The levels of life

Tibor Gánti investigated the theoretically minimal system of life (see also: Definition of Living). A system which contains nothing more than the basics what are necessary to consider the system alive. He approached the life from chemistry and tried to catch the moment when we can say about a mass of chemical material that it is alive! He called this minimal system “chemoton”. But the threshold of the life is crossed again and again by the organisms which are already living. The life is multilevel on the Earth. It is materialized on higher and higher levels, and these new formulas are composed of lower level organisms. The life criteria are fulfilled again and again on higher levels. What do we consider as a new level? How can we identify these levels in the multilevel structure? How can we distinguish a certain level of life from the other levels?

To answer the question let us look at the levels which we can recognize at first sight! We can use the life criteria to help our analyses.

The level of the cells

In the nature we cannot find a so modest, so primitive system like the theoretical unit, the chemoton. The closest “relatives” of it are the prokaryote cells, which do not have cellular compartments. The name of them came from that – among other compartments – they do not have membrane-bound nucleus as well. Prokaryotes are unicellular. They can compose communities but there is no division of labor, no differentiation, no cooperation between them.

There are more complex cells, than prokaryotes: the eukaryotes. They have cellular compartments and most of them have such organelles which are as sophisticated as a prokaryote cell. They do cooperate, and every multicellular organism is composed of eukaryotes.

Multicellular organisms

Ordinary people, when thinking about life, generally thinking about multicellular organisms. And from this point of view everybody belongs to the ordinary people except biologists. Even ethologists are. Why do we do so? Because we are multicellular organisms as well, so for first we can recognize the similar phenomenon to us.

These multicellular organisms definitely represent a higher level of life. The cells are differentiated within it and they are specialized, they compose organs of the organism. The organs perform different tasks. On this way the multicellular organism is without doubt an inherent unit. It cannot survive without the functioning of its parts.

But can the parts of the body, the organs and the cells live alone, without the parent body? The answer is: yes and no – and both are important when we would like to distinguish the different levels of life.

Theoretically yes. And in practice we can also prepare such circumstances in which the parts of a multicellular organism – organs, textures, cells – can be kept alive. So, we can be sure, that the components of the organism are also living organisms.

Practically no. If we would like to keep them alive, we have to prepare artificial circumstances. These circumstances do not appear naturally except inside the parent body of the components. So, the components of the organism, the participants of the cooperation highly rely on the result: the organism’s inherent stability.

What is a level in this multilevel life?

We can define a (next) level of life as the follows:

• The components of the level are also living organisms
• The composed organism is itself a living organism which fulfils the life criteria

Let’s check the multicellular organisms!

The components of them are the eukaryote cells, which are definitely living organisms. Of course, they require special conditions, but this is, why they formed the multicellular organism: to provide them with these conditions. The individuals always receive advantages from creation of a next level of multilevel life.

The organism composed of eukaryotes fulfils the life criteria. Lets’ think any of them: a mushroom, a tulip, a worm, or a horse.

1. A multicellular organism is an inherent unit, it is more than the sum of its components because the components are specialized, they form organs, and perform different tasks. A worm is less complex than a horse, and a mushroom is less complex than a tulip. But they are common in the cooperation of their organs composed of cells. Doing so they are more effective than the sum of the parts.
2. A multicellular organism is functioning. Not only the components – the cells – are functioning, but the new organism is also functioning on its’ level. Its’ organs perform their tasks for the benefit of the whole body. The cooperation is performed also on this new higher level.
3. A multicellular organism is inherently stable. Every organism has its’ own regulatory processes on a higher level. For example, if they are on a warm place both the tulip’s and the horse’s body perspire (sweat) more intensively. Not all their cells perform this task. There are sweat glands on the skin of the horse or gas exchange openings called stomata on the leaves of the tulip. They perform the transpiration for the whole body.
4. A multicellular organism has an information carrying subsystem. Yes, it does have, but where! In the cell. We could think that what can be found in the cell, that is the information carrying subsystem of the cell, and some system of this kind is distributed somewhere among the cells of the multicellular organism as well. But we do not know about such a system. The cell’s information carrying subsystem serves as the information carrying subsystem of the organism as well. The cell holds the information that e.g. it is a cell of a tulip or it is a cell of a horse. The zygote of a horse has no other choice than to develop to a horse and a zygote of a tulip has no other choice than to develop to a tulip. They can perish as well, but regularly it is not their own choice. All the necessary information is available in one zygote cell which is enough for the reproduction of the multicellular organism, and the same information will be present in every cell of it.
   So due to our recent knowledge we find that while every other life criterium is manifested also on the higher level of a multicellular organism, the information carrying subsystem remains on the level of the cell. However it definitely carries information for the whole multicellular organism. The book titled: The Selfish Gene, by Richard Dawkins, Oxford University Press, 1976. reflects this knowledge saying that the whole evolutional “competition” can be traced back to the competition of genes. By the words of Dawkins: “The argument of this book is that we, and all other animals, are machines created by our genes.” He might be right, if really only the genes are carrying information about the multicellular organism. He is possibly right that the genes are “selfish”, in a sense that only the successful gens can survive and populate their habitat.
   But this selfishness is not that one, what meaning of this word we use daily related to people, this selfishness is not the opposite of altruism, this is not the opposite of cooperation. This selfishness means that only the success, only the survival counts. This “selfishness” is calculating, and it will be selfishly altruistic when interested in it. And as one can see, to be a member of a cooperating colony and acting altruistic generally the best attitude to survive. (See also: Game Theory) Certain extremely successful branches of the evolution like social insects and humanity are proving it.
   On the other hand we cannot be sure, that the cells do not have some kind of memory, just think on memory T cells of the immune system. Gametes are “socialized” in the parent body, in the “family” of its’ cells, where they could “learn” something if they had memory, and so they might have more information than they carry in their genes. But these are just speculations without scientific evidence for the sake of symmetry that we would like to see at every level of life according to every life criterium.
5. A multicellular organism is under program control. Every multicellular organism has its’ own lifecycle from birth to death and the organism goes through it step by step. The stages of the growing and development of the organism are predefined and its’ (genetic) program always drives it to the following stage. We know these stages from the spore to the mushroom, from the seed to the flower, from the egg to the larvae, from the colt to the stallion.

