B1 Intermediate US 20947 Folder Collection
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Think about all the things that need to happen
for a human settlement to thrive:
obtaining food,
building shelter,
raising children and more.
There needs to be a way to divide resources,
organize major efforts
and distribute labor efficiently.
Now imagine having to do this without any sort of planning
or higher level communication.
Welcome to the ant colony.
Ants have some of the most complex social organization
in the animal kingdom,
living in structured colonies
containing different types of members
who perform specific roles.
But although this may sound similar to some human societies,
this organization doesn't arise from any higher level decisions,
but is part of a biologically programmed cycle.
In many species,
all the winged males and winged virgin queens
from all the nearby colonies in the population
each leave from their different nests
and meet at a central place to mate,
using pheromones to guide each other to a breeding ground.
After mating, the males die off,
while females try to establish a new colony.
The few that are successful settle down in a suitable spot,
lose their wings,
and begin laying eggs,
selectively fertilizing some using stored sperm they've saved up from mating.
Fertilized eggs grow into female workers
who care for the queen and her eggs.
They will then defend the colony
and forage for food,
while unfertilized eggs grow into males
whose only job is to wait until they are ready to leave the nest
and reproduce, beginning the cycle again.
So how do worker ants decide what to do and when?
Well, they don't really.
Although they have no methods of intentional communication,
individual ants do interact with one another
through touch, sound and chemical signals.
These stimuli accomplish many things
from serving as an alarm to other ants if one is killed,
to signaling when a queen is nearing the end of her reproductive life.
But one of the most impressive collective capabilities of an ant colony
is to thoroughly and efficiently explore large areas
without any predetermined plan.
Most species of ants have little or no sense of sight
and can only smell things in their vicinity.
Combined with their lack of high level coordination,
this would seem to make them terrible explorers,
but there is an amazingly simple way
that ants maximize their searching efficiency;
by changing their movement patterns
based on individual interactions.
When two ants meet,
they sense each other by touching antennae.
If there are many ants in a small area this will happen more often
causing them to respond by moving
in more convoluted, random paths in order to search more thoroughly.
But in a larger area, with less ants, where such meetings happen less often,
they can walk in straight lines to cover more ground.
While exploring their environment in this way,
an ant may come across any number of things,
from threats or enemies, to alternate nesting sites.
And some species have another capability known as recruitment.
When one of these ants happens to find food,
it will return with it, marking its path with a chemical scent.
Other ants will then follow this pheromone trail,
renewing it each time they manage to find food and return.
Once the food in that spot is depleted,
the ants stop marking their return.
The scent dissipates and ants are no longer attracted to that path.
These seemingly crude methods of search and retrieval
are, in fact, so useful that they are applied in computer models
to obtain optimal solutions from decentralized elements,
working randomly and exchanging simple information.
This has many theoretical and practical applications,
from solving the famous traveling salesman problem,
to scheduling computing tasks and optimizing Internet searches,
to enabling groups of robots to search a minefield
or a burning building collectively, without any central control.
But you can observe these fascinatingly simple, yet effective, processes directly
through some simple experiments,
by allowing ants to enter empty spaces of various sizes
and paying attention to their behavior.
Ants may not be able to vote, hold meetings or even make any plans,
but we humans may still be able to learn something
from the way that such simple creatures
are able to function so effectively in such complex ways.
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【TED-Ed】Inside the ant colony - Deborah M. Gordon

20947 Folder Collection
Kevin Tan published on October 21, 2014
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