Synchrony and Physiological Arousal Increase Cohesion and Cooperation in Large Naturalistic Groups

Separate research streams have identified synchrony and arousal as two factors that might contribute to the effects of human rituals on social cohesion and cooperation. But no research has manipulated these variables in the field to investigate their causal – and potentially interactive – effects on prosocial behaviour. Across four experimental sessions involving large samples of strangers, we manipulated the synchronous and physiologically arousing affordances of a group marching task within a sports stadium. We observed participants’ subsequent movement, grouping, and cooperation via a camera hidden in the stadium’s roof. Synchrony and arousal both showed main effects, predicting larger groups, tighter clustering, and more cooperative behaviour in a free-rider dilemma. However, synchrony and arousal interacted on measures of clustering and cooperation: such that synchrony only encouraged closer clustering — and encouraged greater cooperation—when paired with physiological arousal. The research has implications for understanding the nature and co-occurrence of synchrony and physiological arousal in rituals around the world. It also represents the first use of real-time spatial tracking as a precise and naturalistic method of simulating collective rituals

Hydrologic fragmentation-induced eutrophication in Dove Sound, Upper Florida Keys, USA

Anthropogenic impacts to island systems can have deleterious effects on coastal aquatic ecosystems. These effects can alter water quality, primary production as well as habitat. Land development often fragments hydrologic connectivity within aquatic ecosystems forcing alterations in nutrient transport and increases the potential for eutrophication. Dove Sound, a tidal lagoon located in the Upper Florida Keys on Key Largo, has been subjected to anthropogenic influences of land development during the last century. To investigate these influences a short sediment core was collected from within Dove Sound and investigated using 210Pb dating, stable isotopes of carbon and nitrogen, and sedimentary pigments. Results indicated that Dove Sound has undergone eutrophication and the primary producer community structure has shifted from dominantly macrophytic to a system that supports substantial algal production. While septic waste was a possible source for eutrophication, low δ15N did not support this conclusion. However, the timing of the shifts in Dove Sound along with indicators of anoxia leads to the conclusion that fragmentation caused by the construction of a railroad was the root cause. The hydrologic fragmentation reduced the flushing rates, thereby enhancing anoxic conditions in the system and increasing the internal nutrient loading