Before I continue with my possibly rather harsh critique of this article, I want to point out that I rather like the look of crossfit, the workouts sound fun and very challenging, the camaraderie sounds great and very motivating, and it looks like a really good way to develop a high level of all-round strength and fitness. If I wasn’t broke, I’d probably join a crossfit box, at least if believing in pseudoscience isn’t a necessary thing in order to fit in… there’s enough bull floating around the internet from the less well informed among the paleo diet crowd already… now crossfit (who advocate a paleo diet) seem to be adding to that with this article intended to claim that long distance running is bad for you.
This was posted on a health and fitness forum, to warn runners about the “dangers” of running and other forms of endurance cardio exercise: http://crossfitmeanstreets.com/2010/09/08/chronic-cardio-is-forcing-your-body-to-kill-you-and-how-you-can-save-yourself/
The TL;DR (too long; didn’t read) of it is that they are claiming that endurance cardio such as marathon running is really bad for you, in fact it’s “forcing your body to kill you” (whatever that means) because when you run marathons your body thinks its being chased by a lion, which, according to the article, is the only reason why human ancestors would be running long distances. This then causes various stress hormones to be released which allegedly damage the body.
What I would like to say in response is as follows:
1. Seriously?? How fast do you think humans can run compared to lions? Do you think lions toyed with humans, walking behind them slowly, making them keep running for hours before finally putting them out of their misery and killing them? Err… no. There is indeed evidence from the fossil record of lower palaeolithic humans being eaten by big cats, there’s no doubt about that. However the chase would have lasted less than a minute, on account of how humans are slow at running and big cats are not. A palaeolithic human’s best chance of surviving an attack by a big cat would be to attempt to kill it with a spear (if it had one), or for the other humans in the group (we’re social animals) to throw rocks at it and try to chase it away before it managed to maim or kill the human it just attacked. Additionally, the stuff about stress hormones is incorrect… stress hormones are released in response to being in danger, not to running, and the issue of whether or not they cause damage within the body and in what circumstances is too big a topic for this post.
2. Homo erectus is believed to have hunted with the “persistence hunting” method. This method is still used by some modern hunter-gatherer tribes. It involves chasing the prey animal over long distances for hours until the animal dies from heat exhaustion or is too injured to keep on running. Humans are slow sprinters, and cannot catch another animal after a quick chase like a lion can, and Homo erectus didn’t have anything like the weapons technology of Homo sapiens. In this method, you chase the animal, it escapes, you track it down, chase it again, track it… chase it… track it.. chase it… track it… never letting it rest, until it dies from heat exhaustion or is so hot and exhausted you can finally get close enough to kill it.
Humans, with their lack of body hair compared to other mammals and ability to sweat over the whole body, can stay cool for longer and have the ability to endure running marathons, and to keep running for as long as it takes for the prey animal to die. The human gait is very energy efficient, for covering huge distances walking, jogging or running. Later humans may have learned how to trap and corner animals, how to use fire to drive them into traps and stone tipped spears to kill them and Homo sapiens invented long range weapons, but what did Homo erectus have? Homo erectus could run long distances in an energy efficient manner and stay cool by sweating and being less hairy. We evolved to be long distance runners. Does that mean we didn’t also evolve to be strong? Well, middle palaeolithic humans were very strong, neanderthals especially, but I’d be willing to bet you could train up a neanderthal to run marathons, and even if they didn’t use persistence hunting, they would have walked very long distances up and down hills and mountains, probably carrying heavy animals back home. So the fact we evolved as long distance runners does not mean that’s the only kind of exercise that can benefit health. But it does mean that long distance running isn’t bad for humans. In fact if you look at palaeolithic life, you’ll find that people needed high levels of both strength and endurance to survive (which is what crossfit advocate, so I’m not sure why they have to resort to ridiculous psuedoscience).
3. I’m aware of scientific data that links certain health problems to long distance running. However, many people who do a lot of endurance cardio don’t eat properly. It’s so common on health and fitness websites to find people who do 2-3 hours of low intensity cardio a day, while eating very little, either because they have eating disorders, or because they are acting on bad advice and believe that this is necessary in order to lose weight and/or stay thin. (The fact that people can do so much cardio while eating so little is, in my opinion, more proof that this is how Homo erectus hunted, because they wouldn’t survive a food shortage by spending all day sitting on their backside. They’d have to get out there and carry on hunting, until they managed to catch an animal. So we evolved to be able to carry on doing huge amounts of cardio on too few calories because this enabled our ancestors to survive food shortages (though not indefinitely, because the body can only go for so long on inadequate food before it starts breaking down, and it’s not necessarily what’s optimal for good health even in the short term.)) People who do lots of cardio on insufficient food would be more likely to suffer health problems, and this could be skewing the data for the health of runners in general, as it’s very common. However undereating would be the cause of the problems, not running, and undereating is also bad for you even if you don’t do any exercise at all. So I still don’t believe that long distance running is bad for a well-fed human.
The take-home message from this should be that if you’re going to run marathons, your body thinks you’re hunting, so it might be a good idea to eat a nice big meal including a lot of protein after you finish, that way your body thinks you’re succeeding at hunting. Or at the very least, eat a proper, balanced diet that includes a sufficient amount of carbohydrate and calories to support the high volume of long distance running being done. People who run marathons for fun do that, but people who do a lot of running to get fit or lose weight may not realise how much they need to eat and why eating properly is so important.
