Historically, our measures of nonhuman intelligence has looked like this:
Physical measurements: brain to body ratio, brain structure/convolution/neural density, presence of artifacts and physical tools
Observational and sensory measurements: sensory signals, complexity of signals, cross-modal abilities, social complexity
Data mining: information theory, signal/noise, pattern recognition
Experimentation: memory, cognition, language comprehension/use, theory of mind
Direct interfaces: one way and two way interfaces with primates, dolphins, birds
Accidental interactions: human/animal symbiosis, cross-species enculturation
But these are mostly "human-like" attributes and measures. Most scientists are often reluctant to consider other types of intelligence that may not have human analogues.
"[Our] abilities to profile 'types' of intelligence that differ on a variety of scales is weak," writes Herzing. "Just as biologists stretch their definitions of life to look at extremophiles in unusual conditions, so must we stretch our descriptions of types of minds and begin profiling, rather than equating, other life forms we may encounter."
Intelligence is COMPLEX
To that end, Herzing has proposed a new approach to profiling a variety of nonhuman intelligences along multiple dimensions. Called COMPLEX (COmplexity of Markers for Profiling Life in EXobiology), it looks like this:
EQ: Encephalization Quotient
CS: Communication Signal complexity
IC: Individual Complexity
SC: Social Complexity
II: Interspecies Interaction
For example, dolphins have a high encephalization quotient, they engage in complex communication, and have big brains. The octopus is capable of associative learning, tameness, and exploratory behavior. Bees have collective intelligence, a symbolic waggle dance, and are capable of counting and learning. Even bacteria can exhibit complex behavioral responses without having to evolve complex brains. As for machine intelligence, namely AI, it demonstrates intelligence via neural networks, computational power, and algorithms.
To scale these markers, Herzing used a small set of taxa devised by biologists Lori Marino and Kathryn Denning. Each category was scored by experts on a scale from 1 to 10. Using this system, dolphins scored high in most categories, bees and machines scored relatively high in both the Communication Signal and Social Complexity categories, and microbes scored high in terms of Interspecies Interaction.