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posted by hubie on Monday February 26, @08:27PM   Printer-friendly

https://newatlas.com/science/adhd-evolutionary-benefits-foraging-explore-exploit/

While current diagnostic definitions of attention-deficit hyperactivity disorder (ADHD) are relatively new, the general condition has been identified by clinicians under a variety of names for centuries. Recent genetic studies have revealed the condition to be highly heritable, meaning the majority of those with the condition have genetically inherited it from their parents.

Depending on diagnostic criteria, anywhere from two to 16% of children can be classified as having ADHD. In fact, increasing rates of diagnosis over recent years have led to some clinicians arguing the condition is overdiagnosed.

What is relatively clear, however, is that the behavioural characteristics that underpin ADHD have been genetically present in human populations for potentially quite a long time. And that has led some researchers to wonder what the condition's evolutionary benefits could be.

Imagine you are part of a wandering tribe of early humans. Your group comes across a field full of one kind of fruit and everyone is faced with a big question. Do you settle in the field and exploit the fruit stocks until they are all gone, or do you quickly take what you can and continue to explore for more varied foods?

This exploit or explore trade-off is fundamental to the survival of all animals. At what point is the risk of staying in one place greater than the risk of moving on to find out what is over the next hill?

In the early 2000s a team of scientists set out to study the genetics of a unique tribe of people in Northern Kenya. Known as the Ariaal, this population has traditionally been incredibly nomadic. Some members of the Ariaal settled down in one place over the 20th century and adopted modern methods of agriculture while other tribe members continued to live as nomadic pastoralists.

The scientists compared the genetic and health differences between these two cohorts of Ariaal and discovered something incredibly interesting. Generally, all of the Ariaal people carried a unique genetic mutation, dubbed DRD4/7R. This genetic trait had previously been identified commonly in people with ADHD.

...
"The DRD4/7R allele has been linked to greater food and drug cravings, novelty-seeking, and ADHD symptoms," explained study leader Dan Eisenberg back in 2008. "It is possible that in the nomadic setting, a boy with this allele might be able to more effectively defend livestock against raiders or locate food and water sources, but that the same tendencies might not be as beneficial in settled pursuits such as focusing in school, farming or selling goods."

So a fascinating hypothesis emerged. Could the genetic traits of ADHD be somewhat beneficial to a tribe by pushing some people to be 'explorers'? What manifests in modern times as fidgety restlessness could actually have been useful to tribes foraging the countryside for food.
...
Around 450 people participated in the experiment, and all were simultaneously screened for ADHD symptoms. Unsurprisingly, the researchers found those with higher ADHD scores moved on to new bushes sooner than others but more importantly, those with ADHD also tended to collect higher volumes of berries overall.

Writing in the newly published study, Barack and colleagues noted that participants without ADHD characteristics tended to over-harvest single patches. Looking at what would be an optimal harvest strategy for the game it was discovered that players with high ADHD scores were more successful overall.

"In addition, we discovered that participants that screened positive for ADHD more readily abandoned patches and achieved higher reward rates than did participants who screened negative," the researchers concluded. "Given the over-staying displayed by participants overall, those with elevated ASRS scores made exploratory decisions that were more closely aligned with the predictions of optimal foraging theory, and, in this sense, behaved more optimally."

Journal Reference:
Barack David L., Ludwig Vera U., Parodi Felipe, et al., 2024, Attention deficits linked with proclivity to explore while foraging, Proc. R. Soc. B. 2912022258420222584 http://doi.org/10.1098/rspb.2022.2584


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  • (Score: 5, Insightful) by SomeRandomGeek on Monday February 26, @08:52PM (14 children)

    by SomeRandomGeek (856) on Monday February 26, @08:52PM (#1346378)

    Study designs like this really annoy me:
    1. Author hypothesizes that people with ADHD had an evolutionary advantage millions of years ago.
    2. Author writes a computer game that seems to the author to be analogous to berry picking.
    3. People with ADHD are better at the computer game than people without ADHD.
    4. Therefore, ADHD was an adaptive trait that provided an evolutionary advantage millions of years ago.

