AT first glance the humble earthworm appears to have no human characteristics, but if you take a closer look you will see it has a surprising number of similarities.

Earthworms and humans are propelled through the use of muscles which operate in a similar way.

We both have mouths and an alimentary canal for a digestive system, although ours is more complicated.

Our body structure is also similar, with a segmented and roughly symmetrical approach to design. Like the earthworm, all our bodily functions are controlled and regulated through a brain at the centre of our nervous system.

We also share some of our senses with which we explore our world. Worms can analyse the composition of their food through their sense of taste. They feel external objects and even have eyes but these are very simple and at best could only distinguish between light and dark.

Moving further up the evolutionary ladder, you find even more similarities when you start looking at creatures that have vertebrae.

The first of these appeared many millions of years ago and were at first all aquatic. However, 370 million years ago the first of these dragged themselves out of the oceans on to land and evolved over generations into what we now recognise as amphibians.

Amphibians are among the most primitive form of animals with vertebrae, yet from primitive examples of these, it is supposed that all other terrestrial vertebrate life evolved.

However when you look at an amphibian today, you cannot help but recognise the features we share in common. A toad, for example, has a recognisable face with all the feature of humans. They have eyes, noses, mouths, tongues and ears. They have four limbs, which even have the same number of fingers.

On the surface the diversity of vertebrate life may appear amazing, yet it is all really just a variation on a theme.

You have to look to the invertebrates to start finding some real diversity in body form. But even these show a certain level of conformity to pattern.

If one day man visits Mars, it will be interesting to see if evidence of primitive life still exists or if fossil evidence proves that life once existed and whether this life also seems to follow the basic patterns we see in the life here on earth.