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Earth United States Science

The Human Brain Evolved When Carbon Dioxide Was Lower 137

Posted by BeauHD from the cognitively-impaired dept.
An anonymous reader quotes a report from The Atlantic: Kris Karnauskas, a professor of ocean sciences at the University of Colorado, has started walking around campus with a pocket-size carbon-dioxide detector. He's not doing it to measure the amount of carbon pollution in the atmosphere. He's interested in the amount of CO2 in each room. The indoor concentration of carbon dioxide concerns him -- and not only for the usual reason. Karnauskas is worried that indoor CO2 levels are getting so high that they are starting to impair human cognition. In other words: Carbon dioxide, the same odorless and invisible gas that causes global warming, may be making us dumber.

He proposed the idea last week at the American Geophysical Union's fall meeting, the largest annual gathering of earth and space scientists in the world. He also previewed it in an online paper written with Shelly Miller, a mechanical-engineering professor at the University of Colorado, and Anna Schapiro, a neuroscience professor at the University of Pennsylvania. The paper, while not yet peer-reviewed, was uploaded to a website where academics can discuss early-stage or provocative research. The science is, at first glance, surprisingly fundamental. Researchers have long believed that carbon dioxide harms the brain at very high concentrations. [...] Two centuries of rampant fossil-fuel use have already spiked the amount of CO2 in the atmosphere from about 280 parts per million before the Industrial Revolution to about 410 parts per million today. For Earth as a whole, that pollution traps heat in the atmosphere and causes climate change. But more locally, it also sets a baseline for indoor levels of carbon dioxide: You cannot ventilate a room's carbon-dioxide levels below the global average. In fact, many rooms have a much higher CO2 level than the atmosphere, since ventilation systems don't work perfectly. On top of that, some rooms -- in places such as offices, hospitals, and schools -- are filled with many breathing people, that is, many people who are themselves exhaling carbon dioxide. "As the amount of atmospheric CO2 keeps rising, indoor CO2 will climb as well," the report adds. "They project that, in a worst-case emissions scenario, it may be impossible to ventilate a crowded room below about 1,300 parts per million. That could induce some real cognitive damage."

The report goes on to cite a 2016 study by researchers at Harvard and Syracuse University, which found that human cognitive function declined by about 15 percent when indoor CO2 reached 945 parts per million, and crashed by 50 percent when indoor CO2 reached 1,400 parts per million.
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The Human Brain Evolved When Carbon Dioxide Was Lower More

The Human Brain Evolved When Carbon Dioxide Was Lower

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  • You know, in a sane world... (Score:5, Informative)

    by BoogieChile ( 517082 ) on Monday December 23, 2019 @10:38PM (#59552602)

    ...the headline would have a direct relationship to the story.

    Just sayin'...

  • Death spiral? (Score:5, Funny)

    by dgatwood ( 11270 ) on Monday December 23, 2019 @10:39PM (#59552606) Homepage Journal

    So global warming and global warming deniers are a feedback loop?

  • Quoting the article:

    " In fact, many rooms have a much higher CO2 level than the atmosphere, since ventilation systems don't work perfectly. On top of that, some rooms -- in places such as offices, hospitals, and schools -- are filled with many breathing people, that is, many people who are themselves exhaling carbon dioxide."

    Since you have experienced elevated CO2, what do you think?

    I pay a lot of attention to my thoughts. I don't detect any difference in the quality of my thinking when the CO2 lev

    • Re: (Score:3)

      by vux984 ( 928602 )

      "I don't detect any difference in the quality of my thinking when the CO2 level is higher."

      On the one hand that's kind of like relying on a drunk brain to make the same quality decisions as the non-drunk one.

      On the other hand, I absolutely find stepping out for 'fresh air' or opening a window after a roomful of people gets stuffy makes a difference to my ability to concentrate and think.

