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ResearchBlogging.orgMost people typically view Homo sapiens as physically rather weak; reliant upon our technology for survival in the harsh world. Picturing people without technology on the Savannah typically ends up with them becoming lion food in short order.

We’re slower than Cheetahs, less agile than a gazelle, lack the point teeth of a lion and can’t climb half as well as a chimp. Surely technology is our saving grace, the only thing we really have going for us?

Surprisingly, no. Contrary to the classic conceptualisation of people as totally reliant upon technology, we do have some surprising physical adaptations to Savannah life. In particular, we sweat.

Sweating allows us to engage in endurance running. Now, again, running might not seem to be something people are particularly good at – there are a whole host of other animals that can easily outpace us – but they can’t out sweat us.

Combine running with sweat and you have a bipedal ape with the ability to run long distances in the blistering heat, which is something most animals can’t do. Steadily a running man would tire out his prey as he chased it across the Savannah until it collapsed of hyperthermia and he was able to claim his prize.

Endurance running is the ace up our sweaty sleeve and allowed us to become one of the dominant predators on the Savannah in a war of attrition. Which of course begs the question, when and how did this ability evolve?

Which of course calls for some SCIENCE!

The ability of our ancestors to manage heat (or thermoregulate, if you want to sound sophisticated)  has long been an avenue of research in EvoAnth since it ties into that other interesting question – when did we loose our fur? Unfortunately, that means that running and thermoregulation has been an area that was somewhat neglected since people care more about where all our fur went.

This means that all the mathematical models used to calculate the heat management abilities of hominins are based around someone who is standing still which isn’t particularly pertinent to those studying running. So some researchers decided to sort out this oversight and adapted an existing model to be applicable to a running man.

The result is pages and pages of rather complicated maths which I in no meaningful way understand. However, I do know that when they inputed the data for modern Homo sapiens the predictions the model made were accurate when compared to actual, non-imaginary Homo sapiens. So it is seems to be the mathematics is fairly sound, even if I am in no way qualified to comment on it.

I’m not technically qualified to comment on EvoAnth either, but I think I hide that fact quite well

Satisfied the model works, they then ran the calculations for to work out the thermoregulatory abilities of other species of hominin in an effort to see when endurance running became physically possible. Unfortunately, they didn’t have all the data needed to make the model as accurate as possible.

Assumptions had to be made regarding the sweating ability of the past species, as well as how much fur they had and how efficiently they could run. If they used the data from modern humans to fill in these blanks then surprisingly, they found that pretty much every species of hominin could endurance run.

However, for some species these assumptions are particularly weak. Australopithecines weren’t as good at bipedal locomotion as later species, suggesting they couldn’t run as efficiently as modern humans meaning this figure isn’t accurate for them and they would likely be unable to engage in long distance running.

Then there’s the evolution of the human louse, which indicates that hair loss only got to human or near human levels during the time of Homo erectus, eliminating Homo habilisand other earlier members of our genus from those capable of long distance running.

So what about sweating? Was Homo erectus a good enough sweater? Well the maths reveals that provided they could sweat at >80% of the efficiency as modern humans then they could engage in endurance running. Since they had a body that is physically rather similar to modern people this does not seem like much of a stretch.

The predictions for Homo erectus, with the horizontal lines reflecting their ability to loose heat and the curved lines being how much heat is generated by their running.

So, it would seem that Homo erectus was the first hominin that could’ve engaged in long distance running – except for during midday – although that doesn’t mean they actually did. Which leads to the follow-up question of how did they evolve this ability?

Well, given that endurance running requires that they can simply run, sweat and not have much fur (all of which could develop for other reasons) then it might well be that long-distance running is simply a side-effect of other selection pressures.Our ancestors got good at running to sprint and escape from predators/chase prey/whatever and were able to sweat well because the climate was so hot and bingo, they’d accidentally developed the ability to run for long periods of time.

Of course, there might have been other factors involved and I await any further research that tries to shed light on exactly why endurance running emerged. Also, as the field of recreating the bipedal abilities of past hominins expands, the data regarding the running efficiency of these species will improve and so more accurate results can be obtained.

However, given how Homo erectus is already known to be rather human in terms of physiology, I doubt more accurate results will drastically alter the findings of this paper.

Ruxton GD, & Wilkinson DM (2011). Thermoregulation and endurance running in extinct hominins: Wheeler’s models revisited. Journal of human evolution, 61 (2), 169-75 PMID: 21489604

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24 Comments

Mihai Martoiu Ticu · 22nd February 2012 at 6:10 pm

Please forgive me, I hate people pedantic about language myself, but I start sweating when one uses the expression “begs the question” inappropriately. There is only one correct use for it and that is the name of a logical fallacy, also called petitio principii. By the way, I see the expression very often in scientific papers, used incorrectly.

