It’s no secret
that regular exercise maintains and improves a person’s internal and external fitness,
but new hypotheses, discussed in a recent article by The New York Times, are
emerging concerning the extent of advantages that exercise can bring – and may
have already brought – to the human body. Walking is one of the key traits that
researchers in the past have used as evidence for human evolution, acquired
after human ancestors diverged from the ape lineage. Usually, their diet and collaborations
with others to hunt for food are the factors used to explain how humans
continued to evolve, but now, researchers suggest that endurance running could
have also had a major impact in how humans changed over time (Bramble and
Lieberman, 2004).
In
their paper, Dennis Bramble and Daniel Lieberman discuss how humans’ ability to
endurance run – and do so with relative ease – is impressively much greater
than any other comparable quadrupeds. Humans use much more metabolic energy while
endurance running in comparison to other mammals; biomechanical research within
humans today shows that their skeletons, long tendons in the legs, core
stability, and ability to maintain a regular body temperature would have made
running easier (Bramble et. al, 2004) and increased their chance of selection
for future generations. But how does endurance running relate to human evolution?
Bramble and Lieberman suggest that the ability to endurance run would have made
it easier for early, scavenging hominids to gain access to prey. As hominids
evolved into hunters and gatherers, endurance running capability grew more
important. As with early hominids, those who were able to outrun (and catch)
prey the longest, were more likely to be able to support their protein-rich
diet, survive longer, and be more successful in passing on their genes to the
next generation (Reynolds, 2012). However, these suggestions still don’t speak
as clearly to how exercise may have aided human evolution in the past.
In
another paper referenced by The Times, researchers David Raichlen and John
Polk discuss the link between endurance running in human ancestors and the
evolution of the brain. In line with the fact that humans can run longer than
other comparable quadrupeds, we also boast brains that are three times larger
than expected (Raichlen and Gordon, 2011). In recent studies, improved acuity
and an increase in specific areas of the brain were linked with extended exercise.
From experiments in rodents subjected to long bouts of aerobic activity,
researchers saw a significant increase in brain-derived neurotrophic factor
(BDNF), a protein that fosters brain growth and development. Other proteins
such as insulin-like growth factor I (IGF I) and vascular endothelial growth
factor (VEGF) also contribute to brain growth.
Figure from Raichlen & Polk, 2013: “Evolutionary model linking APA and brain size in humans. Solid
arrows denote downstream effects of selection for APA performance. Dashed arrow
indicates a possible adaptive link between neurobiology and exercise
performance.”
All
these experiments and research suggest that as early humans ran for long
periods of time after their prey, they were also slowly contributing to the
evolution of the brain, shifting the species into a more streamlined and
intelligent one than before. The long periods of aerobic exercise would have
not only increased their fitness so that those genes could pass on to
subsequent generations, but would have also increased proteins in the body that
allowed the brain to grow. As the brain grew, humans became more cognizant and
intelligent concerning increasingly complex matters.
So
for those looking for encouragement in keeping up with their new exercise
regimens, researcher Daniel Lieberman is correct when he says “there is a deep
evolutionary basis for the relationship between a healthy body and a healthy
mind” (Reynolds, 2012).
577 words
Cited Sources:
Bramble, D.M.,
& Lieberman, D.E. (2004 November 18). Endurance Running and the
Evolution
of Homo. Nature, 432(7015), p. 345-48.
doi:http://dx.doi.org.ezproxy.rice.edu/10.1038/nature03052
Raichlen, D.A.,
& Gordon, A.D. (2011 June 22). Relationship between Exercise Capacity
and
Brain Size in Mammals. PLos One,
6(6).
doi:10.1371/journal.pone.0020601
Raichlen,
D.A., & Polk, J.D. (2013 January 7). Linking brains and brawn: exercise and
the
evolution of human neurobiology. Proceedings of the Royal Society B, 280(1750).
doi:10.1098/rspb.2012.2250
Reynolds, G.
(2012 December 26). Exercise and the Ever-Smarter Human Brain. The
New York Times. Retrieved from http://well.blogs.nytimes.com/2012/12/26/exercise-and-the-ever-smarter-human-brain/.
Have there been studies recently linking academic performance with exercise levels? It would be interesting to see if there is a correlation between the two.
ReplyDeleteyes, does this mean that much of the current human population is essentially getting dumber due to our lack of exercise? That is a scary thought...
DeleteThere have been studies! I just did a Google search on "exercise and academic achievement" and this great link came up, containing info published in January 2012:
Deletehttp://www.ncbi.nlm.nih.gov/pubmedhealth/behindtheheadlines/news/2012-01-03-exercise-may-boost-school-performance/
It's quite cool to note the link between the two. Of course, lack of exercise doesn't mean one will rapidly evolve in the opposite direction, but it's interesting to know that exercise can help with one's academic performance because it increases flow of blood + oxygen to the brain. Pretty nice perk of adhering to 30 min. of activity about 4 days a week!
