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worldgen:planets:lifelevel [2007/12/17 11:02]
sam created
worldgen:planets:lifelevel [2018/01/14 11:44]
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 The //life level// of a world defines (in very broad terms) how advanced native life is on the world. It ranges from no life at all, through simple single celled organisms, to land animals and extensive (Earth-life) conditions. The //life level// of a world defines (in very broad terms) how advanced native life is on the world. It ranges from no life at all, through simple single celled organisms, to land animals and extensive (Earth-life) conditions.
-The life level of a planet is defined in the enum ''​''​+See:
-===== Levels Explained =====+  * [[./​LifeLevel/​Organic]] 
 +  * [[./​LifeLevel/​Archaean]] 
 +  * [[./​LifeLevel/​Aerobic]] 
 +  * [[./​LifeLevel/​ComplexOcean]] 
 +  * [[./​LifeLevel/​SimpleLand]] 
 +  * [[./​LifeLevel/​ComplexLand]] 
 +  * [[./​LifeLevel/​Extensive]]
-==== None ====+//Organic// and //​Archaean//​ are quite common on worlds that could potentially support life, but life becomes significantly rarer as you move up through the classifications.
-This planet has no life of any note. Note that worlds may have all the building blocks of life, but unless they actually have replicators,​ the world is considered to be lifeless.+===== Evolution ====
-==== Proteins ====+The evolutionary path on worlds can be very different in the details, but the initial steps are broadly similar at the high level. Diversity really comes in beyond the //Aerobic// stage.
-Basic replicators are common, though no complex celled organisms are to be found. A world can stay in this state for quite a while before proceeding to //​Protozoa//​.+==== Early Life ====
-==== Protozoa ====+[[:​worldgen:​commodity:​organicchemicals]] originally formed, which were simple amino acids. Most worlds with liquid water will form basic organic molecules like this, but few progress any further. Such worlds have an [[./​LifeLevel/​Organic]] classification.
-Single celled organisms. Once these develop, evolution starts to proceed rapidly. Such life forms will be found in the world'​s oceans. At this point life will be starting ​to have an effect on the atmosphere ​of the world.+[[:​worldgen:​commodity:​protobionts]] are a form of non-living matter that is the precursor ​to living matter, and are a more complex form of //Organic Chemicals//.
-This is similar ​to the //​Archaean// ​era on Earth. It may last around a billion years.+The marker for [[./​LifeLevel/​Archaean]] worlds ​is the rise of [[:​worldgen:​commodity:​prokaryotes]],​ which are the first living organisms. They are very basic cellular life. Once they arise, they quickly come to dominate ​the ecosystem. They may be found in trace amounts on //Organic// worlds, but an //​Archaean// ​world will be dominated by //​Prokaryotes//​ or more complicated forms of life.
-==== Metazoa ====+Within a few tens of millions of years, these give rise to some form of [[:​worldgen:​commodity:​cyanobacteria]],​ which make use of photosynthesis for energy and produce oxygen. Because they are so much more efficient, they quickly come to dominate the biosphere, and are probably dominant during the late stages of //​Archaean//​ worlds.
-Multi-celled organisms. These are still small and basicbut more complex than the simple ProtozoaThe atmosphere has probably changed to high-energy types such as Oxygen, which will spur the development of more complex life forms.+Howevertheir production of oxygen changes ​the biosphere, and turns //​Archaean//​ worlds into [[./​LifeLevel/​Aerobic]] worlds.
-This is probably similar to the //Proterozoic// period on Earth. It may last a couple of billion years.+[[:​pcl:​EoGaian]] worlds are pre-Aerobic,​ with a mostly methane atmosphere. Once the life classification changes from //Archaean// to //​Aerobic//,​ then terrestrial worlds is classes as [[:​pcl:​MesoGaian]].
-==== Complex Ocean ==== +==== Metazoa ​====
- +
-Complex ocean life is common, including everything up to vertebrates. The land will be still mostly barren at this point, though some animals may have life cycles which involve the land. Note that this is the first level where the world can be said to have native animals. +
- +
-This is pretty much equivalent to the //​Cambrian//​ period and onwards (the start of the //​Phanerozoic//​ eon), and represents a sudden surge in diversity of life forms. It lasts about 100 million years. +
- +
-==== Simple Land ==== +
- +
-Simple land life is common, in the form of algae, mosses, insects, amphibians and later on plants. Modern forests are unheard of for many such worlds, though small tree-like plants and moss forests may exist. There are no large land animals. +
- +
-This marks the //​Silurian//​ period on Earth, where the first land animals were relatives of spiders and millipedes. It generally lasts a few tens of millions of years. +
- +
-==== Complex Land ====+
-Animals which live entirely on land are commonand can be quite large, though ​the range is limitedForests ​and other extensive vegetation are starting to take holdbut much of the land is bare.+With the rise of oxygenso the [[./​LifeLevel/​Aerobic]] stage is reached[[:​worldgen:​commodity:​plankton]] consumes smaller life forms, forcing the evolution of larger ​and more complex organisms. Larger varieties of algae becomes [[:​worldgen:​commodity:​seaweed]] and [[:​worldgen:​commodity:​jellyfish]] evolve. Eventuallythe arrival ​of [[:​world:​commodity:​simple marine]] organisms, such as starfish, sea urchins and worms marks the last stages of the Aerobic classification.
-This is similar to the //Devonian// period ​onwards. Seed bearing plants began to form forests, and the earliest tetrapods began to appear. It may last up to 100-200 million years.+The [[./LifeLevel/ComplexOcean]] ​period ​is heralded by the arrival of [[:​worldgen:​commodity:​crustaceans]][[:​worldgen:​commodity:​fish]] ​and other free swimming vertebrates
-==== Extensive ​====+===== Alien Evolution =====
-Life can be found pretty ​much everywhere, with forests covering much of it where possible, and many large land animals - both predators and prey. It pretty much covers everything from the //​Triassic//​ period onwardsthough ​probably ​started somewhere in the //Permian//.+The above assumes that things progress in much the same way as they did on Earth. This is unlikelybut easy. The above categories ​probably ​fit most evolutionary paths, however ​the details of each are unlikely to be the same on all worlds - e.g. when grasses first evolve and so on.
worldgen/planets/lifelevel.txt · Last modified: 2018/01/14 11:44 by sam