    Adam Benton · 22nd February 2012 at 6:14 pm

    If it helps you sleep at night, mentally replace “begs” with “raises” 😉

Mihai Martoiu Ticu · 22nd February 2012 at 6:14 pm

See for instance here about “begging the question” http://grammar.quickanddirtytips.com/begs-the-question.aspx

eyeonicr · 22nd February 2012 at 7:01 pm

You hide that you’re “not technically qualified to comment on EvoAnth” very well, almost as if that doesn’t matter. 🙂

Oh, and see here.

    Adam Benton · 22nd February 2012 at 8:25 pm

    Give me another year and a half and there’ll be a Bsc saying I am allowed to comment on it.

Calli Arcale · 22nd February 2012 at 10:02 pm

It’s not just sweat. Horses can also sweat (sometimes quite profusely), yet a human marathon runner will easily defeat a horse in a race. This is because of another great thing that humans have going for them — bipedality. Quadripeds, for mechanical reasons, are forced to breathe in time with their strides when running. This actually means they find it more difficult to breathe while running than while standing still, forcing them to be sprinters and not distance runners. Sooner or later, they have to stop and catch their breath, and for them this isn’t just a matter of comfort.

Humans are not so limited; we can adjust our respiration rate independently of our stride. (We can even carry on conversations while jogging!) Compare long-distance horse and human races; there are no races where horses run 24 miles nonstop. It simply cannot be done — it would kill the horses. There *are* long-distance horse races, but the horses have to take breaks.

Sweat is still hugely important, though. We have the luxury of being active in the heat of the day. Even in regions where humans take siestas, we’re more active than most other animals. Lions sleep the noon away; humans can hunt through them. And of course there are bipeds which don’t sweat — such as ostriches.

    Adam Benton · 22nd February 2012 at 10:10 pm

    I didn’t know about the breathing thing, it’s very interesting.

Brett J · 23rd February 2012 at 2:10 am

I remain deeply skeptical of this claim. I would immediately oppose it with the following from a personal perspective.

1: Humans developed sweating along with other primates to relieve the body of toxins.
2: Humans run to flee danger.
2.i… If fleeing is common in the culture (eg African) it becomes an extra capability.
3. Running as an endurance sport is only a spin-off of modern war and training.
4. Humans are hairless due to activity, diet, water proximity, and clothing.
5. Humans revert to hairiness if they walk unclothed in snow for a single generation (as seen with all animals of our domestic stocks).
6. The greatest amount of the human population is (always) never running anywhere.
7. Predator packs were able to catch lonely people occasionally.
8. High water consumption is the main reason for profuse sweating.
9. The sweat of domesticated horses would have inspired warriors to emulate.

Deduction should always unbake the lies people tell as their profession develops.

The premise of those evolutionary discussions is some savannah in Africa. Which could be entirely untrue of a mixing population that spread on coastlines – which then leaves a minimal trace of evolution.

    Adam Benton · 23rd February 2012 at 2:31 pm

    1. Regardless of the reason sweating developed (I’m sketpical it was to do with toxins, it’s a highly inefficient method for doing so) the fact remains that now it is an excellent mechanism for thermoregulation and so is a critical component of endurance running.

    2 a. They also run for other reasons, including hunting.
    2 b. And if that group is ancestral to another then they shall retain that capability, provided there is no reason for them to lose it.

    3. See 2a.

    4. Human lice have been separated for long enough to become different species suggesting that any variation in hair covering is minimal, keeping them separate.

    5 a. Endurance running offers the most advantages in a hot country where hyperthermia becomes a severe problem, rendering what happens when humans are exposed to snow irrelevant.
    b. Humans aren’t domesticated animals – do you have any data pertinent to our species?

    6. The frequency of use of an ability is irrelevant, so long as the cost of having it is outweighed by the benefits gained by it – even if those benefits only come every so often.

    7. See 6.

    8. Taking in a lot of water is required for endurance running, although a requirement shouldn’t be confused with a cause. Unless there is evidence to suggest it is. Do you have any?

    9. Horses were first domesticated in Europe and even there it wasn’t until over one million years since Homo erectus so it was unlikely horse sweat played any part in the lives of the species in question.

Jim Thomerson · 24th February 2012 at 12:41 am

My father told stories of a poor man coming west, riding the train to where some horses where. Getting off with a canteen, sack of parched corn, and a rope. It would take maybe a couple of days to walk a horse down. It was a matter of not letting the herd rest, just keep walking until they gave up. My father never claimed to have done this, but I got the impression it was not unusual.