This is particularly interesting considering that many athletes these days score fairly low on most cognitive performance exams. Perhaps this could be an instance in which too much of a good thing can be bad? It could be that there needs to be a balance between exercise and mental development activities; disrupting it by devoting all of one's energy toward one focus-all exercise and no academics, for example-deprives the body of any positive effects that might have been gained. Moderation in all things is good.
ReplyDeleteI also find it interesting that in society today, athletes are viewed as less intelligent. I think this could be due to the stereotype and expectation that athletes are less intelligent that could influence how much athletes try in academic settings. I wouldn't necessarily think that too much exercise could cause less intelligence, rather the athletic culture that is fostered today.
DeleteI think your last sentence on moderation is especially poignant, Alex. And you're right: I would think that back in ancient times, the exercise helped our ancestors not only be fast enough to catch prey (so that they survived longer), but it also helped them focus on more complex things, such as how to create more advanced technologies to advance themselves.
DeleteAnd I also think your view is definitely part of the "athlete perception" society has today, Sarah. Why try hard when others expect you not to already?
The above comment is very thought provoking. I also think of the other extreme, people who never excercise or do any aerobic activity at all. Do they perform low on cognitive exams? It also makes me wonder as excercise decreases will a population, essentially, become 'dumber'?
ReplyDeleteI wonder that too! But I also wonder how we can quantitate "dumbness" today, especially since we've advanced so far as a species.
DeleteThere are examples of people with severe physical disabilities (e.g. Stephen Hawking) that clearly perform no physical activity yet are incredibly intelligent. The same goes for some athletes (e.g. Ross Ohlendorf, Ryan Fitzpatrick) who are both incredibly active and remarkably intelligent. Cognitive acuity can be found in people with all types of activity levels so the assertion that exercise has a causative relationship to cognitive performance certainly requires more investigation and may have little to do with the long term brain evolution discussed in this article.
ReplyDeleteThat's absolutely true! I guess it can get pretty easy to compare the studies of these researchers to present-day situations, even though their research is based on hundreds of years of past findings.
DeleteI do believe that the whole idea of "many athletes" scoring low on cognitive performance exams is due to the fact that they focus on athletics instead of academic performance because it is their forte. I'm sure there are many intelligent people who would excel at physical activities but choose to portion their time differently.
ReplyDeleteHowever, in regards to the pattern observed, will the human race become less intelligent as sedentary lifestyles become more and more supported by the abundance of technology?
Yeah, I think so too. I think it's just too easy to apply the research on early hominids that were still evolving to our present-day selves directly to how things are perceived in today's society. But in regards to the pattern seen, that's a great question... I wonder how things will play out because technically now, we're so advanced and seem to be getting smarter each day (with all the advents of new technologies) despite amount of exercise one does. Maybe it's just that the early hominids gave us a great running start to where we are today, and we're still working based on that acquired intelligence?
DeleteWould our intelligence truly decrease because of our lack of exercise, however, or other factors such as diet, dependence on technology, increased entertainment, etc.? I feel as though while our lack of exercise is an important idea for future human evolution-especially in relation to disease-a possible decline in intelligence will likely be due to other factors rather than just a lack of exercise.
ReplyDeleteYeah, I agree. I think the major point the researchers were trying to make was just that a large amount of exercise (more than what we're currently used to) in early times was a contributor to how humans evolved, since usually most researchers hadn't considered it as a factor.
DeleteI think that in this case we would have to decide whether we think that intelligence is based purely on genetics or if a person's intelligence is based on various factors. I personally think that a person's smarts are due to many different factors that of course are influenced by genetics but do not depend entirely on them. This is why although I would agree that exercise can lead to a healthier mind however I am not convinced that this connection is due to genetics.
ReplyDeleteI think you're right depending on what time period you're referring to: if it was during the time of early hominids, based on the researchers, exercise could be indirectly linked to genetics in that the fastest and most enduring hunters were the ones who survived long enough to pass on their genes, because they were able to catch their prey. But in today's society, I would agree and say that intelligence is based on various factors.
DeleteElizabeth raises a great point, which I think also may answer other people's comments as well - if we truly have a genetic predisposition to be intelligent, than does exercise strengthen this or have no affect? As bjk3 pointed out, Stephen Hawking is vastly intelligent without the means to exercise - but is that safe enough to assume that if he WERE able to, would his cognition increase? Elizabeth's response could also answer why maybe some athletes, despite their constant exercise, still underperform in cognitive tests, and get the negative stereotype of having a less than average intelligence; it is due to genetics. Ultimately, I feel exercise does (obviously) benefit the body in many ways, so it's not a far stretch to say it could help improve cognitive abilities, if only marginally.
ReplyDeleteThat's a good point. I know that the research is only concerning early human evolution (the hunters + gatherers + scavengers), but I would wonder at the connection between exercise and intelligence in today's society, and whether that concept continues to have any impact on current human evolution.
