from the world's big
Thinking about death: High neural activity is linked to shorter lifespans
After a comprehensive study, researchers came to a startling conclusion.
- Researchers have discovered that higher levels of neural activity cause shorter lifespans, with evidence drawn from studies on roundworms, mice, and humans.
- A protein called REST appears to be a key player; REST regulates the expression of several genes, many of which affect neural activity.
- The findings offer new targets for further studies on longevity and may even lead to the development of a longevity drug.
If there's one thing that humans can't stop thinking about, it's death. But new research published in the journal Nature suggests that all that thinking might be the very thing that brings death on.
More precisely, researchers discovered that higher neural activity has a negative effect on longevity. Neural activity refers to the constant flow of electricity and signals throughout the brain, and excessive activity could be expressed in many ways; a sudden change in mood, a facial twitch, and so on.
"An exciting future area of research will be to determine how these findings relate to such higher-order human brain functions," said professor of genetics and study co-author Bruce Yankner. While it's probably not the case that thinking a thought reduces your lifespan in the same way smoking a cigarette does, the study didn't determine whether actual thinking had an impact on lifespan — just neural activity in general.
The role of REST
To say this was an unexpected finding is an understatement. We expect that aging affects the brain, of course, but not that the brain affects aging. These results were so counterintuitive that the study took two additional years before it was published as the researchers gathered more data to convince their reviewers. Yankner was forbearing about the delay. "If you have a cat in your backyard, people believe you," he said. "If you say you have a zebra, they want more evidence."
Yankner and colleagues studied the nervous systems of a range of animals, including humans, mice, and Caenorhabditis elegans, or roundworm. What they found was that a protein called REST was the culprit behind high neural activity and faster aging.
First, they studied brain samples donated from deceased individuals aged between 60 and 100. Those that had lived longer — specifically individuals who were 85 and up — had unique gene expression profile in their brain cells. Genes related to neural excitation appeared to be underexpressed in these individuals. There was also significantly more REST protein in these cells, which made sense: REST's job is to regulate the expression of various genes, and it's also been shown to protect aging brains from diseases like dementia.
But in order to show that this wasn't simply a coincidence, Yankner and colleagues amplified the REST gene in roundworm and mice. With more REST came quieter nervous systems, and with quieter nervous systems came longer lifespans in both animal models.
A path to longevity
Normal mice (top) had much lower levels of neural activity than mice lacking the REST protein (bottom). Neural activity is color coded, with red indicating higher levels.
Higher levels of REST proteins appeared to activate a chain reaction that ultimately led to these increases in longevity. Specifically, REST suppressed the expression of genes that control for a variety of neural features related to excitation, like neurotransmitter receptors and the structure of synapses. The lower levels of activity activated a group of proteins known as forkhead transcription factors, which play a role in regulating the flow of genetic information in our cells. These transcription factors, in turn, affect a "longevity pathway" connected to signaling by the hormones insulin and insulin-like growth factor 1 (IGF1).
This longevity pathway has been identified by researchers before, often in connection with possible benefits to lifespan from fasting. Additionally, the insulin/IGF1 hormones are critical for cell metabolism and growth, features which relate to longevity in obvious ways.
The most exciting aspect of this research is that it offers targets for future research on longevity, possibly even allowing for the development of a longevity drug. For instance, anticonvulsant drugs work by suppressing the excessive neural firing that occurs during seizures, and in studies conducted on roundworms, they've also been shown to increase lifespan. This recent study shows that this connection might not be coincidental. Similarly, antidepressants that block serotonin activity have also been shown to increase lifespan. Dietary restriction has long been implicated in promoting longer lifespans as well. Dietary restriction lowers insulin/IGF1 signaling, which this study showed affects the REST protein and neural activity. More research will be needed to confirm or reject any of these possibilities, but all represent exciting new avenues to explore, possibly resulting in the extension of our lifespans.
- Mini-brains may already be sentient and suffering - Big Think ›
- After death, you're aware that you've died, say scientists - Big Think ›
Ready to see the future? Nanotronics CEO Matthew Putman talks innovation and the solutions that are right under our noses.
Innovation in manufacturing has crawled since the 1950s. That's about to speed up.
Evolution doesn't clean up after itself very well.
- An evolutionary biologist got people swapping ideas about our lingering vestigia.
- Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
- Here are the six traits that inaugurated the fun.
