how do ants in ant colony know what’s their role? Are they trained for these roles (soldiers, farmers, etc.)? Are there ants that go through “career changes” and switch roles?
In: Biology
It’s easiest to think about ants as finite state machines (FSM). An FSM is a model that defines a number of stages. An ant FSM for example might define the states:
* Eat
* Forage randomly
* Bring food to the colony
* Attack!
* And so on
* Run away / escape
* Many other states
To determine what an FSM or ant will do at any given time, it’ll constantly evaluate all external stimuli to attach importance to each state before selecting one for its current behaviour.
The amazing thing about eusocial insects like ants is that each of them is like a little robot. They have exactly the same states and responses. But those responses work in such a way that many ants together seemingly cooperate in an intelligent manner, even though they don’t really discuss anything or consciously cooperate.
For example:
* Ant A is randomly foraging for food when it finds a discarded cookie. This triggers a state change from foraging to bringing food from the food source to the colony.
* Ant A takes a crumb, heads back to the colony and lays down a scent trail without thinking about it.
* Ant B is foraging randomly when it finds this scent trail. This triggers a decision moment where it weighs the importance of random foraging against the importance of following the scent trail. It’s a weak scent trail so let’s say it’s a 50/50 decision but Ant B’s state changes to following the trail.
* Ant B finds the food and this triggers a state change to grabbing a crumb, heading home and laying down a scent trail. Exactly the same behaviour as Ant A but without realising it Ant B reinforces the scent trail.
* When Ant C finds the scent trail while foraging randomly, it behaves exactly the same as Ant B. It weighs the importance of foraging randomly against the importance of following the scent trail. But the trail is reinforced by Ant B and Ant C is slightly more likely to follow the trail. It does and Ant C grabs some food, heads home and reinforces the trail.
There is zero discussion between ants and each of these ants behaves exactly the same way, like a little robot. But this way a large food source will attract more and more ants who each reinforce the scent trail attracting even more ants. Until the food is gone. A few ants will still follow the scent trail but find no food and as a result, don’t head home while reinforcing the trail. The trail will quickly dissipate and no more ants will be attracted.
A small food source will attract fewer ants because there are fewer opportunities for reinforcing the scent trail before the food is gone. Logistically speaking, any food source will attract an appropriate number of ants to efficiently transport it. Even though no single ant knows what its job is, has a big picture view of what’s happening or is directly communicating to its fellow ants. They all just behave exactly the same and the end result is seemingly intelligent.
Ants do have roles within their society but these roles are the result of different ants placing different emphasis on their canned responses.
For example, in many colonies, only the oldest ants go outside the colony to forage. After all, these are the ants that are already closest to the end of their lifespan and as a result, the most disposable for risking in the dangerous outside world.
Young and old ants have different jobs. But nobody assigned them these jobs. It’s just that a younger ant is more likely to respond place more importance on jobs (or states if you will) inside the colony like digging tunnels or feeding larvae while old ants are more likely to emphasize jobs outside the colony.
Along the same lines, nobody tells ants to go dig a tunnel or make a room. Environmental factors like population density (based on pheromone density) and air quality will encourage individual ants to go dig.
Some ant species do grow physically divergent colony members. For example ant species that have both workers and soldiers (and sometimes many other classes). Nobody tells a soldier to go fight. Soldiers just place more emphasis on defensive or offensive tasks when weighing their states.
Individual ants don’t really know anything. They don’t reason, they don’t think, they don’t maintain dialogues with other ants. They just evolved behaviour that works on an individual level but also achieves very efficient results when all ants behave the same way.
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