signalling theory evolutionary biology signalling theory body theoretical work examining communication individuals species species central question organisms conflicting interests sexual selection expected provide honest signals conscious intention cheating mathematical models organisms advertise condition individuals stable strategy important research field signals given contexts mate selection females subjects males signals selective pressure signals evolve modify behaviour receiver benefit signals honest conveying information increases fitness receiver individual cheat giving signal briefly benefit risk signalling system population question selection signals works level individual organism gene level group debated arguing individuals evolve signal receive signals better including resisting manipulation suggested cheating controlled handicap principle best horse handicap race carrying largest handicap weight according theory male tails genuinely costly produce system stable large tails honest signals attempted verify handicap principle inconsistent results mathematical biologist analysed contribution having copies gene honest signalling demonstrating runaway effect occur sexual selection depending balance costs benefits mechanisms expected humans researchers studied including risk taking young men hunting large game animals costly religious rituals finding appear qualify costly honest signals sexual selection animals choose mates traits signalling subject evolutionary pressure example male gray tree frog produces attract females female chooses mate specific style male calling specific signalling ability signal intensity variation style repetition rate seek explain females select sensory exploitation hypothesis proposes pre existing preferences female receivers drive evolution signal innovation male similar way hidden preference hypothesis proposes successful calls better able match hidden preference female evolved multiple sexual ornaments reasons apparent disputed honest signals biology signals traits including structures evolved specifically change behaviour receivers ways benefit traits actions benefit receiver exclusively called cues alert bird deliberately gives warning stalking predator predator gives hunt sound signal foraging bird inadvertently makes sound leaves attracts predators increases risk predation sound cue signalling systems shaped mutual interests receivers alert bird jay warning stalking predator communicating useful predator detected prey quit time stalking alerted prey unlikely catch predator gives tasks feeding stalking predator detected signalling prey receiving predator mutual interest terminating hunt species mutual interests increase central models signalling relatives instance birds compete food parents concept honesty animal communication controversial difficult determine intent use criterion deception honesty human interactions use phrase honest signals statistical sense biological signals like warning calls tail feathers honest useful receiver signal trait thing value receiver honest biological signals need perfectly reducing uncertainty zero need useful correct average ultimately value signalled information depends extent allows receiver increase fitness honest signals stable class honest signal warning signal generally visual given poisonous dangerous animals yellow banded poison frogs warning signals honest indications prey tandem brighter conspicuous organism toxic usually common effective colours red yellow black white signals mutual conflicting interests animal signalling systems central problem signalling theory cheating example foraging birds safer warning false random case predator nearby cheating cause signalling system collapse signal integrity signalling system reduces fitness group example signalling comes crabs shown bluff conscious intention implied fighting ability lost crab occasionally weaker crabs smaller stronger claws proportion signals low worthwhile crabs test honesty signal combat considered individuals species act attempting applied selfish gene view evolution animals threat displays genes interests signals criticised previous suggesting displays good species argued communication ought viewed evolutionary arms race evolve better manipulating receivers receivers evolve resistant manipulation game theoretical model war attrition similarly suggests threat displays ought convey reliable information intentions sports metaphor proposed verbal model signal costs cheating stabilize honest observed signals qualities based analogy sports systems called idea handicap principle purpose sports system reduce performance making contest competitive handicap race faster horses given heavier weights carry similarly amateur golf better fewer strokes raw scores creates handicap performance work supposed handicap handicapped performance knew race horses amateur likely win horse bigger weight handicap smaller stroke handicap analogy tails large tail covert feathers act system knew sizes tails bigger tail greater quality display costs include social costs form testing punishment rivals production costs example given textbooks extinct irish male irish enormous evolved displays ability overcome handicap point handicap inherited genes ought selected essential idea intuitive probably folk wisdom articulated short story futuristic uses variety mechanisms reduce performance spectator ballet comments easy strongest graceful dancers handicap bags big worn pound men interpreted analogy mean higher quality bigger tails signalling ability waste resource trading bigger tail idea conspicuous consumption extravagant status symbols signal wealth conclusions rest verbal interpretation metaphor initially handicap principle received evolutionary life history theory differences signalling costs form survival reproduction stabilize signalling system roughly imagined genetic models suggested possible showed handicap like signalling system stable higher quality paid lower marginal survival costs signals hamilton proposed specific widely applicable handicap mechanism parasite sexual selection argued ending evolutionary race hosts parasites sexually selected signals indicate health idea tested barn species males long tail found males longer tails offspring fewer fostered young effect genetic confirming hamilton theory example hypothesis dual mutually incompatible roles immune function signalling given animals obtained food hypothesis states animals depended sexual signals demonstrating ability waste sexual signals expense immune system handicap principle proven hard test partly inconsistent interpretations metaphor marginal fitness model partly conflicting results studies individuals bigger signals pay higher costs studies paying lower costs possible explanation inconsistent results given series papers shows proof handicap principle based critical assumption trade costs benefits fashion way humans invest money increase income currency assumption costs benefits trade fashion valid survival cost reproduction benefit assumed evolution sexually selected signals fitness depends producing offspring function reproductive success given individual alive times probability alive given investment signals costly signalling dynamics effort discover costs honest signals qualities built strategic models signalling games assumptions models applied sexually selected signalling animals rarely incorporate fact sexual reproduction noted mathematical biologist early 20th century preference genes females signal genes display traits males females tend mate males generations sons carry genes associated daughters daughters carry genes associated sons cause evolutionary dynamic known runaway males explored genetic model showing dynamics sensitive signalling search costs models incorporate costly signalling runaway models fitness depends survival reproduction having sexy sons daughters stereotypical model