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How come almost no designers or worldcreators thinks about where and what their beings are coming from? And how a different evolution on a very different planet would affect life. The only way mamals could be on top of things here on Earth is because the dinosaurs died out 65 mio years ago, and left the place to us! 
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| Bilba Baggins. Art by lanimalu |
Using what we have learned from life on Earth, what can we say about alien life? While it would probably be vastly different from life on Earth, alien life would probably adhere to certain universal guidelines, as the widely varying life on Earth does. These guidelines or ground rules include the following:Alien life would be governed by laws of physics and chemistry.
Alien life would be based on some type of chemistry (eliminating the sci-fi concept of pure-energy beings).
- Solvent - On Earth, the solvent for all of our biochemicals is liquid water. Other chemicals could be solvents as well, such as ammonia, methane, hydrogen sulfide or hydrogen fluoride.
- Temperature - Alien life may require temperatures at which its solvent can remain liquid.
- Pressure - Alien life may require environmental pressures (and temperatures) that allow solvents to exist in three states of matter (solid, liquid, gas).
- Energy source - Living things require energy to remain organized. This energy may come from a star or from chemical or geothermal energy (as in hydrothermal vents and hot springs). On any alien world, there would have to be some source of energy to sustain life.
- Complex molecules - Living things on Earth are organized and made of complex, carbon-based molecules that carry out biochemical functions. Carbon is a versatile atom that can form bonds with up to four other atoms, in many shapes, to make molecules. Although not as versatile as carbon, silicon can also form up to four bonds with other atoms and has been proposed as a basis for molecules of alien life (silicon-carbon hybrid molecules have also been proposed). It is likely that alien life forms would have some type of complex molecule to carry out similar functions.
Alien beings that are larger than microbes would have some equivalent of cells. As an organism gets larger, its internal volume (cubic function) grows faster than its surface area (square function). This places a limit on the organism's size, because substances from the outside of the organism must pass into and throughout the organism by diffusion, which depends upon large surface areas, short distances and differences in concentrations. As an organism grows larger, the distance to its center increases and diffusion gets slower. To maintain workable diffusion distances, an organism must have many small cells instead of one large cell. So, an alien would be multi-celled if it is larger than a microbe.
- Informational molecule - In Earth organisms, deoxyribonucleid acid (DNA) is a complex molecule that carries genetic information and directs the formation of other molecules in order for life to reproduce and function. Because a characteristic of life is that it reproduces, it seems likely that alien life forms would also have some type of informational molecule.
Alien life would evolve and adapt to its surroundings by the theory of evolution as previously explained.
The physiological make-up of a multi-celled alien would be most suited to its environment. Organ systems would be adapted to environmental conditions such as temperature, moisture and gravity.
A very nice article with a very straight forward approach, focusing on the nature and evolution of an alien world and whatever life might be found there. Especially that life on that planet ought to fit into it's native ecosystems, even if it has removed itself from it's natural place in the food chain (E.g. via civilisation), it would still have kept the same traits, physically as well as psychologic.
- The alien would have some way of bringing solids, liquids and gases inside its body, distributing them to every cell and removing waste products (equivalents of heart, blood vessels and kidneys, for instance).
- The alien would be able to take in energy from its surroundings, extract the energy and eliminate wastes.
- The alien would have senses (such as sight, sound, touch) to obtain information from the environment and respond to stimuli (while we use vision as our primary sense, this may not be true of aliens). They would also have some type of brain or nervous system to process information.
Alien organisms would probably have similar ecological structures to life on Earth.
- The alien would have some means of reproduction, either sexual or asexual.
- Population sizes would be limited based on the predominance of food, predators, disease and other environmental factors.
- Alien life forms would exist in food chains and food webs in their native environment, like life on Earth. Producers will make food, consumers will eat producers and/or other consumers and decomposers will recycle atoms and molecules from dead organisms back into the environment.
As you can see, life of any kind is intimately tied to its environment, so the characteristics of the planet would be extremely important in determining the characteristics of the life form.
- Alien life forms will be integrated with their habitats and ecosystems, like life on Earth.
If one considers the millions of years of pre-history, and the rapid technological advancement occurring now, if you apply that to a hypothetical alien race, one can figure the probabilities of how advanced the explorers will find them. The conclusion is that we will find apes or angels, but not men.I love science - I do. And I find inspiration in it every single day. It has made me see how miraculous our planet must be, just by being here. Where ever you go - There's nowhere like here. It's unique. But there are other places as just wonderfull as this small planet. There has to be. At least that what science and mathematics has tought me.
"A phylum is a broad division in taxonomy: all vertebrates, for example, from fish to humans, are in the chordate phylum. In 1995, Peter Funch and Reinhardt Mobjerg Kristensen, both then at the University of Copenhagen, Denmark, discovered an animal so unlike any other that a new phylum – Cycliophora – had to be created just for it.
Symbion pandora, as they called the new creature, is a tiny animal with a complex body and a bizarre life cycle. They live on the hairy mouthparts of Norway lobsters, with tens or even hundreds per lobster. They feed on bits of leftover food and seem to be harmless to their hosts.
Things start to get complicated when you consider their life cycle. Let's start with a feeding animal living on a lobster's mouthparts: this individual – it's hard to assign a sex – can then produce one of three kinds of offspring: a "Pandora" larva, a "Prometheus" larva or a female.
The Pandora larva develops into another feeding adult – a straightforward case of asexual reproduction. By contrast, the female remains inside the adult and awaits a male – but, attentive readers will be crying, what male?
The answer lies in the Prometheus larva. This attaches itself to another feeding adult, then produces two or three males from within itself. These dwarf males, which are even more internally complex than the other stages, seek out the females and fertilise them – though the details are unknown.
Once the female has been fertilised, she leaves the adult's body and hunkers down in a sheltered region of the lobster's mouthparts. Her body, no longer needed, turns into a hard cyst. Inside this, a fertilised egg develops into yet another stage: the chordoid larva.
In due course this larva hatches and swims off to colonise another lobster. Once it has attached itself to one, it develops into another adult and the cycle begins again."
Hawking’s logic on aliens is, for him, unusually simple. The universe, he points out, has 100 billion galaxies, each containing hundreds of millions of stars. In such a big place, Earth is unlikely to be the only planet where life has evolved. The numbers alone make thinking about aliens perfectly rational.
He concludes that trying to make contact with alien races is “a little too risky”. He said: “If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the Native Americans.”