Societies

Let’s go forward to the next level of the multilevel life: the level of societies. The components of the societies are multicellular organisms. Are they really living units, like their components? Or even more?

We can agree on that the components of a society are living organisms, so a society may be a higher level of life. Do they fulfill the life criteria? When checking the life criteria, we will concentrate on insect societies. Humanity will get a distinct section, because we are special from many points of view, and at last because of the smaller number of our legs and the bigger number of our neurons.

So, let’s check life criteria on insect societies

A warm up to human societies…

1. A society is an inherent unit, it is more than the sum of its components. The best of the known examples are the leafcutter ants: “Among the fungus-growing ants, only species of the two leaf-cutting genera, Acromyrmex and Atta, have highly polymorphic workers, with strong differences in size and anatomical proportion. This remarkable polymorphism is reflected in the complex division of labor exhibited within the colonies.” The citation is from Chapter 5. “The Atta Caste System” The Leafcutter Ants, by Bert Hölldobler and Edward O. Wilson, W.W.Norton & Company, 2011.
2. At many termite species there are two non-reproducing polymorphic castes: soldiers and workers. The polymorphism is interesting because of the irreversible division of labor. On the multicellular level of life, the cells showed very strong polymorphism as well. If the division of labor based on polymorphism then it is burned into the system, because polymorphism cannot be reversed.
   Most of the social insects show however age polyethism, when the division of labor depends on the age of the individual. Best known example of it are the honeybee colony workers. They have four major divisions: cleaners, nurses, storekeepers and foragers. The order of the divisions is according to the increasing age of the members of the divisions. Every worker bee starts her career as a cleaner. The most complex and most dangerous foraging is performed by the oldest, most experienced workers. They not only find the appropriate job for every level of experience, but also maximize the lifetime of the individual by assigning the most dangerous job to the eldest. (Cynically one could say, that they spare on the pension system, but their system is more rational, than to sacrifice the young individuals in the war, like humans do.)
   And do not forget that in every insect society appears the polymorphism: the queen is always remarkably different from the workers, and is functioning as some kind of genital organ of the hive or the colony.
3. A society is functioning. And it is functioning on the level of the hive or colony. Most of the bees in a hive do not collect food. Every of them relies on the foragers and supplied by them. The soldiers of many termite specie cannot feed themselves. The leafcutter ants’ fungus is grown by the common effort of every worker castes. No question that the function is on the level of the colony.
4. A society is inherently stable. There is more and more research on regulatory processes of termite and ant colonies and bee hives. For example, in the excellent book titled The Wisdom of the Hive, by Thomas D. Seeley, Harvard University Press, 1995, lots of regulatory processes of the bee hive are described:
   – The Correct Distribution of Foragers among Nectar Sources
   – Coordination of Nectar Collecting and Nectar Processing
   – Regulation of Comb Construction
   – Regulation of Pollen Collection
   – Regulation of Water Collection
   These regulatory processes obviously appear on the level of the society and work properly only on a mass of individuals, because the operation of them is built on statistical formulas.
   Among the regulatory processes the easiest to study the temperature regulation processes. It is well-known that termite mounds, ant colonies and bee hives are climate controlled. While termites and ants prevent the brood from overheating by appropriate ventilation and isolation, then bees’ tool against overheating is the water evaporation.
5. A society has an information carrying subsystem. The situation is very similar to the level of multicellular organisms. The information is carried by the genes, and the genes specify not only the cells of an ant, but the ant as a whole, and the colony as a whole. The cells of an ant have no other choice than to be a part of an ant, and the ants has no other choice than to compose a colony. This is their inherited trait. All this information is encoded in the genes.
   Insect societies however have other information carrying system than their genes: the pheromones. Especially the pheromones of the queen which identifies the members of the colony. The colony can work as a unit if it has an identity. As there is no such physical border of an ant colony like the multicellular organisms have their chitin skeleton or their skin, therefore the pheromones create an invisible border of the colony.
