Optimization algorithms enable the ant colony to decide how many ants to send to a given food source and when to drastically reduce the number:
Researchers are beginning to understand how, without much in the way of individual decision-making power, ants can make complex decisions. It’s best understood, they say, as something like an optimization algorithm:
Scientists found that ants and other natural systems use optimization algorithms similar to those used by engineered systems, including the Internet. These algorithms invest incrementally more resources as long as signs are encouraging but pull back quickly at the first sign of trouble. The systems are designed to be robust, allowing for portions to fail without harming the entire system. Understanding how these algorithms work in the real world may help solve engineering problems, whereas engineered systems may offer clues to understanding the behavior of ants, cells, and other natural systems.
Cold Spring Harbor Laboratory, “Deciphering algorithms used by ants and the Internet” at ScienceDaily The paper is open access.
The researchers explain in more detail:
The same algorithm used by Internet engineers is used by ants when they forage for food. At first, the colony may send out a single ant. When the ant returns, it provides information about how much food it got and how long it took to get it. The colony would then send out two ants. If they return with food, the colony may send out three, then four, five, and so on. But if ten ants are sent out and most do not return, then the colony does not decrease the number it sends to nine. Instead, it cuts the number by a large amount, a multiple (say half) of what it sent before: only five ants. In other words, the number of ants slowly adds up when the signals are positive, but is cut dramatically lower when the information is negative. Navlakha and Suen note that the system works even if individual ants get lost and parallels a particular type of “additive-increase/multiplicative-decrease algorithm” used on the Internet.
Cold Spring Harbor Laboratory, “Deciphering algorithms used by ants and the Internet” at ScienceDaily The paper is open access.
In some cases, computer programmers have learned better solutions to problems like the Traveling Salesman Problem from ants…
News, “Ants use algorithms similar to those of the internet ” at Mind Matters News
Takehome: Discovering that ants follow the same principles as computer systems raises the question of the ultimate source of intelligence in nature; it’s not the ant.
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