As for the question of when homo-sphere was born, I already gave you the answer. It occurred about 10,000 years ago when we started living on agriculture and stockbreeding. It can be defined as a point in time when people started to live in the way that would make it possible to recognise Earth as a system from space by creating a separate box called farming/stockbreeding-oriented homo-sphere.

　

To put it another way, we became an existence that lives by utilising the flow of energy and matter in the entire planet Earth. Farming and stockbreeding is a way of life is that uses the flow of all energy and matter existing in planet Earth. In contrast, hunting and gathering can be defined as a way of life that utilises the flow of energy and matter in one of the components comprising Earth.

　

You often hear an expression "earth-friendly" nowadays, but living on hunting and gathering as a species in biosphere is an "earth-friendly" way of life in a true sense of the term. Since changing a component of planet Earth means appearance of a new component, flow of energy and matter in the entire planet is naturally disturbed. This is not "earth-friendly" from the viewpoint of earth-friendliness.

　

However, if you ask whether we are capable of living in an earth-friendly manner, the answer is "no" . As far as Earth is concerned, we have been an existence that changes the pre-existing state ever since we started to practice farming and stockbreeding, that is, to live by creating homo-sphere. We are now unable to change our way of life to that other than farming and stockbreeding no matter what. The population in excess of 6 billion in the world cannot survive by way of hunting and gathering. This becomes clear from a quantitative analysis of material and energy flows within the biosphere. Number of people that could be supported through flow of energy and matter within it is estimated to be around 5 to 10 million at the most. The fact that this capacity has been exceeded and more than 6 billion people exist today means that we have no choice but to rely on farming and stockbreeding to support them. In this sense, we cannot afford to give up our way of life based on creation of homo-sphere on the planet we call Earth. And as long as we do that, it becomes unfriendly to Earth no matter how you look at it.

　

Thus we can construct an argument that is completely different from its common counterpart by recognising our world as "homo-sphere". We will have to go beyond that and think about population problems and the future of human society from such viewpoint; I think we are unable to grasp the nature of things that are taking place today by seeing and analysing the situation within the conventional way of thinking.

　

Starting from such understanding, I will now talk about the problems currently faced by humanity, what the future holds for homo-sphere and what are the potential problems that may occur in such event.

　

I'm getting things out of sequence, but there is a question of why we started farming and stockbreeding some 10,000 years ago, or why we started living in homo-sphere. Actually, this involves several problems that are unclear. In terms of environment, the global environment experienced a drastic change around that time. It was not a man-made change; rather, it was a slight change in the system of the planet Earth. It might be easier to understand if I refer to it as "change in climate".

　

The so-called glacial period ended and was taken over by the interglacial period about 10,000 years ago. This can be seen by drilling the ice that has deposited in thick layers on ice sheets in Greenland and South Pole, taking out a sample from deep underground and analysing the ice in it. Today, it is possible to analyse what the climate was like hundreds of thousands of years ago. Based on such analysis results, we know that climate stabilised notably 10,000 years ago. Annual average temperature fluctuated violently prior to that time. Annual average temperature was changing 6 degrees over a 10-year period, but about 10,000 years ago the range of fluctuation was reduced to within 1 degree.

　

Stabilisation of climate meant that people that have been living on hunting and gathering setting aside the question of hunters − the gatherers were able to have some regularity of being able to collect same items at certain times of the year. So it is no wonder if they went in the direction of cultivating the items that they used to gather. This is one possible reason for agriculture having started 10,000 years ago.

　

I think there was another reason intrinsic to us human species. Fossils show that human species existed 5 million years ago and various kinds of people have appeared on this Earth since then. We call ourselves Homo sapiens, and we know that the human species alive today were born between 150,000 to 200,000 years ago in Africa.

　

We actually do not know precisely how Homo sapiens are connected to human species that lived before us. We fall under the same category of human species; but, for example, a human species different from us called Homo sapiens neanderthalensis lived in Europe until 30,000 years ago. The direct ancestor to Homo sapiens also lived in Europe at the time. Both the ancestor of Homo sapiens and Neanderthals lived in the Eurasian Continent around that time, but Neanderthals became extinct and we have built the prosperity we have today.

　

Why did one species prosper and the other become extinct under similar conditions? It is a biological issue concerning ourselves − and when it comes down to this point, some things are scientifically clear and others are quite unclear.

　

One thing that is clear to us is that we Homo sapiens have a "grandmother". We know this from study of fossils. I call her "grandmother" not simply because she has grandchildren, but because females can live for more than 10 years after her reproductive age is over or even longer, for decades. We cannot find existence such as this in species that are closely related to us such as anthropoid ape nor among mammals. In natural world, animals die several years after passing their reproductive age.

　

Monkeys and even also chimpanzees cannot raise the last child they give birth to because mothers die. However, the fair sex of Homo sapiens, for some reasons not known to us, continue to live. They live past the age others would usually die. Let us call them "grandmothers". When grandmothers are there, knowledge about childbirth that they experienced would naturally get passed on to the next generation. Grandmothers also look after their daughters' children.

　

If we assume the reproductive period to be 15 years and 5 years were needed for child rearing if grandmothers were not there, a woman can only give childbirth once every 5 years, which means that she can give birth to 3 children at the most. However, if she is relieved from child rearing after 3 years by having the grandmother look after her child, for instance, she could have 5 children.

　

Therefore, the existence of grandmothers may be a factor in population increase. Homo sapiens is said to have spread from Africa to rest of the world more than 50,000 years ago. It is referred to as "Exodus from Africa" after the Old Testament and marked an occasion in which human species that was originally living in Africa spread worldwide in a very short period of time. That is why we exist all over the world today − and one way to look at this is that population increase was one of the reasons behind it.

