globals[ max-energy ;maximum energy (value) same for all turtles attention-distance ;attention distance (value) same for all turtles attention-angle ;attention angle (value) same for all turtles need-energy-th ;energy threshold for a request (value) same for all turtles share-energy-th ;energy threshold to be able to share (value) same for all turtles initial-trees ;initial number of trees (value) initial-fruit ;fruit in each tree (value) same for all trees ] breed[turts turt] breed[trees tree] turts-own[ energy ;energy to move (value) cooperative? ;cooperative? (boolean) memory? ;memory? (boolean) language? ;language? (boolean) knowledge ;memorized links with other turtles ] trees-own[ fruit ;number of fruit in each tree (value) ] to setup ca ask patches [set pcolor 39] ;set globals set max-energy 100 set attention-distance 9 set attention-angle 120 set need-energy-th 33 set share-energy-th 33 set initial-trees 3 set initial-fruit 5 ;put turts and trees put-turts C true false false let NC 100 - C put-turts NC false false false if experiment = 2 [ask turts with [cooperative?] [set memory? true]] if experiment = 3 [ask turts with [cooperative?] [set memory? true set language? true]] if experiment = 4 [ask turts [set memory? true set language? true]] put-trees initial-trees reset-ticks end to put-turts [v1 b1 b2 b3] create-turts v1 [ set shape "turtle" setxy random-xcor random-ycor set energy (random 99) + 1 set cooperative? b1 set memory? b2 set language? b3 set knowledge turtle-set no-turtles ifelse cooperative? [set color blue][set color red] ] end to put-trees [v1] create-trees v1 [ set shape "tree" setxy random-xcor random-ycor set color green set size 2 set fruit initial-fruit ] end to go ask turts [explore-and-feed] ask turts [if energy < need-energy-th [interact]] ask turts [if energy <= 0 [die]] tick if ticks mod (2 * 2 ^ (3 - rr)) = 0 [put-trees 1] if ticks mod 2000 = 0 [stop] end to explore-and-feed let trees-in-sight trees in-cone attention-distance attention-angle ifelse any? trees-in-sight [ let target-tree min-one-of trees-in-sight [distance myself] face target-tree forward-step if patch-here = [patch-here] of target-tree[ ask target-tree [set fruit fruit - 1 if fruit = 0 [die]] set energy max-energy random-step] ] [ random-step ] end to forward-step fd 1 set energy energy - 1 end to random-step lt random-float attention-angle / 2 rt random-float attention-angle / 2 fd 1 set energy energy - 1 end to interact ;choose target let candidates turts in-cone attention-distance attention-angle with [energy > [energy] of myself and energy > share-energy-th] if any? candidates [ let target one-of candidates ;interaction ;If target is not cooperative the interaction turns bad in selfs perpective. ;If target is cooperative, cooperation is conditional based on memory (of target), or inconditional if target does not have memory or memory is full. ;Note that only bad turts are memorized. If target remembers turt it s because it s bad ;(knowledge from previous interaction between the two or from sharing info with other turts). ;If target remembers turt, energy is not shared by target. The interaction turns bad in selfs perpective. ;Not remembering is equivalent to not having memory or memory full => inconditional cooperation. Energy is shared by target. ;If energy is shared they can also share knowledge. If both have language they also share info about their links with other turtles. ;After interacting, if interaction was bad in selfs perpective, self has memory and memory is not full, the bad turt is memorized. let self-had-a-negative-interaction false ifelse [cooperative?] of target [ ifelse [not remembers? myself] of target[ share-energy self target if language? and [language?] of target [share-info self target] ][ set self-had-a-negative-interaction true ] ][ set self-had-a-negative-interaction true ] if self-had-a-negative-interaction [ if memory? and not memory-full? [memorize target] ] ] ;note that in repeated interactions with the same partner links and records of links in memory are not duplicated, but their are enventuallt subject to changes end to-report memory-full? ifelse count knowledge = memory-limit [report true][report false] end to memorize [t] if not remembers? t [set knowledge (turtle-set knowledge t)] end to-report remembers? [t] ifelse member? t knowledge [report true][report false] end to share-energy [t1 t2] let both (turtle-set t1 t2) let half-of-combined-energies ((sum [energy] of both) / 2) ask both [set energy half-of-combined-energies] end to share-info [t1 t2] first-gets-from-second t1 t2 first-gets-from-second t2 t1 end to first-gets-from-second [t1 t2] let new-bad-turts other ([knowledge] of t2) ask new-bad-turts [ if [not memory-full?] of t1 [ask t1 [memorize myself]]] ;memorized turts are not duplicated in memory end @#$#@#$#@ GRAPHICS-WINDOW 496 10 912 427 -1 -1 8.0 1 10 1 1 1 0 1 1 1 -25 25 -25 25 0 0 1 ticks 30.0 BUTTON 33 21 106 54 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL 1 SLIDER 338 19 479 52 C C 0 100 50.0 1 1 NIL HORIZONTAL SLIDER 21 171 193 204 rr rr 1 3 2.0 1 1 NIL HORIZONTAL BUTTON 116 21 179 54 NIL go T 1 T OBSERVER NIL NIL NIL NIL 1 PLOT 923 10 1285 239 Pop NIL NIL 0.0 10.0 0.0 10.0 true true "" "" PENS "C" 1.0 0 -13345367 true "" "plot count turts with [cooperative?]" "NC" 1.0 0 -2674135 true "" "plot count turts with [not cooperative?]" "T" 1.0 0 -10899396 true "" "plot count trees" MONITOR 930 254 987 299 C count turts with [cooperative?] 3 1 11 MONITOR 993 254 1050 299 NC count turts with [not cooperative?] 