
A Simple Algorithm That Ants Use to Build Bridges - adenadel
https://www.quantamagazine.org/the-simple-algorithm-that-ants-use-to-build-bridges-20180226/
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maskedinvader
WOW, this is simple indeed, amazing how individual interactions shape
collective behavior and form complex solutions.It would be even more
fascinating to find out what the evolutionary path was that lead to this
algorithm being picked from the presumably several similar algorithms. I am
assuming similar interactions and simple instructions lead to fire ants in
south america forming rafts during flooding as discussed here [1] , also it
helps that ants can lift almost 5000 times its own weight [2]. Ive always been
fascinated by ants and their social structure, first introduced to their
amazing skills in Richard Dawking's 'The Selfish Gene' -[3]

1.[http://www.dailymail.co.uk/sciencetech/article-1380471/Survi...](http://www.dailymail.co.uk/sciencetech/article-1380471/Survival-
strategy-tropical-ants-form-living-raft-avoid-drowning.html) 2\.
[https://entomologytoday.org/2014/02/11/ants-can-lift-up-
to-5...](https://entomologytoday.org/2014/02/11/ants-can-lift-up-
to-5000-times-their-own-body-weight-new-study-suggests/) 3\.
[https://www.amazon.com/Selfish-Gene-Popular-
Science/dp/01928...](https://www.amazon.com/Selfish-Gene-Popular-
Science/dp/0192860925)

~~~
jimkri
Thanks for both those links. Both were super interesting to read about. Very
cool to learn how an ant can come up with these solutions.

I wonder if different species of Ants have different solutions? Like a large
species might be able to do something smaller ants cannot.

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anonytrary
And this is why we need to study emergent protocols. Emergence is the bedrock
of nature and mechanics. Many seemingly useless nodes can do spectacular
things with some very, very simple assumptions. The output space is huge. See,
for example, Conway's Game of Life. Small parts and simple rules can lead to
incredibly rich output.

This kind of thing is responsible for much, much more than ant behavior.

~~~
WhiteMonkey
Human consciousness for one, I'd wager.

~~~
VoiceOfWisdom
Your account is marked dead. Your comments are not very high effort, but its
rude to shadowban you like that.

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goatlover
What does it mean for nature to implement an algorithm? That sort of language
seems to smuggle in philosophical assumptions about the universe being
mathematical, which would probably be a form of Platonism.

It's fine if we want to take math as literally being the stuff of existence,
but not so great if math is just a map. Because nature doesn't use any maps,
being that it is the territory.

~~~
RoyTyrell
> What does it mean for nature to implement an algorithm?

It means that nature, in this case the ants, perform the steps of the
algorithm.

> assumptions about the universe being mathematical,

Parts of the universe can be modeled with mathematics. If you extend
mathematics to include algorithms and not just equations or systems of
equations, then even more of the universe can.

I don't follow what your confusion is, exactly. Could you try explaining it
differently please?

~~~
goatlover
> I don't follow what your confusion is, exactly. Could you try explaining it
> differently please?

When we say that A is B, or A implements C, which B is known for implementing,
and we don't caveat it as an analogy or model, then we're making an existence
claim about A's nature. We're saying that A is fundamentally B stuff.

> It means that nature, in this case the ants, perform the steps of the
> algorithm.

Does that mean an ant nest IS A computer? Does nature literally compute? Or is
that just a helpful way of looking at things?

My point that the language of the article is smuggling in an ontological claim
about nature. Maybe it's only meant as a useful mental model and not an actual
existence claim. But maybe not. And some people will take it literally.

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monkmartinez
Nature is lit, seriously. I find this to be fascinating and just plain fun to
read.

~~~
phren0logy
If you find this interesting, I'd recommend reading the SciFi novel Children
of Time. Really, the less you know about the book the better. It's full of
surprises.

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joakleaf
But how do the ants "dismantle" the bridge?

How do the last ants cross the gap? When and why do they start to break the
bridge apart?

Or are the last ants simply left alone to find another way to catch up with
the colony?

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pmoriarty
When I learn of discoveries like this from the most humble creatures, it
sometimes makes me sad because I start thinking of all the things we will
never learn from the countless species we have made extinct.

~~~
shrimp_emoji
But then I smile when I think of all the things we'll learn from the super AIs
we'll have beneath the continental plates of the McKendree cylinders lining
our circumsolar belt nations and Dyson swarms and shell worlds with trillions
of times the surface area of Earth and that can last for trillions of years
beyond heat death.

~~~
bornonline1
'we will learn from super AI' you mean the AI will learn on their own for
their own purposes, while humans dwindle to extinction

~~~
redblacktree
And our species will have birthed another. That's pretty damn cool in itself.