　

Another reason − although this has not been scientifically confirmed to what extent it is true − is the fact that we seem to be able to speak the language clearly. Because of the structure of our throat and tongue, we are able to clearly pronounce "a", "i", "u" ,"e", and "o". The extent to which Neanderthals was able to pronounce clearly is said to be very questionable. The ability to speak a language clearly meant that they could convey to others not only the things that are happening in front of one s eyes but what he or she experienced prior to that − "what happened on the way coming here today" or "what happened during the hunt", for example. Being able to speak clearly significantly enhances one's communication skills. In terms of the level of the brain, it is not a question of whether brain capacity is large or small but how the circuit inside that brain is connected. Homo sapiens seem to have circuit connection that sets them apart from human species that existed prior to them.

　

So my theory is that our ancestors created the homo-sphere and started living in it when the two elements − climate change and change in our own biology − combined some 10,000 years ago.

　

You will be able to engage in abstract thoughts in your head once you figure out how to connect your brain circuit. I call this "collective illusion". You must have ideas about various concepts that distinguish human beings from others. For example, 20th Century-oriented concepts may include "democracy", "human rights", "love", and "god"; these are a few of many things that we are thinking inside our brains.

　

When such concepts are born, many communities will emerge in the homo-sphere by using it as unifying force. As a result of various communities being born inside it, the system of homo-sphere becomes diverse. That's what I see as the history of civilization.

　

Incidentally, I define civilization as our way of life realised by creating homo-sphere in the Earth system. This civilization becomes increasingly diverse as a system when various communities are born in it This development of homo-sphere can roughly be divided into two stages.

　

What I mean by this is that − while I mentioned that system is made up of components − there is another important issue of "relationship between components" and "driving force". A phenomenon similar to movement of matter that occurs between the components comprising a system is "relationship". And some kind of "driving force" is needed to bring about movement of this matter.

　

In the case of Earth system, radiation energy from the sun and energy inside Earth are the driving force. Although not usually recognised, the energy inside Earth moves what's inside Earth and creates a convective movement of mantle, for example. As a result, materials near the Earth's surface move horizontally − this is called "plate tectonics" − and subducts into Earth's interior while materials inside Earth's interior come out of mid-oceanic ridges. In short, it is triggering a material recycling that connects Earth's surface with Earth's interior.

　

The development stage of homo-sphere can be roughly divided into two parts by directing our attention to driving force. Homo-sphere is also one of the Earth system's components and is therefore involved in the flow of energy and matter in the entire planet. One conceivable stage is us simply bypassing that flow of matter to maintain our homo-sphere. The other stage is that in which we possess the driving force within the homo-sphere and create a movement of matter in the entire planet Earth. I think you can see that there are these two stages of development in the system of homo-sphere.

　

To put it in simple terms, the first stage. for example, can be likened to an agricultural civilisation. It is a way of life that maintains the entire homo-sphere by simply allowing the flow of energy and matter in planet Earth to bypass the homo-sphere. In contrast, the second stage involves maintaining the homo-sphere by having a driving force inside the homo-sphere and creating new overall flow − you may want to call it "industrial civilisation". It is a way of life that digs out fossil fuel and other things from other components of the Earth system and uses it as driving force to create its own flow of matter in the entire planet.

　

The constraints that determine the size of homo-sphere will naturally differ when these two stages are compared. The flow per unit of time is called "flux", and the size of homo-sphere it can sustain will be limited to certain scale if this flux is constrained by the flow of matter in the planet Earth.

　

You can think about Japan in the Edo Period to get an image of this. The lives of people in Japan in those days were based on the plants that grew over a period of one year using sunlight. In other words, they were creating homo-sphere by relying on sunlight almost exclusively for circulation of energy and matter. When that happens, the size of material and energy circulation would remain the same because the amount of rain and sunlight available in one year was obviously constant. As a result, population did not change much for several hundred years in the Edo Period, although it did increase by some 5 million through expansion of cultivated acreage.

　

Meanwhile, when you look at present-day Japan, all kinds of energy and matter are coming from all over the world. The Japanese population, which once remained between 30 million to just over 30 million, has now increased to 120 million. Japan's population increased by nearly fourfold in the 100 years since the beginning of Meiji. This means that we were able to amplify the flow of matter by having our own driving force and that homo-sphere became large as a result of such amplified flow entering the homo-sphere.

　

This is what led to population increase and expansion of homo-sphere. There are these two stages. Today, homo-sphere is no longer created by depending on the flow of energy and matter on planet Earth; instead, you can say that we are creating the homo-sphere by having our own driving force and creating the flow of "matter" and "energy" to suit our desire in a planet we call Earth.

　

As a result, how big did homo-sphere become in the 20th Century, for example? If you base your judgment on population, you can say that it increased by about four times. This fourfold increase in population means that the size of homo-sphere has expanded by four times in the Earth system, so relocation will naturally occur in terms of distribution of matter. That is the problem we now call "contamination". The problem is manifesting in the form of a disturbance in flow of energy and matter or a change in accumulation of respective components on this planet Earth.

　

It is meaningless to try to solve this problem as a mere ethical issue or an issue of right and wrong. I don't think we can solve this problem unless we think about what is the harmonious homo-sphere within the Earth system. There is no point in using a sentimental expression such as "earth-friendly", either. We must sort out the problem by thinking about the adequate size of homo-sphere in the Earth system and about the kind of flow of energy or matter we should use. I think that is the stage we are now in.