Bugs Build Intricate Structures Without Thinking Big

Termites are tiny insects, but they are capable of
moving tons of soil to build giant nests. Now
scientists are discovering simple rules these
insect architects might follow that could help
explain how they build complex homes without a
master plan.
Such research could lead to robot swarms that
can organize to assemble intricate structures.
These findings could also help decipher the rules
governing complex systems ranging from blood
vessels to neural networks.

  Termites are eusocial insects that are classified at the taxonomic rank ofinfraorder Isoptera, or as epifamilyTermitoidae within the cockroach orderBlattodea. Termites were once classified in a separate order from cockroaches, but recent phylogeneticstudies indicate that they evolved from close ancestors of cockroaches during the Jurassic or Triassic. It is possible, however, that the first termites emerged during the Permian or even theCarboniferous. Approximately 3,106 species are currently described, with a few hundred more left to be described. Although these insects are often called white ants, they are not ants. Click to continue reading about termites..... 

Termites can build mounds more than 10 meters
high and 15 meters across, home to city-like
networks of chambers and tunnels. Previous
research suggested these networks possessed a
number of features that could not have simply
emerged by chance, such as tree-like structures
that can help soldier termites easily isolate parts
of the nest to defend them better. However, it
was uncertain how these insects could build
such orderly networks without a blueprint or
central supervision.
To learn more about how termites behave,
scientists used X-rays to scan and map
networks of chambers and tunnels in 12 mounds
from three different genuses of African termites
— Cubitermes, Thoracotermes and Procubitermes.
These mounds varied in shape depending on the
termite genus — mushroom shapes for
Cubitermes, straight pillars for Thoracotermes ,
and cones for Procubitermes.
The scientists developed a new model to explain
the nature of these networks. In the model,
termites are each only aware of their immediate
vicinity. A nest starts growing from a single
tunnel that ends in a chamber. The rest of the
nest then develops from a series of simple rules.
The model suggests that new tunnels can branch
out from any chamber, but they are most likely
to emerge from the most recently built
chambers. Termites mark construction materials
with chemicals that dissipate over time, so they
can tell if chambers were built recently.
The model also proposes that the direction and
length of each new tunnel are random, although
termites do not extend tunnels over empty
space. Each tunnel ends in a new chamber from
which more tunnels can branch. Adjacent
chambers are merged together, and tunnels that
are used less often are randomly pruned off by
sealing them shut.
The scientists compared real termite nests with
500 simulated nests created using their model
and simulated nests created using two other
models — one involving random pruning of
tunnels instead of pruning of less-frequented
tunnels, and one involving randomly generated
networks of chambers and tunnels. They found
their model usually generated better matches for
real nests than ones created using the other
models when it came to structural qualities such
as the shortest paths linking chambers. The
scientists detailed their findings Dec. 9 in the
journal Physical Review E.
"The new work shows that a rather simple
behavioral algorithm where termites only need
access to locally available information can lead
to this kind of architecture — no need for a
central coordinator or an explicit blueprint in the
individual," said study co-author Christian Jost , a
biological modeler at the University of Toulouse
in France.
The researchers identified three qualities of
termite nest tunnel networks that could help
pinpoint their main functions. Low average
distances between any two points inside nests
are key for tunnel networks that enable fast,
efficient transportation of cargo such as food.
Reducing the number of redundant tunnels can
help in nest defense, since blocking a tunnel
would force invaders to take long detours, and
as previously mentioned, tree-like structures for
tunnel networks can also help in nest defense.
The scientists found that termite nests prioritized
low average distances between areas inside
them, suggesting they are optimized for
transport instead of defense strategies.
"The benefit of these networks is that it helps
them move nutrients and wastes through their
colony most efficiently," said physiological
ecologist Scott Turner at the SUNY College of
Environmental Science & Forestry in Syracuse,
New York, who did not take part in this research.
One potential application for this research could
be simple rules for swarms of robots to follow in
order to build complex architectures.
"Such an algorithm may indeed be inspiring for
an engineer who wants to coordinate the action
of autonomous robots without central
coordination," Jost said.
Complex biological networks often display
similar structures. Jost noted that research on
termites, where it is easy to observe both
individuals and the whole colony, might help
shed light on other biological systems.
"The same kind of dynamics, where tunnels give
rise to branches that give rise to more branches,
help lay out networks of blood vessels and the
inside surfaces of our lungs," Turner said.
Other critical matters for termite research to
focus on include how the structures the insects
build depend on their environments and on
interactions between termites, Turner said.
"There's just an awful lot we still need to learn
about these things," he said.