How Animal Intelligence Helps Us Speculate About the
Arik Kershenbaum on the Role of Evolutionary Biology
in Brain Development
Much of our uncertainty over what alien intelligence will be like arises from our uncertainty about the nature of intelligence on Earth. With regards to this, scientists have suggested at least two possibilities. Is intelligence a general capability, something that can equally well be put to use for wildly different challenges; for instance, both to solve equations and to catch a flying tennis ball? Or is intelligence made up of multiple different specific skills; one for solving equations, and one for catching balls? If intelligence is general, then we can all perform all tasks requiring intelligence, but some people will be better than others.
Alternatively, if intelligence is specific, any particular type of intelligence could be completely absent in some species, and even in some individuals. What does it tell us that some animals (and humans) can catch balls with precision, but are hopelessly bamboozled by mathematics, and vice versa for others? For the record, my dog can do neither. His genius clearly lies in some as yet undiscovered field.
This question is crucial in understanding the nature of alien intelligence. If intelligence is a general (and universal) ability, varying only in degree, rather than in kind, we would expect intelligent aliens to be intelligent in much the same way as us.
However, if intelligence is based on specific abilities, and is linked to the specific problems an animal needs to solve—such as an archerfish accurately spitting out a jet of water to shoot down an insect perched above—then it is quite possible that alien intelligence will be based on experiences so fundamentally different from ours that mutual understanding between us, or even recognizing the presence of intelligence in the other, may, unfortunately, be impossible.
Scientists have pondered this dilemma for many years: do animals evolve a range of very specific intelligent abilities to solve specific problems in their environment, or is intelligence one general property that is widely put to use, including in solving those same specific problems? Like all dichotomies, this is almost certainly a false dichotomy, but nonetheless, the arguments for and against each have revealed a great deal about the different ways that evolution may and may not operate towards the development of intelligence.
It may seem obvious that different species have evolved different capabilities: living in water or on land, eating plants or chasing other animals, and so on. As the problems that needed to be solved in each of these very different niches are in themselves very different, those animals possess different “intelligences” for solving their particular problems. This seems uncontroversial on the face of it: the archerfish can accurately hit an insect, despite the refraction of light through the surface of the water; a bat can catch flying insects using a phenomenal capability to predict their movements in three dimensions; and a colony of leafcutter ants can construct a nest many meters deep that contains specialist chambers where the ants farm a specially domesticated fungus. Surely these are examples of different intelligences, and could not be considered variations on a single theme?
However, this position, taken to its logical conclusion, would argue that humans are not, in fact, more intelligent than jellyfish; we are just intelligent “in different ways.” This claim would be counterintuitive to most people; at the very least, we can say that humans appear to be intelligent in multiple different ways: we use logic to build scientific understanding of the world around us, create unique compositions of art and music, and use our social abilities to flourish in cities and countries consisting of millions of individuals.
Jellyfish, on the other hand, barely cut it in the “floating through the sea” category. But claiming that humans “must” be more intelligent than jellyfish is a somewhat circular argument: if we assume from the start that intelligence is “what we (humans) have,” then inevitably we will have more than other animals. A more objective approach is to look at what kind of intelligence we would expect to evolve and why, and then reassess how that property is distributed throughout our ecosystem.
The argument that there is a single kind of intelligence that varies between species primarily in degree, rather than in type, rests largely on an observation from the study of human psychology, something that has been somewhat tentatively observed in other animals too. Psychologists suggest that many different measures of intelligence appear to be correlated with each other. People who are good at maths tend to also be good at languages and music. This (they say) implies that there is something in common going on in the brains of these “clever” people. But many of the original studies into “general intelligence,” or “g-factor” (dating back to the 1900s) have, since the 1980s, been largely debunked.
Testing human intelligence in a way that controls for upbringing, socio-economic status, and even the cultural biases of the tester is an area hugely fraught with difficulties. At best, human intelligence testing has been used naively, assuming a scientific objectivity that probably does not exist, and at worst it has been used maliciously to promote division and racism.
The idea that it is possible to achieve a single number like “IQ” (an Intelligence Quotient) that summarizes an individual’s intelligence is controversial. Does it make sense to extend the idea of IQ tests to animals, which have evolved to solve different kinds of problems, and use different kinds of information to humans? The idea seems farcical. Anyone who has seen videos of an octopus unscrewing the cap of a jar from within, has a feeling that this animal cannot be anything other than intelligent, but no IQ test would capture the nature and extent of that intelligence, and how similar it is to human intelligence, or how different.A more objective approach is to look at what kind of intelligence we would expect to evolve and why.
The proponents of general intelligence do make one important point related to the evolution of intelligence, which we have to take seriously. Much intelligent behavior depends on a few core abilities, specifically: learning, memory and the ability to make decisions. These abilities are ostensibly rather simple but seem to be necessary for many of the intelligent tasks that animals, including us, perform. We know that it is possible to train a huge variety of species to “learn” certain behaviors, from rats finding their way around a maze, to fish that can recognize faces. The same psychological techniques that you use to teach your dog to sit can be used to teach a chicken to skateboard.
Famously, Ivan Pavlov observed in 1897 that dogs could be conditioned to respond to a completely neutral signal—a ringing bell—as if it indicated that a reward was expected. The dogs salivated when they heard the bell, because they had come to associate one with the other. But a bell has nothing to do with food, so this cannot be an instinctive or evolutionarily innate response. And yet, what could be more evolutionarily useful? If you can predict the arrival of food using some signal that isn’t the food itself, you are clearly ahead of the game and have an advantage over your competitors.
