by Doctor Science
Soundtrack/earworm for this post.
You probably came across science news reports last week with headlines like Up Late? Looks Like Our Paleo Ancestors Didn't Sleep Much Either, Do We Really Need to Sleep 7 Hours a Night?, or Chances are, you’re getting enough sleep. The research in question, by Jerome Siegal of UCLA and his colleagues, is Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies. It's most interesting to me for what it implies but doesn't examine about the evolution of human sleep patterns. Basically, it looks as though one distinctive feature of human evolution is that we stay up late due to technology.
Siegel et al. studied three different cultures: two foraging ("hunter-gatherer") groups in Africa, and one foraging+ horticulture group in the Bolivian Amazon. They all had very similar circadian rhythms: everyone wakes up about an hour before dawn, is most active in the morning, then quiet (though not usually napping) during the hottest part of the day at noon and just after. People then become somewhat active at sunset, and stay awake for 3-4 hours (or more) after that. The net result is that of the (average) 11 hours of darkness (12 hours of sundown minus a half hour of twilight on either end), no more than about 8-9 are spent resting, and around 7 are spent sleeping -- which isn't a whole lot different from the sleep humans get in industrial societies with lots of artificial light.
Siegel calls the foragers' habits the sleep amount and the sleep pattern selected by a million years of evolution -- but he doesn't seem to have noticed how very *odd* they are, compared to the sleeping habits of wild animals. Wild chimpanzees, for instance, seem to sleep 10 to 11 hours a day. Adult chimps weave leafy beds in trees in the late afternoon, and usually are tucked in before sunset. They get up at sunrise or in the pre-dawn twilight, having slept through the night.
Why would chimps need so much more sleep than humans? As Siegel and his colleagues have argued, sleep has multiple functions. One possible function of nighttime sleep for diurnal animals like apes (and humans) is that it keeps them out of trouble: they don't move around and attract the attention of nocturnal predators, while conserving energy they'll need for useful daylight activities. For chimpanzees, the most important predators (aside from humans) are the big cats: lions and especially leopards (because they climb trees).
My theory, which is mine, is that hominid sleep patterns made a huge shift when our ancestors started to control fire -- which was, in fact, at least one million years ago. Fire made it possible to eat more efficiently, because cooked food is easier to digest than raw, but it also opened up part of the night for useful activity, it changed us so we are no longer strictly diurnal animals like the other apes.
The useful activities around the fire are social: eating, food-sharing, and talking -- the equivalent of the social grooming that takes up a lot of other apes' time. And our ancestors could afford to make noise and delicious smells after dark, because fire is a really strong deterrent for big cats and other predators.
In other words: there is no such thing as "pre-technological" humans. Our ancestors tamed fire, and fire tamed them right back. At least a little artificial light is natural to us.
It's always astonishing how even people whose educations should have taught them better still define "technology" at a far higher level of development that is warranted by the evidence.
As you note, fire has been around for a very long time with humans. (And, to use a term of dubious accuracy, with pre-humans.) But an amazing number of anthropologists who are not specialists in stone tools, not to mention virtually all historians, seem to ignore just how much technical skill it requires to shape a hand axe. Let alone the flakes which form part of early human tools. They should try it some time.
Posted by: wj | October 27, 2015 at 01:56 AM
I've tried. It is pretty easy to make a paleolithic-style chopper but anything more sophisticated is beyond me. I'm pretty sure that I could do better tools, but it would require weeks or months of practice. I am not so hard-core survivalist that I would care to do that.
It means that technology-wise, I am about at the same level as our Australopithecus ancestors, if I lose my phone and my steel knife.
Posted by: Lurker | October 27, 2015 at 03:14 AM
this is a pretty awesome demonstration of what can be done with no tools but a lot of practical knowledge.
https://www.youtube.com/watch?v=nCKkHqlx9dE
Posted by: cleek | October 27, 2015 at 09:55 AM
and this one is even better:
https://www.youtube.com/watch?v=P73REgj-3UE
Posted by: cleek | October 27, 2015 at 09:59 AM
His videos showing how to make the tools he's using are also excellent.
If only to have you appreciate more fully how much of a time investment it is to make your own tools.
Posted by: Slartibartfast | October 27, 2015 at 02:54 PM
So, which came first; fire or living in caves? Or did they happen concurrently?
I visited Pilanes wildlife preserve in South Africa a few years ago, and I'll tell you, after seeing the big predators from an open jeep I truly appreciated early man. Especially after I locked eyes with one and a chill went up my spine.
Posted by: Anne Wittke | October 27, 2015 at 02:59 PM
Not just predators. I recall as a teen approaching a small group of American bison on foot with nothing between me and them. About the time the group shifted around so that the big bull was closest, and paying attention to me, it seeped through even my teenaged male brain that this wasn't a smart place to be.
