Rowers high: behavioral synchrony is correlated with elevated pain
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Transcript Rowers high: behavioral synchrony is correlated with elevated pain
Rowers high: behavioral synchrony is
correlated with elevated pain threshold
Cohen, Ejsmond-Frey, Knight, & Dunbar (2010)
The role of endorphins
Physical exercise
release of endorphins
Psychological effects of endorphins?
Release of endorphins
Physical Exercise
+
X?
Synchrony
social bonding
heightened social bonding
Rowers high
Purpose: Will behavioral synchrony result in
elevated release of endorphins??
Why rowers?
Ergometeters (rowing machines)
Materials & Methods
12 male athletes (M = 24.25, SD = 3.769)
Two week testing period
Within-subjects design: Individual vs. Group
Medisave Littman Classic II sphygmomanometer
Blood pressure cuff
Measured before and after training
Results
Endorphin hypothesis (general)
Pain threshold increased following exercise
Ruling out alternative explanations
No differences in work effort
No carry-over effects
Results
Group pain threshold changes were significantly
elevated above those for individual trials
Discussion
Synchronized activity heightens opioidergic
activity
Other evidence – runners ‘high’
Synchronous activities
Wiltermuth & Heath, 2009
Old wives’ tales: the gossip hypothesis
and the reliability of cheap signals
Power (1998)
Dunbar’s ‘grooming and gossip’
hypothesis of language origins
Vocal communication
Adaptive response to increases in group size
Replaced physical grooming
More efficient
Purpose: address problems with this theory
Coevolution of neocortex size,
group size, and language
Cost of group living
Reproductive suppression
Coalitions serve as a buffer against costs
The neocortex ratio
Social grooming (Dunbar, 1991)
Evolution of larger groups
A feedback process
Vocal grooming:
the commitment problem
Manual grooming: hard-to-fake currency
Demonstrates commitment
Cheney & Seyfarth (1990)
Problems for vocal grooming hypothesis:
Easy to fake
Reduced commitment
Does not produce natural opiates
Gossip: the reliability problem
The ‘gossip’ hypothesis of language origins
Rising group sizes
Increased pressures on group cohesion
New developments in vocal communication
Problems for gossip hypothesis:
Reliability
Cheap signals
Requires more energy expenditure
Contexts for gossip:
male and female reproductive strategies
Contexts for gossip:
male and female reproductive strategies
Male vs. female philopatry
Ancestral human societies have been viewed
as organized around male philopatry
Evidence for female philopatry
Modern societies (Dunbar & Spoors, 1995)
Molecular genetics
Sexual signs and behavioral change
Extracting energy from new sources
Male investment
Sexual signals
Female signals elicit behavior change in males
The material value of menstruation
Female coalitionary strategies:
proto-ritual
Coalitionary strategies
Manipulating menstrual signals
Recruits male investment for female coaltions
Sham menstruation (Power & Watts, 1996)
Evolved into ritualistic displays involving:
Red paint
Song
Dance
Menstrual ritual as
costly signal of commitment
Cooperation vs. self-interest?
Commitments
Menstrual ritual: hard-to-fake
Speech: easy-to-fake
Predictions from ‘sham menstruation’
model: archeological evidence
Predicts increased male attraction to cosmetics
Red pigment
Evolution of ritual (Power & Watts, 1996)
Increased stress on females
Development of cosmetic rituals
More abundant use of iron ochre
Archeological evidence supports these predictions
Evidence of ethnography: female
alliances, puberty rituals, and cosmetics
Rituals associated with onset of menses
1. Advertise prospective fertility in coalitional
contexts
2. Menstruant participants as probationers until
initiated
Traditional Cultures
E.g., Venda of the Transvaal
Conclusion:
ritual and the gossip hypothesis
Model: ritual as costly signaling of
commitment (hard-to-fake)
Origins of ritual developed in collective manipulation
of menstrual signals
Necessary for establishing ‘gossip’ as a basis of trust
Menstrual ritual = Super grooming
Conclusion: a necessary condition for the evolution
of language as gossip is the coevolution of ritual
Synchrony and ritual in the Andes
Synchronized
opioidergic activity
Social bonding
Analgesia
Rituals as a signal of commitment
Social bonding