DeleteSince we live such a sedentary lifestyle and use our brains more by creating new technology and critical thinking more and don't use our physical body as much, wouldn't that make our cognition evolve more? I feel that exercise is important, but I don't think it has such a huge impact on improving our cognitive abilities.
ReplyDeleteI think both should have an impact. In my reply to ClaireK, I posted a link to a great article on the link between exercise and academic performance; it definitely doesn't hurt. But I think that the impact on human's evolution (and the brain) may have been much larger and more important in the times of the early hominids, which is really what the research references. They don't seem to extrapolate their findings to present times.
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ReplyDeleteThis is really cool to read about. I was a serious athlete through high school and (while there are always other factors that play into my experiences) I felt I excelled a little more than now. While I respect and certainly see Anthony's point of view regarding athletes scoring low on cognitive tests and their athletics being their "forte", I would have to respectfully remind readers that there are plenty of athletes who excel academically, I feel, with less effort than than someone like myself, who does not work out as intensely in that way at all. I would even venture to say that for athletes, they are forced to make athletics their forte since it pays for said education and thus they are forced to budget their time differently than non-athletes. That is a lot of pressure for anyone, so to say that low cognitive scores appear despite their high athletic activity due where they choose to put their time, but also where they are forced to put their time. Rice students are examples of how many manage to do quite well with both.
ReplyDeleteAs mentioned before however, there are countless social factors and pressures that we all experience. Has anyone else noticed that at times in your classes, it seems like those who are more active seem to understand concepts or have greater concentration, work ethic or discipline? I have many times and so that is why I definitely found this article to be insightful and evidence to me that the pattern I see may not just be coincidental.
These are great points, and I totally agree! The comments have really gotten me thinking to how one would apply these findings to present day. It's so easy to think of how the endurance running could have aided an early hominid in catching prey + surviving to the next generation, but I wonder now how great of an impact exercise has on our current evolution, our brains, our cognitive abilities and intelligence, and on everything else everyone's said above. It definitely can't hurt, like you're saying, and that article I posted in response to ClaireK supports a link between exercise and academic performance.
DeleteFrom what I read, although running does help improve brain performance, it seems like this improved performance is an within-generation phenotypic expression that cannot be passed down to future generations. The abovementioned example seems parallel to saying that drinking more milk will give us denser bones and because people that drink milk are not selected against (or "selected for"), future generations will have denser bones.
ReplyDeleteOn a side note, Alex's comment really put some food for thought into this whole issue. If running or other aerobic exercises do help us be smarter and this trait is passed down over generations, wouldn't all of the most aerobically-athletic people technically be the brightest bulbs on Earth?
All in all, I think that while exercise does help improve within-generation intelligence, i am doubtful that this extends on to future generations; but maybe I'm reading this wrongly.
Yeah, I don't know if/how intelligence is passed on (is it at all)? This is how I think of it (and what I hopefully got across in my other comments): I think nowadays, there are so many factors that play into passing things on to next generations - technology, genetics, etc. But back in the early hominid days, when individuals had to hunt for food, only the ones who ran the fastest and longest (endurance running) would survive to pass on their genes to the next generation (because they got the food, essentially). And while they ran (extensively), they were contributing to the evolution of the human brain (as discussed in the articles/research). But now? I don't know if the same thing occurs because humans are already so advanced. But like I said above in a comment: maybe it's just that the early hominids gave us a great running start to where we are today, and we're still working based on that acquired intelligence?
DeleteI was in track and field and cross country in my high school years. But I guess I'm still not completely convinced that running for an extended period of time would contribute to the evolution of the brain. Maybe there's a balance in running times, intensity with brain performance. Nowadays, not too many people can endure long distance running, even though we are smarter than hominids. Something to think about, definitely.
ReplyDeleteIt's definitely something to ponder, and the way I see it/have asked in comments above: maybe it's just that the early hominids gave us a great running start to where we are today (from their extensive running contributing to brain evolution), and we're still working based on that acquired intelligence? Since they were so much less "smart" than we are today, perhaps the strides of their endurance running were more impacting on them then, allowing us to get to where we are today, but maybe now, the impact is more constrained to individuals rather than the entire species.
DeleteI agree that the culture of being an athlete as well as the lifestyle (training for the majority of the day, main focus being athletics) could account for low performance on tests. I think it would be interesting to explore why there is a connection between cognitive performance and exercise. Do you think there is any evolutionary reason why physical and cognitive performance seem to be linked?
ReplyDeleteHm, I guess there should be some evolutionary reason! I can definitely see biological reasons from research (increased blood + oxygen flow to the brain, etc) but as for evolutionary reasons, maybe in early hominid times there was more of a reason - increased cognitive performance would help those individuals make crucial decisions on hunting prey/how they lived and travelled that determined who survived and who didn't? What do you think?
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