Study Shows Cockroaches Make Group Decisions

By SamuelRose, published at 10 May 2007 - 8:12pm, last updated 12 years 18 weeks ago.

[via Slashdot]

A study outlined in ths month'sPNAS talks about evidence that cockroaches communicate and make group deicisions.

Discover Channel News Online reports:

Halloy tested cockroach group behavior by placing the insects in a dish that contained three shelters. The test was to see how the cockroaches would divide themselves into the shelters.

After much "consultation," through antenna probing, touching and more, the cockroaches divided themselves up perfectly within the shelters. For example, if 50 insects were placed in a dish with three shelters, each with a capacity for 40 bugs, 25 roaches huddled together in the first shelter, 25 gathered in the second shelter, and the third was left vacant.

When the researchers altered this setup so that it had three shelters with a capacity for more than 50 insects, all of the cockroaches moved into the first "house."

Halloy and his colleagues found that a balance existed between cooperation and competition for resources.

[...]He explained to Discovery News, "Cockroaches are gregarious insects (that) benefit from living in groups. It increases their reproductive opportunities, (promotes) sharing of resources like shelter or food, prevents desiccation by aggregating more in dry environments, etc. So what we show is that these behavioral models allow them to optimize group size."

The models are so predictable that they could explain other insect and animal group behaviors, such as how some fish and bugs divide themselves up so neatly into subgroups, and how certain herding animals make simple decisions that do not involve leadership.