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The invention that made us human: Fire
Did fire change the development of the human brain?
- The earliest evidence for fire dates back nearly 440 million years.
- Our hominin ancestors first used natural wildfires to flush out prey and forage for food.
- Richard Wrangham's cooking hypothesis suggests that a ready supply of cooked food allowed the Homo lineage to develop its large, complex brains.
Of humanity's greatest inventions, fire remains as important today as in the time of our ancient ancestors. If not as apparent.
We have replaced the hearth with electric ovens and central heating, but the burning of fossil fuels accounts for 63.5 percent of U.S. electricity generation. We still heat our homes and cook our food with fire — just in a more roundabout manner.
We even use fire in ways our ancestors couldn't have imagined. The internal combustion engine has replaced animals and our own wobbly legs as the preferred method of travel. We can go farther in a day than the vast majority of our ancestors did in a lifetime and even escape the confines of our planet. Thanks to fire.
But fire has done more than create the energy that makes our lives comfortable. By one Harvard professor's account, fire altered the course of our evolution.
Fire, a brief history
Wildfires, such as this one at Yellowstone National Park, have been a recurring phenomenon for more than 440 million years.
First, some Chem 101. Fire requires three elements for its reaction: oxygen, a fuel, and a heat source. Since two of the three elements are provided naturally by plants, the history of fire became intricately tied to them.
Some of our earliest evidence for fire goes back 440 million years to the Silurian period, when Earth's climate stabilized and plants and animals began to move to land. Of note, this period provides the earliest fossil evidence of vascular plants.
From this point, fire becomes a recurrent phenomenon with times of high and low activity based on environmental conditions. During the Carboniferous period, atmospheric oxygen hit a record high of 31 percent and plants spread across the supercontinent Pangea, so charcoal records suggest a lot of fire activity during this period. Conversely, the pittance of charcoal from the Triassic period suggests low atmospheric oxygen and fewer plants.
Jumping a few million years to the late Miocene, hominins moved to the grasslands and begun to further diverge from their ape relatives — likely due to the difference between the African savanna and the dense jungle. Here, they would have also encountered wildfires with far more regularity.
We didn't start the fire
Prometheus Brings Fire to Mankind by Heinrich Fuger. Our early reliance on nature for fire draws parallels to later mythologies.
Low-hanging references aside, Billy Joel was on to something. Popular culture conjures the image of a caveman banging two stones together. Sparks fly, and then the eureka moment. Yet, our ancestors' first usage of fire probably wasn't a matter of control or invention. It was more likely opportunistic.
In a review for the Royal Society Philosophical Transactions B, J.A.J. Gowlett hypothesizes that hominins took advantage of natural wildfires for foraging. "For hominins," he writes, "benefits could include retrieval of birds eggs, rodents, lizards and other small animals, as well as invertebrates. Although fire does not create such resources, it renders them far more visible, and chance cooking might well improve their digestibility."
Gowlett notes that analogues to this behavior exist in the natural world today. Savanna chimpanzees use fires to locate resources, and several bird species follow fires to snatch up any prey flushed out by the smoke and flames. There has even been anecdotal evidence of some raptors, such as Australia's "firehawks," picking up smoldering wood from one fire and carrying it elsewhere to start another.
Early hominins would have also begun to discover fire's properties by observing and interacting with these blazes. For example, if a meaty morsel proved too raw, they may have learned to place it on embers to continue the cooking process.
Given our early reliance on nature for fire, it's little wonder that the theft of fire theme has appeared time and again in the world's mythologies.
But we kept it burning
It's difficult to follow the development of hominin control over fire because of what Gowlett calls its "disappearing act." Fire isn't as well preserved in the archeological record as, say, middens or flint tools. And progress was incremental, with fire control being learned in different places at different times.
Certain archeological sites have proffered a bounty of stone tools, suggesting long-term quartering. Such occupancy could mean hominins learned to at least maintain fire as far back as 2.5 million years ago. But direct evidence is scarce.
As we move forward, we see more evidence of hominins' control over fire. Archaeologists have discovered campfire traces and charred animal and plant remains at Wonderwerk Cave in South Africa. These have been dated back to approximately one million years ago. And the oldest known hearth, found at Qesem Cave, Israel, dates back more than 300,000 years ago.
