On July 17th, 2017 we learned about

Grandparents’ earlier bedtimes may have evolved to ensure security for the family

Humans didn’t evolve in a world of deadbolts and heavy doors. Even a cave has a entrance that you might need to keep an eye on, but the average family or village probably didn’t have a sentry staying up to look for lions. Instead, security was likely assured thanks to restless grandparents and the fact that older people’s sleep schedules rarely sync up with those of younger adults.

Duke researchers built this “poorly sleeping grandparent hypothesis” around sleep data from the Hazda people of northern Tanzania. Hazda villagers will often work separately during the day, then come together to sleep at night in groups of 20 to 30 people. With no artificial lighting and simple bedding laid out on the ground near and outdoor hearth, the Hazda are thought to be a good proxy for early human societies, possibly providing insight into how our sleep needs evolved long ago. To get the details on this lifestyle, study participants were asked to wear activity monitors so that each individual’s schedule could be compared.

Sleeping in unscheduled-shifts

The pattern that emerged is likely very familiar to many of us, even if we’re not used to sleeping outdoors. Older people tended to go to bed earlier, around 8:00 pm, while younger adults stayed up later. Appropriately, older people also woke up earlier as well, but that doesn’t fully explain how this kind of sleep schedule could be a benefit to a group’s security. The other element is how restless people were during the the night— at any given moment during the night, at a little over a third of the group was dozing or alert. There were only 18 minutes in a night when every adult was completely at rest.

This suggests that a group of mixed ages could sleep without sentries because everyone was “on duty” for part of the night. The fact that older people tend to sleep and wake early may have then evolved to reinforce this system. With sleep schedules staggered by a few hours, an extended family would have very little risk of being truly unguarded throughout the night. This is all without factoring the further disruptions of young children, who would presumably add another layer of schedules to the mix (while creating new demands of their own that a grandparent might be able to help with.)

Interestingly, these overlapping but different schedules not only avoided lion-surprises, but also provided sufficient rest. Nobody complained of sleep deprivation, suggesting that while we obviously need good amounts of sleep, the idea that a good night’s rest has to be a single, uninterrupted block of time may be a modern expectation.

Source: Live-in grandparents helped human ancestors get a safer night's sleep, Popular Archaeology

On June 7th, 2017 we learned about

Moroccan fossils may force a reevaluation of when and where Homo sapiens got our start

In 1961, miners in Morocco found what appeared to be human skulls, jaws, arm and hip bones. The bones were all fossilized, but pinning down their exact age was difficult since they’d been removed from their original location. Now a second round of excavations from the same site, known as Jebel Irhoud, has uncovered more fossils, plus stone tools and crucially, charred flint from a campfire. Using a technique known as thermoluminescence with that flint, the site is now thought to have been inhabited between close to 300,000 years ago… just 100,000 years before anyone thought humans even existed.

(Im)perfect model for modernity

The idea that there were ancient hominids in Africa 300,000 years ago isn’t that shocking by itself. Other species, like Homo naledi, lived at that time too. Neanderthals had already left Africa altogether. However, the bones from Jebel Irhoud look strikingly like modern humans, and have been labeled as Homo sapiens. They’re not a perfect match though— they don’t have a modern chin, one specimen had a rather pronounced brow, and the shape of the brain case is tapered towards the back of the head. This has some anthropologists suggesting that these people were a transitional species, rather than truly modern humans, but even if that were the case, their overall similarity and age still merit some reexamination of humanity’s origins.

Overhauling our origin story

On one hand, 300,000-year-old humans may help make sense of a few things. The so-called Florisbad skull from South Africa was dated to be 260,000 years old, which made it seem like a weird outlier in the human family tree. However, if the Jebel Irhoud do represent even older members of H. sapiens, then the Florisbad skull fits into the story more neatly. Similarly, the tools found in Morocco were generally light weight, with spears that were appropriate for throwing instead of just stabbing. They’re not the only tools from this time period to have this degree of sophistication, and the thought is that if modern humans arose around 300,000 years ago, these tools might be more tightly bound to our evolution and success.

Of course, on the other hand, the location of Jebel Irhoud opens a whole host of new questions. Previously, the leading model was that H. sapiens started in Ethiopia around 200,000 years ago, with our oldest confirmed specimen dated as 195,000 years old. From that birthplace, it was though that humans started spreading out to other parts of the world, a narrative that doesn’t have space for humans to somehow be on the opposite side of the continent 100,000 years earlier. It seems that humans, or our very close ancestors, were actually spread across Africa, with no clear point of origin standing out at this point. To fill in more gaps, more fossils are needed. For better or for worse, those fossils might be all over the continent.

