Slashdot Mirror
The Rules of the Swarm
Hugh Pickens writes "Researchers are starting to discover the simple rules that allow swarms of thousands of relatively simple animals to form a collective brain able to make decisions and move like a single organism. To get a sense of swarms, Dr. Iain Couzin, a mathematical biologist at the Collective Animal Behaviour Laboratory at Princeton University, builds computer models of virtual swarms with thousands of individual agents that he can program to follow a few simple rules. Among the findings are that swarm behavior has patterns common to many different species, that just as liquid water can suddenly begin to boil, swarm behavior can also change abruptly in character, and that just a few leaders can guide a swarm effectively by creating a bias in the swarm's movement that steers it in a particular direction. The rules of the swarm may also apply to the cells inside our bodies and researchers are working with cancer biologists to discover the rules by which cancer cells work together to build tumors or migrate through tissues. Even brain cells may follow the same rules for collective behavior seen in locusts or fish. "How does your brain take this information and come to a collective decision about what you're seeing?" Dr. Couzin says. The answer, he suspects, may lie in our inner swarm."
Spawn more overlords.
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
Researchers are starting to discover the simple rules that allow swarms of thousands of relatively simple animals to form a collective brain able to make decisions and move like a single organism.
Strangely enough, it also explains republican voting habits.
The theory of relativity doesn't work right in Arkansas.
We are already "cells" of a thing called "economy", for an alien the earth may just look like a single living being.
1st RULE: You do not talk about THE SWARM. 2nd RULE: You DO NOT talk about THE SWARM.
Great new book on Evolution: The Greatest Show on Earth by Richard Dawkins
Swarm Subtype
A swarm is a collection of Fine, Diminutive, or Tiny creatures that acts as a single creature. A swarm has the characteristics of its type, except as noted here. A swarm has a single pool of Hit Dice and hit points, a single initiative modifier, a single speed, and a single Armor Class. A swarm makes saving throws as a single creature. A single swarm occupies a square (if it is made up of nonflying creatures) or a cube (of flying creatures) 10 feet on a side, but its reach is 0 feet, like its component creatures. In order to attack, it moves into an opponent's space, which provokes an attack of opportunity. It can occupy the same space as a creature of any size, since it crawls all over its prey. A swarm can move through squares occupied by enemies and vice versa without impediment, although the swarm provokes an attack of opportunity if it does so. A swarm can move through cracks or holes large enough for its component creatures.
A swarm of Tiny creatures consists of 300 nonflying creatures or 1,000 flying creatures. A swarm of Diminutive creatures consists of 1,500 nonflying creatures or 5,000 flying creatures. A swarm of Fine creatures consists of 10,000 creatures, whether they are flying or not. Swarms of nonflying creatures include many more creatures than could normally fit in a 10-foot square based on their normal space, because creatures in a swarm are packed tightly together and generally crawl over each other and their prey when moving or attacking. Larger swarms are represented by multiples of single swarms. The area occupied by a large swarm is completely shapeable, though the swarm usually remains in contiguous squares.
Traits
A swarm has no clear front or back and no discernable anatomy, so it is not subject to critical hits or flanking. A swarm made up of Tiny creatures takes half damage from slashing and piercing weapons. A swarm composed of Fine or Diminutive creatures is immune to all weapon damage. Reducing a swarm to 0 hit points or lower causes it to break up, though damage taken until that point does not degrade its ability to attack or resist attack. Swarms are never staggered or reduced to a dying state by damage. Also, they cannot be tripped, grappled, or bull rushed, and they cannot grapple an opponent.
A swarm is immune to any spell or effect that targets a specific number of creatures (including single-target spells such as disintegrate), with the exception of mind-affecting effects (charms, compulsions, phantasms, patterns, and morale effects) if the swarm has an Intelligence score and a hive mind. A swarm takes half again as much damage (+50%) from spells or effects that affect an area, such as splash weapons and many evocation spells.
Swarms made up of Diminutive or Fine creatures are susceptible to high winds such as that created by a gust of wind spell. For purposes of determining the effects of wind on a swarm, treat the swarm as a creature of the same size as its constituent creatures. A swarm rendered unconscious by means of nonlethal damage becomes disorganized and dispersed, and does not reform until its hit points exceed its nonlethal damage.
Swarm HD Swarm
Base Damage
1-5 1d6
6-10 2d6
11-15 3d6
16-20 4d6
21 or more 5d6
Swarm Attack
Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover. A swarm's statistics block has "swarm" in the Attack and Full Attack entries, with no attack bonus given. The amount of damage a swarm deals is based on its Hit Dice, as shown in the table.
A swarm's attacks are nonmagical, unless the swarm's description states otherwise. Damage reduction sufficient to reduce a swarm attack's damage to 0, being incorporeal, and other special abilities usually give a creature immunity (or at least resistance) to damage from a swarm. Some swarms
When I read the summary my immediate response was that this was old news. It has been known for quite a while that cellular automata with simple rules can form universal Turing machines. That means that they can "form a collective brain" and "make decisions and move like a single organism". The interesting question then becomes; What "program" is your machine running, and how do you make it robust so that it works in the real world (with all the noise of nature)?
The article is a popular science article, but addresses this, more interesting, question much more than the summary. They discuss some of the rules involved in specific situations (ants), and even look at "human swarms" (although that bit is a little cheesy). There is no general theory posited about how to make these rule sets though, apart from trial and error (in simulation if you can). They say that the researchers are starting to see patterns, but don't talk about what those patterns are - pity really, as that would have been very interesting.
There are several very interesting optimization algorithms based on swarm behavior, such as particle swarm optimization and ant colony optimization. These methods have a similar ability for non-linear optimization (and pattern recognition) as neural networks.
- Demosthenes
cynicsreport.com
Cool to see Couzin on slashdot... I coincidentally saw a talk of his last week and gave him a brief lab tour. His own research is somewhat outside my area, but one of the most surprising things I recall from his talk is that marching locust swarms are apparently propelled by cannibalistic behavior. If I'm remembering correctly, baby locusts (before they've grown wings) in a region will feed in a pretty disorderly fashion. However, once salt and protein supplies start running low, they get hungry and start trying to eat each other. The researchers realized this when the locusts in their enclosure seemed to be mysteriously disappearing at a steady rate, due to being consumed by their peers. ;)
In any case, once they start eating each other, the locusts start trying to chase the locusts in front of them, while simultaneously avoiding the locusts behind them trying to eat them. The emergent behavior is that the entire swarm moves as a mass until a new area is found where salt and protein supplies are plentiful enough to cause them to switch out of cannibalism-mode. This presumably has a number of ramification on how to control migration of locust swarms, which are an immense destroyer of food resources in the developing world.
and that just a few leaders can guide a swarm effectively by creating a bias in the swarm's movement that steers it in a particular direction.
In human populations, we call those marketers.
There's a distinct phase transition that forms a discontinuity. Here are some Phase diagrams showing how state depends on pressure and temperature. The point is that you don't get a continuous transition between liquid and gas, say, with a half-liquid/half-gas state. Phase diagrams exhibit distinct lines separating quite distinct regions. The idea here is that maybe swarms also have these kinds of discontinuous phase transitions.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.