      • Indeed - in fact one of the great dangers of operating in low-oxygen environments (such as at extreme high-altitude) is that you typically don't realize just how incredibly badly impaired you are until reviewing the experience afterward. Intoxicants like alcohol, etc. have lots of mental side effects that give them away - without those it's really hard to detect "silent" impairement.

        Add to that the fact that we have a lifetime of practice ignoring the effects of low-grade CO2 "intoxication" in poorly vent

    • Re: Since you have experienced it, what do you thi (Score:5, Interesting)

      by phantomfive ( 622387 ) on Monday December 23, 2019 @10:50PM (#59552642) Journal
      It can get as high as 6000ppm in a car: https://www.co2meter.com/blogs... [co2meter.com] If you feel cognitive decline from CO2, it's more likely you will experience it as being drowsy.

      • I used to put my air on recirculate when I drove past oil refineries. I reasoned that whatever I was smelling couldn't be good for me. However I would often forget to set it back. I'd get 20 or 30 miles down the road and feel a vague sort of "stuffy" or "it's just wrong" feeling. Then I'd realize it was still recirculating. Now I just smell the oil and don't worry about it. I figure whatever transient effect those fumes has is less dangerous than me getting "drowsy" and causing an accident. This isn'

    • Re: (Score:3)

      by XXongo ( 3986865 )
      I often feel that when I'm in a conference room with a dozen other people I don't think very well, and when I'm alone outdoors my thoughts are clearer.

      That's not a controlled observation, since there may be other factors about being in a conference room with a dozen people that makes one ready to snooze, but yes, in response to your question, my personal observational experience validates the claim.

      • I've been curious what the actual CO2 levels in my home, office, and on the train are, but I don't work somewhere with gas detection equipment on hand anymore. Shame, since the meters are about $100-200 a pop.

    • I pay a lot of attention to my thoughts. I don't detect any difference in the quality of my thinking when the CO2 level is higher.

      Self reported state isn't a reliable guide to *anything* except phenomenology.

      What you *believe* is happening isn't relevant.

    • Re:Since you have experienced it, what do you thin (Score:5, Insightful)

      by sjames ( 1099 ) on Monday December 23, 2019 @11:56PM (#59552776) Homepage Journal

      In alcohol intoxication and in oxygen deprivation, the first faculty to go is judgement about one's state of mind.

      That's why pilots are trained to don O2 masks immediately when there is a cabin pressure issue even if they don't think it's bad enough to warrant that.

      It's also why self-assessment of driving ability at a party is discouraged in favor of a designated driver and/or minimum wait times.

    • Since you have experienced elevated CO2, what do you think? I pay a lot of attention to my thoughts. I don't detect any difference in the quality of my thinking when the CO2 level is higher.

      When I was at university, I'd frequently have the experience in a particular class of being very drowsy -- completely unable to stay awake. After the class I'd go find a bench in the atrium to take a quick power-nap, only to be completely wide awake. Eventually I concluded that it must be the CO2 in the classroom: it

    • "I pay a lot of attention to my thoughts. I don't detect any difference in the quality of my thinking when the CO2 level is higher."

      Thanks for that. I like to start my day with a laugh.

    • Re: (Score:2)

      by cusco ( 717999 )

      Puts me to sleep.

    • I pay a lot of attention to my thoughts. I don't detect any difference in the quality of my thinking when the CO2 level is higher.

      Elevated CO2 levels affect your ability to concentrate. As your ability to think decreases, so does your ability to notice.

  • Isn't CO2 still on the order of 0.05% of atmospheric gases by volume?

    • Re: (Score:3)

      by XXongo ( 3986865 )

      Isn't CO2 still on the order of 0.05% of atmospheric gases by volume?

      I'm not sure what your point is. Hydrogen cyanide is lethal at about 0.01%, so low concentrations can have significant effects.

      • Re: (Score:3, Insightful)

        by FuzzMaster ( 596994 )
        Do you think CO2 is poisonous? Humans exhale CO2 in concentrations around 40,000 ppm.

