On a lighter note today, let's look at fictional alien life forms, and how the principles of evolution apply, as far as their physical appearance and behaviours are concerned. For those of you who have watched the films "Alien" and "Predator", you will be familiar with these characters, but if you haven't, don't worry; their pics are below. The first one to look at is the alien.
The aliens are filled with a very strong acid which destroys every material known to man, suggesting that the chemistry of the place these aliens evolved from was very different to that on Earth. Research so far does indeed suggest that there may be silicon-based life forms, rather than carbon-based. All life on Earth is carbon-based.
The mature alien looks like this, and in the film is a vicious fighter with two mouths.
On the other hand, the Predator is an intelligent humanoid who uses advanced technology to defeat its prey. The predator's body, however shows certain features that may surprise.
One of these is the predator's dreadlocks. They don't seem to serve any particular function, so they may be purely aesthetic. Not to us humans, but to them, predators. Another weird thing is their mouth surrounded by two teeth on the outside which can move to trap a victim. Presumably, the predators were great chasers and killers a long time before their intelligence provided them with their guns and spaceships. Presumably, as predators use their fangs less and less, they will diminish and fade, just like humans' bigger sharper teeth have evolved into simple, smaller teeth, the ones we all have today. The predator's body is less resilient than the alien's, due to the aliens being more physically aggressive, while the predators use their technology more. Similarly, humans are the weakest of primates, simply because we no longer make use of strength.
That is why, perhaps, the film makers decided to make a joint film, "Aliens versus Predators" where the two species are faced with each other in battle.
This is it for now, come back for the next post on the human body and evolution, where we'll look at the human, the same way we have looked at these aliens, in more detail!