Interestingly, archeologists aren't sure which hominin species got cozy at Qesem. "It is clearly different than [Homo] erectus and has affinities of both [Homo] sapiens and Neanderthals," Ran Barkai, Tel Aviv archaeologist, told National Geographic. "Since Neanderthals appear very late in the Levant and are of European origin, and since the Qesem teeth bear more resemblance to early Homo sapiens in the Levant, we believe they are closer to Homo sapiens."
Hearths and campfires tell us hominins could maintain fires for cooking and warmth. They do not, however, prove our ability to create fire. After transferring a brand from a wildfire, a tribe member could have been given fire duty and tasked with fueling the fire to prevent its extinguishing.
Good evidence for fire creation appears around 120,000 years ago, when hominins had access to twine, a requisite to developing the bow drill. And archeologists have dated two glues used in hafting, bark pitch and gypsum plaster, to between 50 and 100 thousand years ago. Neither of these can be prepared without fire.
At this point, Gowlett argues, the invention of fire belongs to our ancestors. "[A]n understanding is emerging that fire use is not a single technology or process, but that several scales of use, and probably several intensifying technologies, evolved over a long period, intertwined, and sometimes eventually became bound together," he writes.
Fire (and food) for thought
Cooked meats are easier to chew and digest; as a result, our bodies can extract more nutrients from the same amount of meat. Similarly, cooking vegetables increases levels of healthy stuff like antioxidants. That's because the cooking process breaks down the plants' cell walls and, like meat, makes them easier to digest and process. (Though, it is a tradeoff. Some veggies are healthier raw, and it depends on how you cook them.)
Wrangham argues that the ability to create cooked foods shaped the brains and bodies of our Homo ancestors. Since our ancestors spent less energy digesting foods and could draw out additional nutrients, they had more to nutrients to spend, and evolution spent those dividends on maintaining larger brains — not to mention smaller teeth and jaws. Larger brains allowed us to process more information, create more dynamic social groups, and adjust to unfamiliar habitats. All of which benefited us evolutionarily.
With that said, the cooking hypothesis has its detractors. Some argue there is little proof that humans were cooking or maintaining fire in concurrence with Homo erectus' brain-size explosion (roughly 1.5 million years ago). It's also possible that a diet of raw meat and veggies could have provided the necessary nutrients for bigger brains.
Other hypotheses exist to explain the increase in hominin brain size. The social brain hypothesis, for example, argues our brains evolved to meet the challenges of living in large social groups. But even here, fire plays a role. Remember that before our ancestors could ignite fire, they had to maintain it. This required a division of labor, which is only possible in a species with a highly structured social network.
Fire may or may not ultimately prove to be principal in our evolutionary development. For any such hypothesis more evidence is needed — though fire, cooked food, and social networks likely all played a part.
Without a doubt, fire has proved a primary mover in the evolution of civilization. It helped us migrate to climates that would otherwise prove inhospitable. It was essential to the development of cuisine, agriculture, metallurgy, architecture, and a host of other industries. In short, the invention of fire has taken humanity places no other species has gone.
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Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.
- Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
- As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
- The film is perfectly timed for a world sheltering at home during a pandemic.
Richard Feynman once asked a silly question. Two MIT students just answered it.
Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.
But science loves a good challenge<p>The mystery remained unsolved until 2005, when French scientists <a href="http://www.lmm.jussieu.fr/~audoly/" target="_blank">Basile Audoly</a> and <a href="http://www.lmm.jussieu.fr/~neukirch/" target="_blank">Sebastien Neukirch </a>won an <a href="https://www.improbable.com/ig/" target="_blank">Ig Nobel Prize</a>, an award given to scientists for real work which is of a less serious nature than the discoveries that win Nobel prizes, for finally determining why this happens. <a href="http://www.lmm.jussieu.fr/spaghetti/audoly_neukirch_fragmentation.pdf" target="_blank">Their paper describing the effect is wonderfully funny to read</a>, as it takes such a banal issue so seriously. </p><p>They demonstrated that when a rod is bent past a certain point, such as when spaghetti is snapped in half by bending it at the ends, a "snapback effect" is created. This causes energy to reverberate from the initial break to other parts of the rod, often leading to a second break elsewhere.</p><p>While this settled the issue of <em>why </em>spaghetti noodles break into three or more pieces, it didn't establish if they always had to break this way. The question of if the snapback could be regulated remained unsettled.</p>
Physicists, being themselves, immediately wanted to try and break pasta into two pieces using this info<p><a href="https://roheiss.wordpress.com/fun/" target="_blank">Ronald Heisser</a> and <a href="https://math.mit.edu/directory/profile.php?pid=1787" target="_blank">Vishal Patil</a>, two graduate students currently at Cornell and MIT respectively, read about Feynman's night of noodle snapping in class and were inspired to try and find what could be done to make sure the pasta always broke in two.</p><p><a href="http://news.mit.edu/2018/mit-mathematicians-solve-age-old-spaghetti-mystery-0813" target="_blank">By placing the noodles in a special machine</a> built for the task and recording the bending with a high-powered camera, the young scientists were able to observe in extreme detail exactly what each change in their snapping method did to the pasta. After breaking more than 500 noodles, they found the solution.</p>
The apparatus the MIT researchers built specifically for the task of snapping hundreds of spaghetti sticks.
