Introduction to Natural Computation Lecture 3
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Introduction to Natural Computation
Lecture 3
Firefly Co-ordination1
Leandro Minku
1
Notes adapted from Intro to NC Year 2010.
1 / 29
Announcements
Maths centre drop-in sessions:
https://intranet.birmingham.ac.uk/as/libraryservices/asc/
mathematicalsupport.aspx
Intro to NC programming and maths tutorials (MSc and ICY).
Lectures on Thursdays moved to 9-10am, LT3 Sports and Exercise Science.
2 / 29
Overview of the Lecture
What are fireflies and what is firefly synchronisation?
Why do fireflies synchronise?
How do fireflies synchronise?
How can we use this in Computer Science?
3 / 29Fireflies
Actually beetles, also called lightning bugs.
Use of bioluminescence to attract mates.
Mainly found in Thailand, but elsewhere
also.
Enormous congregations of fireflies
blinking on and off in unison, in displays
stretching for miles along the riverbanks.
Different species have different
frequencies. Females use this to identify
mates.
Mysterious mass synchrony.
[ videos ]
4 / 29Why do fireflies synchronise?
Or is it an optical Illusion?
In 1917 Philip Laurent wrote up an explanation in Science:
The apparent phenomenon was caused by the twisting or sudden lowering
and raising of my eyelids; the insects had nothing to do with it.
5 / 29Why do fireflies synchronise?
Or is it an optical Illusion?
In 1917 Philip Laurent wrote up an explanation in Science:
The apparent phenomenon was caused by the twisting or sudden lowering
and raising of my eyelids; the insects had nothing to do with it.
Photographic analysis quickly discounted this!
6 / 29Why do fireflies synchronise?
Or is it an optical Illusion?
In 1917 Philip Laurent wrote up an explanation in Science:
The apparent phenomenon was caused by the twisting or sudden lowering
and raising of my eyelids; the insects had nothing to do with it.
Photographic analysis quickly discounted this!
Why might this behaviour be advantageous?
Possibly:
Since females select mates based on frequency, chaotic flashing may make this
difficult.
Females emit a lower intensity response flash. This would be difficult to detect
without a period of darkness.
Signal enhancement may be more likely to attract more females.
Just an “evolutionary accident”?
7 / 29A little experiment...
8 / 29How do fireflies synchronise?
What is the underlying principle of firefly synchronisation?
9 / 29How do fireflies synchronise?
What is the underlying principle of firefly synchronisation?
Sense of rhythm? “On the same wavelength”?
E.g. anticipation like humans.
Environmental triggers?
E.g. puffs of wind.
Following a leader?
Something else?
10 / 29Experiments with individual fireflies
Studies of the central nervous system of fireflies:
Suggest that the rhythmic flashing of male fireflies is controlled by a timing
mechanism in the brain that oscillates at a constant frequency.
Found that each flash is triggered by nerve impulses in the brain that reach the
lanternal nerves through the ventral nerve cord.
How does the oscillatory mechanism work?
11 / 29Experiments with individual fireflies
Studies of the central nervous system of fireflies:
Suggest that the rhythmic flashing of male fireflies is controlled by a timing
mechanism in the brain that oscillates at a constant frequency.
Found that each flash is triggered by nerve impulses in the brain that reach the
lanternal nerves through the ventral nerve cord.
How does the oscillatory mechanism work?
Individual fireflies were isolated in a dark room and observed.
Experiment 1
Fireflies were deprived of any light (including their own).
Each firefly spontaneously flashed regularly, every 965ms ± 90ms.
That’s approximately one flash per second.
12 / 29Experiments with individual fireflies
Experiment 2
The fireflies were given 40ms signal flashes, at random intervals.
When the signal occurred at the same time as the firefly’s spontaneous flash, it
appeared to have no effect on the normal rhythm.
When the signal occurred between 100ms and 800ms after the flash, the next
flash was delayed, such that it occurred approximately 1 second after the signal.
When the signal occurred after 800ms after a flash, but before the next flash, the
flash was not delayed - but the subsequent flash arrived up to 200ms early!
In all cases, following the signal’s effects, the flashes were again about 1 second apart.
Source: J. Buck and E. Buck. Synchronous fireflies. Scientific American, 234:74–85, 1976.
13 / 29Experiments with individual fireflies
Experiment 2
The fireflies were given 40ms signal flashes, at random intervals.
When the signal occurred at the same time as the firefly’s spontaneous flash, it
appeared to have no effect on the normal rhythm.
When the signal occurred between 100ms and 800ms after the flash, the next
flash was delayed, such that it occurred approximately 1 second after the signal.
When the signal occurred after 800ms after a flash, but before the next flash, the
flash was not delayed - but the subsequent flash arrived up to 200ms early!
In all cases, following the signal’s effects, the flashes were again about 1 second apart.
Source: J. Buck and E. Buck. Synchronous fireflies. Scientific American, 234:74–85, 1976.
