Evolution on Alien Worlds
Life on Earth is purely the product of evolution, a fundamental characteristic of which is the ability to adapt to the conditions provided.
Absolutely every characteristic of every lifeform that ever existed is a product of evolution, natural selection due to the survival of the fittest being a key element. Humans walk on two legs so they can keep their hands free to use tools. Certain dinosaur species grew so enormous, probably as a self-defence mechanism or an excess of vegetation to feed on. Early whales had legs that evolved into flippers as they adapted to an amphibious and, finally, a fully aquatic lifestyle. Giraffes grew long necks so they could reach foliage that no other herbivore could get to. All life evolves to adapt to its environment, and there’s no reason that rule shouldn’t apply to any alien world.
So, what would alien life look like? That depends on three main factors:
Whether that life came from somewhere else, a hypothesis known as panspermia, and a favourite, but unrealistic, explanation for humanoid aliens.
The environmental qualities influencing the evolutionary adaptations of the extraterrestrial lifeforms.
The biochemical properties. However, alternative biochemistries are currently purely speculative.
We’ll disregard the third point for now, since this article is supposed to give an in-depth answer into what extraterrestrial life would look like based on what we know, and not what we might wilfully imagine. The first point is also rather a moot one, since life would still either adapt to any alien conditions or die. Additionally, panspermia really only concerns extremely basic forms of life rather than humans and other animals. The second point provides by far the best approach to determining the qualities of alien life, since there are relatively few things in evolution that happen purely by mistake. In the following sections, we’ll explore the fascinating effects of evolution and how they determine what our celestial neighbours might look like.