Sergey Gavrilets has coauthored a recent paper in PNAS called “Collective action and the evolution of social norm internalization.” Following social norms can sometimes be costly for individuals if norms require sacrifice for the good of the group. The study sheds light on the power of norms and the origins of cooperation. Read the NIMBioS press release about the article, here.
Sergey Gavrilets has a new open-access paper in PNAS, which is getting a great deal of media attention in places like Nature (links below). The paper is entitled, “War, space, and the evolution of Old World complex societies.”
Significance: How did human societies evolve from small groups, integrated by face-to-face cooperation, to huge anonymous societies of today? Why is there so much variation in the ability of different human populations to construct viable states? We developed a model that uses cultural evolution mechanisms to predict where and when the largest-scale complex societies should have arisen in human history. The model was simulated within a realistic landscape of the Afroeurasian landmass, and its predictions were tested against real data. Overall, the model did an excellent job predicting empirical patterns. Our results suggest a possible explanation as to why a long history of statehood is positively correlated with political stability, institutional quality, and income per capita.
Press Coverage:
| Austrian Tribune | Nature |
| The Conversation | Pacific Standard |
| El Mundo | Popular Mechanics |
| Huffington Post | Science World Report |
| Los Angeles Times | Smithsonian |
| National Monitor | Wired |
Research Assistant Professor Alison Boyer was interviewed today on local NPR station WUOT about her recent PNAS paper about extinctions of birds on Pacific islands. The interview can be heard here.
UTK Distinguished Professor Sergey Gavrilets’ work on the evolution of monogamy, published in PNAS, has been featured in an article in the online magazine Slate. In his model, low-ranked males begin providing resources to females, who begin selecting them rather than higher-ranked males. Such behavior then becomes optimal for males higher and higher up the hierarchy.
UTK Distinguished Professor Sergey Gavrilets’ work on the evolution of monogamy, published in PNAS, has been featured in an article in the online magazine Slate. In his model, low-ranked males begin providing resources to females, who begin selecting them rather than higher-ranked males. Such behavior then becomes optimal for males higher and higher up the hierarchy.
UTK Distinguished Professor of Ecology & Evolutionary Biology and Mathematics Sergey Gavrilets recently published a paper in PNAS on the evolutionary origins of egalitarianism. It shows why individuals may be selected for interfering in a conflict between a bully and a victim on the side of the victim.
Abstract:
The evolutionary emergence of the egalitarian syndrome is one of the most intriguing unsolved puzzles related to the origins of modern humans. Standard explanations and models for cooperation and altruism—reciprocity, kin and group selection, and punishment—are not directly applicable to the emergence of egalitarian behavior in hierarchically organized groups that characterized the social life of our ancestors. Here I study an evolutionary model of group-living individuals competing for resources and reproductive success. In the model, the differences in fighting abilities lead to the emergence of hierarchies where stronger individuals take away resources from weaker individuals and, as a result, have higher reproductive success. First, I show that the logic of within-group competition implies under rather general conditions that each individual benefits if the transfer of the resource from a weaker group member to a stronger one is prevented. This effect is especially strong in small groups. Then I demonstrate that this effect can result in the evolution of a particular, genetically controlled psychology causing individuals to interfere in a bully–victim conflict on the side of the victim. A necessary condition is a high efficiency of coalitions in conflicts against the bullies. The egalitarian drive leads to a dramatic reduction in within-group inequality. Simultaneously it creates the conditions for the emergence of inequity aversion, empathy, compassion, and egalitarian moral values via the internalization of behavioral rules imposed by natural selection. It also promotes widespread cooperation via coalition formation.
It has also garnered widespread press coverage:
Los Angeles Times: Evolution stands up to bullies
http://www.latimes.com/news/science/sciencenow/la-sci-sn-stop-bullying-20120813,0,7921942.story?track=rss
Health: Fight the Power: Standing Up to Bullies Benefits Us All
http://news.health.com/2012/08/13/standing-up-to-bullies-benefits-society-study-suggests/
Knoxville New Sentinel: Science and bullying: Why we are programmed to help others
Tennessee Today: UT, NIMBioS Study Finds Bullies Squelched When Bystanders Intervene
http://www.utk.edu/tntoday/2012/08/13/ut-nimbios-study-bullies-squelched/
Decoded Science "Egalitarian Drives as a Response to Bullying"
https://evolution-institute.org/egalitarian-drives-as-a-response-to-bullying/
Discover Magazine: Against the Übermensch
http://blogs.discovermagazine.com/gnxp/2012/08/against-the-ubermensch/
Examiner.com: Bullying intervention is genetically evolutionary 'right thing to do’
http://www.examiner.com/article/bullying-intervention-is-genetically-evolutionary-right-thing-to-do
United Press International: Fighting bullies pushed evolution
http://www.upi.com/Science_News/2012/08/14/Study-Fighting-bullies-pushed-evolution/UPI-73181344980881/?spt=hs&or=sn
Piteå-Tidningen (Sweden): Thus arose the sense of equality
French Tribune: Standing against Bullying is in Genes
Folha de S. Paulo (Brasil): O altruísmo egoísta
http://teoriadetudo.blogfolha.uol.com.br/2012/08/14/o-altruismo-egoista/
Korea Herald: Fighting bullies pushed evolution
http://view.koreaherald.com/kh/view.php?ud=20120815000175&cpv=0
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http://www.ria.ru/science/20120813/722911416.htm
Alison Boyer, Research Assistant Professor in the UTK EEB department, recently coauthored a paper in PNAS on the drivers and hotspots of extinction risk in marine mammals.
