Why Your Brain Is Slow (And Fast, Too)
Carl Zimmer is a science writer, lecturer, and frequent guest on such radio programs as Fresh Air and This American Life. His books include "Soul Made Flesh," "Evolution: The Triumph of an Idea," and "Parasite Rex." In addition to writing books, Zimmer contributes articles to The New York Times, as well as magazines including National Geographic, Time, Scientific American, Science, and Popular Science. He also writes an award-winning blog, The Loom. From 1994 to 1998 Zimmer was a senior editor at Discover, where he remains a contributing editor and writes a monthly column about the brain.
Zimmer is a lecturer at Yale University, where he teaches writing about science and the environment. He is also the first Visiting Scholar at the Science, Health, and Environment Reporting Program at New York University’s Arthur L. Carter Journalism Institute.
Zimmer is a Big Think Delphi Fellow.
Question: How and why does “the speed of thought” vary across the brain?
Carl Zimmer: We tend to think of our experience as just sort of happening to us instantaneously, so I don’t think when I talk to someone that they are across the room and therefore there is a certain amount of time that it takes for me to hear what they’re saying. We just think that everything happens in real time, but you know the fact is that we perceive the world through this organ the brain and it works a lot… kind of like a telegraph, so if you were to send a message to somebody with a telegraph and you started tapping out your message they’re not going to get the message immediately. It’s going to take time for all those dots and dashes to make their way down the wire and get to the other end. We have wiring in our own brains. We have neurons, which work a lot like telegraph wires in some ways. They actually use kind of a biological set of dots and dashes. They have little spikes of voltage that we use to process information, so you know if I see something it takes awhile for it to get from my eye into my brain and then it takes awhile for it to spread to different parts of the brain and then for that information to get integrated in lots of different ways.
The way that you can think about this really vividly was brought home to me once when I was talking to a neuroscientist named Michael de Zuniga, and he just basically, all he did was, he took his finger and he stuck it on his nose and he said, “You know it’s interesting is that you feel your finger touching your nose and you feel your nose touching your finger at the same time, but the fact is that the signal from your fingertip had a lot longer to go than the signal from your nose and yet they got to your brain and it felt like it was happening at the same time.” So your thoughts have this speed and your brain has to… your brain had to deal with that speed, had to deal with that delay. Now you might think well you know we should just have brains that work as fast as possible, so we should just have you know fast neurons and just to speed everything up you know because time is money, because you know your survival might depend on a fast signal. There is a problem though is that speeding up these signals doesn’t come for free, so one strategy that we have evolved for fast thought as it were is to insulate our neurons and this is actually you know something that is used a lot in engineering. I mean if you don’t want a signal to dissipate out of a wire you want to insulate it. We insulate our neurons with sort of fatty molecules, like myelin. Another thing you can do is you can actually take another trick that telegraph engineers first developed which is to make your neurons thick, so signals will go through a fast wire… I’m sorry. Signals will go through a fat wire quickly faster than a thinner wire. Now the problem is that insulating your neurons and making them fat is a big cost. It takes a lot of energy to do that, energy you could be using for other things and not only that, but you know your brain is a pretty tightly packed place. If you were to you know double or triple the width of your neurons your head might not be able to fit through a doorway. So evolution has come up with these wonderful optimizing tradeoffs. Our signals work quickly in some neurons and slower in others. We have sort of found this nice balance to speed it up as fast as possible without making the cost too high and the fact is that you know when I put my nose… touch my finger to my nose I actually don’t want the signal from my nose to go too fast. I actually want the timing to make everything seem to be happening at once, so actually sometimes you need to slow thought down a little bit in order for the world to make any sense.
Recorded on January 6, 2010
Interviewed by Austin Allen
Your finger is farther from your nose than your brain. So when your finger touches your nose, why do both organs feel the sensation at the same time?
Once a week.
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The distances between the stars are so vast that they can make your brain melt. Take for example the Voyager 1 probe, which has been traveling at 35,000 miles per hour for more than 40 years and was the first human object to cross into interstellar space. That sounds wonderful except, at its current speed, it will still take another 40,000 years to cross the typical distance between stars.
Worse still, if you are thinking about interstellar travel, nature provides a hard limit on acceleration and speed. As Einstein showed, it's impossible to accelerate any massive object beyond the speed of light. Since the galaxy is more than 100,000 light-years across, if you are traveling at less than light speed, then most interstellar distances would take more than a human lifetime to cross. If the known laws of physics hold, then it seems a galaxy-spanning human civilization is impossible.
Unless of course you can build a warp drive.
Ah, the warp drive, that darling of science fiction plot devices. So, what about a warp drive? Is that even a really a thing?