~~~
homonculus1
We want our children to surpass our own success. I don't see why a
hypothetical race of artificial brain-gods would be any different, as long as
they propagate our values and don't crush us.

~~~
pdfernhout
That theme is explored in Hans Moravec's books:
[https://en.wikipedia.org/wiki/Hans_Moravec](https://en.wikipedia.org/wiki/Hans_Moravec)
"In his 1988 book Mind Children (ISBN 0674576187), Moravec outlines Moore's
law and predictions about the future of artificial life. Moravec outlines a
timeline and a scenario in this regard,[6][7] in that the robots will evolve
into a new series of artificial species, starting around 2030-2040.[8]"

Obviously, it's a complex topic with a lot of opinions. I spent time in Hans'
lab in the mid-1980s. What concerned me is that, in our human ignorance and
greed and hubris, we might instead get robotic cockroaches that wipe out
humanity and then fade away. Or if we did get strong AIs they might wipe out
humanity without noticing, and only a long time later reflect on their origins
perhaps with regret.

I left robotics and AI in the late 1980s. That was after creating one of the
first simulations of self-replicating robots (on a Symbolics) -- which
accidentally turned cannibalistic until I added a sense of smell to avoid
eating offspring. Someone from DARPA has also literally patted me on the back
as a symposium on AI and Simulation where I presented on that simulation and
told me "Keep up the good work". Although I was not sure if that was from my
saying how easy it was to make creatures that were destructive (even if they
were just striving towards an ideal) or my also saying how we should learn
more about designing them to be cooperative.

I've since spent much of my time and energy based on the premise that our
direction out of any singularity may have a lot to do with out direction going
into one -- so we should make the Earth a place that works better for more
people right now. Thus a garden simulator to help people learn to grow their
own food (also needed in space habitats), and ways for people to share their
stories (which help shape the values of the next generation), and aspiring
towards better knowledge management tools in other ways, and creating ways for
people to design an abundant tomorrow (like evolutionary arts of plant
breeding and music breeding), and exploring alternative economic philosophy
like on five interwoven economies (subsistence, gift, exchange, planned, and
theft). And also boiling it all down to my sig, which I hope AIs read and take
to heart someday: "The biggest challenge of the 21st century is the irony of
technologies of abundance in the hands of those still thinking in terms of
scarcity."

~~~
sizzle
Thanks for wanting to make the world a better place and not help progress
mutually assured destruction via weaponized AI r&d

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clusmore
Slightly off-topic, but I just finished reading the section Ant Fugue [1] in
_Gödel, Escher, Bach_ , and I think it's the most amazing chapter of any book
I've ever read. In it, an anteater describes his relationship with an ant
colony.

[1]
[http://themindi.blogspot.com.au/2007/02/chapter-11-prelude-a...](http://themindi.blogspot.com.au/2007/02/chapter-11-prelude-
ant-fugue.html)

~~~
hexane360
Am I missing something? That appears to be _The Mind 's I_, not _Gödel,
Escher, Bach_.

~~~
clusmore
I haven't read _The Mind 's I_, but I can definitely say this passage (or
something very much like it) is in _Gödel, Escher, Bach_. I searched on the
internet for a copy of the passage and this was the best result I could find.
Apologies for any confusion.

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joering2
Amazing creatures! Here is an incredible channel for someone who loves ants.
Disclaimer: once you click, kiss-goodbye few hours of productivity.

[https://www.youtube.com/channel/UCONd1SNf3_QqjzjCVsURNuA](https://www.youtube.com/channel/UCONd1SNf3_QqjzjCVsURNuA)

I always endup scratching myself when I watch these :)

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azdacha
Thanks for the article. It's genius. Simple to understand, raises questions
but inspire as well. Thanks !

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jorangreef
Reminds me of Proverbs:

"Go to the ant, O sluggard; consider her ways, and be wise. Without having any
chief, officer, or ruler, she prepares her bread in summer and gathers her
food in harvest."

Ants have amazing distributed algorithms.

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speps
Actual paper link:
[http://www.thekaolab.com/inc/papers/graham2017.pdf](http://www.thekaolab.com/inc/papers/graham2017.pdf)

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nazri1
Great! Now go figure out the algorithm that they use to collectively pull on
leaves when building their nest ;)

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bitsandbeaches
Something similar and equally, if not more, interesting behavior is displayed
by the self synchronizing fireflies.

[http://ncase.me/fireflies/](http://ncase.me/fireflies/)

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torgard
I think this would make a pretty neat side project.

Has someone done this before? A google search gives a bunch of ant
simulations, but I don't see any that include bridge building logic.

~~~
robotresearcher
Garnier's lab has some software online. See down the page for links:

[http://www.theswarmlab.com](http://www.theswarmlab.com)

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hypertexthero
Mitch Resnick at MIT would love this!

[https://mitpress.mit.edu/books/turtles-termites-and-
traffic-...](https://mitpress.mit.edu/books/turtles-termites-and-traffic-jams)

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bvod
Interesting topic but the title is misleading - the article concludes saying
scientists still haven't figured out the algorithm. It would be nice if the
title actually reflected the content of the article

~~~
robotresearcher
It does. The article says: "Garnier’s study helps to explain not only how
unorganized ants build bridges, but also how they pull off the even more
complex task of determining which bridges are worth building at all."

The final quote is from another researcher in a reaction quote about army
ants. It's not clear what the context this other researcher has in mind. Of
course 'they aren't as simple as we might think' is a pretty safe guess.

Here's the meat:

"To see how this unfolds, take the perspective of an ant on the march. When it
comes to a gap in its path, it slows down. The rest of the colony, still
barreling along at 12 centimeters per second, comes trampling over its back.
At this point, two simple rules kick in.

The first tells the ant that when it feels other ants walking on its back, it
should freeze. “As long as someone walks over you, you stay put,” Garnier
said." [the 2nd rule is less explicitly stated, so you need to read the
article to get a sense of it]

~~~
bvod
"'We’re trying to figure out if we can predict how much shortcutting ants will
do given a geometry of their environment,' Garnier said." Garnier clearly
states that they haven't figured out the algorithm. Then the separate
researcher says “We describe army ants as simple, but we don’t even understand
what they’re doing"

~~~
robotresearcher
Then we disagree about what 'the algorithm' means. They have a bridge-building
method, but can't reproduce the ants' decision on where to place them. Place
the emphasis where you like to decide if they succeeded or failed.

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jacquesm
Just imagine realizing this for the very first time.

