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The effective collective: Grouping could ensure animals find their way in a changing environment

January 31, 2013
Princeton University
Researchers report that collective intelligence is vital to certain animals' ability to evaluate and respond to their environment. The results should prompt a close examination of how endangered group or herd animals are preserved and managed because wild animals that depend on collective intelligence for migration, breeding and locating essential resources could be imperiled by any activity that diminishes or divides the group, such as overhunting and habitat loss.
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Princeton University researchers found that collective intelligence is vital to certain animals' ability to evaluate and respond to their environment. Conducted on golden shiners (above), the research demonstrated that social animals such as schooling fish rely heavily on grouping to effectively navigate their environment.
Credit: Photo by Sean Fogarty

For social ani­mals such as school­ing fish, the loss of their num­bers to human activ­ity could even­tu­ally threaten entire pop­u­la­tions, accord­ing to a find­ing that such ani­mals rely heav­ily on group­ing to effec­tively nav­i­gate their environment.

Prince­ton Uni­ver­sity researchers report in the jour­nal Sci­ence that col­lec­tive intel­li­gence is vital to cer­tain ani­mals' abil­ity to eval­u­ate and respond to their envi­ron­ment. Con­ducted on fish, the research demon­strated that small groups and indi­vid­u­als become dis­ori­ented in com­plex, chang­ing envi­ron­ments. How­ever, as group size is increased, the fish sud­denly became highly respon­sive to their surroundings.

These results should prompt a close exam­i­na­tion of how endan­gered group or herd ani­mals are pre­served and man­aged, said senior researcher Iain Couzin, a Prince­ton pro­fes­sor of ecol­ogy and evo­lu­tion­ary biol­ogy. If wild ani­mals depend on col­lec­tive intel­li­gence for migra­tion, breed­ing and locat­ing essen­tial resources, they could be imper­iled by any activ­ity that dimin­ishes or divides the group, such as over­hunt­ing and habi­tat loss, he explained.

"Processes that increase group frag­men­ta­tion or reduce pop­u­la­tion den­sity may ini­tially appear to have lit­tle influ­ence, yet a fur­ther reduc­tion in group size may sud­denly and dra­mat­i­cally impact the capac­ity of a species to respond effec­tively to their envi­ron­ment," Couzin said. "If the mech­a­nism we observed is found to be wide­spread, then we need to be aware of tip­ping points that could result in the sud­den col­lapse of migra­tory species."

The work is among the first to exper­i­men­tally explain the extent to which col­lec­tive intel­li­gence improves aware­ness of com­plex envi­ron­ments, the researchers write. Col­lec­tive intel­li­gence is an estab­lished advan­tage of groups, includ­ing humans. As it's under­stood, a group of indi­vid­u­als gain an advan­tage by pool­ing imper­fect esti­mates with those around them, which more or less "aver­ages" sin­gle expe­ri­ences into sur­pris­ingly accu­rate com­mon knowl­edge. For instance, the paper in Sci­ence cites a 1907 study that pre­dicted with near pre­ci­sion the weight of an ox based on the esti­mates of 787 people.

With their work, Couzin and his coau­thors uncov­ered an addi­tional layer to under­stand­ing col­lec­tive intel­li­gence. The con­ven­tional view assumes that indi­vid­ual group mem­bers have some level of knowl­edge albeit incom­plete. Yet the Prince­ton researchers found that in some cases indi­vid­u­als have no abil­ity to esti­mate how a prob­lem needs to be solved, while the group as a whole can find a solu­tion through their social inter­ac­tions. More­over, they found that the more numer­ous the neigh­bors, the richer the indi­vid­ual -- and thus group -- knowl­edge is.

These find­ings cor­re­late with recent research show­ing that col­lec­tive intel­li­gence -- even in humans -- can rely less on the intel­li­gence of each group mem­ber than on the effec­tive­ness of their com­mu­nal inter­ac­tion, Couzin said. In humans, research sug­gests that such coop­er­a­tion would take the form of open and equal com­mu­ni­ca­tion among indi­vid­u­als regard­less of their respec­tive smarts, he said.

The researchers placed fish known as golden shin­ers in exper­i­men­tal tanks in groups as low as one and as high as 256. The tanks fea­tured a mov­ing light field that was bright on the outer edges and tapered into a dark cen­ter. To reflect the chang­ing nature of nat­ural envi­ron­ments, they also incor­po­rated small patches of dark­ness that moved around ran­domly. Pro­lific school­ers and enthu­si­asts of dark­ness, the golden shin­ers would pur­sue the shaded areas as the researchers recorded their move­ment using com­puter vision soft­ware. Although the fish sought the shade regard­less of group size, their capa­bil­ity to do so increased dra­mat­i­cally once groups spanned a large enough area.

The researchers then tracked the motion of indi­vid­ual fish to gauge the role of social influ­ence on their move­ment. They found that indi­vid­u­als adjusted their speed accord­ing to local light level by mov­ing faster in more brightly lit areas, but with­out social influ­ence the fish did not nec­es­sar­ily turn toward the darker regions. Groups, how­ever, read­ily swam to dark areas and were able to track those pre­ferred regions as they moved.

This col­lec­tive sens­ing emerged due to the coher­ent nature of social inter­ac­tions, the authors report. As one side of the group slowed and turned toward the shaded area, the other mem­bers did as well. Also, slow­ing down increased den­sity and resulted in darker regions becom­ing more attrac­tive to these social animals.

Couzin worked with lead authors Andrew Berdahl, a Prince­ton grad­u­ate stu­dent, and post­doc­toral fel­low Colin Tor­ney, both cur­rently in Couzin's lab, as well as with for­mer lab mem­bers Chris­tos Ioan­nou and Jolyon Faria, who are now at the Uni­ver­sity of Bris­tol and the Uni­ver­sity of Oxford, respectively.

This work was sup­ported in part by grants from the National Sci­ence Foun­da­tion, the U.S. Office of Naval Research, the U.S. Army Research Office and the Nat­ural Sci­ences and Engi­neer­ing Research Coun­cil of Canada.

Story Source:

The above story is based on materials provided by Princeton University. The original article was written by Mor­gan Kelly. Note: Materials may be edited for content and length.

Journal Reference:

  1. A. Berdahl, C. J. Torney, C. C. Ioannou, J. J. Faria, I. D. Couzin. Emergent Sensing of Complex Environments by Mobile Animal Groups. Science, 2013; 339 (6119): 574 DOI: 10.1126/science.1225883

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Princeton University. "The effective collective: Grouping could ensure animals find their way in a changing environment." ScienceDaily. ScienceDaily, 31 January 2013. <>.
Princeton University. (2013, January 31). The effective collective: Grouping could ensure animals find their way in a changing environment. ScienceDaily. Retrieved May 23, 2015 from
Princeton University. "The effective collective: Grouping could ensure animals find their way in a changing environment." ScienceDaily. (accessed May 23, 2015).

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