 in a one-inch-wide artificial nest.)
CROWD SOURCING: A colony of the common acorn ant (Temnothorax curvispinosus) in a one-inch-wide artificial nest.
Image: Stephen Pratt
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Humans often make irrational choices when faced with challenging decisions. Ant colonies, however, can make perfectly rational selections when confronted by tough dilemmas. This isn't because lone ants are especially knowledgeable—they're not. Instead, when ants are grouped together, a kind of "wisdom of the crowds" avoids the kind of mistakes that individuals can make, new research shows.
In terms of evolutionary biology, animals strive to maximize their fitness. Still, actions that seem counterproductive and irrational occur not only in human societies, but also all over the animal kingdom. For instance, when honeybees and hummingbirds have two equally tempting choices of nectar, a third alternative inferior to both can sway them to prefer one of the initial two options over the other. The animals apparently compare the inferior choice against the originals and conclude that one of the originals is better, even though nothing about them has changed.
Such irrationality can lead to deep insight, because "finding what makes the system fail can give a clue about how it works," explains Stephen Pratt, a behavioral ecologist at Arizona State University's School of Life Sciences in Tempe. Of special interest to Pratt is how groups of animals such as ant colonies make collective decisions. "We can even think of a colony as an analogue for a nervous system—by understanding how decisions emerge from interactions among ants in a colony, we may learn something about how decisions emerge from the interactions among neurons in a brain," he says.
To see if collectives behave rationally, Pratt and his student Susan Edwards investigated a common acorn ant of eastern North America, Temnothorax curvispinosus, which is tiny—a colony of 50 to 200 such ants can make its home inside a single nutshell. When their nest is damaged beyond repair, the ants choose their new home en masse. Scouts look for potential nests, and if enough of them close in on the same area, they then carry nest mates over.
The researchers made two artificial nests as potential homes. Nest A had a larger, less defensible entrance but a dark interior that suggested strong, thick walls, whereas nest B had a smaller entrance (more defensible) but a bright interior (weaker walls). As expected, when the researchers ran 26 ant colonies past these nests, the insects split roughly equally on the nests.
Then they provided inferior "decoy" nests to spur irrational choices. For instance, if they presented a decoy that was similar to nest B yet had an even brighter interior, the ants might irrationally prefer nest B over nest A, if past results with humans and animals are any guide.
Surprisingly, the decoys had no effect on the colonies—they always made rational decisions.
"All minds, both collective and individual, have limited capacity—they have to use shortcuts and rules of thumb to solve difficult decision problems, and those shortcuts are expected to sometimes cause mistakes," Pratt says. "The ant colonies, however, were unfazed by a challenge that often elicits such mistakes in other animals."
So what makes these colonies so rational? Surprisingly, the very ignorance of the lone ants might be key. Instead of making comparisons between choices that can sway humans toward irrational decisions, individual ants typically know of just one option, which prevents them from making potentially misleading comparisons. Although the researchers expected the ants to behave irrationally, "we accidentally got a different insight about a possible advantage of collective cognition," says Pratt, whose findings appear today online in the Proceedings of the Royal Society B: Biological Sciences.
"We thought our brains and those of most animals could not always decide rationally because it was impossible to do so," notes behavioral ecologist Anna Dornhaus of the University of Arizona in Tucson, who did not participate in this study. "The ants show us that…there is a way to construct a decision-making system" that doesn't make irrational choices. The question then, she observes, is why our brains have evolved to act irrationally on occasion.
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16 Comments
Add CommentGreat article. I'm curious though, how do ants collectively decide? What is the mechanism behind this decision? How do they do it?
Reply | Report Abuse | Link to thisAnts yes, humans no. The human mind is like a raid processor in reverse. Quality in inverse coefficient to quantity.
Reply | Report Abuse | Link to thisI have this fear [probably irrational, but there none the less] that computers one day will get this type of wisdom. We don't understand the ant colonies process, so why would it be far fetched to see it in a computer network?
Reply | Report Abuse | Link to thisThe article is interesting. It makes perfect sense since the ants, for that most living beings apart from Humans have the ego's or the other types of Hippocrates.
Reply | Report Abuse | Link to thisMost of the time when we sit in a group and observe, we always tend to make our point the only the right one. We would not like others making a better decisions or observations and allow others to disagree with our point.
May be the scientists should induce a ego gene into the ants and do the experiment.
2 things.
Reply | Report Abuse | Link to this1- I like when people test my conclusions, and I return the favor. I see that as healthy.
2- stampeding cows run off cliffs as a group.
That doesn't seem a better decision.
Generally, in mass groups, humans seem to get dumber, rioting for football games, etc.
Comparing humans and ants it like comparing apples and humans. ;-)
Interesting article but the research doesn't back the headline at all. Humans have complex interactions between choices and this makes their decision making seem, at times, irrational against the backdrop of an individual objective. Ants are only driven to survive and thats a simple problem to solve. Interestingly, it did take an irrational human to write the headline and to be fair an ant colony never would have, but that is not because they are "better at rational decision making"
Reply | Report Abuse | Link to thisIf mindless collectives are so good at making decisions... then why is government so inept? Surely there's no better example of a mindless collective.
Reply | Report Abuse | Link to thisAmen...
Reply | Report Abuse | Link to thisriddle me this,
If 'Progress' means moving forward, then what does 'Congress ' mean?
Mindless Collectives are always better?
Reply | Report Abuse | Link to thisSamuel Johnson refuted a specious argument against motion by kicking a rock, creating motion and saying: I refute it thus.
I refute it thus: I spray and kill the ants.
The ants are perfect bureaucrats. They can't see me coming with the spray. They can't prevent me from spraying in the future. They cannot retaliate against me. Big brains win and the ants are too stupid to understand this.
