Dec 12, 2018 07:25 PM
https://aeon.co/ideas/an-ant-colony-has-...-dont-have
EXCERPT: Like a brain, an ant colony operates without central control. Each is a set of interacting individuals, either neurons or ants, using simple chemical interactions that in the aggregate generate their behaviour. [...] Any living being can exhibit the simplest form of memory, a change due to past events. Look at a tree that has lost a branch. It remembers by how it grows around the wound, leaving traces in the pattern of the bark and the shape of the tree. [...]
Past events can alter the behaviour of both individual ants and ant colonies. [...] The Finnish myrmecologist Rainer Rosengren showed that when the ants emerge in the spring, an older ant goes out with a young one along the older ant’s habitual trail. The older ant dies and the younger ant adopts that trail as its own, thus leading the colony to remember, or reproduce, the previous year’s trails.
Foraging in a harvester ant colony requires some individual ant memory. The ants search for scattered seeds and do not use pheromone signals; if an ant finds a seed, there is no point recruiting others because there are not likely to be other seeds nearby. [...] Once back at the nest, a forager drops off its seed, and is stimulated to leave the nest by the rate at which it meets other foragers returning with food. On its next trip, it leaves the trail at about the same place to search again.
Every morning, the shape of the colony’s foraging area changes, like an amoeba that expands and contracts. No individual ant remembers the colony’s current place in this pattern. On each forager’s first trip, it tends to go out beyond the rest of the other ants travelling in the same direction. The result is in effect a wave that reaches further as the day progresses. Gradually the wave recedes, as the ants making short trips to sites near the nest seem to be the last to give up.
From day to day, the colony’s behaviour changes, and what happens on one day affects the next. [...] Ants use the rate at which they meet and smell other ants, or the chemicals deposited by other ants, to decide what to do next. A neuron uses the rate at which it is stimulated by other neurons to decide whether to fire. In both cases, memory arises from changes in how ants or neurons connect and stimulate each other. It is likely that colony behaviour matures because colony size changes the rates of interaction among ants. In an older, larger colony, each ant has more ants to meet than in a younger, smaller one, and the outcome is a more stable dynamic. Perhaps colonies remember a past disturbance because it shifted the location of ants, leading to new patterns of interaction, which might even reinforce the new behaviour overnight while the colony is inactive, just as our own memories are consolidated during sleep. Changes in colony behaviour due to past events are not the simple sum of ant memories, just as changes in what we remember, and what we say or do, are not a simple set of transformations, neuron by neuron. Instead, your memories are like an ant colony’s: no particular neuron remembers anything although your brain does....
MORE (details): https://aeon.co/ideas/an-ant-colony-has-...-dont-have
EXCERPT: Like a brain, an ant colony operates without central control. Each is a set of interacting individuals, either neurons or ants, using simple chemical interactions that in the aggregate generate their behaviour. [...] Any living being can exhibit the simplest form of memory, a change due to past events. Look at a tree that has lost a branch. It remembers by how it grows around the wound, leaving traces in the pattern of the bark and the shape of the tree. [...]
Past events can alter the behaviour of both individual ants and ant colonies. [...] The Finnish myrmecologist Rainer Rosengren showed that when the ants emerge in the spring, an older ant goes out with a young one along the older ant’s habitual trail. The older ant dies and the younger ant adopts that trail as its own, thus leading the colony to remember, or reproduce, the previous year’s trails.
Foraging in a harvester ant colony requires some individual ant memory. The ants search for scattered seeds and do not use pheromone signals; if an ant finds a seed, there is no point recruiting others because there are not likely to be other seeds nearby. [...] Once back at the nest, a forager drops off its seed, and is stimulated to leave the nest by the rate at which it meets other foragers returning with food. On its next trip, it leaves the trail at about the same place to search again.
Every morning, the shape of the colony’s foraging area changes, like an amoeba that expands and contracts. No individual ant remembers the colony’s current place in this pattern. On each forager’s first trip, it tends to go out beyond the rest of the other ants travelling in the same direction. The result is in effect a wave that reaches further as the day progresses. Gradually the wave recedes, as the ants making short trips to sites near the nest seem to be the last to give up.
From day to day, the colony’s behaviour changes, and what happens on one day affects the next. [...] Ants use the rate at which they meet and smell other ants, or the chemicals deposited by other ants, to decide what to do next. A neuron uses the rate at which it is stimulated by other neurons to decide whether to fire. In both cases, memory arises from changes in how ants or neurons connect and stimulate each other. It is likely that colony behaviour matures because colony size changes the rates of interaction among ants. In an older, larger colony, each ant has more ants to meet than in a younger, smaller one, and the outcome is a more stable dynamic. Perhaps colonies remember a past disturbance because it shifted the location of ants, leading to new patterns of interaction, which might even reinforce the new behaviour overnight while the colony is inactive, just as our own memories are consolidated during sleep. Changes in colony behaviour due to past events are not the simple sum of ant memories, just as changes in what we remember, and what we say or do, are not a simple set of transformations, neuron by neuron. Instead, your memories are like an ant colony’s: no particular neuron remembers anything although your brain does....
MORE (details): https://aeon.co/ideas/an-ant-colony-has-...-dont-have