Source: Scientists Have Found the Oldest Known Human Fossils by Ed Yong, The Atlantic

On April 16th, 2017 we learned about

Drilled and filled cavities put dentistry’s start date in the Stone Age

5000 years ago, someone in Sumeria was worried they had “tooth worms.” It was probably just run-of-the-mill cavities, but people didn’t really know why their teeth could break down in their mouths. Lacking a real understanding of the root causes of tooth aches didn’t stop people from looking for remedies though, and people have been removing, wiring and medicating teeth for thousands of years. A discovery in Italy shows that dentistry may predate those Sumerian tooth worms though, with evidence of Stone Age fillings from nearly 13,000 years ago.

Carving for cavities

The two teeth show a lot of damage, but the assumption is that much of it was intentional. While paleolithic peoples likely demanded a lot of their teeth, using them as a third hand to hold or soften wood, hides and plants, these teeth seem to have been scraped on purpose. Instead of rough, random damage, an impressively smooth, regular pit was carved in the center of each tooth, much like your dentist would do with their drill to remove any infected tooth around a cavity and make a better seat for a filling.

Aside from the fact that this work was done without a modern dental drill, there obviously wasn’t modern fillings available either. To fill the teeth, it appears that fillings made of bitumen was used to fill the drilled hole. Bitumen is a thick, sticky substance that is usually derived from petroleum, and is most commonly used today in making asphalt cement. In Paleolithic era, bitumen was more often used as a glue in tools, but apparently dentists at the time felt it was a good way to fill in damaged teeth as well.

No signs of Novocaine

None of this sounds terribly pleasant for the patient, but a persistent tooth ache is hard to ignore. Hopefully, the dentist in question could at least recommend some of the pain-killing techniques used by Neanderthals in what is now Spain, as their teeth have turned up with traces of salicylic acid, the active ingredient in aspirin. It wouldn’t have made this a painless procedure, but it seems better than nothing.

Source: Stone Age hunter-gatherers tackled their cavities with a sharp tool and tar by Bruce Bower, Science News

On April 10th, 2017 we learned about

Concerns and questions about the nutritional needs of ancient cannibals

From a modern human’s perspective, cannibalism seems like a particularly monstrous course of action. While my kids have heard about animals eating members of their own species, the idea that humans have been known to eat each other was still surprising enough that my four-year-old felt the need to fact-check this concept with his mom. Nonetheless, humans have been eating each other since the Stone Age, with just enough regularity that researchers believe there may have been a pattern or repeating motivation to do so. Such as… nutrition?

Calories worth the cost?

While the tragic events surrounding Uruguayan Air Force Flight 571 famously demonstrate that cannibalism can keep you alive, researchers wanted to know if it was actually well-suited for that job. Were repeated instances of cannibalism in the archaeological record, as indicated by butchered bones or opened brain cases, simply because human bodies were a good source of food, even if you hadn’t been stranded in the mountains? After a thorough survey of earlier measurements of the calorie content of human anatomy, the answer was that humans aren’t especially nutritious. A whole human body, from the brain to the bones, really only yielded around 126,000 calories, much less than the 600,000 calorie bears living in the same ecosystem.

This suggests that humans probably weren’t being eaten because of a sense of nutritional efficiency, and were thus on the menu for other, possibly more ritualistic, reasons. However, this assumes that, outside of obviously skinny compatriots, these early humans could really assess the potential nutrition of eating one creature over another. Even in a highly measured, labeled world, many people today might be surprised about the caloric gap between a gram of chicken breast versus thigh meat, much less the 100-calorie difference between lamb loin and pork loin.

Difficulty measuring meat

Part of the difficulty in measuring meat is how much cooking it changes its nutritional value. Like starches, the sugars and proteins in meat open up when they’re cooked, allowing digestive enzymes a better chance to break them down into useful nutrients. Collagen also softens, making the meat literally easier to chew and ingest. Even mice, who don’t naturally encounter cooked meat, will favor it over raw options.

Our ancient ancestors likely had access to fire by the time they were eating each other, which begs a question about how the calorie count of human flesh was calculated. Most of the numbers came from older literature, measured in a time when calories were measured simply by burning the food in a container to see how much it heated water. Modern food measurements are a little more sophisticated now, doing a better job of how food will be digested. If the human body were remeasured to modern standards, we still might not match the caloric bounty of a one-ton short faced bear, but properly roast thighs might not seem like such a waste after all.