Has anybody heard of Hive Intelligence?
Reply | Report Abuse | Link to thisIts been known for a long time.
Termites and a whole heap of insects who live in colonies exhibit hive intelligence.
Take it one step further and we have planetary intelligence.
Maybe this is Gia theory?
Humans evolution has worked at both the individual and group (i.e. family group) levels for maximizing fitness. That is, there is always a tension in humans between what is good for the me (the individual) and what is good for the the group (the collective). That is one reason why human decisions are very often detrimental to the individual (why tip money to that waitress you'll never see again?) but are beneficial to the collective.
Reply | Report Abuse | Link to thisAnts are different. They have evolved such that an ant's individual fitness is of almost no worth, except with regards to how it can benefit the collective. Just like a neuron. Or any cell in a multicellular organism.
Ultimately, cooperation has been a great boon for evolution. That is, for survival of the fittest. That leads on to conclude that is would be so for human society as well, given enough time to evolve to such a level. Indeed, the ratcheting mechanisms for cooperation initially involve trust, which is time consuming to build and easily destroyed. More permanent, more physical ways of ensuring cooperation are needed for things to change. And so we have politics.
The question then becomes, is survival of the fittest the end that we ought to submit to? If collectivism is the ultimate destiny of life on Earth and perhaps the Universe, is it something to strive for or to resist? Or maybe the dichotomy needs no willful action at all?
And then we have philosophy.
Humans evolution has worked at both the individual and group (i.e. family group) levels for maximizing fitness. That is, there is always a tension in humans between what is good for the me (the individual) and what is good for the the group (the collective). That is one reason why human decisions are very often detrimental to the individual (why tip money to that waitress you'll never see again?) but are beneficial to the collective.
Reply | Report Abuse | Link to thisAnts are different. They have evolved such that an ant's individual fitness is of almost no worth, except with regards to how it can benefit the collective. Just like a neuron. Or any cell in a multicellular organism.
Ultimately, cooperation has been a great boon for evolution. That is, for survival of the fittest. That leads on to conclude that is would be so for human society as well, given enough time to evolve to such a level. Indeed, the ratcheting mechanisms for cooperation initially involve trust, which is time consuming to build and easily destroyed. More permanent, more physical ways of ensuring cooperation are needed for things to change. And so we have politics.
The question then becomes, is survival of the fittest the end that we ought to submit to? If collectivism is the ultimate destiny of life on Earth and perhaps the Universe, is it something to strive for or to resist? Or maybe the dichotomy needs no willful action at all?
And then we have philosophy.
I think this is failed logic. We have many more complex decisions to make. Our social structure is more complicated than an ant. We make personal friends, enemies, fall in and out of love, etc. Our emotion and social nature makes our individual decision making needs far more complex and greater than an ant. Therefore, evolution could not go backwards and make us a collective species as what made us evolve with greater individual decision making skills would not provide the same selective advantage in reverse.
Reply | Report Abuse | Link to thisPerhaps we lost the ability to always be rational, but we gained so much more by being able to make more individual decisions that has allowed us to thrive as a species. 6 billion and growing. Ants do well, but our model isn't so bad. If the author would rather be an ant, so be it. However, I'll take my sometimes irrational thinking over the hive mentality if it means that I get to keep my individuality and what makes me human.
How do you figure that governments make bad decisions? They make excellent decisions. For themselves. What we need is a system that makes the best decisions for the people as a whole rather than for the insiders.
Reply | Report Abuse | Link to thisThere is a field of consciousness in nature-we may call it as universal intelligence field. It can induce intelligence in dumb[apparently] things like ants,which collectively are induced to behave consciously under the influence of the above field. This is applicable to humans too,but our learning processes cause a localized self system to form,to differentiate ourselves intelligently from the surroundings and rest of the world or crowd.Hence we cause the universal field of consciousness or natural intelligence to collapse to a more localized intelligence. Some brain or neural circuitry studies reveal that extended self systems are intrinsic to us,though as we learn things by growing up we actually get out of the extended system to a more localized one,which is acting as a virtual system with disparate parts,at different brain locations.Unconscious decision making or thinking can sometimes get us to truths that more elaborate analysis may eventually bring us to cognitively-this gut feeling or intuition based thinking is a remnant of the innate extended consciousness field that is native to us.Ants do not isolate themselves from the nature through any elaborate learning process,so they are collectively guided by natural intelligence ,and induced by the universal consciousness field.In humans too many a times it has been empirically established that we tend to make conscious decisions after these have already been made unconsciously-though meta cognitive functions come to play a role altering the decisions,and sometimes lead to irrational decisions.This is true even for the sciences,since it has been verified and found that there is a lot of meta reason and logic like fashions,emotions and passions or lobbies in science,associated not only with theory making but also measurement and interpretation of observations.
Reply | Report Abuse | Link to thisSURESHKUMAR.S,SCIENTIST AND ADVISER,NIIST,TRIVANDRUM[CSIR],INDIA
It's the alienated individual that promotes irrational decisions in humans. Non-alienated people are much better at decision-making cos they can better relate the problems to their real needs. (For "alienated" you can read "one-dimensional" or a member of a "lonely crowd", for "non-alienated" you can read "integrated", "whole")
Reply | Report Abuse | Link to thisIf a whole society or its representatives (government) are alienated from the real human needs they have, ie ruled by inhuman motives like profit or power over others, they'll make irrational decisions too. Hobbes argued that the state is the individual/group in power with all the means and wealth of society at its disposal.
So it's not a flaw in human beings or humanity, but the pressures of an irrational society on them that make things go wrong. As our present situation amply illustrates.