(Courtesy of the researchers)
What possible application could this have?<p>The snapback effect is not limited to uncooked pasta noodles and can be applied to rods of all sorts. The discovery of how to cleanly break them in two could be applied to future engineering projects.</p><p>Likewise, knowing how things fragment and fail is always handy to know when you're trying to build things. Carbon Nanotubes, <a href="https://bigthink.com/ideafeed/carbon-nanotube-space-elevator" target="_self">super strong cylinders often hailed as the building material of the future</a>, are also rods which can be better understood thanks to this odd experiment.</p><p>Sometimes big discoveries can be inspired by silly questions. If it hadn't been for Richard Feynman bending noodles seventy years ago, we wouldn't know what we know now about how energy is dispersed through rods and how to control their fracturing. While not all silly questions will lead to such a significant discovery, they can all help us learn.</p>
The multifaceted cerebellum is large — it's just tightly folded.
- A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
- The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
- This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.
Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).
A neural crêpe
A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.
So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.
The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."
Study's cross-sections of a folded cerebellum
Image source: Sereno, et al.
A complicated map
Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."
That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.
It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."
This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."
Bigger and bigger
The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.
"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."
As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."
Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."
What happens if we consider welfare programs as investments?
- A recently published study suggests that some welfare programs more than pay for themselves.
- It is one of the first major reviews of welfare programs to measure so many by a single metric.
- The findings will likely inform future welfare reform and encourage debate on how to grade success.
Welfare as an investment<p>The <a href="https://scholar.harvard.edu/files/hendren/files/welfare_vnber.pdf" target="_blank">study</a>, carried out by Nathaniel Hendren and Ben Sprung-Keyser of Harvard University, reviews 133 welfare programs through a single lens. The authors measured these programs' "Marginal Value of Public Funds" (MVPF), which is defined as the ratio of the recipients' willingness to pay for a program over its cost.</p><p>A program with an MVPF of one provides precisely as much in net benefits as it costs to deliver those benefits. For an illustration, imagine a program that hands someone a dollar. If getting that dollar doesn't alter their behavior, then the MVPF of that program is one. If it discourages them from working, then the program's cost goes up, as the program causes government tax revenues to fall in addition to costing money upfront. The MVPF goes below one in this case. <br> <br> Lastly, it is possible that getting the dollar causes the recipient to further their education and get a job that pays more taxes in the future, lowering the cost of the program in the long run and raising the MVPF. The value ratio can even hit infinity when a program fully "pays for itself."</p><p> While these are only a few examples, many others exist, and they do work to show you that a high MVPF means that a program "pays for itself," a value of one indicates a program "breaks even," and a value below one shows a program costs more money than the direct cost of the benefits would suggest.</p> After determining the programs' costs using existing literature and the willingness to pay through statistical analysis, 133 programs focusing on social insurance, education and job training, tax and cash transfers, and in-kind transfers were analyzed. The results show that some programs turn a "profit" for the government, mainly when they are focused on children:
This figure shows the MVPF for a variety of polices alongside the typical age of the beneficiaries. Clearly, programs targeted at children have a higher payoff.
Nathaniel Hendren and Ben Sprung-Keyser<p>Programs like child health services and K-12 education spending have infinite MVPF values. The authors argue this is because the programs allow children to live healthier, more productive lives and earn more money, which enables them to pay more taxes later. Programs like the preschool initiatives examined don't manage to do this as well and have a lower "profit" rate despite having decent MVPF ratios.</p><p>On the other hand, things like tuition deductions for older adults don't make back the money they cost. This is likely for several reasons, not the least of which is that there is less time for the benefactor to pay the government back in taxes. Disability insurance was likewise "unprofitable," as those collecting it have a reduced need to work and pay less back in taxes. </p>