The plica semilunaris<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgwMS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYxMTgyMzg1NX0.ZY8qmhtoZfbRMAqrNnmbgyk7GLabglx_9lBq3PKcy7g/img.png?width=980" id="99882" class="rm-shortcode" data-rm-shortcode-id="68e8758894b0359c6ef61b2c158832b2" data-rm-shortcode-name="rebelmouse-image" />
The human eye in alarming detail. Image source: Henry Gray / Wikimedia commons<p>At the inner corner of our eyes, closest to the nasal ridge, is that little pink thing, which is probably what most of us call it, called the caruncula. Next to it is the plica semilunairs, and it's what's left of a third eyelid that used to — ready for this? — blink horizontally. It's supposed to have offered protection for our eyes, and some birds, reptiles, and fish have such a thing.</p>
Palmaris longus<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgwNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMzQ1NjUwMn0.dVor41tO_NeLkGY9Tx46SwqhSVaA8HZQmQAp532xLxA/img.jpg?width=980" id="879be" class="rm-shortcode" data-rm-shortcode-id="970e9c15f3c3d846dde05e2b2c6ebf12" data-rm-shortcode-name="rebelmouse-image" />
Palmaris longus muscle. Image source: Wikimedia commons<p> We don't have much need these days, at least most of us, to navigate from tree branch to tree branch. Still, about 86 percent of us still have the wrist muscle that used to help us do it. To see if you have it, place the back of you hand on a flat surface and touch your thumb to your pinkie. If you have a muscle that becomes visible in your wrist, that's the palmaris longus. If you don't, consider yourself more evolved (just joking).</p>
Darwin's tubercle<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NjgxMi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0ODUyNjA1MX0.8RuU-OSRf92wQpaPPJtvFreOVvicEwn39_jnbegiUOk/img.jpg?width=980" id="687a0" class="rm-shortcode" data-rm-shortcode-id="b38a957408940673ccc744f0f6828d18" data-rm-shortcode-name="rebelmouse-image" />
Darwin's tubercle. Image source: Wikimedia commons<p> Yes, maybe the shell of you ear does feel like a dried apricot. Maybe not. But there's a ridge in that swirly structure that's a muscle which allowed us, at one point, to move our ears in the direction of interesting sounds. These days, we just turn our heads, but there it is.</p>
Goosebumps<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMxNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNzEyNTc2Nn0.aVMa5fsKgiabW5vkr7BOvm2pmNKbLJF_50bwvd4aRo4/img.jpg?width=980" id="d8420" class="rm-shortcode" data-rm-shortcode-id="f735418322b34382dcd882299c9ccc48" data-rm-shortcode-name="rebelmouse-image" />
Goosebumps. Photo credit: Tyler Olson via Shutterstock<p>It's not entirely clear what purpose made goosebumps worth retaining evolutionarily, but there are two circumstances in which they appear: fear and cold. For fear, they may have been a way of making body hair stand up so we'd appear larger to predators, much the way a cat's tail puffs up — numerous creatures exaggerate their size when threatened. In the cold, they may have trapped additional heat for warmth.</p>
Tailbone<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMxNi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMDMzMDc3N30.p9BEtkf3-PV3EtDSQMUGUeopsimiCHUagx97P4f8IBw/img.jpg?width=980" id="e8ab8" class="rm-shortcode" data-rm-shortcode-id="0063ce99bdd22fbebe1279244b87935c" data-rm-shortcode-name="rebelmouse-image" />
Coccyx. Image source: decade3d-anatomy online via Shutterstock<p>Way back, we had tails that probably helped us balance upright, and was useful moving through trees. We still have the stump of one when we're embryos, from 4–6 weeks, and then the body mostly dissolves it during Weeks 6–8. What's left is the coccyx.</p>
The palmar grasp reflex<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTA5NzMyMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNjY0MDY5NX0.OSwReKLmNZkbAS12-AvRaxgCM7zyukjQUaG4vmhxTtM/img.jpg?width=980" id="8804c" class="rm-shortcode" data-rm-shortcode-id="45469ca5ee5f43433a782f7d4ac0a440" data-rm-shortcode-name="rebelmouse-image" />
Palmar reflex activated! Photo credit: Raul Luna on Flickr<p> You've probably seen how non-human primate babies grab onto their parents' hands to be carried around. We used to do this, too. So still, if you touch your finger to a baby's palm, or if you touch the sole of their foot, the palmar grasp reflex will cause the hand or foot to try and close around your finger.</p>
Other people's suggestions<p>Amir's followers dove right in, offering both cool and questionable additions to her list. </p>
Fangs?<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Lower mouth plate behind your teeth. Some have protruding bone under the skin which is a throw back to large fangs. Almost like an upsidedown Sabre Tooth.</p>— neil crud (@neilcrud66) <a href="https://twitter.com/neilcrud66/status/1085606005000601600?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Hiccups<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Sure: <a href="https://t.co/DjMZB1XidG">https://t.co/DjMZB1XidG</a></p>— Stephen Roughley (@SteBobRoughley) <a href="https://twitter.com/SteBobRoughley/status/1085529239556968448?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Hypnic jerk as you fall asleep<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">What about when you “jump” just as you’re drifting off to sleep, I heard that was a reflex to prevent falling from heights.</p>— Bann face (@thebanns) <a href="https://twitter.com/thebanns/status/1085554171879788545?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script> <p> This thing, often called the "alpha jerk" as you drop into alpha sleep, is properly called the hypnic jerk,. It may actually be a carryover from our arboreal days. The <a href="https://www.livescience.com/39225-why-people-twitch-falling-asleep.html" target="_blank" data-vivaldi-spatnav-clickable="1">hypothesis</a> is that you suddenly jerk awake to avoid falling out of your tree.</p>