6. A society is under program control. The processes of growing and reproduction are under control in a hive or in a colony. The control process is based on the availability of resources. At the beginning of their life the colonies are growing. This means that (almost) only workers are reproduced, and the size of the colony increases. When a colony reaches a certain size, it is mature. If there are still enough resources, then starts the reproduction of queens and drones. In parallel the feeding of the old queen is stopped, because she must be able to fly within few weeks and therefore she must lose her weight. The honeybee hive’s reproduction is some kind of a cleavage, a division. About 60% of the workers leave the hive with the old queen in a swarming. We don’t know the exact triggers of the queen reproduction and the colony reproduction. We don’t know where and how the decision is made about them. But we can see that it is programmed, and every bee hive will grow and reproduce in appropriate conditions. We can see that it is not a single decision of an individual, but a process of the colony. The queen and the workers do their best in the process. The workers prepare the cells in which the queen lays her eggs. For developing a queen, a larger cell – a so called queen cell – is necessary. The queen lays eggs in some queen cells, and the workers feed the new queen with royal jelly. This diet makes the difference between workers and the queens. At the end of the process there is a swarm with the old queen, and the new queen’s nuptial flight for insemination, by which she can maintain the old-new hive.
   The ant colonies’ reproduction process is different. The new virgin queen leaves the colony alone and after insemination founds a brand new colony from scratch. Because of it the success rate of founding a new colony is only a few percent at the ants while at bees it is much higher.
   There are differences specie by specie. The common thing is that the programmed process of growing and reproducing appears on the level of the colony. As the workers do not reproduce at any of the social insects, from this point of view they are blind alley. The “real” reproduction, which progresses generation by generation is performed by the queens and the drones. And as the queens represent colonies, we can say that the reproduction of social insects is performed on the level of the colony. Just like when we talk about the reproduction of rabbits we don’t mean that the cells of the rabbit in its muscles or in its other organs are reproducing by division. We mean the reproduction of the rabbit as a whole. So, when we speak about the reproduction of the honeybee we shouldn’t mean the individual – the individual with which we meet by the way is a worker bee, which doesn’t reproduce – but we should mean the colony, the hive, because the reproduction is performed on that level. And it is the same at every social insect.

Signs of life on a higher level

There are certain signs by which one can identify the higher level of life. These are not the criteria of life because they can be derived from the life criteria, or they can be beyond the life criteria, they mean more than the simplest criteria of life. They are useful because sometimes it is much easier to recognize these signs than to analyse the fulfilling of life criteria.

• When individuals are unable to survive without the colony (the body, the organism) this shows that a very high level of the division of labor achieved. In this case surely the higher level must be considered as the unit of life because the lower level itself is unviable.
• If there are individuals who are unable to reproduce in their whole life, then this is a certain sign of that some other individual reproduces even instead of them. Otherwise the specie would disappear. It also means that the natural selection of the evolution is shifted to the next level. This kind of the division of labor, when an individual gives up the reproduction and lets other individuals of the community to reproduce, is a positive evidence of that we have actually found a higher level of life beyond these individuals.
• The competition is always very low within the unit of life while it is strong between this units. So, the competition always appears between the units which are on the ultimate level of the multilevel life. The formulation of this level needs cooperation, and because of it all the lower levels do cooperate and almost lack of competition. In this case the competition on the lower levels is some kind of a defect, an illness of the body or the organization.
• Together with the competition the ability for evolution – as a potential life criterium – is shifted to the next level. The selection is a driving force of evolution taking its’ effect through influencing the frequency of genotypes. Competition is the driving force of selection. In case of unlimited resources, without competition only the fecundity would have influence on the frequency of alleles.
• Group identity is also a sign of that the level of life is elevated to a higher level. The greatest challenge in transplantation of organs that our body identifies the transplanted organ as an alien and attacks it. The cells of our body have the same (genetical) identity, and strangers are not allowed among them. The social insects also recognize by pheromones if an individual does not belong to the colony and attack the foreigners.