        • Just about anything is poisonous at high enough levels. And that definitely includes CO2. The question is what levels have what effects? When does it produce measurable effects on your thinking, like slower recall? When do the effects become more severe? And are the effects transient, or does chronic exposure cause permanent damage?

          There's some data on this, but not nearly as much as we'd like given that the whole planet is participating in an unplanned experiment on it. We need to get more data quick

        • Re: (Score:3)

          by ceoyoyo ( 59147 )

          CO2 is definitely poisonous. About twice the concentration in human exhalations will kill you if you breathe it long enough. The concentration in exhalation will definitely degrade your cognitive abilities.

        • Re:0.05% by volume (Score:5, Insightful)

          by quonset ( 4839537 ) on Tuesday December 24, 2019 @06:44AM (#59553258)

          Do you think CO2 is poisonous? Humans exhale CO2 in concentrations around 40,000 ppm

          The key word being exhale. We don't keep the CO2 within ourselves. Our body is expelling the poison.

  • Well, obviously there is a critical level. If there's no CO2 in the air, then people will die because they forget to breathe. And in the other direction, WWII submarines found strongly degraded performance when they had high levels of CO2. But what's the optimal range, and how flat is the peak?

    This guy seems to be thinking that the peak isn't very flat, and that ordinary room air is so high it's shoving people off the peak. He may well be right, but that's not the way to prove it.

    That said, he's collect

    • Re: (Score:2)

      by rossdee ( 243626 )

      I think the important point as far as the brain is concerned is not the level of CO2, but the level of oxygen.

        • Re: (Score:2)

          by ceoyoyo ( 59147 )

          Yes, but the breathing stimulus is controlled by *blood* CO2 level. You can breathe zero CO2 air quite happily, although it is possible to forget to breathe enough if you're doing vigorous exercise in it.

      • The level of oxygen is very rarely a problem unless you're being actively suffocated by drowning (in liquid or an inert gas that displaces O2,) or mechanical asphyxiation.

        If you lock a person in a hermetically-sealed room, they'll have problems (including death) with CO2 toxicity well before O2 deprivation becomes a real factor.

    • Well, obviously there is a critical level. If there's no CO2 in the air, then people will die because they forget to breathe

      Err, no. Autonomic breathing isn't a function of CO2 levels in the air; it's a function of CO2 levels in the blood, which, without breathing, will automatically increase with time as your cells respire. This is why you don't hear about people dying from forgetting to breathe when they're on pure oxygen or breathing nitrogen-oxygen atmospheres (which do not incorporate added CO2).

      • Re: (Score:2)

        by HiThere ( 15173 )

        Given: https://www.sciencefocus.com/t... [sciencefocus.com]
        I doubt that you can show that it doesn't cause people to die, though that's talking about lung damage. There is hyperbaric oxygen, but that's handed as a special medical treatment, so again I can't say that you'd be allowed to forget to breathe.

        So perhaps I'm wrong, but not in a way that's useful to the argument. What I found seems to just say "it will kill you unless medically supervised".

        I suppose I could be nitpicky and say "Well, if you're breathing in an enclo

        • Prolonged exposure to pure O2 can indeed cause lung damage. I'm not arguing that.

          However, you're still incorrect; no one's going to suffocate in pure O2. In a pure O2 atmosphere, someone will take a breath ... and eventually, CO2 levels will build up in their blood to the point where they have the desire to exhale. While they may indeed breathe at a lower rate in a pure-O2 atmosphere, it's like running a car on high octane fuel -- you get more miles per fill-up.

          The amount of actual oxygen used up in each

  • Its still very much monkey see monkey do...

  • I heard that using dark mode reduces the amount of CO2 as well.

  • Just as Kevin Costner grew gills in Waterworld to adapt, I'm turning into a plant. My wife always called me a vegetable anyhow.

  • I don't believe the human brain actually evolved at all.
  • CO2 levels have oscillated from 100ppm - 300ppm over the past 800,000 years. https://www.climate.gov/news-f... [climate.gov]
    Since the industrial revolution they've increased to the current over 410ppm. https://www.co2.earth/ [www.co2.earth]
    I would bet should levels exceed 1000ppm humans will not be the only species in trouble.