    Not covered: We know next to nothing about what survival skills were necessary millions of years ago, since all the evidence we have of that time comes from a few fossilized bones. We have no idea whether being a more productive berry forager mattered even a little. If it did matter, we have no idea whether being good at the computer game correlates in any way with being better at real life berry picking.

    • (Score: 5, Insightful) by JoeMerchant on Monday February 26, @09:01PM (5 children)

      by JoeMerchant (3937) on Monday February 26, @09:01PM (#1346379)

      >We know next to nothing about what survival skills were necessary millions of years ago

      Oh, that's not true. Observation of uncontacted tribes and the like give a pretty good picture to extrapolate from.

      >We have no idea whether being a more productive berry forager mattered even a little.

      Fair point, in some places it would, in other places it wouldn't, in basically any time of your choosing (pre-supposing sufficient berries in that time-place to matter...)

      >we have no idea whether being good at the computer game correlates in any way with being better at real life berry picking.

      It's not about the berry picking skill - it's about the pre-disposition to flit from task to task vs. fitting in with keepy nosey to the grindstone or it gets the strap again societies...

      Do I like their methods, no not much. Would they benefit from a little less divergent thinking and a little more conformance to accepted methods? Probably. Would they have been pre-disposed to research ADHD if they were more traditional conformists?...?...?

      I think the core analysis should transcend ADHD and look at diversity overall, ADHD is just one small component of societal values found in diversity.

      --
      🌻🌻 [google.com]
      • (Score: 4, Insightful) by shrewdsheep on Monday February 26, @09:20PM (4 children)

        by shrewdsheep (5215) on Monday February 26, @09:20PM (#1346388)

        Oh, that's not true. Observation of uncontacted tribes and the like give a pretty good picture to extrapolate from.

        I do object. Any such analogous thinking is speculative. Even the "uncontacted" tribes have evolved. Going back more than a few thousand years in terms of behavior/selective pressures seems difficult to me.

        • (Score: 5, Insightful) by JoeMerchant on Monday February 26, @11:04PM (3 children)

          by JoeMerchant (3937) on Monday February 26, @11:04PM (#1346404)

          I find your objection objectionable...

          Sure, everything evolves, but do you think we can successfully speculate what crocodiles were doing to survive 50,000 years ago?

          The real point in the research is that the "ADHD genes" were conserved in populations over long spans of time, and thus are either exceptionally lucky across many varied populations around the globe, or are being conserved for some practical reason(s). The video game is crap, yes, but it's a crappy tentative link to how those genes differentiate our population today.

          --
          🌻🌻 [google.com]
          • (Score: 5, Insightful) by mhajicek on Tuesday February 27, @01:40AM (2 children)

            by mhajicek (51) on Tuesday February 27, @01:40AM (#1346417)

            As a successful modern machinist, I find that most successful modern machinists that I meet are "on the spectrum". I believe certain categories of work benefit significantly from hyper focus and other spectrum traits, while to other categories of work they are a detriment.

            --
            The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
            • (Score: 5, Interesting) by JoeMerchant on Tuesday February 27, @02:52AM (1 child)

              by JoeMerchant (3937) on Tuesday February 27, @02:52AM (#1346425)

              In my 20s and 30s I was pretty good at sustained attention / hyperfocus. After 20 years of raising children (both at home and at work), I have devolved to a much shorter attention span - it's easier to slip into "management mode" where you tell somebody what they should be doing and let them do it themselves "as a learning experience" rather than doing it yourself in frustration that you can make stuff happen 10x faster by just doing it rather than helping others to understand how it should be done.

              Then there's the sad fact: younger me was quite a bit faster than present me, too.

              --
              🌻🌻 [google.com]
              • (Score: 4, Insightful) by Mykl on Tuesday February 27, @03:28AM

                by Mykl (1112) on Tuesday February 27, @03:28AM (#1346432)

                Needs a "+1 Me too" mod

    • (Score: 4, Insightful) by aafcac on Monday February 26, @09:21PM (5 children)

      by aafcac (17646) on Monday February 26, @09:21PM (#1346389)

      It's not a bad starting point, clearly highly heritable conditions like ADHD and autism serve some benefit to some portion of those with it, or at least don't prevent reproduction, otherwise they'd go extinct, if it's a similar proportion in different societies, it likely does something useful.

