In the course of reading sci-fi over many decades, I have encountered many different varieties.

I have seen intelligent life on other planets represented as gas, slime, blobs, mechanised beings, shape changers or humanoids.

The humanoids usually have big heads, slender bodies, huge eyes and elongated tapering limbs. Some have tentacles, others hands and feet.

It is possible that through the zillions of planets in the universe that we are the only intelligent life. The Earth may be an oasis in a vast desert.

On the other hand, it is also possible that life may be a common occurrence.

As a biologist, I am intrigued.

The earth has existed for a little over 4.5 billion years. It took just short of 2 billion years for the first life to evolve. For the next 2 billion life was merely a bacterial slime. All life on the…