Let's start with the "warping" part of a warp drive. Without doubt, Albert Einstein's theory of general relativity ("GR") represents space and time as a 4-dimensional "fabric" that can be stretched and bent and folded. Gravity waves, representing ripples in the fabric of spacetime, have now been directly observed. So, yes spacetime can be warped. The warping part of a warp drive usually means distorting the shape of spacetime so that two distant locations can be brought close together — and you somehow "jump" between them.
This was a basic idea in science fiction long before Star Trek popularized the name "warp drive." But until 1994, it had remained science fiction, meaning there was no science behind it. That year, Miguel Alcubierre wrote down a solution to the basic equations of GR that represented a region that compressed spacetime ahead of it and expanded spacetime behind to create a kind of traveling warp bubble. This was really good news for warp drive fans.
The problems with a warp drive
There were some problems though. Most important was that this "Alcubierre drive" required lots of "exotic matter" or "negative energy" to work. Unfortunately, there's no such thing. These are things theorists dreamed up to stick into the GR equations in order to do cool things like make stable open wormholes or functioning warp drives.
It's also noteworthy that researchers have raised other concerns about an Alcubierre drive — like how it would violate quantum mechanics or how when you arrived at your destination it would destroy everything in front of the ship in an apocalyptic flash of radiation.
Warp drives: A new hope
Credit: Primada / 420366373 via Adobe Stock
Recently, however, there seemed to be good news on the warp drive front with the publication this April of a new paper by Alexey Bobrick and Gianni Martre entitled "Introducing Physical Warp Drives." The good thing about the Bobrick and Martre paper was it was extremely clear about the meaning of a warp drive.
Understanding the equations of GR means understanding what's on either side of the equals sign. On one side, there is the shape of spacetime, and on the other, there is the configuration of matter-energy. The traditional route with these equations is to start with a configuration of matter-energy and see what shape of spacetime it produces. But you can also go the other way around and assume the shape of spacetime you want (like a warp bubble) and determine what kind of configuration of matter-energy you will need (even if that matter-energy is the dream stuff of negative energy).
Warp drives are simpler and much less mysterious objects than the broader literature has suggested.
What Bobrick and Martre did was step back and look at the problem more generally. They showed how all warp drives were composed of three regions: an interior spacetime called the passenger space; a shell of material, with either positive or negative energy, called the warping region; and an outside that, far enough away, looks like normal unwarped spacetime. In this way they could see exactly what was and was not possible for any kind of warp drive. (Watch this lovely explainer by Sabine Hossenfelder for more details). They even showed that you could use good old normal matter to create a warp drive that, while it moved slower than light speed, produced a passenger area where time flowed at a different rate than in the outside spacetime. So even though it was a sub-light speed device, it was still an actual warp drive that could use normal matter.
That was the good news.
The bad news was this clear vision also showed them a real problem with the "drive" part of the Alcubierre drive. First of all, it still needed negative energy to work, so that bummer remains. But worse, Bobrick and Martre reaffirmed a basic understanding of relativity and saw that there was no way to accelerate an Alcubierre drive past light speed. Sure, you could just assume that you started with something moving faster than light, and the Alcubierre drive with its negative energy shell would make sense. But crossing the speed of light barrier was still prohibited.
So, in the end, the Star Trek version of the warp drive is still not a thing. I know this may bum you out if you were hoping to build that version of the Enterprise sometime soon (as I was). But don't be too despondent. The Bobrick and Martre paper really did make headway. As the authors put it in the end:
"One of the main conclusions of our study is that warp drives are simpler and much less mysterious objects than the broader literature has suggested"
That really is progress.
The Black Death wasn't the only plague in the 1300s.
- In a unique study, researchers have determined how many people in medieval England had bunions
- A fashion trend towards pointed toe shoes made the affliction common.
- Even monks got in on the trend, much to their discomfort later in life.
Late Medieval England had its share of problems. The Wars of Roses raged, the Black Death killed off large parts of the population, and passing ruffians could say "Ni" at will to old ladies.
To make matters worse, a first of its kind study published in the International Journal of Paleopathology has demonstrated that much of the population suffered from another plague — a plague of bunions likely caused by a ridiculous medieval fashion trend.
If the shoe fits, it won't cause bunions
The outlines of a leather shoe from the King's Ditch, Cambridge. It is easy to see how these shoes might be constricting. Copyright Cambridge Archaeological Unit.
The bunion, known to medicine as "hallux valgus," is a deformity of the joint connecting the big toe to the rest of the foot. It is painful and can cause other issues including poor balance. The condition is associated with having worn constrictive shoes for a long period of time as well as genetic factors. Today, it is often caused by wearing high heeled shoes.
The medieval English didn't care for high heeled shoes as much as modern fashionistas, but there was a major fashion trend toward shoes with long, pointed toes called "poulaines" or "crakows" for their supposed place of origin, Krakow, Poland.
