Are we all Martians?

 

 

Credit: NASA

 

The face on Mars: this image photographed during the Viking missions looks like a human face, but is only a mundane feature that gives this appearance due to the angle of the sun.

 

The origin of life on Earth is one of the big mysteries that scientists still haven’t solved. According to evolutionary biologists, life appeared from non-living matter between 3.9 and 3.5 billion years ago, and probably started in a wet environment like a sea, tide pool or in clay, emerging from a mixture of organic elements. There are clues as to the type of conditions in which early life might have thrived, but how life was created from non-life is still very hazy.

Amino acids are widely accepted as the building block of life, and a famous experiment conducted in the 1950s by American chemist Stanley Miller showed that they could have been created in the primordial soup of early Earth. But some scientists theorize that life could have been transported from outside the Earth, from another planet or from space. What evidence is there for life beginning outside the Earth, when today we are not even aware of life outside of our planet?

Panspermia – the idea that “seeds” of life exist in the universe and develop when they find favourable conditions – was popularized by the Nobel prize winning chemist Svante Arrhenius in 1908. He thought that radiation from the sun and stars created pressure which dispersed microbes through space – sort of like how the wind blows dandelion fluff and seeds to different areas. Even though temperatures are freezing in space, Arrhenius believed bacteria could survive and could also withstand being heated up as it entered the Earth’s atmosphere. Astronomers Fred Hoyle and Chandra Wickramasinghe reintroduced this idea in the 1970s – showing that organic polymers that could have sprouted life were present in dust from space.