      • (Score: 2) by HiThere on Monday February 26, @09:53PM (2 children)

        by HiThere (866) Subscriber Badge on Monday February 26, @09:53PM (#1346395) Journal

        I'd say, on the contrary, that "if it's a similar proportion in different societies, it likely" doesn't do something useful that varies between those societies.

        Thus a sedentary society should be expected to have a DIFFERENT frequency than a nomadic society for something that was valued differently in those two societies.

        --
        Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
        • (Score: 3, Insightful) by aafcac on Tuesday February 27, @01:15AM

          by aafcac (17646) on Tuesday February 27, @01:15AM (#1346414)

          I wouldn't, there's a lot of things that don't vary from society to society. There haven't been any genes that have been identified that make somebody one culture it another. There are genes that are more commonly found in one group or another, but not anything that would be sufficient to make them.

          In this case, ADHD does a lot that would be necessary in any society, the military pretty much runs on folks like that in most countries, same good for the late shift. ADHD doesn't uniquely advantage or disadvantage reproduction in any society.

        • (Score: 0) by Anonymous Coward on Tuesday February 27, @07:49AM

          by Anonymous Coward on Tuesday February 27, @07:49AM (#1346446)

          Thus a sedentary society should be expected to have a DIFFERENT frequency than a nomadic society...

          From TFS:

          Generally, all of the Ariaal people carried a unique genetic mutation, dubbed DRD4/7R. This genetic trait had previously been identified commonly in people with ADHD.

      • (Score: 4, Interesting) by Mykl on Tuesday February 27, @03:36AM (1 child)

        by Mykl (1112) on Tuesday February 27, @03:36AM (#1346433)

        It is also entirely possible that conditions like ADHD and autism naturally happen at a particular rate, but are not advantageous. Where those individuals may have had lower survivability in the past (therefore keeping the rate of those conditions stable across the population), our ability to now manage those conditions and care for those who have them will now result in those conditions being passed on more, and the proportion of the population inheriting them steadily increasing. Interesting how the rates of those two conditions seems to have exploded in the last generation.

        See also: short-sightedness

        Assuming we do manage these conditions and are able to provide a level playing field in society between those who do and don't have the condition, it shouldn't really matter to us if someone has these conditions or not. If they are no longer advantageous or disadvantageous for survival then there is no reason to worry about whether the rate is going up, down or staying the same.

        • (Score: 2) by aafcac on Wednesday February 28, @05:36AM

          by aafcac (17646) on Wednesday February 28, @05:36AM (#1346598)

          That certainly is possible, however, if that were the case, then why would it be seen at roughly the same rate across the world? Genes that don't really do anything useful, doesn't do anything to ensure their continued existence. Genes like that you would expect would vary depending upon the culture as it's unlikely that there wouldn't be another gene that is on the same allele that would improve fertility and reproduction, at least marginally.

    • (Score: 5, Touché) by Thexalon on Monday February 26, @10:23PM (1 child)

      by Thexalon (636) on Monday February 26, @10:23PM (#1346400)

      Not covered: We know next to nothing about what survival skills were necessary millions of years ago

      A reasonable hypothesis, though: Having one person in your group of hominids who notices the orange and black striped fur that everyone else wasn't paying attention to might be useful.

      --
      The only thing that stops a bad guy with a compiler is a good guy with a compiler.
      • (Score: 3, Funny) by Freeman on Tuesday February 27, @02:42PM

        by Freeman (732) on Tuesday February 27, @02:42PM (#1346477) Journal

        Hey look, squirr...err..sabertooth!

        --
        Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
  • (Score: 4, Interesting) by hendrikboom on Monday February 26, @10:30PM (6 children)

    by hendrikboom (1125) Subscriber Badge on Monday February 26, @10:30PM (#1346401) Homepage Journal

    There's ADHD, discussed in the article.
    There's also ADD -- without the hyperactivity.
    They are closely related.
    This discussion deals with the H more than the ADD.
    How would ADD fare at berry-picking? Would it aid survival in a similar manner, or a different one?