Nails screeching on a blackboard response?<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Everyone hate the sound of fingernails on a blackboard. It's _speculated_ that this is a vestigial wiring in our head, because the sound is similar to the shrill warning call of a chimp. <a href="https://t.co/ReyZBy6XNN">https://t.co/ReyZBy6XNN</a></p>— Pet Rock (@eclogiter) <a href="https://twitter.com/eclogiter/status/1085587006258888706?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Ear hair<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Ok what is Hair in the ears for? I think cuz as we get older it filters out the BS.</p>— Sarah21 (@mimix3) <a href="https://twitter.com/mimix3/status/1085684393593561088?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Nervous laughter<blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">You may be onto something. Tooth-bearing with the jaw clenched is generally recognized as a signal of submission or non-threatening in primates. Involuntary smiling or laughing in tense situations might have signaled that you weren’t a threat.</p>— Jager Tusk (@JagerTusk) <a href="https://twitter.com/JagerTusk/status/1085316201104912384?ref_src=twsrc%5Etfw">January 15, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Um, yipes.<blockquote class="twitter-tweet" data-conversation="none" data-lang="en"><p lang="en" dir="ltr">Sometimes it feels like my big toe should be on the side of my foot, was that ever a thing?</p>— B033? K@($ (@whimbrel17) <a href="https://twitter.com/whimbrel17/status/1085559016011563009?ref_src=twsrc%5Etfw">January 16, 2019</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
A clever new study definitively measures how long it takes for quantum particles to pass through a barrier.
- Quantum particles can tunnel through seemingly impassable barriers, popping up on the other side.
- Quantum tunneling is not a new discovery, but there's a lot that's unknown about it.
- By super-cooling rubidium particles, researchers use their spinning as a magnetic timer.
When it comes to weird behavior, there's nothing quite like the quantum world. On top of that world-class head scratcher entanglement, there's also quantum tunneling — the mysterious process in which particles somehow find their way through what should be impenetrable barriers.
Exactly why or even how quantum tunneling happens is unknown: Do particles just pop over to the other side instantaneously in the same way entangled particles interact? Or do they progressively tunnel through? Previous research has been conflicting.
That quantum tunneling occurs has not been a matter of debate since it was discovered in the 1920s. When IBM famously wrote their name on a nickel substrate using 35 xenon atoms, they used a scanning tunneling microscope to see what they were doing. And tunnel diodes are fast-switching semiconductors that derive their negative resistance from quantum tunneling.
Nonetheless, "Quantum tunneling is one of the most puzzling of quantum phenomena," says Aephraim Steinberg of the Quantum Information Science Program at Canadian Institute for Advanced Research in Toronto to Live Science. Speaking with Scientific American he explains, "It's as though the particle dug a tunnel under the hill and appeared on the other."
Steinberg is a co-author of a study just published in the journal Nature that presents a series of clever experiments that allowed researchers to measure the amount of time it takes tunneling particles to find their way through a barrier. "And it is fantastic that we're now able to actually study it in this way."
Frozen rubidium atoms
Image source: Viktoriia Debopre/Shutterstock/Big Think
One of the difficulties in ascertaining the time it takes for tunneling to occur is knowing precisely when it's begun and when it's finished. The authors of the new study solved this by devising a system based on particles' precession.
Subatomic particles all have magnetic qualities, and they spin, or "precess," like a top when they encounter an external magnetic field. With this in mind, the authors of the study decided to construct a barrier with a magnetic field, causing any particles passing through it to precess as they did so. They wouldn't precess before entering the field or after, so by observing and timing the duration of the particles' precession, the researchers could definitively identify the length of time it took them to tunnel through the barrier.
To construct their barrier, the scientists cooled about 8,000 rubidium atoms to a billionth of a degree above absolute zero. In this state, they form a Bose-Einstein condensate, AKA the fifth-known form of matter. When in this state, atoms slow down and can be clumped together rather than flying around independently at high speeds. (We've written before about a Bose-Einstein experiment in space.)
Using a laser, the researchers pusehd about 2,000 rubidium atoms together in a barrier about 1.3 micrometers thick, endowing it with a pseudo-magnetic field. Compared to a single rubidium atom, this is a very thick wall, comparable to a half a mile deep if you yourself were a foot thick.
