Rowers high: behavioral synchrony is correlated with elevated pain threshold
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Transcript of Rowers high: behavioral synchrony is correlated with elevated pain threshold
Rowers high: behavioral synchrony is correlated with elevated pain threshold
Cohen, Ejsmond-Frey, Knight, & Dunbar (2010)Rowers high: behavioral synchrony is correlated with elevated pain thresholdThe role of endorphinsPhysical exercise release of endorphins
Psychological effects of endorphins?
Release of endorphins social bonding
Physical Exercise+ X? heightened social bondingSynchronyRowers highPurpose: Will behavioral synchrony result in elevated release of endorphins??
Why rowers?
Ergometeters (rowing machines)
Materials & Methods12 male athletes (M = 24.25, SD = 3.769)
Two week testing period
Within-subjects design: Individual vs. Group
Medisave Littman Classic II sphygmomanometerBlood pressure cuffMeasured before and after trainingResultsEndorphin hypothesis (general)Pain threshold increased following exercise
Ruling out alternative explanationsNo differences in work effortNo carry-over effects
Results
Group pain threshold changes were significantly elevated above those for individual trialsDiscussionSynchronized activity heightens opioidergic activity
Other evidence runners high
Synchronous activities Wiltermuth & Heath, 2009
Power (1998)Old wives tales: the gossip hypothesis and the reliability of cheap signals
Dunbars grooming and gossip hypothesis of language originsVocal communicationAdaptive response to increases in group sizeReplaced physical groomingMore efficient
Purpose: address problems with this theory
Coevolution of neocortex size, group size, and languageCost of group livingReproductive suppression
Coalitions serve as a buffer against costsThe neocortex ratioSocial grooming (Dunbar, 1991)
Evolution of larger groupsA feedback process
Vocal grooming: the commitment problemManual grooming: hard-to-fake currencyDemonstrates commitmentCheney & Seyfarth (1990)
Problems for vocal grooming hypothesis:Easy to fakeReduced commitmentDoes not produce natural opiates
Gossip: the reliability problemThe gossip hypothesis of language originsRising group sizes Increased pressures on group cohesionNew developments in vocal communication
Problems for gossip hypothesis: ReliabilityCheap signalsRequires more energy expenditure
Contexts for gossip:male and female reproductive strategies
Contexts for gossip:male and female reproductive strategiesMale vs. female philopatry
Ancestral human societies have been viewed as organized around male philopatry
Evidence for female philopatryModern societies (Dunbar & Spoors, 1995)Molecular genetics
Sexual signs and behavioral changeExtracting energy from new sourcesMale investment
Sexual signalsFemale signals elicit behavior change in malesThe material value of menstruation
Female coalitionary strategies: proto-ritualCoalitionary strategiesManipulating menstrual signalsRecruits male investment for female coaltions
Sham menstruation (Power & Watts, 1996)Evolved into ritualistic displays involving:Red paintSongDance
Menstrual ritual as costly signal of commitmentCooperation vs. self-interest?
CommitmentsMenstrual ritual: hard-to-fakeSpeech: easy-to-fake
Predictions from sham menstruation model: archeological evidencePredicts increased male attraction to cosmeticsRed pigment
Evolution of ritual (Power & Watts, 1996)Increased stress on females Development of cosmetic rituals More abundant use of iron ochreArcheological evidence supports these predictions
Evidence of ethnography: female alliances, puberty rituals, and cosmeticsRituals associated with onset of menses1. Advertise prospective fertility in coalitional contexts2. Menstruant participants as probationers until initiated
Traditional CulturesE.g., Venda of the Transvaal
Conclusion: ritual and the gossip hypothesisModel: ritual as costly signaling of commitment (hard-to-fake)Origins of ritual developed in collective manipulation of menstrual signalsNecessary for establishing gossip as a basis of trustMenstrual ritual = Super grooming
Conclusion: a necessary condition for the evolution of language as gossip is the coevolution of ritualSynchrony and ritual in the AndesSynchronized opioidergic activitySocial bondingAnalgesia
Rituals as a signal of commitmentSocial bonding