This trend, already silly-looking to a modern observer, got out of hand in a hurry. According to some records, the points on nobleman's shoes could be so long as to require tying them to the leg with string so the wearer could walk. At one point, King Edward IV had to ban commoners from wearing points longer than two inches. A couple years later, he saw fit to ban the shoes altogether.
But, just knowing that people back in the day made poor fashion choices doesn't prove they suffered for it. That is where digging up old skeletons to look at their feet comes in.
Beauty is pain: the price of high medieval fashion
To learn how bad the bunion epidemic was, the researchers looked to four burial sites in and around Cambridge. One was a rural cemetery where poor peasants were buried. Another was the All Saints by the Castle parish, which had a mixed collection of people that tended toward poverty. The Hospital of St. John's burial ground contained both the poor charges of a charity hospital and wealthy benefactors. Lastly, they considered the cemetery of a local Augustinian friary, home to monks and well-to-do philanthropists.
The team considered 177 adult skeletons that were at least a quarter complete and still had enough of their feet to make studying them possible. The remains were classified by age and sex by observation and DNA testing. Each was examined for evidence of bunions and signs of complications from the condition, such as falling.
Those buried in the monastery's graveyard were the most affected. Nearly half, 43 percent, of the remains found there had bunions. This includes five of the eleven members of the clergy they found. Twenty-three percent of those laid to rest at the Hospital of St. John had bunions, though only 10 percent of those at the All Saints by the Castle parish graveyard did.
The rural cemetery had a much lower rate of instances, only three percent, suggesting that these peasants were able to avoid at least one plague.
Overall, eighteen percent of the individuals examined had bunions, with men more likely to have them than women. Those at cemeteries known for exclusivity were more likely to have them as well, though it is clear that the condition also affected members of other classes. This makes sense, as it is known that these shoes had mass appeal.
The authors note that the rural cemetery having fewer cases is partly because that cemetery "went out of use prior to the wide adoption of pointed shoes, and it is likely that those residing in the parish predominately wore soft leather shoes, or possibly went barefoot."
Those skeletons with evidence of bunions were more likely to have fractures indicative of a fall. This was more common on those estimated or recorded as having lived past age 45.
In our much more enlightened times, 23 percent of the population currently endures having bunions, most of them women, and one of the leading culprits behind this is the high heeled shoe.
Some things never change.
So much for rest in peace.
- Australian scientists found that bodies kept moving for 17 months after being pronounced dead.
- Researchers used photography capture technology in 30-minute intervals every day to capture the movement.
- This study could help better identify time of death.
We're learning more new things about death everyday. Much has been said and theorized about the great divide between life and the Great Beyond. While everyone and every culture has their own philosophies and unique ideas on the subject, we're beginning to learn a lot of new scientific facts about the deceased corporeal form.
An Australian scientist has found that human bodies move for more than a year after being pronounced dead. These findings could have implications for fields as diverse as pathology to criminology.
Dead bodies keep moving
Researcher Alyson Wilson studied and photographed the movements of corpses over a 17 month timeframe. She recently told Agence France Presse about the shocking details of her discovery.
Reportedly, she and her team focused a camera for 17 months at the Australian Facility for Taphonomic Experimental Research (AFTER), taking images of a corpse every 30 minutes during the day. For the entire 17 month duration, the corpse continually moved.
"What we found was that the arms were significantly moving, so that arms that started off down beside the body ended up out to the side of the body," Wilson said.
The researchers mostly expected some kind of movement during the very early stages of decomposition, but Wilson further explained that their continual movement completely surprised the team:
"We think the movements relate to the process of decomposition, as the body mummifies and the ligaments dry out."
During one of the studies, arms that had been next to the body eventually ended up akimbo on their side.
The team's subject was one of the bodies stored at the "body farm," which sits on the outskirts of Sydney. (Wilson took a flight every month to check in on the cadaver.)Her findings were recently published in the journal, Forensic Science International: Synergy.
Implications of the study
The researchers believe that understanding these after death movements and decomposition rate could help better estimate the time of death. Police for example could benefit from this as they'd be able to give a timeframe to missing persons and link that up with an unidentified corpse. According to the team:
"Understanding decomposition rates for a human donor in the Australian environment is important for police, forensic anthropologists, and pathologists for the estimation of PMI to assist with the identification of unknown victims, as well as the investigation of criminal activity."
While scientists haven't found any evidence of necromancy. . . the discovery remains a curious new understanding about what happens with the body after we die.
Being mortal makes life so much sweeter.
- Since the beginning of time, humans have fantasized over and quested for "eternal life."
- Lobsters and a kind of jellyfish offer us clues about what immortality might look like in the natural world.
- Evolution does not lend itself easily to longevity, and philosophy might suggest that life is more precious without immortality.
One of the oldest pieces of epic literature we have is known as the Epic of Gilgamesh. It's easy to get lost in all the ancient mythology — talking animals and heroic battles — but at its heart lies one of the most fundamental and universal quests of all time: the search for immortality. It's all about Gilgamesh wanting to live forever.
