We've seen that microbial life started on the Earth within the first half-billion years after the Earth formed. When conditions were very inhospitable. It could be argued that it's likely that microbes will form on a habitable planet. In which case, we might expect to see microbes elsewhere on many of the habitable worlds currently being found by planet hunters. If we found microbes on another planet, people would get excited, scientists particularly, but maybe the excitement would fade. Perhaps what would really get us excited is the discovery of creatures like us, or at least akin to us, creatures of much higher function and form that have intelligence, or sentience, or self-awareness. What is the role of intelligence in the universe in terms of the evolution of life? As with the general question, we have no idea but it helps to take a slightly broader view of intelligence among the creatures on this planet without claiming that they're intelligent in any way, even plants have complex capabilities and ways of responding to their environment that seen from afar shows a signature perhaps of intelligence. To the people who study them, social insects are fascinating and also illustrative of the fact that intelligence sometimes comes from the combine or the commune, rather than the individual. Social insects are capable of engineering marvels and fairly complex behavior. Even if this behavior is wired, it also shows the ability to adapt to the environment and change over time. Remember, the largest structures of the social insects rival in complexity and in size, scale to their size, are best structures. Communication among these creatures often takes place by chemical means, pheromones. Although this seems simplistic, if we take a social insect colony, the bandwidth and the sum of all the chemical communications, exceeds the conversation bit rate of two people talking. What's important here is that evolution doesn't stand still. There are many insect species on this planet, 300,000 species of beetles alone. What we might wonder is how natural selection will sculpt their behavior given sufficient time. What will this social creatures evolve to in their capabilities? Or what might they have evolved to if they developed on other planets? Moving up to more familiar creatures, the corvid family, which includes crows and ravens and their close cousins the parrots, have shown signs of significant intelligence. Not only being able to learn the rudiments of human language and a significant vocabulary, but in some cases even abstract concepts, or the ability to construct words from individual pieces. People who work with small mammals, rodents for example, understand that rats have distinct personalities, can anticipate punishment and reward. They have the ability for metacognition and this is quite a high-level behavior for any creature, the ability to think about your own thinking process. We think we're special in the realm of intelligence, but in terms of brain mass relative to body mass, we're not off the charts smart. We're on a continuum with other creatures on the planet and in fact, our brains are actually smaller than some of the marine mammals. Also, brain mass itself is a poor guide to complexity. It's the level of cortical folding and complexity in the structure of the brain that really dictates these results in intelligence. In this situation, all you need to know is that the Caledonian crow called Betty, had never been in the situation before. Crows in the wild do poke sticks into holes in trees to get bugs and ants for food. But in this situation, the crow is confronted with a cylinder containing one of its favorite objects, meat, in a small basket with no way to get the meat. The crow also had a wire and had never encountered a wire before. There was a slot in the base of the jar holding the meat and you can see what happens. Crows and other animals like otters display tool use, something that humans developed that epitomizes them as the most advanced species on the planet. What about the comparison to orcas or killer whales, which people who work with them will say are highly sophisticated animals. The comparison doesn't always favor us. Both orcas and humans have no natural enemies. Their only natural enemy is in fact us. They have very large brains, they have complex language. The orca pods in the Puget Sound, have been shown to have different dialects among the different family groupings that move around that large body of water. They're highly social animals, raising their children and educating them for substantial fraction of their lives. They mate for life, something that can't always be said about humans. Perhaps the only difference, is they don't have opposable thumbs since they have never developed the technology that graces our civilization. In all the branching points and contingencies in the history of evolution, something apparently extraordinary happened after 4 billion years of evolution of life on Earth. Apes developed the ability to walk upright and work in small social groups, both to farm and herd animals and harvest the food and energy they needed from the natural environment. They roamed around the planet, radiating from a center point in Africa around the world and a few tens of thousands of years. These are our precursors humans. To take a cosmic perspective on our recent evolution, let's compare ourselves to dolphins and toothed whales, where we can study skull casings which given indication of brain size. Looking at 50 million years of primate and marine mammal evolution, what we see is steady growth in the brain size of the marine mammals. What happened with the primates was different. Steady but slow growth from very small brains and a recent surge, most of which has occurred in the last 0.5 million years, doubling our brain size to vault us to the top of the evolutionary pile. If intelligent aliens had visited the Earth, virtually anytime in the last 50 million years and asked where the brainiest creatures were, the answer would have been in the oceans not on the land and not with our ancestors. Even as we search for alien life forms in the universe, perhaps the aliens are among us. Cephalopods deviated from us in the tree of life almost 300 million years ago, a quite different branch. They function quite differently with distributed brains, a central node at the top of their bodies and subsidiary brains one on each arm. This allows for example, an arm when it's severed to continue moving over the sea floor and even changing its camouflage as a distraction. In addition to the distributed processing power of this cephalopod brain, they also have an extraordinary coloration mechanism. Cephalopod skins consist of a 100 million or more chromatophores, which are able to change color 10 times a second, over a full palette of the spectrum, even though cephalopods are colorblind. Not only that, but the skin can also change its texture or rugosity. So cephalopods are observed to take the texture of smooth stones, or planks of wood, or rusty iron filings. It's an amazing capability. Because they're solitary creatures, it's very hard to understand their true intelligence. But they've been known to lead divers on wild goose chases through the three-dimensional labyrinth of a coral reef occasionally coming back to rescue the divers when they seem to be lost. These are extraordinary creatures that we barely understand the aliens among us. Without an ability to communicate with these species, we can only speculate as to their inner lives. Just how smart are humans compared to other species on the planet? We're undoubtedly attached to our own exceptionalism and there's no doubt that large brains and opposable thumbs have taken us to a preeminent position on the planet, able to bend it to our will. But going down the spectrum of animals, there are significant capabilities. Probably any creature with a central nervous system can experience pain. Sentience is limited to perhaps a smaller number of creatures. We have evidence of problem-solving and use of tools in a set of about a dozen or so mammals. Moving up the spectrum to the largest marine mammals, there are large brains and very complex behavior. We can only speculate what the inner lives of these creatures are. Part of the problem is the difficulty of communication. Dolphins and killer whales or orcas, have been taught how to make communication with humans in large tanks by tapping symbols on the side of the pool and being trained into how to use them. But that's making marine mammals communicate on our terms. We have no idea how their own language works and the same is true for other creatures such as cephalopods. We can't even communicate with the apes, with whom we share 99 percent of our DNA. Dolphins are exquisitely adapted creatures whose evolutionary form has not changed for 10 or 15 million years. They're so perfectly adapted, they don't need to evolve much. Again, we don't know what goes on in their lives. Do they have qualia, which is what philosophers define as the particularly human attribute of knowing what the color red is, or of experiencing a sunset, or being able to communicate an emotion that we feel to somebody else. We simply don't know. There may be intelligent creatures on other planets, but as some people have pointed out, if we traveled light-years from the Earth to an Earth-like planet and found something like an elephant, or a dolphin, or an orca there, we'd think it was so marvelous that we do everything we could to learn about it, protect it and celebrate it. But we already have the dolphins, we already have the orcas, we already have the elephants, right here. We are almost certainly the most intelligent creatures on the planet. But the diversity of intelligence and the way it operates among species on this planet, is worth studying more closely because what evolution might have led to on other planets in the universe, could be equally diverse and more so, we've probably underestimated the intelligence of some of the core denizens of the planet, simply because we don't have the ability to communicate with them.