14 / 29Experiments with individual fireflies
Experiment 2
The fireflies were given 40ms signal flashes, at random intervals.
When the signal occurred at the same time as the firefly’s spontaneous flash, it
appeared to have no effect on the normal rhythm.
When the signal occurred between 100ms and 800ms after the flash, the next
flash was delayed, such that it occurred approximately 1 second after the signal.
When the signal occurred after 800ms after a flash, but before the next flash, the
flash was not delayed - but the subsequent flash arrived up to 200ms early!
In all cases, following the signal’s effects, the flashes were again about 1 second apart.
Source: J. Buck and E. Buck. Synchronous fireflies. Scientific American, 234:74–85, 1976.
15 / 29Experiments with individual fireflies
Experiment 2
16 / 29A model of a firefly brain
Source: J. Buck and E. Buck. Synchronous fireflies. Scientific American, 234:74–85, 1976.
17 / 29But what about interactions?
So far we’ve just considered how one firefly behaves.
It’s understandably quite simplistic.
What about when thousands of fireflies interact?
18 / 29But what about interactions?
So far we’ve just considered how one firefly behaves.
It’s understandably quite simplistic.
What about when thousands of fireflies interact?
Well we already know that the repeated interaction of simple rules can lead to
complex global behaviours.
Just look at cellular automata!
19 / 29But what about interactions?
So far we’ve just considered how one firefly behaves.
It’s understandably quite simplistic.
What about when thousands of fireflies interact?
Well we already know that the repeated interaction of simple rules can lead to
complex global behaviours.
Just look at cellular automata!
Synchronisation
Initially we would expect independently arriving fireflies to be flashing at the same
frequency, but randomly out of phase.
But quickly a small region (i.e. just a few fireflies) will synchronise.
This region then stands out against the other flashes, and it “captures” other
neighbouring fireflies.
This eventually grows to include all the fireflies.
20 / 29But what about interactions?
So far we’ve just considered how one firefly behaves.
It’s understandably quite simplistic.
What about when thousands of fireflies interact?
Well we already know that the repeated interaction of simple rules can lead to
complex global behaviours.
Just look at cellular automata!
Synchronisation
Initially we would expect independently arriving fireflies to be flashing at the same
frequency, but randomly out of phase.
But quickly a small region (i.e. just a few fireflies) will synchronise.
This region then stands out against the other flashes, and it “captures” other
neighbouring fireflies.
This eventually grows to include all the fireflies.
[ simulation ]
21 / 29So why is this interesting for Computer Scientists?
22 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
23 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
Synchronisation of fireflies (components) emerges, without any cleverness or
conscious effort on the part of the fireflies (components).
24 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
Synchronisation of fireflies (components) emerges, without any cleverness or
conscious effort on the part of the fireflies (components).
Excellent, because software / hardware components aren’t usually very clever or
conscious!
25 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
Synchronisation of fireflies (components) emerges, without any cleverness or
conscious effort on the part of the fireflies (components).
Excellent, because software / hardware components aren’t usually very clever or
conscious!
But they are good at following simple rules!
26 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
Synchronisation of fireflies (components) emerges, without any cleverness or
conscious effort on the part of the fireflies (components).
Excellent, because software / hardware components aren’t usually very clever or
conscious!
But they are good at following simple rules!
The synchronisation occurs through the repeated interaction of simple rules.
27 / 29So why is this interesting for Computer Scientists?
Self-organisation!
Self-organisation is the process where a structure or pattern emerges in a system with
no central authority or external element imposing it through planning. This globally
coherent pattern emerges from the local interaction of the elements that make up the
system.
Synchronisation of fireflies (components) emerges, without any cleverness or
conscious effort on the part of the fireflies (components).
Excellent, because software / hardware components aren’t usually very clever or
conscious!
But they are good at following simple rules!
The synchronisation occurs through the repeated interaction of simple rules.
Examples of applications: synchronisation of devices such as wireless ad hoc networks;
robot fault detection; etc.
[ robot video ]
28 / 29Further Reading
Camazine S, Deneubourg JL, Franks NR, Sneyd J, Theraulaz G, Bonabeau E.
Chapter 10: Flashing Among Fireflies.
In: Self-Organization in Biological Systems. Princeton University Press; 2001. p.
143–166.
Christensen AL, O’Grady R, Dorigo M.
From Fireflies to Fault-Tolerant Swarms of Robots.
IEEE Transactions on Evolutionary Computation. 2009;13(4):754–766.
Tyrrell A, Auer G, Bettstetter C.
Fireflies as Role Models for Synchronization in Ad Hoc Networks.
In: Bio-Inspired Models of Network, Information and Computing Systems; 2006.
p. 1–7.
Strogatz S. Steven Strogatz on Sync;.
TED Talk.
Available from: http://www.ted.com/talks/steven_strogatz_on_sync.html.
29 / 29You can also read
