Being fit boosts your tolerance for cold weather

Yet another reason to keep exercising.

  • A new study on mice shows that exercise helps them shiver longer.
  • Brown fat did not seem to be the deciding factor in the mice's ability to combat the cold.
  • The combination of exercise and brown fat is a more likely reason why we can endure extreme temperatures.

Scott Carney was skeptical when he first visited Wim Hof. Ice baths, hyperventilation, long breath holds, and scaling world-class mountains shirtless sounded suspect. Yet once he experienced the results of Hof's unique training method, he was hooked. As he writes in What Doesn't Kill Us:

There is an entire hidden world of human biological responses that lies beyond our conscious minds that is intrinsically linked to the environment.

"Hacking" your biology, as one popular sentiment goes, means discovering those hidden responses. In Hof's method, this includes, at the entry level, daily ice baths or showers and a sequence of hyperventilations and breath retentions. If you've ever heard Hof speak, you know he treats breathing as the gateway to seemingly inhuman feats.

But why the cold? As Carney argues, humans were, for a very long time, adapted to their environments. Automation and industry have changed that. We generally no longer need to kill or grow our food, build our own shelter, or flee from predators. Our tightly wound energy for physiological responses sits dormant. Exercising is one release, though the ways we often exercise—repetitive movements on machines—does not honor our diverse physiological ancestry. Our ability to survive in non-climate controlled environments fending for ourselves has been negated.

One key to surviving in extreme environments is the accumulation of brown fat, or so Hof espouses. Brown adipose tissue is different than its white counterpart. Specifically, brown fat's main role is thermoregulation. It helps us shiver. The more we have of it, the sentiment goes, the more adapted we are to colder environments.

Not so fast, says a new study in The Journal of Physiology. Two groups of mice were exposed to cold climates. One group was put on a voluntarily wheel jogging regimen for twelve days before exposure; the other was comprised of couch mice. The exercising group fared much better. Their muscles were better suited to longer bouts of shivering.

Shivering is one of the first defences against cold, and as skeletal muscle fatigues there is an increased reliance on non‐shivering thermogenesis. Brown and beige adipose tissues are the primary thermogenic tissues regulating this process. Exercise has also been shown to increase the thermogenic capacity of subcutaneous white adipose tissue.

Photo: Shutterstock

Interestingly, how much brown fat each mouse had was not a factor. This doesn't mean Hof is entirely wrong, however. In general, no mammal has an excess of brown fat, and it declines as we age. Hof's argument is that we can build it through practices, such as his method. But movement seems to be a necessary key to this process of thermoregulation. As Discover reports on Hof's ideas,

A crucial part of his "method," however, also seems to be exercise, and as this most recent research indicates, being fit is probably another big boost to our bodies' furnaces.

As the article notes, the researchers from the University of Guelph and University of Copenhagen did not measure the mice's muscles while they were enduring 40-degree temperatures, so the link between exercise and thermoregulation is not completely solid. That said, they exhibited longer shivering bouts, meaning they were better adapted to the cold. Or, as the researchers conclude,

We speculate that prior exercise training could potentially enhance the capacity for muscle‐based thermogenesis.

But really, is it any surprise that exercise increases the likelihood we'll survive in challenging environments?

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New fossils suggest human ancestors evolved in Europe, not Africa

Experts argue the jaws of an ancient European ape reveal a key human ancestor.

Surprising Science
  • The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
  • Researchers speculate it could be a previously unknown species and one of humanity's earliest evolutionary ancestors.
  • These fossils may change how we view the evolution of our species.

Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.

A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.

Rethinking humanity's origin story

The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)

As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.

David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.

The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.

Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"

He recently outlined this idea at a conference of the American Association of Physical Anthropologists.

It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.

"Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."

Migrating out of Africa

In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.

Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.

The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.

The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.

Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.

Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.

Did we head east or south of Eden?

Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.

Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.