With the wall prepared, a second laser nudged individual rubidium atoms toward it. Most of the atoms simply bounced off the barrier, but about 3% of them went right through as hoped. Precise measurement of their precession produced the result: It took them 0.61 milliseconds to get through.
Reactions to the study
Scientists not involved in the research find its results compelling.
"This is a beautiful experiment," according to Igor Litvinyuk of Griffith University in Australia. "Just to do it is a heroic effort." Drew Alton of Augustana University, in South Dakota tells Live Science, "The experiment is a breathtaking technical achievement."
What makes the researchers' results so exceptional is their unambiguity. Says Chad Orzel at Union College in New York, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say." He calls the research, "one of the best examples you'll see of a thought experiment made real." Litvinyuk agrees: "I see no holes in this."
As for the researchers themselves, enhancements to their experimental apparatus are underway to help them learn more. "We're working on a new measurement where we make the barrier thicker," Steinberg said. In addition, there's also the interesting question of whether or not that 0.61-millisecond trip occurs at a steady rate: "It will be very interesting to see if the atoms' speed is constant or not."
So far, 30 student teams have entered the Indy Autonomous Challenge, scheduled for October 2021.
- The Indy Autonomous Challenge will task student teams with developing self-driving software for race cars.
- The competition requires cars to complete 20 laps within 25 minutes, meaning cars would need to average about 110 mph.
- The organizers say they hope to advance the field of driverless cars and "inspire the next generation of STEM talent."
Indy Autonomous Challenge<p>Completing the race in 25 minutes means the cars will need to average about 110 miles per hour. So, while the race may end up being a bit slower than a typical Indy 500 competition, in which winners average speeds of over 160 mph, it's still set to be the fastest autonomous race featuring full-size cars.</p><p style="margin-left: 20px;">"There is no human redundancy there," Matt Peak, managing director for Energy Systems Network, a nonprofit that develops technology for the automation and energy sectors, told the <a href="https://www.post-gazette.com/business/tech-news/2020/06/01/Indy-Autonomous-Challenge-Indy-500-Indianapolis-Motor-Speedway-Ansys-Aptiv-self-driving-cars/stories/202005280137" target="_blank">Pittsburgh Post-Gazette</a>. "Either your car makes this happen or smash into the wall you go."</p>
Illustration of the Indy Autonomous Challenge
Indy Autonomous Challenge<p>The Indy Autonomous Challenge <a href="https://www.indyautonomouschallenge.com/rules" target="_blank">describes</a> itself as a "past-the-post" competition, which "refers to a binary, objective, measurable performance rather than a subjective evaluation, judgement, or recognition."</p><p>This competition design was inspired by the 2004 DARPA Grand Challenge, which tasked teams with developing driverless cars and sending them along a 150-mile route in Southern California for a chance to win $1 million. But that prize went unclaimed, because within a few hours after starting, all the vehicles had suffered some kind of critical failure.</p>
Indianapolis Motor Speedway
Indy Autonomous Challenge<p>One factor that could prevent a similar outcome in the upcoming race is the ability to test-run cars on a virtual racetrack. The simulation software company Ansys Inc. has already developed a model of the Indianapolis Motor Speedway on which teams will test their algorithms as part of a series of qualifying rounds.</p><p style="margin-left: 20px;">"We can create, with physics, multiple real-life scenarios that are reflective of the real world," Ansys President Ajei Gopal told <a href="https://www.wsj.com/articles/autonomous-vehicles-to-race-at-indianapolis-motor-speedway-11595237401?mod=e2tw" target="_blank">The Wall Street Journal</a>. "We can use that to train the AI, so it starts to come up to speed."</p><p>Still, the race could reveal that self-driving cars aren't quite ready to race at speeds of over 110 mph. After all, regular self-driving cars already face enough logistical and technical roadblocks, including <a href="https://www.bbc.com/news/technology-53349313#:~:text=Tesla%20will%20be%20able%20to,no%20driver%20input%2C%20he%20said." target="_blank">crumbling infrastructure, communication issues</a> and the <a href="https://bigthink.com/paul-ratner/would-you-ride-in-a-car-thats-programmed-to-kill-you" target="_self">fateful moral decisions driverless cars will have to make in split seconds</a>.</p>But the Indy Autonomous Challenge <a href="https://static1.squarespace.com/static/5da73021d0636f4ec706fa0a/t/5dc0680c41954d4ef41ec2b2/1572890638793/Indy+Autonomous+Challenge+Ruleset+-+v5NOV2019+%282%29.pdf" target="_blank">says</a> its main goal is to advance the industry, by challenging "students around the world to imagine, invent, and prove a new generation of automated vehicle (AV) software and inspire the next generation of STEM talent."