Posted by: Michael Cain | October 27, 2015 at 05:46 PM
Speaking of fear of big predators, I'm looking forward to Di Caprio's new movie, the Revenant, where he portrays Hugh Glass. From the wikipedia entry on Glass
In August 1823, near the forks of the Grand River in present-day Perkins County, South Dakota, while scouting for game for the expedition's larder, Glass surprised a grizzly bear with two cubs. The bear charged, picked him up, and threw him to the ground. Glass managed to kill the bear with help from his trapping partners, Fitzgerald and Bridger, but was left badly mauled and unconscious. Ashley (who was also with them) became convinced he would not survive his injuries.
Ashley asked for two volunteers to stay with Glass until he died, and then bury him. Jim Bridger (then 19 years old) and Fitzgerald (then 23 years old) stepped forward, and as the rest of the party moved on, began digging his grave.[4] Later claiming that they were interrupted in the task by an attack by "Arikaree"[citation needed] Indians, the pair grabbed Glass's rifle, knife, and other equipment, and took flight. Bridger and Fitzgerald later caught up with the party and incorrectly reported to Ashley that Glass had died.
The route of the 1823 odyssey by Hugh Glass
Despite his injuries, Glass regained consciousness, but found himself abandoned, without weapons or equipment. He had festering wounds, a broken leg, and cuts on his back that exposed bare ribs. Glass lay mutilated and alone, more than 200 miles (320 km) from the nearest American settlement at Fort Kiowa on the Missouri. Glass set his own leg, wrapped himself in the bear hide his companions had placed over him as a shroud, and began crawling. To prevent gangrene, Glass laid his wounded back on a rotting log and let maggots eat the dead flesh.
Glass crawled overland south toward the Cheyenne River using Thunder Butte as a navigational tool. The journey took him six weeks. He survived mostly on wild berries and roots; on one occasion he was able to drive two wolves from a downed bison calf, and feast on the meat. Glass was aided by friendly Native Americans who sewed a bear hide to his back to cover the exposed wounds and provided him with food and weapons. He made his way to the Cheyenne River, fashioned a crude raft and floated downstream, eventually reaching the safety of Fort Kiowa.
I remember as a kid thinking I could be like Jerimiah Johnson, so this movie will probably disabuse me of that.
Posted by: liberal japonicus | October 27, 2015 at 07:08 PM
Anne:
Fire *definitely* came first. Living in caves has been a very occasional lifestyle over the course of hominid history.
I personally suspect that fire (and cooking) are as good a marker for "genus Homo" as we'll find. Note that genus Homo is *very* poorly defined, at present -- as is Homo sapiens, the only species for which there is no type specimen.
Posted by: Doctor Science | October 27, 2015 at 08:32 PM
On the one hand, it's nice to know that sleeping less than 7 hours with some regularity isn't likely to be a death sentence, as THEY would have you think.
On the other hand, why am I so tired all the time?
Posted by: JakeB | October 27, 2015 at 11:30 PM
Jake, have you considered that it isn't actually lack of sleep? It's the lack of time spend lounging around in the early afternoon.
Posted by: wj | October 27, 2015 at 11:38 PM
Jake:
I basically agree with wj, here. It turns out that foragers aren't actually much more physically active than people in industrial societies, but our lives are *much* more stressful. In particular, we have to make many more decisions, and we meet and interact with many more people. These activities take a lot of mental processing time, and that's why we need so much sleep. I think.
Posted by: Doctor Science | October 28, 2015 at 12:12 AM
Yes, I was speaking facetiously. I agree with you entirely.
It's odd to think that saber-tooth tigers are less stressful coexistents than dickhead coworkers, but I reckon it is true.
Posted by: JakeB | October 28, 2015 at 12:34 AM
JakeB,
a sabre tooth tiger is like a traffic accident: they are rare and though they are a real danger, they are not a pressing concern. We don't stress about them too much, though we are mindful of them.
Most importantly of all, we don't care about what the tiger thinks about us. We care about our coworkers. That is a big difference.
Posted by: Lurker | October 28, 2015 at 08:27 AM
I remember as a kid thinking I could be like Jerimiah Johnson...
That's how I've always pictured you, lj, based on your frontiersman-like writing style.
Posted by: hairshirthedonist | October 28, 2015 at 09:09 AM
"Most importantly of all, we don't care about what the tiger thinks about us. We care about our coworkers. That is a big difference."
Posted by: Julian | October 28, 2015 at 01:43 PM
"Most importantly of all, we don't care about what the tiger thinks about us. We care about our coworkers. That is a big difference."
Posted by: Julian | October 28, 2015 at 01:43 PM
hairshirthedonist,
the urban nature of American frontiersmen was a topic that many Europeans observed upon during the 19th century. They were coming from countries with deep countrysides where people lived in villages where their families had lived since the early Middle Ages, and where large swathes of any country (outside Britain) still were in pre-capitalist phase.
The American frontiersman of late 19th was a product of capitalist society. He had very possibly grown up in a town. The economy and socialmstructure he brought with him was integrated to the capitalist economy of the nation. For his material needs, he had a mail order catalog. For his educational needs, correspondence courses and public schools. For his religious needs, an endless series of denominations. What he did not have were extensive family ties and a generational tradition tying him to his home.
Most likely, aa contemporary redneck in deep South or Appalachia or a black ghetto youth in an inner-city slum are less integrated in the national economy than a 19th century homesteader in the Rockies.