Abstract:
The world’s oceans are undergoing profound changes as a result of human activities. However, the consequences of escalating human impacts on marine mammal biodiversity remain poorly understood. The International Union for the Conservation of Nature (IUCN) identifies 25% of marine mammals as at risk of extinction, but the conservation status of nearly 40% of marine mammals remains unknown due to insufficient data. Predictive models of extinction risk are crucial to informing present and future conservation needs, yet such models have not been developed for marine mammals. In this paper, we: (i) used powerful machine-learning and spatial-modeling approaches to understand the intrinsic and extrinsic drivers of marine mammal extinction risk; (ii) used this information to predict risk across all marine mammals, including IUCN “Data Deficient” species; and (iii) conducted a spatially explicit assessment of these results to understand how risk is distributed across the world’s oceans. Rate of offspring production was the most important predictor of risk. Additional predictors included taxonomic group, small geographic range area, and small social group size. Although the interaction of both intrinsic and extrinsic variables was important in predicting risk, overall, intrinsic traits were more important than extrinsic variables. In addition to the 32 species already on the IUCN Red List, our model identified 15 more species, suggesting that 37% of all marine mammals are at risk of extinction. Most at-risk species occur in coastal areas and in productive regions of the high seas. We identify 13 global hotspots of risk and show how they overlap with human impacts and Marine Protected Areas.
A recent paper in the Proceedings of the National Academy of Sciences by Michael Bode, Lance Bode, and UTK EEB assistant professor Paul Armsworth examines a novel mechanism that maintains diversity in patchy habitats. Abstract is below. See the full paper here.
Abstract: The coexistence of multiple species on a smaller number of limiting resources is an enduring ecological paradox. The mechanisms that maintain such biodiversity are of great interest to ecology and of central importance to conservation. We describe and prove a unique and robust mechanism for coexistence: Species that differ only in their dispersal abilities can coexist, if habitat patches are distributed at irregular distances. This mechanism is straightforward and ecologically intuitive, but can nevertheless create complex coexistence patterns that are robust to substantial environmental stochasticity. The Great Barrier Reef (GBR) is noted for its diversity of reef fish species and its complex arrangement of reef habitat. We demonstrate that this mechanism can allow fish species with different pelagic larval durations to stably coexist in the GBR. Further, coexisting species on the GBR often dominate different subregions, defined primarily by cross-shelf position. Interspecific differences in dispersal ability generate similar coexistence patterns when dispersal is influenced by larval behavior and variable oceanographic conditions. Many marine and terrestrial ecosystems are characterized by patchy habitat distributions and contain coexisting species that have different dispersal abilities. This coexistence mechanism is therefore likely to have ecological relevance beyond reef fish.
EEB grad student Premal Shah (now a postdoc in the Plotkin lab at the U. of Pennsylvania) and his adviser, Associate Prof. Mike Gilchrist, recently published a paper in the Proceedings of the National Academy of Sciences on “Explaining complex codon usage patterns with selection for translational efficiency, mutation bias, and genetic drift.”
Abstract: The genetic code is redundant with most amino acids using multiple codons. In many organisms, codon usage is biased toward particular codons. Understanding the adaptive and nonadaptive forces driving the evolution of codon usage bias (CUB) has been an area of intense focus and debate in the fields of molecular and evolutionary biology. However, their relative importance in shaping genomic patterns of CUB remains unsolved. Using a nested model of protein translation and population genetics, we show that observed gene level variation of CUB in Saccharomyces cerevisiae can be explained almost entirely by selection for efficient ribosomal usage, genetic drift, and biased mutation. The correlation between observed codon counts within individual genes and our model predictions is 0.96. Although a variety of factors shape patterns of CUB at the level of individual sites within genes, our results suggest that selection for efficient ribosome usage is a central force in shaping codon usage at the genomic scale. In addition, our model allows direct estimation of codon-specific mutation rates and elongation times and can be readily applied to any organism with high-throughput expression datasets. More generally, we have developed a natural framework for integrating models of molecular processes to population genetics models to quantitatively estimate parameters underlying fundamental biological processes, such a protein translation.
The Jim Tanner award for outstanding dissertation was given to Premal Shah. One of Premal’s dissertation chapters (coauthored with advisor Michael Gilchrist) will be appearing in a future issue of PNAS.