As yet another incarnation of the Star Trek franchise takes to the airwaves this week, devoted fans will be thrilled to set off on another continuing mission to seek out new life and new civilizations.
But why do so many of those aliens always look humanoid? The reality is, when we do contact civilizations from other worlds, chances are, they will look nothing like us.
It is much easier and cheaper for Hollywood producers to simply alter the forehead and skin colour of an actor, then place them in a creative costume to make them look alien, than it is to create something completely new from scratch.
The original Star Trek series tried a few times with creatures such as the Horta, which were silicon-based life that could move through rock like fish swim through water. The creature looked like a piece of hot lava and skittered around the floor like a lumpy vacuum cleaner.
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So most intelligent alien creatures in Star Trek, whether they be Vulcan, Romulan, Klingon, Cardassian, Ferengi or Borg, look like us, with one head, two arms and two legs. And they all speak English!
You might also notice that whenever the crew beams down to the surface of an alien planet, the weather is always really nice. The sky may be a different colour, but the temperature is always warm, winds are calm and no one wears as much as a sweater.
This is not what the universe is like.
Planets we have explored in our solar system, as well as those found orbiting other stars, are all very different from Earth. They are either searing hot like Venus, giant balls of poisonous gas like Jupiter, or as we've discovered outside our solar system, there are planets so close to their star one side is permanently baked while the other is permanently frozen.
The hunt for an "Earth-like" planet is on, but even when we find one with liquid water and comfortable temperatures, it will still not be exactly like Earth. And that means any life that has evolved there will not be exactly like life on our planet.
Famous paleoanthropologist, the late Stephen Jay Gould said:
"Homo sapiens [are] a tiny twig on an improbable branch of a contingent limb on a fortunate tree."
He believed that if we were to rewind the tape of evolution on Earth and run it again from the beginning, we would end up with something different from the life we have today. That's because evolution is guided by random events, such as genetic mutations, asteroid impacts, climate change and many other factors that alter the course of life. There is very little chance that the sequence of events that led to humans to evolve on Earth will take place in exactly the same order on another planet.
The search for life
So the possibilities of what that life could look like are endless. Just take a look at the variety of life in the ocean to see how many forms it can take. The octopus, for example, is considered to be very intelligent. Can you imagine trying to communicate with an alien creature that looks like an octopus and uses changing skin colour to communicate?
How would you relate to something that looks so different, has such a different cultural background, yet has an intelligence that would make Einstein look like a simpleton?
Finding alien life in any form is proving to be very hard. The most likely candidate worlds are the ice-covered moons of the giant planets, such as Europa, Enceladus, which appear to harbour salty oceans beneath their icy crusts. That means any life there would be aquatic.
Finding intelligent life will be even harder, and once contact is made, communicating with them will be harder still. Overcoming language and cultural barriers will be almost as challenging as the search for life itself. But those barriers can be overcome and, as long as we don't shoot at them — which often happens in science fiction — the knowledge we could gain would be enormous.
So come on Star Trek, show us what could really happen when we seek out new civilizations. Throw away the face makeup, stretch your imaginations and give us some really interesting aliens.