Posted by: Lurker | October 28, 2015 at 01:52 PM
The movie "Man in the Wilderness" takes elements of the Glass experience (time period, mauled by bear and left for dead by companions) but is a fiction drama, not biopic or historical fiction. 1971, Richard Harris, John Huston.
Posted by: Priest | October 28, 2015 at 10:08 PM
we do one thing much differently than our paleo ancestors: we don't get up with the sun, we get up with our alarm clocks. and as everyone in the northern hemisphere knows, this time of year makes that especially painful. suddenly, it seems, we're waking up in the dark, instead of with or after the sunrise.
Posted by: cleek | October 29, 2015 at 10:12 AM
I'm not sure what's worse, though - having to get up when it's still dark or being inadvertently awakened at 5:45 AM in the middle of June to find the sun beaming through the insufficiently opaque curtains.
Posted by: hairshirthedonist | October 29, 2015 at 10:19 AM
What's worse is being awaken by the cell phone beeping**, even before the alarm goes off, because people on the east coast feel compelled to send early morning e-mails. Sigh.
** Actually, even on vibrate, it still can be enough to wake me up.
Posted by: wj | October 29, 2015 at 10:31 AM
wj, turn off the damd ringer and vibrate for anything except phone calls, get some sleep. Mine is that way all the time, but at night for sure.
Posted by: Marty | October 29, 2015 at 10:59 AM
Yeah, a new habit that I need to work on forming. (Can't leave it that way duringthe day. Too many e-mails from my boss where she needs something fast...and I tend to get buried in the code I am working on.)
Posted by: wj | October 29, 2015 at 11:08 AM
mine is always on vibrate. and we charge them in the kitchen. so, my phone never bothers me at night.
Mrs leaves her sounds on. so sometimes when her friends get all SMS-chatty late night she has to get up to turn the sounds off.
Posted by: cleek | October 29, 2015 at 11:20 AM
I'm a touch dubious. It seems to me that sleeping habits and needs could evolve quite differently in different environments. The three societies studied here are quite similar in that respect, including, maybe, climate.
I'm pulling things out of thin air, or somewhere, here, so please bear that in mind. To the extent sleep requirements have a physical basis it resides, I suppose, in brain function. Would that be more malleable than having two eyes, or a thumb, or some other clearly physical trait. If so, it seems to me that sleep requirements would vary across environments more widely, and change more quickly, than these sorts of characteristics.
Maybe not, but it strikes me as awfully glib to talk about " the sleep amount and the sleep pattern selected by a million years of evolution" based on these studies. Far too broad a claim, I think.
Posted by: byomtov | October 29, 2015 at 11:44 AM
Never too broad for the internet!!
Posted by: dr ngo | October 29, 2015 at 12:59 PM
A "twenty four hour" daily cycle always seems a bit short to me. A more natural fit would be something like 24 hours + 37 minutes.
Posted by: Snarki, child of Loki | October 29, 2015 at 01:31 PM
could we maybe take 10 minutes out of each weekday afternoon hour and make each weekday 6AM hour two hours long ?
or, just have work start at 10.
Posted by: cleek | October 29, 2015 at 01:54 PM
There is a difference between nominal and real starting time. For me the latter was always 10 or so.
Posted by: byomtov | October 29, 2015 at 02:14 PM
I like to think of myself as a real "morning person." That is, left to myself I will stay up until 2 AM or so (usually reading), and the sleep in until 10 -- that's 8 hours sleep, right? Unlike some fake "morning person" who just gets up at 5 AM . . . when the morning has been going on for hours.
Of course, I haven't really been left to myself since I got morning, rather than afternoon, kindergarten. Including all those 8 AM engineering classes in college. Ah well, maybe some day in retirement....
Posted by: wj | October 29, 2015 at 02:59 PM
People who go to bed the same day they woke up are slackers.
When I was young, my standard response to any proposed 8AM meeting was "Sure. I can stay up that late."
I sometimes think I evolved on a planet with a 26-hour day. No matter what I try, if I wake up at 8AM today, I cannot wake up before 10AM tomorrow. Except when I've been on business trips (explain that!), I have not been able to string together 5 consecutive days of waking up at the same hour since I was in junior high.
--TP
Posted by: Tony P. | October 29, 2015 at 03:29 PM
I recall one of those natural sleep experiments discussed in James Gleick's _Chaos_ (which I read the year it came out, so my memory on it is a bit rusty, but anyways) in which it is mentioned that people living in a cave* with no information about time or daylight would end up having days around 25-26 hours long.
I once heard someone conjecture that this was because it is a lot easier to reset a spring with a naturally longer period than the optimum period than it is to stretch one out that is too short -- so it wouldn't be surprising if our "natural" day is somewhat longer than 24 hours, especially given the effects of changing daylight hours through the year. Maybe you're just a bit more rigid and insensitive to the external cues than the average Joe, Tony.
*which of course does bring up the question as to whether the sitcoms shown in Plato's Cave were always on at the same hour.
Posted by: JakeB | October 29, 2015 at 05:17 PM