Cheating on the Edge

We present the results of an individual agent-based model of antibiotic resistance in bacteria. Our model examines antibiotic resistance when two strategies exist: “producers”–who secrete a substance that breaks down antibiotics–and nonproducers (“cheats”) who do not secrete, or carry the machinery associated with secretion. The model allows for populations of up to 10,000, in which bacteria are affected by their nearest neighbors, and we assume cheaters die when there are no producers in their neighborhood. Each of 10,000 slots on our grid (a torus) could be occupied by a producer or a nonproducer, or could (temporarily) be unoccupied. The most surprising and dramatic result we uncovered is that when producers and nonproducers coexist at equilibrium, nonproducers are almost always found on the edges of clusters of producers

Zoomed-in version of upper left hand section of a snapshot at generation 1000.

<p>B/C = 0.62, help = 0.09. Red lines outline some cases in which nonproducers exist at the boundary between empty space and clusters of altruists. In all figures, yellow = nonproducers, green = producer, white = empty slot.</p

Two-dimensional snapshots of the 10,000 slot torus.

<p>B/C = 0.56, help = 0.19. a) Generation 1, b) Generation 10, c) Generation 20, d) Generation 40, e) Generation 300 and f) Generation 1000. Note that for generations 1–999, any yellow (nonproducers) cells surrounded by only yellow or by only yellow and white cells would die and be replaced the next generation.</p

Two-dimensional snapshots of the 10,000 slot torus.

<p>B/C = 0.62, help = 0.14 (this “help” value was chosen, in part, as the result of unpublished experimental work on β–lactamase secretion in producer cells). a) Generation 1, b) Generation 10, c) Generation 20, d) Generation 40, e) Generation 300 and f) Generation 1000. Note that for generations 1–999, any yellow (nonproducers) cells surrounded by only yellow or by only yellow and white cells would die and be replaced the next generation.</p

Notas para uma aproximação entre o neodarwinismo e as ciências sociais Notes on an approximation between neo-Darwinism and the social sciences

O objetivo deste trabalho é apresentar a psicologia evolutiva, uma ciência que procura compreender a mente humana (cultural, social, histórica) como produto de processos biológicos e evolutivos, e a memética, uma teoria ainda incipiente que pretende tratar a informação cultural e as próprias tradições como complexos de idéias, que usam os cérebros humanos para se reproduzirem. Essas duas novas abordagens pretendem contribuir para integrar as ciências biológicas e as ciências sociais.<br>Evolutionary psychology is a science that endeavors to understand the human mind (cultural, social, historical) as a product of biological and evolutionary processes. Memetics is an incipient theory that views cultural information and traditions as sets of ideas that reproduce themselves within the human brain. The article introduces these two new approaches and explores how they intend to contribute to the integration of the biological and social sciences

Teaching Bioeconomics

Bioeconomics is a relatively young field that uses an expanded microeconomics to examine animal behavior, human behavior, and animal and human social institutions. A voluminous literature is rapidly accumulating. There are as yet no standard textbooks, but there are several excellent books and/or articles that can be used in combination with videos and other aids to make a course that students will enjoy and that teachers can use to advance the frontiers of scholarship in economics and biology. Copyright Springer 2005altruism, conflict, cooperation, evolution, game theory, institutions, rationality,