  • Everything makes you dumb (Score:4, Interesting)

    by wakeboarder ( 2695839 ) on Tuesday December 24, 2019 @12:30AM (#59552818)

    Smartphones make you dumb, the internet makes you dumb, TV makes you dumb, and now.... air makes you dumb. If we're so dumb then why are we inventing reusable rockets, colliding new particles and building fusion reactors?

    • Re:Everything makes you dumb (Score:4, Interesting)

      by bluegutang ( 2814641 ) on Tuesday December 24, 2019 @05:24AM (#59553158)

      Well, the Flynn effect has ended [wikipedia.org] in wealthy countries, and mean intelligence has stopped rising and possible started to decrease...

    • If we're so dumb then why are we inventing reusable rockets, colliding new particles and building fusion reactors?

      Because the inventors come from an elite cast whose people make sure to prevent early exposure of children to smartphones and probably lives in less polluted area than most of us. They are the real humans, we are just their beasts of budren.

    • Re: (Score:3)

      by jiriw ( 444695 )

      Apparently some people don't know the concept of moderation. None of those things make you 'dumb'. They may have a negative effect on you when you use them excessively. And about those brilliant researchers creating those wonderful inventions. I guess they have a nice garden or forest behind their offices to catch some inspiration when they feel slow, take regular breaks and know the importance of a good night's rest (of which everyone should need at least 8 hours a day of) in a well ventilated room.

    • Luckily with modern technology 98.9% of the population can be dumb, and the remainder are able to pick up our slack and do the cool things that we tweet about with #ilovescience.

    • This comment just made me dumb.

  • Everyone has a carbon monoxide detector already, but did you know that you can buy carbon dioxide detectors for home use as well? There are some units on Amazon for $120 or so. And they're about the size of a CO detector, so you can bring them to your office, too.

    The other thing I've been Googling is "how effective are houseplants as CO2 scrubbers". Some interesting studies have been done on that (including some by NASA). My sloppy back-of-the envelope calculations tell me, though, that I would need som

    • My sloppy back-of-the envelope calculations tell me, though, that I would need something like 40 houseplants.

      An algal reactor's much more space efficient.

    • Re: (Score:2)

      by Falos ( 2905315 )

      Subject comes up now and then, and yes, I've heard you need an assload of plants to have significant effect. Some people mentioned mechanical air scrubbers, I guess with filters that are occasionally changed.

      I don't typically need to be at peak cognitive strength at home, but it wouldn't hurt. It might help improve sleep, for instance. More chronic exposure to slightly-elevated-CO2 (ie work at home, shut-in, etc) is of unknown effect. Well, It's probably not significant, too subtle to be overly concerned wi

  • ... that is responsible for the spreading epidemic of the stupid disease.

  • Dartmouth College CO2 measurements (Score:5, Informative)

    by rapjr ( 732628 ) on Tuesday December 24, 2019 @03:08AM (#59553014)
    We measured CO2 levels around a small New England town using a CO2 meter on a bike in our 2007 SenSys paper: http://sensorlab.cs.dartmouth.... [dartmouth.edu] We found that car traffic caused CO2 levels to rise as much as 80 ppm in the center of town when traffic density was higher during rush hour. There are buildings right next to that location where people live and work. I imagine that downtowns in big cities have much higher spikes in CO2 due to vehicle traffic, especially on still days.

