Ants and their return paths

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I'm a software engineer and as a side project I'm creating an ant simulator. When I say "ant simulator" I mean just that - I'm not attempting to create an application that uses / benefits from ACOA (Ant Colony Optimization Algorithms), but rather an application that attempts to accurately, as best as I can understand / research provides, model the behavior of ants.

For example, my research shows that foraging ants return to the nest in a more direct path once they find their food instead of following the more random trail back.

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I can easily assume that the ant will always do this and it will yield a 100% shortest route from the ant's current position to the nest, but I don't think ants "behaviorally" are capable of those calculations.

So my question is how do they deterministically normalize their return path? Do they normalize based on any path intersections from their original? If so this would yield the shortest return route based on the original, but it wouldn't necessarily be the shortest route possible... which is more plausible.

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Euhhh..I think bees are also "smart" that way, no ?!

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Bees communicate mostly through a series of dances, but yes they are rather smart as well...

anyone have any insight regarding my question?

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I've long suspected that the trail starts "eroding" based on multiple slight deviations. i.e. if every ant cuts a corner a bit the line gets straighter.

But I was never able to directly observe this because I was always more interested in doing other experiments with their path (like making them reroute it and watching what happened).

I should also note that I have nothing other than curiosity as a credential on this subject.

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Oh, and as to my theory on how it would work. I noticed that ants meander a bit around their path. That is, some of the ants tend to stray from it.

I also noticed they can pick it up even if they are a bit away from the path.

So, on the way there, I suppose they meander in search. On the way back I suppose some ants meander off, can detect a future point on the path and rejoin and by doing so create a shortcut that others may follow and subsequently reinforce. Each one of them seems to be leaving something fairly complex that the rest follow. As a child when I would play with ants sometimes simply scaring the ants at a certain point in the trail led to subsequent ants becoming agitated when they reached the same point.

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Richard Feynman on the process:

Quote:

One question that I wondered about was why the ant trails look so straight and nice. The ants look as if they know what they're doing, as if they have a good sense of geometry. Yet the experiments that I did to try to demonstrate their sense of geometry didn't work. Many years later, when I was at Caltech some ants came out around the bathtub I put some sugar on the other end of the bathtub The moment the ant found the sugar, I picked up a colored pencil and behind where the ant went I drew a line so I could tell where his trail was. The ant wandered a little bit wrong to get back to the hole, so the line was quite wiggly, unlike a typical ant trail.

When the next ant to find the sugar began to go back, I marked his trail with another color he followed the first ant's return trail back, rather than his own incoming trail. (My theory is that when an ant has found some food, he leaves a much stronger trail than when he's just wandering around.) This second ant was in a great hurry and followed, pretty much, the original trail. But because he was going so fast he would go straight out, as if he were coasting, when the trail was wiggly. Often, as the ant was "coasting," he would find the trail again. Already it was apparent that the second ant's return was slightly straighter. With successive ants the same "improvement" of the trail by hurriedly and carelessly "following" it occurred. I followed eight or ten ants with my pencil until their trails became a neat line right along the bathtub.

Much more here:

http://www.mathpages.com/home/kmath320/kmath320.htm

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Well, it's proven that ants do not leave trails all the time, they only deposit pheromone when they're returning, so the second ant following the first ant's return trail vs. its own is normal.

The question is whether the ants collectively and progressively generate a shortest distance route over time or if they have some way to deterministically normalize their path back to the nest on their own.

I'm leaning towards the collectively and progressively bit, as pheromones are detected via scent, so it's possible to obtain a "general" direction bias without actually following the trail which would allow the second ant to "improve" the trail.

If this was the case, I would need to implement a guidance of some sorts so that if the trail deviates from the "general" direction of the nest, the successive ants would plow ahead in a straight line in hopes that it either linked back up to the trail or found the nest.

Anyone have any actual papers on the subject? I did some googling and nothing so far from an actual study with facts and such.

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I haven't read it yet, but this thread sent me looking and I'd found this:

The hidden spiral: systematic search and path integration in desert ants, Cataglyphis fortis

http://www.springerlink.com/content/l21217t6pw686314/

I also read bits and pieces of other papers (that I don't recall) that indicated that ants have directional information provided by celestial cues.

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Ants leave a stronger pheromone trail once they have sampled a food source. The better the food source, the stronger the trail they leave when returning to the nest.

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How serendipitous that this thread is here because I was going to start one and now I don't have to.

The motel owner and I were chatting on his patio this morning and we began to watch these two teeny ants. One was brownish-red, the other black. They were having a tug of war - one would start off and pull the other one along, then the other would do the same thing. At various points, you could see them stop, face each other, with both tugging on whatever it was they were both not going to let go of. This went on for quite some time, then suddenly they were wrestling. This wrestling went on for a while and they travelled all over the place like a little knot. I couldn't see whether they still had hold of whatever it was they were tugging on or if they were even both holding onto something. Too tiny.

Any explanation for their decision to wrestle?

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Maybe one accidentally stuck it's finger in the other one's eye when they were pulling.

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Ants and their return paths

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