Physically active adults are less inclined to be depressed, say Oxford and Yale researchers

But we already knew that, didn't we?

  • American adults that exercise spend an average of 18 fewer days depressed every year.
  • The large-scale study includes data from over 1.2 million Americans over a five-year period.
  • The researchers note that too much exercise negatively impacts mental health.

Weekends in Los Angeles are dominated by physical activity: hiking, surfing, running, cycling, yoga. It's easy to affix stereotypes to this city's denizens, yet year-round sunshine affords residents every opportunity to stay fit. Many take advantage; staying active is part of the culture.

Not that everyone partakes, of course, but lack of opportunity can never be an excuse. Having grown up on the East Coast, I recall when outdoor physical activity was seasonal. You have to work harder during winter months to maintain the same fitness output. Those who endure the ravages of winter to make it to the gym seemed happier for it.

Such speculation was recently put to the test by researchers at Oxford and Yale. In a study of more than 1.2 million Americans, they discovered physical fitness is more important to your mental health than how much money you make. To be exact: exercisers are, on average, depressed 35 days a year; for non-active participants that number is 53 days.

Using data between 2011–2015 provided by the Centers for Disease Control and Prevention Behavioral Risks Surveillance System, researchers found that physically active adults self-report feeling depressed much less than couch potatoes. They point to the fact that exercise is correlated with numerous health benefits, including reduced risk of overall mortality, cardiovascular disease, obesity, stroke, and cancer.

If you feel good, your perspective tends to follow.

The brain-changing benefits of exercise | Wendy Suzuki

It's not only the diseases you avoid. Exercise is linked with improved musculoskeletal health and stress regulation. Studies centered on mental health have been a bit more ambiguous, though it has long been known that exercise helps curb anxiety and depression. For this study, researchers note that intervention has never been more needed considering that "depression is now the leading cause of global disability burden."

Reducing this burden is the main goal of this research. Thinking outside of the gym, they included 75 types of physical activity in the survey, including golf and gardening. They grouped "mindful exercises," such as yoga and tai chi together—a slightly strange decision, given that even those two disciplines leave distinct imprints on your nervous system. Still, the underlying goal is to better understand the difference between movement versus no movement. The former made a statistically significant impact.

While movement scores above money, the results were actually U-shaped. Three to five weekly sessions of thirty minutes to an hour appears to be the magic zone for achieving optimal mental health. Those working out three or more hours a day did not show better results than those who don't work out at all. There are likely two reasons for this: fatigue, which can drain your emotional output, and obsessive-compulsive disorder, a real problem in gyms. For example, some former addicts devote themselves to the "high" of working out, but really only move their addiction to another focus. Healthier, sure, but incessant anxiety about working out still follows.

Competitors warms up prior to the start of day one of the 2013 Australian National Surf Lifesaving Titles on April 17, 2013 in Gold Coast, Australia. Photo credit: Chris Hyde / Getty Images)

Team sports and cycling proved to be associated with the lowest mental health burden; the "mindful exercises" scored higher on the satisfaction index than walking.

The researchers note that while they believe these results are causal, more research is needed to prove direct links between specific exercises and mental health. Still, they feel comfortable stating the difference between working out and not working out is the same as "between individuals with a difference in household income of more than U.S. $25,000."

Point being: making more money is not necessarily the road to satisfaction. Regular movement is. This makes sense, given that for most of history, survival required physical output more than monetary exchange. There is measurable progress made in building shelter or hunting food; watching a number increase on a screen does not offer the same biological rewards, regardless of how happy we believe money will make us. Another recent study points out that the highest increase in depression and anxiety in recent years has been in the wealthiest demographic.

A rather old lesson, yet one we seem to keep forgetting. The chemistry of satisfaction and self-assurance relies on blood flow, not cash flow. Money is helpful. Movement is necessary.

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Stay in touch with Derek on Twitter and Facebook.

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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.