ANTHROPOLOGY
Articulated inhumation from Vlasac, Serbia.
Prehistoric microbiomes and transition to agriculture
The collections of commensal microbes living in the human mouth vary by population and, in addition to reflecting diet, can drive health and disease. During the transition from foraging to farming in the Neolithic Period, the human diet significantly changed. Claudio Ottoni et al. reconstructed ancient oral microbiomes and report a microbial species that expanded in concert with the expansion of agriculture in two regions of Southern Europe: the Balkans and Italy. The authors reconstructed the oral microbiomes of 44 individuals, spanning more than 10,000 years during the transition from foraging to farming, and sequenced ancient DNA from the dental calculus, or tartar. A species from the family Anaerolineaceae was the dominant oral microbe, and its genome records its geographic diversification over time. The authors observed only minor differences in the microbiomes of foragers and farmers, perhaps due to a gradual transition to agriculture. However, comparing the species of microbes represented in the prehistoric samples with oral microbiomes from the present revealed significant differences. According to the authors, these differences may have arisen, in part, due to the accumulation of antibiotic resistance pathways in the oral commensal species of present-day populations. — T.H.D.
EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES
Volatile chemicals drive ozone production in large cities
Air quality improvements in recent decades have significantly decreased motor vehicle emissions of volatile organic compounds (VOCs), thereby reducing ozone pollution. Currently, volatile chemical products (VCPs), which are emitted into the atmosphere from consumer and industrial products, contribute up to half of petrochemical VOCs in major urban areas. Matthew Coggon et al. report that VCPs are widespread in dense cities, substantially contribute to the formation of ozone, and can be identified by unique VOC fingerprints. The authors measured VOCs from a mobile laboratory in cities in the United States and Europe and from a ground site in New York City. Modeling revealed that VCPs may be as important as fossil fuel VOCs in terms of ozone formation. Emissions from fragranced VCPs, such as personal care and cleaning products, account for at least half of the ozone produced by VCPs. Moreover, the results suggest that additional chemical reactions are needed in air quality models to capture the atmospheric chemistry of VCPs. According to the authors, ozone mitigation strategies should account for the combined impacts of nitrogen oxides and VOC reductions at local and regional scales, as well as how these changes affect ozone formation during extreme heat events. — J.W.
ECOLOGY
Mangrove forest. Image credit: Pixabay/kmarius.
Functional diversity of mangrove invertebrates
Mangroves have dwindled at alarming rates worldwide. Although these ecosystems support a broad range of invertebrates, little is known about the impact of mangrove deforestation on the functional diversity and resilience of resident fauna. Stefano Cannicci et al. compiled a dataset of 209 crustacean species and 155 mollusk species from 16 mangrove forests around the world. The authors classified the species into 64 functional entities based on unique combinations of functional traits. More than 60% of the locations showed no functional redundancy on average, with most functional entities consisting of only one species. Comparison with other datasets revealed that mangrove ecosystems are among those with the lowest recorded faunal functional redundancy. On average, 57% of functional entities are fulfilled by a single species, suggesting that even a modest local loss of invertebrate diversity could significantly harm mangrove functionality and resilience. Moreover, the low functional diversity of the resident invertebrates indicates that mangroves are among the world’s most vulnerable ecosystems. According to the authors, studying the functional diversity of the resident faunal assemblages is crucial for assessing mangrove vulnerability to environmental change and for designing effective management, conservation, and restoration plans. — J.W.
SOCIAL SCIENCES
People at the periphery of social groups often sow the seeds of social change. This image—titled Amicitia, by artist Kirell Benzi—shows teenage social networks in 82 US communities. Each network, represented by a different color, presents the pattern of friendship connections, as determined by student questionnaires, in a particular community. Image credit: Kirell Benzi.
Well-connected members of tight-knit groups spread controversial ideas much more readily than “influencers”
Posted on July 30, 2021
Amy McDermott
The people who spread new and controversial ideas—changes in diet, exercise routine, political leaning, or even attitudes about vaccination—may not be the Kim Kardashians and Paris Hiltons. According to a recent study in Nature Communications, those with the most actual influence are often on the periphery of the social network. Coauthor and computational sociologist Douglas Guilbeault says that what makes these people special is that they are embedded in a tight-knit group with many connections to other tight-knit groups, even if each individual has fewer contacts than the most popular or famous person in the network.