4. You made Homo erectus cry. He is good at running. He is!
image: my own sketch
If there’s one thing that really annoys me, it’s when people talk about “neanderthals and humans” when what they really mean is “neanderthals and homo sapiens” or “neanderthals and modern humans”, because neanderthals are human, and saying “neanderthals and humans” as though the two groups were mutually exclusive, is a bit like saying “I need to buy some tables and furniture for my new house” like tables are not a kind of furniture.
Firstly there’s the fact that from a scientific point of view, anything in the genus Homo counts as human. Then there’s the fact that if you do choose to consider only Homo sapiens to qualify as human you will have basically reduced the definition of human to having a vertical forehead, dome shaped cranium, reduced brow ridge and a pointy chin. I mean really…? That’s what human means to you? Not anything to do with having a large brain brain or being able to make and use technology and transmit cultural knowledge from one generation to the next… ?
If neanderthals were alive today, most of what is said about them nowadays would be considered horribly racist. And if they were alive and you met one (especially one who’d been raised in modern culture and spoke the same language as you) you wouldn’t begin to suggest that they weren’t human (unless you were an utterly dimwitted racist clod), so I don’t get why it’s acceptable to deny the humanity of our cousin species, just because they went extinct 30,000 years ago and can’t complain about it?
One of the things I really like about palaeoanthropology is that it’s basically forensic science, just like CSI Miami or something, but from much further back in time. They have this body, and they have to figure out who this person was and how they died… except that the body is just a few fragments of bone and they died thousands and thousands of years ago, and they’re not just trying to find out how they died, but how they lived as well.
In some cases, it kind of does end up being just like a “whodunnit” – like when they find human bones that are all covered in stone tool marks and are dumped along with animal bones that are also all covered in stone tool marks… (and there are some who will say that this is not evidence of cannibalism but that’s possibly for another blog post in the future)
…so imagine my enthusiasm upon coming across claims of inter-species murder, or more specifically, that a particular neanderthal whose skeleton was discovered many years ago was thought to have been murdered by a Homo sapiens. This seemed to me to be quite an outrageous claim, especially as the alleged murder victim died fifty thousand years ago or earlier, and Homo sapiens has a pretty solid alibi in that they had yet to leave Africa according to conventional theories. It’s perfectly reasonable to suggest that stone tool marks on an individual’s ribs were caused by another human in an act of malice. I mean this is humans we’re talking about; I’m pretty sure the first victim of attempted or actual murder with a stone tool lived not very long after the invention of stone tools. So claims of murder are not so far fetched… but knowing what species of human did it…? Well that warranted a second look…
I haven’t actually managed to read the journal article yet, having only read this from less academic sources, so I may be mistaken on some of the details here, but from what I understand, the suggestion is that based on the kind of damage done to a pig’s rib cage by reconstructed stone age weapons, the closest match to the marks on the rib cage of the individual in question, was the damage done to the pig by a throwing spear. That’s all well and good, however I’m still inclined to think that it’s a bit of a stretch to suggest that it was a Homo sapiens who threw the spear. Possible, yes. But just because neanderthals didn’t generally use projectile weapons, does not mean they didn’t ever throw stuff around or at each other sometimes. I mean a neanderthal spear is not very aerodynamic, but that doesn’t make it impossible to throw. A brick is not very aerodynamic either but someone could still throw a brick at someone in a fit of rage and injure them, and the same could apply to a neanderthal spear, even though it wasn’t designed for throwing:
A and B have a big argument. A walks away in a huff, B angrily throws his spear, which he happened to be holding at the time, at A. B didn’t expect the spear to actually hit A, but beginner’s luck comes into play, kind of like when someone manages to get a triple-twenty the first time they try to play darts, even though their throwing technique more closely resembles a toddler throwing his toys around than a professional darts player… so anyway, the spear actually manages to hit A in the ribs, hard enough to pierce his lung. He goes back to his cave struggling to breathe but his other lung is still functioning so he doesn’t die, and B helps to look after him feeling really guilty about throwing the spear, but then A’s wound gets a nasty infection which becomes pleurisy, causing him to die a couple of weeks later. B never recovers from the remorse he feels because he really didn’t mean to hurt A. Well that’s kind of stretching the evidence a bit too far (err… a lot too far, I have too much imagination for my own good sometimes), but you get the general idea – just because neanderthals didn’t typically use projectile weapons for hunting, doesn’t mean they can’t deliberately or accidentally kill each other by throwing stuff in a fit of rage. I mean slightly smaller range of movement in the shoulder joint or not, I don’t believe they were incapable and/or unwilling to ever throw anything for any reason ever. They were probably better at throwing things than the average city dwelling, sedentary Homo sapiens who can’t even accurately throw a paper ball into a bin at a distance of 3-4 metres.
Additionally (and here I may be mistaken on the details) – a hunting weapon designed to take down a large animal such as a deer, ought to be able to do enough damage to a human to kill them quickly, not die a slow and agonising death that was drawn out over a number of weeks. If it was a purpose build projectile hunting weapon, surely it would have killed the man a lot more quickly? I mean if you’re hunting a deer, you want to kill it right away, not wait until it collapses several days later. This scenario is kind of more consistent with someone throwing something other than a purpose built throwing spear at the victim.
Anyway it’s a very interesting study and it’ll be great when I finally track down the actual journal article. For now, I think I need a new category for my blog, a “theories I haven’t decided if I disagree with or not just yet, pending a more thorough view of the evidence” cateogory. And really, it is pretty amazing that people can try to solve murder mysteries from 50,000 years ago!