17 1 11 SLIDER 308 67 480 100 memory-limit memory-limit 0 100 100.0 1 1 NIL HORIZONTAL PLOT 1077 256 1277 406 knowledge NIL NIL 0.0 10.0 0.0 10.0 true false "" "" PENS "default" 1.0 0 -16777216 true "" "plot mean ([count knowledge] of turts)" CHOOSER 226 10 318 55 experiment experiment 1 2 3 4 0 TEXTBOX 22 84 443 181 1 = no memory or language\n2 = cooperative (C) have memory\n3 = cooperative have memory and language\n4 = non-cooperative (NC) also have memory and language 12 0.0 1 @#$#@#$#@ ## WHAT IS IT? This model investigates the success of cooperation when under ecological pressure, including when non-cooperative agents are also present in the system and take advantage of cooperative efforts for the survival of the group. In particular, two cognitive abilities are tested in such circumstances: memory and language, which are necessary to build and maintain a network of direct and indirect reciprocity, thus allowing for stable cooperation and better survival chances. ## HOW IT WORKS 100 agents are placed randomly in space with random initial energy between 1 and 100 (maximum possible energy). A population size of 50 to 100 individuals is considered based on estimates for the group size of hunters–gatherers societies. Trees are randomly put in space, each with 5 fruits. Trees die when all fruit is collected. Ecological pressure is determined solely by the nature’s regrowth rate rr, that is, a new tree comes to existence whenever (ticks mod 2 x (2^3 - rr )) = 0. Agents move randomly: one step per tick inside their perception field, defined by a 120º attentional angle and a 9 step attentional distance. Agents loose 1 unit of energy per step and when they loose all their energy they die. If a tree is detected in the agent’s perception field he moves towards the tree to collect one fruit. If more than one tree is detected he moves towards the closest tree. If other agents with energy greater than 33 are detected in his perception field and ego has energy less than 33, he sends an energy request to one of these agents. If the request is accepted, their energy is summed and divided by both. If the request is refused he may be able to memorize the other’s identity. If an energy transfer is successful, agents may also share information in memory, independently of who made the request. In that case, their memory after the interaction is the concatenation of their personal records (before the interaction) of the identities of the non-cooperative agents. Agents can be cooperative (C) or selfish/non cooperative (NC). Cooperative agents are always available to share their energy (if greater than 33 units), unless they know their partner from previous interactions or "rumors" (conditional cooperation based on memory or memory and language). Selfish agents are never available to share their energy. ## HOW TO USE IT Control the regrowth rate my manipulating rr. High, medium and low ecological pressure are defined by rr = 1, 2 and 3 respectively. The initial number of cooperative agents in the system is controlled by C, the rest (100 - C) are not cooperative. The number of agents an agent is able to memorize is controlled by memory-limit. (only relevant in experiments 2 to 4; See below) Select experiment: 1. no memory or language. 2. cooperative (C) have memory. 3. cooperative have memory and language. 4. non-cooperative (NC) also have memory and language. setup and go. ## THINGS TO NOTICE How do you compare the impact of different rr values on global survival chances? How is the success of cooperation changed by the initial number of cooperative agents in the system? How to interpret the effect of memory and language on the success of cooperation? ## THINGS TO TRY Try comparing the success of cooperation across experiments for different values of C and rr. ## EXTENDING THE MODEL This model was developed specifically to test the importance of reciprocity and underlying cognitive mechanisms for stable cooperation under ecological adversity. As such, all parameters were set empirically such that, on one hand, survival chances are affected by ecological pressure, and on the other, promoted by an interaction frequency that is enough to allow many reciprocity opportunities. For that reason parameters where set implicitly in the code. But it could be interestign to manipulate all parameters parameters explicitly and try for example different proportions of energy sharing. Ideas: 1. Create obstacles and let the agents follow the walls by avoiding them. 2. Allow the agents to reconsider their strategy based on their previous experience. Things like gratitute and other complex social emotions and moral rules may be interesting to investigate in this type of setting. 3. Allow agents to reproduce. ## RELATED MODELS In NetLogo Modeling Commons: Cooperation Altruism Reciprocal Altruism in Vampire Bats ## CREDITS AND REFERENCES This model was originaly inspired by: Zibetti, E., Carrignon, S., & Bredeche, N. (2016). ACACIA-ES: an agent-based modeling and simulation tool for investigating social behaviors in resource-limited two-dimensional environments. Mind & Society, 15(1), 83-104. The present model was coded by David N. Sousa (davidnsousa@gmail.com) with the collaboration of Luis Correia and Leonel Garcia-Marques at Universidade de Lisboa. The model was developed in the context of a master's thesis by David N. Sousa: http://hdl.handle.net/10451/32768 Feel free to contact us with comments or questions. July 25, 2018, Lisboa, Portugal. @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 butterfly true 0 Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240 Polygon -7500403 true 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cooperative?] count trees setup go count turts with [cooperative?] count turts with [not cooperative?] count trees setup go count turts with [cooperative?] count turts with [not cooperative?] count trees setup go count turts with [cooperative?] count turts with [not cooperative?] count trees setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts setup go count turts setup go count turts with [cooperative?] count turts setup go count turts with [cooperative?] count turts @#$#@#$#@ @#$#@#$#@ default 0.0 -0.2 0 0.0 1.0 0.0 1 1.0 0.0 0.2 0 0.0 1.0 link direction true 0 Line -7500403 true 150 150 90 180 Line -7500403 true 150 150 210 180 @#$#@#$#@ 0 @#$#@#$#@