Alien life may be abundant in the universe. In the Milky Way alone, there could be as many as 10 billion potentially habitable planets. Extend this further, and the chance of extraterrestrial life existing becomes highly probable. But whether any lifeforms will evolve the intelligence required to communicate with us is another question. And if it did, would it be the sort of intelligence we could ever understand?

This was the focus of a workshop at the opening of the National Space Society's International Space Development Conference, which is currently taking place in Puerto Rico. Organised by METI International, talks focused on looking at the variety of intelligence on Earth – and trying to extrapolate how this might translate to intelligence on alien worlds.

Douglas Vakoch, president of METI International, told IBTimes UK that over the past 50 years, huge strides have been made in uncovering new planets. During this time, the search for extraterrestrial intelligence (SETI) has largely been dominated by radio astronomers. He believes that to take the search forward, there should be "rethinking what SETI means". While we understand far more about exoplanets and the extreme environments in which life on Earth can survive, "what we haven't caught up with is the real understanding of intelligence".

Allen Telescope Array
Allen Telescope Array used by SETI to detect radio waves from alien civilisations Colby Gutierrez-Kraybill/Flickr

The workshop brought together scientists from a variety of fields, including biologists, linguists and anthropologists. "The meeting asks people to look at patterns across intelligence to help us grapple with the question of how unique is human intelligence when you compare it to other species. Some of the big take-home points are that first of all we should be wary of assuming intelligence on other worlds is going to engage with the environment in the way we do here on earth," Vakoch said.

One of the talking points looked at how human intelligence evolved – a question we still do not know the answer to, but one which will be fundamental to understanding life on other planets. In her paper, University of Arizona biologist Anna Dornhaus looks at the possibility sexual selection played a bigger role in the evolution of human intelligence than natural selection.

Sexual selection says our big brains are an "exaggerated trait unnecessary for survival but impressive to potential mates", she said. "We don't really understand why we need a brain as big as ours. In hindsight, now that we have populated the whole planet, and paved everything with asphalt, it seems obvious that it made us the dominant lifeform. But at the time we evolved these larger brains, that wasn't really the case. Humans were a very low population size and it's really not clear why evolving those larger brains somehow gave us an edge over other animals."

Another possibility is the social brain hypothesis, which says that as we started living in larger groups, we needed larger brains to track social relationships and what they meant to an individual. However, Dornhaus says there are problems with both of these scenarios. Neither allows for predicting which animals will evolve intelligence.

peacock tail sexual selection
Human intelligence could be as rare as the occurrence of a peacock's tail mika/Flickr

"If it is sexual selection then the trait that's chosen by evolution is incredibly arbitrary – any trait potentially works possibly – colourful plumage, difficult songs for birds. All of these things have been sexually selected. What they have in common is that they're costly and are hard to do. And so is growing a brain.

"If we're talking about aliens, extraterrestrial intelligence, we have to somehow be able to extrapolate. We have to be able to say we understand why humans got these bigger brains. And because we understand that we can now predict – for another organism that we know nothing about – whether they're going to be intelligent or not. If we can't even predict if another species on Earth is going to be intelligent, based on the hypothesis of why humans evolved intelligence, then our chances of predicting it for aliens are pretty slim.

"If [sexual selection] is true, then we should expect cognitive ability, i.e., learning, memory, abstraction, and many other elements of intelligence to be commonplace in the galaxy as they are among organisms on Earth; but 'exaggerated' intelligence as in humans may be a rare accident of chance, as rare as a peacock's tail."

So what are the chances of finding an alien civilisation with human-like intelligence? "There's often been this view among astronomers and physicists that there's almost something inevitable about intelligence," Vakoch said. "Once you have life – it's been adaptive here on Earth, it worked for human beings – it could well work on other planets. But biologists will tell how contingent intelligence is. I think in one sense the work we're seeing is how it may be much more difficult to find other intelligence, it may be much rarer."

Dornhaus agrees. She said the way biologists define intelligent behaviour is "not necessarily human intelligence". This would include behaviour like problem-solving, seen in all walks of life from insects to monkeys. "That is really abundant on Earth," she said. "I think that is likely to happen – if we find any alien lifeforms of any kind, I think they will have smart problem-solving, like any organism on Earth.

"However, the kind of smart intelligence that we have seems extremely in excess to what any other animal appears to need. From a biologist's point of view, humans are really an extreme oddity. If we use that to predict anything, I think we should be an oddity in space as well. I don't think we will find anything that will have the mental ability that we have."

Vakoch is more hopeful, but says the chances of having an intelligible conversation will rely on creating messages that can be understood by a host of varying lifeforms. And to do that, ideas of intelligence must continue to be addressed. "In this new approach, we're putting the intelligence back into SETI," he said.

Furthermore, Vakoch said it is an "exciting time" to be searching for aliens. A number of privately funded initiatives, like the recently announced Breakthrough Starshot, have led to a huge influx in support for SETI, while advanced telescopes should make the detection of life elsewhere in the universe all the more possible. Missions currently being planned could lead to the discovery of microbial or more complex life within the coming decades. "But of course with SETI, the detection could be today," he added.