OXYGEN-CONSUMPTION AND THE EVOLUTION OF ORDER - NEGENTROPY CRITERIA APPLIED TO THE EVOLUTION OF ANTS

Optimization of energy use by evolving organisms, predicted by theoret ical extensions of the neo-Darwinian theory, is contrasted with that o f irreversible thermodynamics, which predicts an increase in orderline ss and thus an increase in energy consumption per unit of biomass. We compared this index with estimates of social complexity among ant gene ra and species. Our results show that simple optimization models canno t explain experimental data, and that social complexity correlates dif ferently with negentropy at different levels of analysis. Comparing th e genera among Formicidae, workers (not colonies) from genera with hig hly social species are less negentropic than those of socially primiti ve ones. At the sub-generic level, social complexity correlated positi vely with negentropy among species, for major workers in Acromyrmex an d for minor workers in Atta. The results illustrate the complexity of thermodynamic criteria in the study of evolution but also hint at thei r usefulness. In this case, they show that two different evolutionary routes to the complex Attini ant societies may exist.