Jim Birch · 24th February 2012 at 1:32 am

Sweating is a dangerously inefficient way of eliminating toxins. If your sweat is made of body fluid minus the large solids then sweating x% of your body fluid loses only x% of your toxins but also x% of the valuable stuff like salt. You’d need to sweat your entire body fluid volume a few times over to secrete half of a toxin in your body by which time you’d be dead from the salt loss. This is a fully mixed model, but probably not a bad first approximation. A skin pore might try to minimise salt loss but it’s too small and simple to do this well – and this would probably limit toxin loss as well.

Better to get your liver to neutralise toxins, and for anything that can’t be handled by the liver, use a kidney that dumps body fluid then reclaims the useful components before eliminating it.

Brett J · 26th February 2012 at 8:25 am

Humans have the ability to test alternates hypothesis ad infinitum.

10. No earlier shoes have been recovered. The shoe is an absolute necessity for endurance running in snow with large padded feet.

11. Large padded feet would have shorten for any large running placentals.

12. Humans along with other primates follow tracks and only escaped this necessity with the development of roads and shoes.

13. Trekking cultures while avoiding seasonal change developed the need to traverse greater tracks with unfortunate surfaces.

Mostly the newer developments for endurance running would point at modern humans adapting to the Earth after the last ice age. But our feet structure still retain the property of all other primates in normal primate trekking.

* If there was only one task per function in the human body then all excreta would travel through a singular orifice. Toxin removal is a complex task undertaken by several mechanisms throughout the body – e.g. pimples form despite kidneys, liver, or veins.

*The slow Loris is the my perfect example of typical evolution on Earth. Primates having evolved long enough would eventually develop a poisonous facility in complete match to other evolved (aged) creatures. Where they developed it is telling of primate development.

*There isn’t any animal running in severe heat. If any particular group achieved this feat it would be a short lived culture – not a niche. Human’s learn’t to carry a sufficient amount of water. Where is the evidence for an early primates water canister to accomplish these feats?

I still remain deeply skeptical of this study’s findings.

    Adam Benton · 26th February 2012 at 10:40 pm

    10a. I quoth myself: “Picturing people without technology on the Savannah…we do have some surprising physical adaptations to Savannah life…Combine running with sweat and you have a bipedal ape with the ability to run long distances in the blistering heat….one of the dominant predators on the Savannah”
    10b. And just in case you didn’t pick that up from the post, my comment also contained a similar point: “Endurance running offers the most advantages in a hot country where hyperthermia becomes a severe problem, rendering what happens when humans are exposed to snow irrelevant.”
    10c. Before you try and test a hypothesis it might be wise to understand what the hypothesis is actually saying to begin with.

    11. Humans have a whole suite of adaptations for bipedal locomotion, including for moving at great rapidity. H. erectus also seems to have had the vast majority of these adaptations.

    12. Whilst some primate species are restricted to tracks they know (and thus, should an obstacle on that trail arise they are unable to continue on until that obsticle is removed since they cannot plot a way around it), some species – including chimps and humans – have the ability to engage in geometric planning and will actively seek out new, more efficient routes and not limit themselves to tracks.

    *1a. Given the inefficiency of sweat at removing toxins, I’m skeptical that this function was the primary cause of its evolution. That doesn’t mean it can’t remove toxins, or that it wasn’t later co-opted to remove toxins, just that it didn’t originally evolve for that function
    *1b. As I said earlier, on the off-chance toxin removal was the original function of sweat, that doesn’t change the fact that it is a useful and important part of thermoregulation now.

    *2. Evolution is not a ladder progressing towards some notion of perfection. Instead it works with what is available to it in the gene pool to craft the best adapted organism to their environment it can, within the confines of the population variability. Thus regardless of what you view as good, there is nothing to indicate the development of slow-loris style venom excretion is guaranteed or even favourable in all conditions.

    *3a. Research suggests that water loss would begin to hamper the ability to run after ~2 hours. However, even being able to run up to ~1-2 hours would be enough for the advantages of sweating to show, with many prey animals suffering from hyperthermia after running for this length of time
    *3b. There is some evidence to suggest that individuals can run even long without dehydration negatively effecting them too much, although evidence for this is limited.
    *3c. Longer distance running ability is certainly contingent upon humans (or their ancestors) being able to consume enough water to keep up this ability.
    *3d. At present there is no evidence that hominins prior to humans carried water with them.

Jim Birch · 26th February 2012 at 10:28 pm

Man v Horse race: Run in Wales, over a distance of 22 km, man has won only twice in 31 years, both times in hot weather. This suggests that man may do better in African heat. Also, a horse is bred for running including endurance running. A gazelle is more of a sprinter, and tastes better than a horse.

http://www.bbc.co.uk/news/10302388

Also 🙂 http://www.futilitycloset.com/2012/02/18/hoofbeats-2/

    Adam Benton · 26th February 2012 at 10:43 pm

    I’m skeptical that any weather Wales experiences can be classed as “hot” 😉

Douglas Young · 9th March 2012 at 6:53 pm

Me too unqualified to comment…. but could the adaption not be running, but endurance… stamina. A lind of meta-adaption, which would affect all modes of action.

