Cognitive Exaptations for Extraterrestrial Intelligence

Peter M. Todd
Indiana University, USA

All terrestrial organisms have evolved to solve concrete physical tasks such as finding constituent chemicals, energy sources, and shelter, and avoiding threats such as predators, parasites, and toxins.  However, only a few species have evolved cognitive mechanisms for dealing with more abstract information-processing challenges – analogous to human ‘general intelligence.’  The space of possible cognitive mechanisms that could support general intelligence might seem vast and unconstrained, making it hard to predict the likely psychology of ETIs.  Yet in even the most abstract cognitive mechanisms, we can often see traces of the physical task-solving adaptations from which they evolved. 

Given new selection pressures, adaptations that evolved originally to serve one function are often copied, modified, and re-purposed to serve new functions, resulting in ‘exaptations.’  We argue that many information-processing adaptations are exaptations of mechanisms initially evolved to deal with challenges of the physical environment. Physical-task adaptations like foraging strategies may often be exapted to deal with more abstract, strategic social and sexual tasks in group-living species with mating markets, and then further exapted to deal with still more abstract, higher-level cognitive tasks such as conceptual reasoning, symbolic communication, technological innovation – while still retaining hints to their ancestral origins and functions.  This ‘cognitive turn’ from physical domains through socio-sexual domains to abstract cognitive domains may characterize not just the evolution of terrestrial social primates over 70 million years, but also the emergence of many ETIs.  Common types of exaptations that may be useful in understanding how life-forms could advance through this cognitive turn to achieve intelligence include:

Search: Organisms evolve to search efficiently for fitness affordances, balancing exploring new areas versus exploiting familiar areas. These explore/exploit search strategies can generalize from spatial search to socio-sexual domains (searching for mates or reliable friends) and then to more abstract domains (searching episodic memory, exploring strategic alternatives). 

Sequential behavior: Organisms evolve sequencing mechanisms to control complex physical movements (dismembering prey, building nests); these may be exapted to socio-sexual domains (controlling multi-step courtship rituals or offspring-grooming bouts) and then to cognitive/communicative domains (e.g., speaking sentences, telling stories, planning/reasoning).

Behavioral immune systems: Larger organisms evolve to avoid infestation by smaller pathogens, partly through a ‘behavioral immune system’ that avoids exposure to pathogens. Anti-pathogen disgust (e.g., avoiding germs in rotting meat or corpses) works at the physical level. But the emotional machinery of disgust has been exapted to serve social functions (‘moral disgust’ to avoid bad clan-mates) and sexual functions (‘sexual disgust’ to avoid bad mates). At a more abstract level, ‘intellectual disgust’ may reduce exposure to bad ideas: stupid memes, unreliable factoids, fallacious arguments – helping intelligent species avoid epistemological pitfalls.

Such exaptation pathways – the evolutionary repurposing of cognitive mechanisms from physical to socio-sexual to abstract domains – may be especially common ways for alien life forms to reach the general intelligence levels necessary for large civilizations and advanced technologies.  Thus, cognitive exaptations may be useful units of analysis for considering the likely origins and functions of thoughts, feelings, and preferences in other intelligent species.


Peter M. Todd is Provost Professor at Indiana University in the Cognitive Science Program, the Department of Psychological and Brain Sciences, and the Center for Complex Systems and Networks Research. He grew up in Silicon Valley, received a Ph.D. in psychology from Stanford University, developed artificial life models during a postdoc at the Rowland Institute for Science, and in 1995 moved to Germany to help found the Center for Adaptive Behavior and Cognition (ABC), based at the Max Planck Institute for Human Development in Berlin. The Center's work on decision making was captured in the books Simple Heuristics That Make Us Smart (OUP, 1999) and Ecological Rationality: Intelligence in the World (OUP, 2012). Todd moved to Indiana University in 2005 where his research focuses on the evolved cognitive mechanisms that people and other animals use to make decisions about adaptively important resources—including mates, information, and food—in space and time. His most recent book is Cognitive Search: Evolution, Algorithms, and the Brain (Todd, Hills, and Robbins, eds.; MIT Press, 2012). He is currently serving as the first Director of the IU Food Institute.