Source: Cannibals Weren't Calorie Counters, But Humans Aren't Very Nutritious by Shaena Montanari, Forbes

On March 23rd, 2017 we learned about

Capuchin monkeys inadvertently muddle the history of human tool making

Some of the first technology created by humans were sharpened stone flakes. While they might appear to be simple rocks at first glance, archaeologists have come to note the single sharp edge and flat sides that transform these rocks into tools. The edge would have allowed early hominids to cut meat, remove skin, or work with wood and grass. To create such a tool, our ancestors are thought to have needed advanced hand-eye coordination, as well as the ability to plan the flakes’ design.

…or they would have needed to be weirdo capuchin monkeys making flakes without even noticing.

Capuchin craftsmanship

Capuchin monkeys have been observed experimenting with tool use for many years. They use rocks like shovels to dig up spiders, twigs to poke into crevices for caterpillars, and may have been cracking open cashews in a hammer-and-anvil arrangement for over 700 years. They’re one of an ever-growing list of animals that partake in at least casual tool usage, but their creativity, and perhaps dumb luck, has set them apart.

Bearded capuchins (Sapajus libidinosus) in Brazil’s Serra da Capivara National Park were observed banging rocks together, but not for the sake of getting at fruit or nuts. They were hitting pieces of quartz together with two-handed, overhead strikes, and then licking the broken stones. Researchers aren’t sure if they were trying to lick up silicon or possibly lichen to fill some sort of nutritional need, but they were sure about the stone byproducts of this activity. Many of the resulting pieces of stone were nearly identical to what has been assumed to be carefully crafted stone flakes of human ancestors. The monkeys took no notice of the fine edges or flat sides that would attract an archaeologist, but even the accidental creation of such an object is very significant.

Accident or innovation?

Sharp flakes of stone have always been assumed to be a marker of human-like intelligence and development. They were supposed to be the starting point for human artifacts, kicking off the chain of development that gives us the computer you’re reading this on. Even with other tool-using animals in the world, the sharp flakes of rock were supposed to require more deliberate creation, and were different from the broken rocks wielded by other primates like Chimpanzees and Macaques. If capuchins are making them accidentally, it means that stone flakes alone can’t be considered a reliable marker for hominid activity. Sometimes flakes have been found with other artifacts, like butchered bones or old fire pits, but on their own, we can’t be so sure we’re seeing signs of an innovative Australopithecus, or just a lucky one that wanted to lick some lichen.

In the mean time, we’ll have to watch the capuchins to see if they take notice of the utility of their flaked stones. Maybe this is a window to how specific tool creation got started in the first place?

Source: Capuchin monkeys produce sharp stone flakes similar to tools, Science Daily

On January 19th, 2017 we learned about

Making a political or personal point by pitching your poop

Poop Week!

The first, and most important thing my kids need to know on this topic, is that we do not throw poop. It’s yucky, you shouldn’t be touching it, much less throwing it, etc. That said, humans actually have a decent track record of throwing poop, particularly as an act of angry protest. The reasoning is probably obvious— if someone is going to go against the very important warnings their parents told them about handling pathogen-carrying feces, then presumably whatever they’re upset about is important enough to risk exposure to say… cholera, maybe? There’s also the ick factor, the shock value, and the fact that some of this behavior may be sort of built into our brains.

Forcing an issue with feces

Effective protest usually requires that the aggrieved party knows what they want, and that they can get someone else to listen to them. Poop probably can’t help with the first point, but if other outreach methods don’t work, anecdotal evidence suggests that properly-employed poop certainly captures people’s attention. Sometimes this has meant covering symbolic statues, such as at the University of Cape Town, in feces. In India, a rally of 30,000 people was somehow overlooked, but when protesters publicly defecated on copies of the land bill that had caused the uproar, more attention was given to the matter.

Unfortunately, not every poop gets thrown with such clear purpose. In some cases people have used feces mainly for the sake of offending others, with very little justice in mind beyond their immediate gratification. Documented cases of smearing abandoned dog poo in it’s negligent owners hair, or throwing turds at a neighbor’s house, usually lead to little more than criminal charges. Even with something as viscerally arresting as unexpected piece of poo, there are still nuances to be protesters need to appreciate in order to wield them effectively.

Scat and the beginnings of self expression

The weirdest details about tossed turds may be what they say about the evolution of our brains. We’re not the only animal to fling our feces, but we might want to feel proud to be counted as members of this unhygienic club. A study of chimpanzees found that the chimps who threw poo more often had more brain development between the their motor cortex and a speech-oriented structure called the Broca’s area. Chimps that didn’t throw poop didn’t show the same degree of connectivity in those locations, or the left brain hemispheres in general.