Do humans have greater or stamina than a) other primates and/or b) other animals in Africa? As Jim pointed out, you don’t need to run down animals with a marathon, you can walk (with jogging?) them down.

    Adam Benton · 9th March 2012 at 7:28 pm

    Like I’ve said all you need to endurance run is the ability to sweat efficiently and the ability to run. Both of these could’ve evolved for different reasons and then endurance running would just be a coincidence. No secret x factor is needed, just running and sweating.

Brett J · 25th April 2012 at 3:15 am

The only animal we could outrun is a chicken. That means every herbivore, that can eat grass, will start restocking within the first ten minutes of evading our slow paced running. The greatest advantage we have is cornering an animal that has limited options in finding water.

But if you look at the very activity of hunting you’ll notice we rely on both surprise attacks and ambush. If you’ve ever chased an animal you’ll know that you rely on the fact it sees little danger of you ever catching it. (This would require studies of hunting strategies which rely on best hunting practices).

Endurance running may only be a good performer for amassing a greater number of forces in the area, or for obtaining intelligence in a timely fashion. But all of this was better done by horseback, considering they eat grass and drink water after much higher paced activities.

Superior human endurance was rarely noted as a reason for winning wars. Copper, steel, horsemanship, armor, explosives, machines but rarely anything about marathon running armies. Of course the pace of army A versus army B really matters, but then that’s why they took to horses, wasn’t it?!

    Adam Benton · 25th April 2012 at 9:24 am

    You’re just plain wrong, people can and do use endurance running to hunt. It’s been documented in several tribes currently and even more were known to do it before the introduction of dogs and horses.

    These chases would last for upwards of 3 hours and travel 10s of kilometres.

      Brett J · 7th May 2012 at 9:19 am

      How can I be plain wrong? You just described a few anecdotal cases. There’s more proof available to show hunting as an art-form of strategy and subterfuge. You could say that perhaps I exaggerated the useless nature of running (which I didn’t intend), but to say I’m plain wrong is just being defensive.

        Adam Benton · 7th May 2012 at 4:03 pm

        You suggested the only animal we could outrun was a chicken. Examples of endurance running, regardless of how anecdotal, show this to be wrong.

marc verhaegen · 2nd December 2013 at 11:52 pm

It’s not difficult to show this fantasy wrong: “It is often stated that human locomotion was an adaptation to running on the open plains, which is illustrated by expressions such as ‘Savannahstan’, ‘endurance running’, ‘born to run’, ‘le singe coureur’ etc., even on the cover of the most influential scientific journals. Verhaegen et al. (2007) disproved in detail all endurance running arguments (Bramble & Lieberman, 2004) that our Homo ancestors during most of the Pleistocene were adapted to running over open plains. When we analyse human locomotion into more elementary components, the running ‘explanation’ appears to be a just-so interpretation (cherry-picking): Bramble & Lieberman (2004) interpret every locomotor trait in humans as having evolved ‘for’ running, without even considering possible wading or swimming scenarios. A comparative approach shows that, for each trait, semi-aquatic scenarios provide more parsimonious explanations (google ‘econiche Homo’ table 4), and that extant human running is a secondary and conspicuously imperfect adaptation which evolved late in the human past, for instance, we run maximally 32 km/hr over short and 20 km/hr over long distances, about half as fast as typical open plain mammals.” (Hum.Evol.28:237-266, 2013).
Human Evolution publishes in 2 special editions the proceedings of the symposium on human waterside evolution ‘Human Evolution: Past, Present & Future’ in London 8-10 May 2013:
SPECIAL EDITION PART 1 (end 2013)
– Peter Rhys-Evans: Introduction
– Stephen Oppenheimer: Human’s Association with Water Bodies: the ‘Exaggerated Diving Reflex’ and its Relationship with the Evolutionary Allometry of Human Pelvic and Brain Sizes
– JH Langdon: Human Ecological Breadth: Why Neither Savanna nor Aquatic Hypotheses can Hold Water
– Stephen Munro: Endurance Running versus Underwater Foraging: an Anatomical and Palaeoecological Perspective
– Algis Kuliukas: Wading Hypotheses of the Origin of Human Bipedalism
– Marc Verhaegen: The Aquatic Ape Evolves: Common Misconceptions and Unproven Assumptions about the So-Called Aquatic Ape Hypothesis
– CL Broadhurst & Michael Crawford: The Epigenetic Emergence of Culture at the Coastline: Interaction of Genes, Nutrition, Environment and Demography
SPECIAL EDITION PART 2 (begin 2014) with 12 contributions

    Adam Benton · 3rd December 2013 at 1:12 am

    Please just stop spamming your abstract all over the place.

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