Introduction to Type Two lifeforms
Even with the most generous of calculations, Type Two lifeforms make up less than 5 per cent of the total volume of life on our planet - however that figure may be calculated. Type Two life is in many ways restricted: it is restricted to land, for instance, having almost no presence in Kalieda's oceans, seas (what remain of them), great lakes or rivers; it is also marked by its co-dependence, and the key role that our species - humanity - has in maintaining and extending its range through actions such as cultivation. How this situation came about is one of the great unanswered questions for science, philosophy and religion - though many have attempted answers throughout the course of recorded human existence.
The development of Type Two life
One of the biggest mysteries is how did Type Two life develop? Records show that there have been many archaeological and palaeontological investigations that have attempted to answer this question, but as far as we are aware nobody has yet been able to find evidence of Type Two fossil sequences dating back more than 6-8 thousand orbits, compared to Type One fossil sequences which are far more extensive and have been found in far older rock layers.
However, when Type Two life does start to appear in the fossil record, it appears suddenly and completely - all groups of Type Two life have been found. This has led to the hypothesis that Type Two life developed later than Type One life, probably on an isolated area such as an island where it managed to outcompete the existing Type One life by being able to adapt and evolve at a much faster rate.
This hypothesis, however, has many flaws and depends quite heavily on a number of (as yet) untestable conditions and occurances taking place. An alternative hypothesis is that Type Two life was in fact the first lifeform to evolve (to an extent that saw the establishment of lifeforms that founded all our major kingdoms), and Type One life evolved from us and then outcompeted us many millions of years ago. This hypothesis relies on Type Two life surviving and evolving in geographical "havens", and occasionally being able to break out of those havens to compete more directly across the planet - the last outbreak happening some 8 thousand orbits ago, after humanity evolved into a social lifeform and began harnessing our environment through strategies such as cultivation.
Other 'theories' that have been proposed, though with less scientific rigour, are the interventionist theories - such as those of a deity (or deities) who intervened in the natural evolution of the planet to create Type Two life, or the possibility that Type Two life arose on a different planet and then travelled to Kalieda. Current scientific thought tends to discount these theories on the grounds that despite the manifest differences between Type One and Type Two life, the similarities between them are striking: DNA, for instance, is built from the same biochemical building blocks, and the two life Types share an astonishing 16 amino acids.
The range of Type Two lifeforms
Type Two life in many ways mirrors Type One life in its variety, if not in its quantity. Similar to germulas and microfilms, bacteria form the backbone on which all other Type Two lifeforms depend for their continuing success. This is particularly true of the soil bacteria, gut bacteria and other bacteria that live on and within other organisms. Even today, our understanding of the full diversity of this kingdom, and of its role in the greater scheme of things, remains incomplete. Vey similar to bacteria are the cyanobacteria, which are much less common than their single cell brethren and yet just as essential to Type Two life.
The plant kingdom is similarly complex, ranging from single-cell organisms living in soil and water to the great trees and grasses that benefit from cultivation. All plants are marked by their ability to photosynthesise, producing nutrients from sunlight, water and carbon dioxide. For a long time, many scientists considered fungi to be a degenerate form of plants. However, advances in science over the past 100 orbits have allowed us to confirm that these strange lifeforms, so closely involved in the recycling of wastes, discards and the dead, are indeed different enough from plants to form a kingdom of their own.
Animals, on the other hand, need to feed off plants and other animals in order to survive and thrive. They are marked by their ability to move and the wide array of forms they take, from worms to humans. Most animals appear to be closely associated to humans in one way or other (either we cultivate them for food and labour, or they cultivate us through parasitism and disease). For many scientists this is a key issue for debate, as there appears to be no Type One organism that plays a similar role to that of humans for their lifeforms: a leading hypothesis suggests that Type Two life almost became extinct sometime in the past 100,000 orbits, and only those species that learned to co-operate with each other managed to survive the extinction event. Some scientists have gone as far as to suggest the threat of extinction was one of the key drivers that led to the development of human intelligence and human society.
The last kingdom - that of the viruses - appears to be something of an enigma. Some scientists still refuse to think of viruses as living, but rather consider them to be a rogue messenger system developed by bacteria that has invaded all other Type Two lifeforms. But the fact that viruses do include genetic information and are subject to the vagaries of change and evolution is enough for most scientists to class them as living. Viruses are unique to Type Two life: no Type One virus analogues have yet been discovered - though that does not mean they do not exist.