    • (Score: 2) by JoeMerchant on Tuesday February 27, @02:56AM (2 children)

      by JoeMerchant (3937) on Tuesday February 27, @02:56AM (#1346426)

      Then there's the old psychological threshold rule of "it's only a D if it negatively impacts your 'normal daily functioning'", whatever the hell that's supposed to mean.

      My wife and younger child are OCd - it's more who they are than a "disorder" per se.

      --
      🌻🌻 [google.com]
      • (Score: 3, Interesting) by hendrikboom on Tuesday February 27, @04:03PM (1 child)

        by hendrikboom (1125) Subscriber Badge on Tuesday February 27, @04:03PM (#1346484) Homepage Journal

        Well, if you are effectively using your ability to hyperfocus to get ahead, it might be an asset instead of a disability.
        But if it interferes with your daily life to the extent that you forget to pay attention to essential daily activities such as going to work or eating or using the toilet or showing up to defend yourself in court, it might not be so great.
        If it's not too severe it can be a tradeoff.
        The attention-deficit stereotype in popular culture is the absent-minded professor.

        • (Score: 3, Insightful) by JoeMerchant on Tuesday February 27, @04:38PM

          by JoeMerchant (3937) on Tuesday February 27, @04:38PM (#1346489)

          >The attention-deficit stereotype in popular culture is the absent-minded professor.

          I have a friend, probably born around 1948, who had a saying about smart people: "really smart, but not so smart they need a keeper." Meaning, beyond a certain level of "smart" in a given topic, typical very smart people start dropping pieces of their life in deference to the thing they're focused on. Exceptions abound, but there is definitely a reason stereotypes exist.

          --
          🌻🌻 [google.com]
    • (Score: 2) by The Vocal Minority on Wednesday February 28, @02:11AM (2 children)

      by The Vocal Minority (2765) on Wednesday February 28, @02:11AM (#1346585) Journal

      From memory ADD is the older name for ADHD and does not exist in more recent versions of the DSM.

      • (Score: 2) by aafcac on Wednesday February 28, @05:39AM (1 child)

        by aafcac (17646) on Wednesday February 28, @05:39AM (#1346599)

        Yes, although it still seems odd to me that they'd add the H rather than just standardizing on ADD. That being said, while not all ADDers are hyperactive physically, we're pretty much all hyperactive mentally.

        And really, the entire name is a misnomer based on bad research from the past. People with ADHD do not have a deficit in focus, we have a deficit in our ability to direct our focus. It can look like we're super distracted, but it's really because our brains are hyper-reacting to various stimuli, rather than lacking in the ability to focus. ADDers are some of the most focused people in the world when we're engaged in the right things. Unfortunately, those "right things" are often not what we're supposed to be doing or the things that would lead to an easier time succeeding in life.

        • (Score: 2) by hendrikboom on Wednesday February 28, @12:13PM

          by hendrikboom (1125) Subscriber Badge on Wednesday February 28, @12:13PM (#1346629) Homepage Journal

          People with ADHD do not have a deficit in focus, we have a deficit in our ability to direct our focus.

          Agree. This is how I've been describing myself for years now.

          It's not an inability to pay attention -- it's an inability to control my attention.

  • (Score: 4, Funny) by krishnoid on Tuesday February 27, @01:42AM

    by krishnoid (1156) on Tuesday February 27, @01:42AM (#1346418)

    It is possible that in the nomadic setting, a boy with this allele might be able to more effectively defend livestock against raiders ...

    "Wolf!"
    "Hey, let's defend the flock against the wolf!"

    ... some time later ...

    "Wolf!"
    "Let's defend the flock against the wolf again, if there really is one."

    ... some time later ...

    "Wolf!"
    <crickets>
    "Wolf- er, *man*! And a [youtu.be] ... uh ... chupacabra! And the Wolf-man is acting as the spotter this time!"
    "Ok, at least this is interesting enough to check out."

  • (Score: 5, Funny) by ElizabethGreene on Tuesday February 27, @03:02AM (2 children)

    by ElizabethGreene (6748) Subscriber Badge on Tuesday February 27, @03:02AM (#1346427) Journal

    My confirmation bias likes this very much

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