Eusociality is the form of animal social organization with a reproductive division of labor, most prominently known from ants and bees. Here I ask the question why this enormously successful form of social organization is missing in the largest and most diverse group of vertebrates, the teleost fishes. I first briefly review the phylogenetic distribution and likely evolutionary origins of eusociality. Then, after an equally very brief review of the diverse life history strategies of teleosts, I conclude that it is (...) not the lack of evolutionary pre-adaptations which is keeping teleosts from becoming eusocial. Rather, I argue, that the absence of eusocial fish is caused by a number of differences between aquatic (chiefly marine) and terrestrial ecosystems: (1) Greater offspring dispersal in aquatic ecosystems reduces the role of kin-selection. (2) Lesser predictability of the environment at larger timescales in marine ecosystems disfavors eusociality. (3) A briefer impact of resource pulses in aquatic ecosystems will cause less evolutionary pressure towards cooperation, and eventually eusociality. Finally, I conclude by predicting that the most likely places to find eusocial fishes will be the deep-water regions of the ocean and the African rift lakes. (shrink)

With the advent of powerful parallel computers, efforts have commenced to simulate complete mammalian brains. However, so far none of these efforts has produced outcomes close to explaining even the behavioral complexities of animals. In this article, we suggest four challenges that ground this shortcoming. First, we discuss the connection between hypothesis testing and simulations. Typically, efforts to simulate complete mammalian brains lack a clear hypothesis. Second, we treat complications related to a lack of parameter constraints for large-scale simulations. To (...) demonstrate the severity of this issue, we review work on two small-scale neural systems, the crustacean stomatogastric ganglion and the Caenorhabditis elegans nervous system. Both of these small nervous systems are very thoroughly, but not completely understood, mainly due to issues with variable and plastic parameters. Third, we discuss the hierarchical structure of neural systems as a principled obstacle to whole-brain simulations. Different organizational levels imply qualitative differences not only in structure, but in choice and appropriateness of investigative technique and perspective. The challenge of reconciling different levels also undergirds the challenge of simulating and hypothesis testing, as modeling a system is not the same thing as simulating it. Fourth, we point out that animal brains are information processing systems tailored very specifically for the ecological niches the respective animals live in. (shrink)

I propose that a dishonest signaling system can be evolutionarily stable in eusocial animal societies if the amount of dishonesty is balanced by the chance of non-reproductive workers to advance to the reproductive caste in the future. I express this trade-off in a modified form of Hamilton’s rule, where I distinguish between the real and perceived cost of an altruistic act, and between the real and perceived genetic relatedness between colony members. Furthermore, I elaborate how the vertebrate neuromodulator oxytocin could (...) serve as an internal representation of the perceived cost of an altruistic act and of perceived relatedness. Behavioral and receptor localization data support this hypothesis. The encoding of cost and relatedness by oxytocin is likely integrated with a number of other functions related to social bonding. I conclude with a discussion of honesty in signaling, an outline of testable consequences of this hypothesis, and a comparison between vertebrate and insect eusociality. (shrink)