From Mesopotamian poetry to Indiana Jones and the Last Crusade, from golden apples to the philosopher's stone, humans, everywhere, have wanted and sought after eternal life.
And yet, perhaps the secret to immortality is not as elusive as we might think. Rather than holy objects or science fiction, we need only look to the animal world to see how nature, that most magical of places, might be able to answer one of the oldest questions there is.
If you ever find yourself at Red Lobster or about to munch into a lobster roll, take a moment to consider that you might just be eating a clue to perpetual youth. To see why, we have to know a tiny bit about aging.
As you get older, it's impossible not to notice how everything creaks a little more, how easy jobs now require great effort, and how hangovers are no longer a laughing matter. Our bodies are designed to degrade and wear away. This deterioration, known as "senescence" in biology, occurs at the cellular level. It's when the cells in our body stop dividing, yet remain in our body, active and alive. We need our cells to divide so that we can grow and repair. For instance, when we cut ourselves or lift weights in the gym, it is cell division that replaces and rebuilds the damage done. But, over time, our cells just stop dividing. They stay around to do the best they can, but like the macroscopic humans they make up, cells get slower and more error-prone — and so, we age.
But not lobsters. In normal cases of cell division, the shields at the end of our chromosomes — called telomeres — are remade a bit smaller, and so a bit less effective after each subsequent cell division at protecting our DNA. When this reaches a certain point, the cell enters senescence and will stop dividing. It won't self-destruct but will just carry on and wallow as it is. Lobsters, though, have a special enzyme (unsurprisingly, called telomerase) which makes sure that their cells' telomeres remain as long and brilliant as they've always been. Their cells will never enter senescence, and so a lobster just won't age.
However, what evolution giveth with one hand, it taketh with another. As crustaceans, their skeleton is on the outside, and having a constantly growing body means they are always outgrowing their exoskeletal homes. They need to abandon their old shells and regrow a new one all the time. This, of course, requires huge reserves of energy, and as the lobster reaches a certain size, it simply cannot consume enough calories to build the shell equivalent of a mansion. Lobsters do not die from old age but exhaustion (as well as disease and New England fisherman).
The jellyfish that reverses its life cycle
Although lobsters might not have perfected immortality, perhaps there's something to learn.
But there's another animal that does even better than the lobster, and it's the only creature recognized to be properly immortal. That's the jellyfish known as Turritopsis dohrnii. These jellyfish are tiny — about the size of a fly at their biggest — but they've mastered one ridiculous trick: they can reverse their life cycle.
An embryonic jellyfish starts as a fertilized egg before hooking onto some kind of surface to then grow up. In this stage, they will stretch out to look like any other jellyfish. Eventually, they will break away from this surface to become a mature, fully developed jellyfish, which is in turn ready to reproduce. So far, so normal.
Yet Turritopsis dohrnii does something remarkable. When things get tough — like the environment becomes hostile or there's a conspicuous absence of food — they can change back to one of the earlier stages in their lifecycle. It's like a frog becoming a tadpole or a fly becoming a maggot. It's the human equivalent of a mature adult saying, "Right, I've had enough of this job, that mortgage, this stress, and that anxiety, so I'm going to turn back into a toddler.". Or, it's like an old man deciding to become a fetus again, for one more round.
Obviously, a fingernail sized jellyfish is not immortal as we'd probably want the word to mean. They're as squishable and digestible as any animal. But, their ability to change back to earlier forms of life, ones which are better adapted to certain environments or where there are fewer food sources, means that they could, in theory, go on forever.
Why do we want to live forever?
Although the quest for immortality is as old as humanity itself, it's surprisingly hard to find across the diverse natural world. Truth be told, evolution doesn't care about how long we live, so long as we live long enough to pass on our genes and to make sure our children are vaguely looked after. Anything more than that is redundant, and evolution doesn't have much time for needless longevity.
The more philosophical question, though, is why do we want to live forever? We're all prone to existential anguish, and we all, at least some of the time, fear death. We don't want to leave our loved ones behind, we want to finish our projects, and we much prefer the known life to an unknown afterlife. Yet, death serves a purpose. As the German philosopher Martin Heidegger argued, death is what gives meaning to life.
Having the end makes the journey worthwhile. It's fair to say that playing a game is only fun because it doesn't go on forever, a play will always need its curtain call, and a word only makes sense at its last letter. As philosophy and religion has repeated throughout the ages: memento mori, or "remember you'll die."
Being mortal in this world makes life so much sweeter, which is surely why lobsters and tiny jellyfish have such ennui.Jonny Thomson teaches philosophy in Oxford. He runs a popular Instagram account called Mini Philosophy (@philosophyminis). His first book is Mini Philosophy: A Small Book of Big Ideas