The search for a better email spam filter has researchers turning to nature and taking inspiration from the way an ant colony defends itself against intruders.
Ant defense behavior operates according to distributed network rules, similar to that of human immune systems. Researchers say this suggests that evolution has at least twice created a natural security protocol that, mimicked by email servers, would make it much harder for spammers to successfully infiltrate a system and avoid detection.
In vertebrate animals, dedicated surface molecules recognize pathogens. They are amazingly specific, usually responding to just one or sometimes two strains of bacteria or viruses.
Immune cells are typically on the lookout for only one type of intruder, as carrying a molecule for every existing pathogen would be impractical for any individual cell.
If an intruder gets past an immune cell, another will eventually pick it up, with the whole immune system acting in what is described as a distributed decision network.
Stanford biologist Deborah M. Gordon and computer scientist Fernando Esponda from the Instituto Tecnologico Autonomo de Mexico report they've observed ants using a similar strategy to keep intruders out of their nests.
Just as with human immune cells, an individual ant has a restricted capacity for holding knowledge. The ant's capacity is based in scent, which allows it to tell friend from foe.
The colony depends on the overlapping, distributed collective knowledge of its resident ants, as Gordon and Esponda reported in The Royal Society Proceedings B.
"No one ant knows every foreigner, but because each ant knows a few foreigners, the whole colony knows how to keep foreigners out most of time," Gordon said. "It's not perfect, but it's a lot cheaper.
"The system works very much like the immune system, but unlike the immune system, it's easy to observe what's happening," she noted.
The researchers suggest that the findings could have surprising applications in the technology field, singling out email filters as a prime candidate.
Email services mostly attempt to block spam messages by maintaining a master list of "good" and "bad" email senders — but the list is vulnerable to hacking and must constantly change.
Breaking up the list and coming up with a method to share the task of detecting new threats – as ants do – could possibly lead to improved spam filters, Gordon said.
"It's an arms race," she explained. "But a distributed decision network, similar to how ants and immune cells operate, might be a better defense against hackers, because they can't simply penetrate the central system's code."