    I also brought the CO2 meter to several large lectures at Dartmouth and found CO2 readings of 2000 to 2500 ppm towards the ends of the lectures. People in the room were getting obviously sleepy at that time. I found the same thing happening in a smaller, though longer (3 hour) meeting in our lab with about 7 people attending. Everyone was getting sleepy. So during one meeting I opened a window and everyone woke up and became clearer. We left a window slightly open from then on in the lab. The schools policy however was that no windows could be left open because it raised heating and cooling costs. HVAC people are well aware of this tradeoff between heating/air conditioning costs and room air quality and are supposed to keep rooms properly ventilated. However they can't account for times when lots of people are in the rooms (they have no CO2 sensors in the rooms), so they adjust for an average or set the air exchange rate when no one is in the rooms. Management weighs on the side of lower costs, so people suffer the consequences. It's possible this is lowering the quality of research and education in the US and in other places in the world.

    We also tried measuring carbon monoxide using BikeNet but found almost no measurable amounts around town. CO2 is heavier than air while carbon monoxide is lighter than air and drifts up and away.

  • I'm no expert on human physiology, but I was under the impression that our bodies actively regulate CO2.

    • Re: (Score:2)

      by jtgd ( 807477 )
      "Regulate" as in expel as fast as possible, yeah. But your lungs can't reduce the CO2 to a concentration lower than the ambient air.

  • What are the oldest indoor places of mass assembly in the world? Consider that parliaments and other legislative chambers like were designed long before modern HVAC systems existed.

    • Re: (Score:2)

      by jtgd ( 807477 )
      ...and modern methods of sealing up a building. I expect they were pretty leaky.

  • This fits perfectly with some observations. For example, the con artist has lived most of his life in New York City breathing in air polluted by vehicles and people. As a result, he believes the noise from windmills cause cancer [thehill.com]. He knows this, because he's studied them more than anyone [businessinsider.com].

  • Classrooms are places where you pack a lot of people and expect them to be as smart as they can.
    If the findings are true, we should see a correlation between grades and CO2 concentrations in classrooms, and maybe a cheap way of making people smarter (just check classroom ventilation systems).

  • Oh, really? (Score:2, Insightful)

    by CrimsonAvenger ( 580665 )

    Does this explain why average SAT scores have been going up for the last 50 years, as CO2 levels have risen?

    Humans evolved in an Ice Age (which we're still in - an Interglacial, but still the same old Ice Age that's been going on for 10+ megayears), so we definitely evolved at a time of lower (than world historical average, which is rather higher than now) CO2), but I don't see an issue - CO2 levels have been fluctuating since life first appeared here.

    • Re:Oh, really? (Score:4)

      by twocows ( 1216842 ) on Tuesday December 24, 2019 @01:48PM (#59554260)
      It provides evidence that, isolated from other factors, there's reason to suspect that CO2 levels might have a detrimental effect on human cognition. As far as experimental results go, that's about as much as you could hope to establish with any experiment.

      As for why human cognition may be increasing despite the increase in CO2 levels, I can think of several reasons. First, the educational system has generally been getting better where the SAT is used. Second, CO2 levels haven't really increased all that much at ground level -- most of the increases are in the upper atmosphere.

  • Is this really the next level in strident climate change claims.

    Here's some food for thought: scare people too much and you might see all kinds of crazy solutions suddenly seem sane and get adopted by anxious politicians. "Adopt better recycling practices": yay! "Let's dump millions of tons of iron filings in the ocean to better absorb CO2": uh ... what?

  • Karnauskas is worried that indoor CO2 levels are getting so high that they are starting to impair human cognition. In other words: Carbon dioxide, the same odorless and invisible gas that causes global warming, may be making us dumber.

    Stop worrying, it obviously works.

    On a more serious note: hospitals for a number of years have had a non-invasive, fairly simple and probably inexpensive method of determining the oxygen concentration in a person's blood in real time: shining an appropriate light through such person's finger onto a sensor. It seems that the body is fairly capable of keeping oxygen at a good level by raising things like pulse rate and respiration rate. That's why people in general can acclimatize to environments from sea l

  • Perhaps we should look at all this technology they're developing to remove CO2 from the atmosphere to combat global warming and scale it down for use in classrooms, offices and homes. It ultimately benefits the planet, but benefits us first. Sadly it won't benefit indoor plants, but will probably lower it more than the plants would.

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