Are aliens already here on Earth?

Space scientists scouring the skies for aliens should be looking for them here on Earth, a top scientist claims. Professor Paul Davies says creatures quite different to life as we know it may already be living on our own planet.

He says finding where they are hiding would be a breakthrough in answering the question of whether life is common in the universe.

The professor adds: “It would undoubtedly be the biggest discovery in biology since Darwin and evolution.”

Alien-hunters have spent billions of pounds seeking ET by listening for radio signals from space, checking out Mars and looking for organic materials in space.

UK-born Professor Davies, now at Arizona State University, tells the NASA’s Astrobiology journal that a hunt should begin in earnest for what he calls “weird life”.

That means microbial organisms that may look similar to life as we know it, but whose biochemical makeup is distinctly different.

Such alien organisms will be relatively easy to find in environments too harsh for normal life such as extremely hot vents like volcanoes on the ocean floor, says Professor Davies. They will be harder to spot if they exist with us in familiar surroundings, such as the soil in your back garden.

Cosmologist Professor Davies, director of BEYOND, the Centre for Fundamental Concepts in Science, is famous for thinking outside the box. He recently suggested that the first astronauts visiting Mars could be sent on a one-way trip.

It might seem odd that such alien life has not already been found. Professor Davies suggests that is because the tools used to detect new life forms are tuned to look for life as we know it, containing DNA. Weird life might not have DNA. To standard life-detection tools, a non-DNA life form would be invisible.

He says a microscopic type of bacteria called a nanobe, which appear to contain no DNA, should be check out more closely it is really an alien.

Professor Davies says: “If we found that there is an alternative form of life on Earth, then immediately the central question of astrobiology is answered – that life is obviously easy to make.”

He believes that if life arose twice on a single planet, then it would be almost certain to arise on other Earth-like planets too. It would show that we are not alone.

Picture: A hydrothermal vent, such as that pictured in the Atlantic, is one place to look for alien life. (Photo: National Oceanic and Atmospheric Administration).

• What do you think? Skymania welcomes your comments and views.

★ Keep up with space news and observing tips. Click here to sign up for alerts to our latest reports. No spam ever - we promise!