animals on this list. Genetic similarity is about 93%.
  8. Eastern Chipmunks: As rodents, chipmunks have a genetic similarity with humans of around 68%.
  9. Bumblebee Bats: Like all bats, bumblebee bats are genetically about 52% similar to humans.
  10. Alpine Marmots: As rodents, alpine marmots have a genetic similarity with humans of around 68%.
  11. European Hedgehogs: Similar to other hedgehogs, the genetic similarity is approximately 49%.
  12. Thirteen-lined Ground Squirrels: As another rodent species, the genetic similarity between these squirrels and humans is also around 68%.
  13. Etruscan Shrews: Shrews, despite their small size, are part of the group Eulipotyphla and are more closely related to humans than rodents or bats. Genetic similarity is approximately 70%.
  14. Pygmy Possums: Possums are marsupials, a group of mammals that is relatively distant from primates. Genetic similarity is around 50%.

The concept of human hibernation is an intriguing and promising field, albeit one in its nascent stages. Rigorous research and empirical evidence are required before we can fully comprehend the intricacies involved, let alone begin safely inducing hibernation in humans. However, the potential benefits it holds for medical science and space exploration are tantalizing and could revolutionize these fields in ways we can only begin to imagine.