increasing fitness having healthy sons daughters examples proposed autumn leaf colour signal trees pest species migrate autumn trees theory bright autumn coloration costly trees require energy investment help reduce parasite load example cited example signalling jump close predator instead escaping signal strength human honest signals human behaviour provide examples costly signals general signals provide information person quality cooperative tendencies evidence costly signalling found areas human interaction including risk taking hunting religion costly signalling hunting large game hunting studied extensively signal men willingness physical risks showcase strength coordination costly signalling theory useful tool understanding food sharing hunter applied situations delayed viable explanation instances particularly inconsistent delayed hypothesis hunter shares kill members large group situations individuals sharing meat control free riding attractive strategy receiving meat free riders people benefits group living contributing maintenance fortunately costly signalling theory fill gaps left delayed hypothesis suggested men target large game publicly share meat draw social attention display resulting favorable attention improve hunter reputation providing information quality high quality successful acquiring mates allies costly signalling theory explain apparently behaviour order effective costly signals fulfill specific criteria firstly different levels cost benefit signalling behaviour secondly costs benefits reflect quality information provided signal directed accessible audience receiver stands benefit information sending potential mates allies competitors honesty guaranteed individuals high quality pay high costs signalling honest signalling impossible low quality individuals fake signal fool receiver observed turtle hunting spear fishing patterns community publishing findings men able accumulate high gains time spent turtle hunting spear fishing reaching threshold measured daily catch fish carried home hand turtles frequently served large members community know men reliably brought turtle meat fish turtle hunting costly signal furthermore turtle hunting spear fishing actually productive foraging success depends time dedicated searching foraging poor signal skill strength suggests energetic gains primary reason men turtle hunting spear fishing follow study found successful hunters experience greater social benefits reproductive success skilled hunters people share food possibly gain reputation hunters sharing meat mainly provision families gain benefits teenage boys away meat wives children costly signalling qualities likely explanation qualities include good coordination strength knowledge endurance bravery hunters pair highly fertile hard working wives non hunters woman benefits mating man possesses qualities children likely inherit qualities increase fitness benefit husband high social status hunting honest costly signal quality men costly signalling theory explain men torch fish torch fishing method fishing men use dried catch large dog toothed preparation torch fishing requires significant time investments involves great deal organization time energetic costs preparation torch fishing results net losses torch fishing handicap serves signal men productivity torch fishing advertised fishing occupation women usually spend time observing sail reef local rituals help broadcast information successful enhance torch fishing season ritual constraints clearly distinguish torch men males permitted torch fish participated day fishing season community informed day easily identify torch second torch receive meals canoe house prohibited eating certain foods people frequently discuss qualities torch fishermen women claim looking hard working mates distinct sexual division labor highly valued characteristic males torch fishing provides women reliable information work ethic prospective mates makes honest costly signal human cases strong reputation built costly signalling man social status men signal successfully northern foraging groups traditional hunters usually capture maximum year said particularly successful hunter said returned hunt having killed larger people connected ate great deal meat popularity grew hunter sharing meat framework general model costly signalling individuals share acquire mates allies costly signalling applies situations foraging groups giving goes recipients little offer return young hunter motivated impress community members daughters obtain wife older hunters wish attract women interested relationship wife northern groups killing large animal indicates man mastered art hunting support family generally women seek man good hunter character generous social ties hunting ability marriage men good hunters enter marriage market earliest costly signalling theory explains seemingly foraging displays physical risks costly signal costly signalling applied situations involving physical strain risk physical injury death research physical risk taking important information people especially young men high risk activities help development prevention programs reckless driving lethal problem young men western societies male takes physical risk sending message strength skill survive extremely dangerous activities signal directed peers potential mates study risk taking types risk physical heroic risk benefit viewed favorably types risk taking drugs males females valued different degrees heroic risk mates sex friends males valued heroic risk taking male friends preferred female mates females valued heroic risk taking male mates female friends females attracted males inclined physically defend children males prefer heroic risk taking male friends good allies western societies voluntary blood donation common extreme form risk taking costs associated donations include pain risk infection blood donation opportunity send costly signals donors perceived generous physically healthy survey donors non donors expressed perceptions health ability blood donors operate situations religion costly signal costly religious rituals male food water snake handling look evolutionary terms devout religious beliefs traditions practiced appear religion arisen increase maintain cooperation cooperation leads behaviour costly signalling explain religions involve costly elaborate rituals performed publicly demonstrate loyalty religious group way group members increase allegiance group signalling investment group interests group size increases humans threat free riders grows costly signalling theory accounts proposing religious rituals costly deter free riders proposed costly signalling theory explain costly religious behaviour argued hard fake religious displays enhanced trust solidarity community producing emotional economic benefits showed display signals northern iran helped secure trade agreements displays signalled commitment islam strangers group members demonstrated people religious communities times likely live longer secular counterparts longer positively number costly requirements demanded religious community members excluded studied effects costly signals religious communities self reported survey church increased attendance contributions church increased effect people willing participate church stringent demands members despite experimental support hypothesis remains controversial common critique easy fake simply attending religious service hypothesis people likely join contribute religious group rituals costly critique specifically asks religion evolutionary advantage evolving religion signals commitment admits reinforcement religious rites reward punishment system found religion makes ideal candidate increasing cooperation finally insufficient evidence increase fitness result religious cooperation argues benefits religion increased longevity improved health assistance crises greater psychological
Signalling theory