Researchers aren’t suggesting that throwing poop boosts language ability, or that human evolution was set to its present course when an ancestor threw their feces. Instead, they suggest that throwing any object, even cleaner ones, may have arisen at least partly in thanks of primates’ drive for self expression and communication with their peers. It wasn’t so much that the poop-tossers were better athletes, but that they had something to say, and tossing a poop was sometimes the best way to say it.

Source: ​A Brief History of People Protesting Stuff with Poop by Mark Hay, Vice

On December 19th, 2016 we learned about

Finding efficiency in the weird way we walk

You probably haven’t thought too hard about how to walk since you were a toddler, but that doesn’t mean that the human stride is a simple concept. The fact that each of our steps lands on our heel is actually a strange trait, since most animals handle everything on the balls of their feet, with their heels never touching the ground. As humans are fairly efficient walkers, scientists have been looking for ways that we might benefit from such an unusual stride.

Part of what makes heel-first walk so strange is that it goes against concepts understood to help make an animal walk with more efficiency. When other animals walk with their heels up, they’re orienting their skeleton to effectively have a longer leg, and longer legs are more efficient per step than shorter ones. So by stepping on our heels, we’re essentially shortening the possible length of our leg, which should be a waste of energy.

Looking past our legs

Researchers think that the answer may be to look beyond our actual legs, and focus on the overall arch of motion. When we step, we rock our weight from heel to the middle of our foot, which makes our leg move over our foot like an inverted-pendulum. However, by starting on the heel, the true center of this pendulum motion isn’t right at our foot at ground level. To swing our leg forward from the back of our foot, the true fulcrum point would be about six inches below the ground.

This sort of “virtual leg” length seems to make real biomechanical difference. In a lab, people asked to walk by landing on the front of their feet had to work 10 percent harder than people walking with their normal stride. Only once you change your gait to more of a run (when barefoot) does landing on the balls of your feet begin to make sense again.

Pedestrians of times past

Our ancient ancestors didn’t always move exactly like this. Based on fossilized footprints from 3.6 million years ago, early bipeds landed on their heels, but with relatively larger, stiffer feet. They were probably very efficient walkers, but not great runners. It’s suggested that modern humans’ shorter toes and feet likely evolved to help us get off our heels and run, which we’re actually better at than you might think, and not just because of our toes.

Source: Why we walk on our heels instead of our toes, Scienmag

On December 12th, 2016 we learned about

Estimating the mass of everything on Earth made by humans

As you dive into holiday shopping, it might help to consider just how much of humanity’s 30 trillion tons of stuff you want to be the owner of. A lot of that stuff isn’t really for sale, or even gift-wrappable, but it’s all part of the impact our species has made on the planet, for better or for worse. On a day-to-day basis, it’s easy to ignore some of this buildup and focus on the subset of things we want as individuals, but these new calculations aim to help us see that new tablet or toy from a new perspective, since on some level we share it all anyway.

The mountains of material shaped by humans isn’t just a single, 30-trillion-ton monolith of course. It’s spread out over time and space, including every building, tool, widget or piece of waste we’ve manufactured. In some cases, large collections of a single substance can be counted, such as the nearly trillion tons of carbon dioxide produced by human activity. Other objects are a bit more granular, such as the 130 million book titles published in human history, and all the various printed copies of each of those titles. From the perspective of an archaeologist or paleontologist, each of these items counts when considering humanity’s impact on the world around us.

In total: the technosphere

Altogether, this collection of intentional and unintentional products can be called the technosphere. That name isn’t just supposed to sound like jargon, but rather to evoke the relative gravity of all our junk. The calculated mass of the technosphere actually puts it on par with major components of our planet, like the hydrosphere, atmosphere or even biosphere (yes, our loot is easily as influential as life itself.)

It’s fair if that still feels too abstract to really deal with. To bring things a bit closer to home, it may help to look at your own living room, thinking about the messiest day you’ve seen. Now consider if your room, and every other inch of the 196.9 million square miles across the surface of the Earth was covered in a few inches of densely collected debris, with each square foot of space weighing in at 36 pounds of stuff. If wading through debris doesn’t capture your imagination, we can just divide up the technosphere to everyone that has ever contributed to it. By 2011, it’s thought that over 107 billion people had ever been born, giving every human ever our own 279 ton nugget of human creation. Apparently we’re all more prolific than we realize, for better or for worse.