In the years immediately following Pavlov, scientists uncovered another uncanny behavior that seems to be shared by almost all animals: an animal can learn to change its behavior to produce a favorable outcome—even if that behavior itself is neutral. No one is surprised that a dog can discover food by searching for food—that’s just evolutionary adaptation. But you can also teach a dog to sit by rewarding her with food. The fact that a dog can learn to get food by sitting is exceptional. Sitting has nothing to do with searching for food—it is behaviorally neutral. Clearly, the dog has associated its own response to the command “sit” with the arrival of food. It has learned, and it has learned a way to get food by being flexible. And that kind of flexibility seems to be a key part of what it means to be intelligent.
Amazingly, the ability to learn in this way seems exceptionally widespread across animals on Earth. Mammals like dogs and monkeys learn, as do birds that recognize predators by watching the responses of other birds, and fish that identify good feeding patches from the feeding success of other fish. Even insects learn, despite the fact that insect brains are minuscule.
Researchers recently trained bees to “play football” by manipulating a small ball into a “goal” to get a sugary reward. The ubiquity and diversity of learning among animals on Earth—as well as its obvious evolutionary benefits—make it seem almost certain that the ability to learn to associate certain actions with certain outcomes is a universal feature of intelligence. If alien animals have evolved intelligence to solve problems on alien planets, then they must have evolved the ability to associate actions and outcomes. Associative learning, as it is called, must be universal.
“Learning” is an appealing criterion for intelligence. We do not generally consider animals to be intelligent if they are following purely instinctive drives. A frog that catches an insect with its tongue is undoubtedly doing something “clever,” but on the other hand, it is “merely” performing instinctive behaviors. The flexibility involved in learning something new is clearly distinct from this—and is something that intuitively feels like a prerequisite for intelligence. Is this, then, a universal definition? Intelligence is learning, no more, for animals on Earth and for aliens as well?
Most evolutionary biologists would not accept that we have reached the end of this particular enquiry. Observing animals in the real world reveals a very different picture from those that came out of the sterile laboratories of Pavlov and his intellectual descendants in the first half of the 20th century. The image of white-coated scientists with clipboards watching rats running around a maze may be a huge part of our cultural perception of science, but it portrays only a part of the picture. In the logical desire to drill down to the most basic of behaviors, and to remove all possible distracting and irrelevant information, scientists placed animals in highly controlled environments and presented them with very specific tasks. Scientific experiments are always simplified, but that can sometimes be misleading.
Animals did not evolve in a university laboratory, but in the outside world, where sensory stimuli wash over them with dizzying diversity and, crucially, with conflicting information. Rats in the real world never have to choose between two identical paths, left and right, and they certainly did not evolve to do so. The results that come from studying animal behavior in the wild often clash with those from the psychology laboratories, and arguments about the validity of these experiments continue to this day.
A key piece of evidence in our search for what is universal about intelligence is that in the wild different animal species behave very differently to each other. The mental skills needed for a chimpanzee to survive in the forests of East Africa are quite different from those needed by a crow on the island of New Caledonia in the South Pacific. Both are intelligent—among the “most” intelligent animals on the planet—but do they both have the same kind of intelligence? Studying animal behavior in the wild raises two problems with the idea that intelligence is no more than a general learning capability.
Firstly, looking at the incredibly advanced and complex behaviors of animals like the chimpanzee and the New Caledonian crow casts doubt on the idea that all the intelligence in the animal world could result from some kind of shared ability. In 1960, Jane Goodall described how chimpanzees fashioned tools out of sticks, to extract termites from a nest. With this discovery, she rocked the foundations of supposed human uniqueness—we used to think that we were the only species that used tools!
And Goodall’s discovery opened the floodgates. New Caledonian crows are rather unremarkable-looking birds that live on the French colony of New Caledonia in the South Pacific. They too make tools, taking twigs and using their beaks to get them into the right shape for extracting insects from holes in logs. Furthermore, these crows have recently been shown to have another, even more surprising skill.Animals did not evolve in a university laboratory, but in the outside world, where sensory stimuli wash over them.
They can make tools, to make other tools. In these experiments (admittedly, in a laboratory setting) the birds used a short stick to retrieve a longer stick that was necessary to get at food. These crows can also choose between tools that are likely to work, and those that won’t, and can even fashion tools into different shapes with their beaks depending on the nature of the problem facing them. It isn’t just that we aren’t the only ones making tools, we aren’t even the only ones using technology.
That this is intelligence, there can be no doubt. But consider that tool-using chimpanzees and crows last shared a common ancestor 320 million years ago, at a time when the land was dominated by giant fern forests and giant insects, with dragonfly-like creatures up to a meter across.
All mammals, from shrews to whales, as well as all modern reptiles and birds, share this same common ancestor. If intelligence comes from a common ancestor, it should be found in all (or at least most) of its descendants. Why aren’t all birds, mammals, and reptiles that intelligent? Is it likely that the intelligence of the chimpanzee and the New Caledonian crow is inherited from this ancient ancestor, and that intelligence just withered away in the vast majority of other families of animals, like lizards, turtles, canaries, opossums, and wildebeest?
Of course not. The only sensible explanation is that both chimps and crows evolved their exceptional intelligence afresh, as did many other species, including dolphins that cooperate to herd fish into shallow water, capuchin monkeys that use rocks to crack nuts, and of course humans, with all of our problem-solving capabilities. Intelligence evolves all the time to fit specific needs—it is not merely an inherited trait from the dawn of time. The patterns that we see here—intelligence evolving again and again and again to solve different problems in different domains—are a compelling indication that alien animals too will evolve problem-solving intelligence, on different planets throughout the galaxy. Earth creatures are not so uniquely special and smart.
Excerpted from The Zoologist’s Guide to the Galaxy: What Animals on Earth Reveal About Aliens—and Ourselves. Used with the permission of the publisher, Penguin Press, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2021 by Arik Kershenbaum.