Source: Our ‘Technosphere’: 30 Trillion Tons of Man-Made Stuff by Tracy Staedter, Seeker

On December 8th, 2016 we learned about

Throwing rocks regarded as a significant step in hominid development

Don’t tell my three-year-old, but throwing rocks may a sign of brain development and the rise of human civilization. Actually, from a parental perspective it’s even worse, because the key behavior that has anthropologists excited was throwing rocks at animals. As a group. Of course, as hominids have evolved, every bit of behavior has, at some point, been cutting edge innovation. While often this is more obvious, such as when stones have been carved into specific tools, sometimes even unremarkable rocks may hint at important milestones in human history.

The key trait about the rocks in question is their quantity and their location. Any individual stone would easily be overlooked, but an unusual collection of egg-sized stones has been found amongst bone beds in the hills of Georgia. 1.8 million years ago, when most of the animal bones were deposited here, the area would have had plenty of large, predatory cats, wolves and hyenas, plus a population of Homo erectus. H. erectus was an ancestor of humans, standing around five feet tall with brains smaller than our own. At this time, nobody was carving tools, but researchers believe the piles of rocks found around animal skeletons indicates that these hominids had at least figured out throwing.

What’s so special about throwing stones?

Throwing a rock doesn’t sound like a big deal at first, especially since other primates more distantly related to humans can throw things as well. The significance is that it appears that these rocks were gathered together on purpose, likely as an ammo cache to be thrown at some of the big cats roaming the area. Just like hyenas and lions in Africa today spend a lot of energy chasing each other off downed prey, clawless and squishy members of H. erectus needed a strategy to defend, or steal, food from other predators. Coordinating a group enough to gather and throw rocks would have required a considerable amount of brain power to pull off.

Beyond the social cooperation of these proto-militias, the physical act of throwing a rock may be tied to brain development as well, specifically around Broca’s area. This region of the brain that helps us manage hand-eye coordination, say for flicking a small stone at a lion, has also been associated with language functions. Throwing rocks didn’t push H. erectus to spoken language, but if we can figure out how coordinated they were, it may help us better estimate how developed their cognitive abilities may have been.

Source: Did Chucking Stones Make Us More Human? by Paul Salopek, National Geographic

On November 2nd, 2016 we learned about

Discrepancies found in how people read the feelings on each other’s faces

The combination of being social and visually oriented animals has made humans experts at reading each other faces. There are obviously exceptions here and there, but for the most part the hundreds of muscles in our faces that shape the smiles, frowns, scowls and more are such a big part of our lives that we can even take them for granted. For the past 50 years, there’s been a hypothesis that some of these basic expressions were actually ingrained in our brains, and that anyone, anywhere, regardless of other cultural influences, would be able to understand the basic meaning behind a smile or a furrowed brow. This hypothesis is being tested though, and there’s a chance things aren’t as universal as a simple smiley face would have us believe.

If you’re happy and you know it…

Researchers made extended contact with the Trobriander people on some isolated islands on the eastern side of Papua New Guinea. The tribe of 60,000 has minimal contact with the outside world, from television to emoji, and thus could provide a rare example of humans not raised by what is increasingly becoming a globalized culture. If the rest of us have possibly been unavoidably taught that smiles correspond to happiness, the Trobrianders might be able to demonstrate an unadulterated, or at least alternative, interpretation of common facial expressions.

The tests themselves involved asking Trobrianders to select faces from an array of photos that best matched various questions. Sometimes the questions were as straightforward as “who looks happy?” but other people were asked things like “which person is likely to start a fight?” For the most part, there weren’t any surprises, with smiling faces being matched to happiness in each case. However, what most of us would call an angry scowl, as well as a fearful gasp, seemed to complicate things. What researchers saw as a scared or at least surprised expression was consistently associated with anger and threats by the Trobrianders.

Different takes on displeasure

This contrast with more common interpretations opens up a lot of questions about the origins of our facial expressions, and just how malleable they may be. It’s possible that there is still a consistent, shared thread in our emotional expression, but that the language and thought structure we attach to them varies— so a face that many of us read as feeling fear is interpreted by Trobrianders as a face instilling it. Fear is still part of the equation, but how it’s being processed varies enough that we can’t assume that everyone’s faces can be read the same way. This is important to understand not just to know how humans evolved and function, but also for practical uses like the growing number of facial recognition programs and robots that will soon be trying to get a handle on how humans feel, preferably without us having to type in emoji first.

Source: Facial expressions—including fear—may not be as universal as we thought by Michael Price, Science Magazine