Chapter 1.b
THE POSITION OF MAN IN EVOLUTION
Let‘s look back, trying to extend the concept of family tree to the whole history of the Earth and then let’s try to understand on which branch man is and since when is there.
To achieve this objective, we must have some basic notions of evolutionary history of life on our planet, then stop and consider, with greater awareness, the position of the human being.
1.b.1 – Is it important to know the evolutionary history?
Is it important to know the evolutionary history?
History is a systematic narration of facts considered in their evolution through time.
The history of evolution of life on Earth is therefore the science based reconstruction of how the ancient forms of life have resulted in the successive ones until today.
It should be remembered that this is something quite different from the theory of evolution of species, which tells us that species change and evolve, but not how they did it.
The scientific theories generally consist in a description of the laws of nature that remain unchanged over time and are therefore still valid; history instead reconstructs a series of past and, in principle, unrepeatable events. It follows that the theory of the evolution of species is a pure scientific theory and history is a historical and scientific reconstruction.
The incredible variety of living beings on Earth is the result of the phenomena at the basis of evolution: the randomness of mutations leads over time to exploit all the possible opportunities, including to colonize new environments; in these new environments, mutations resume the process of adaptation and natural selection leads to the creation of new species, all in a cycle without end. The consequence of all this is a progressive increase in the variety until there are available environments and resources.
The growth of the variety is also favored by another phenomenon: the mutations tend indeed to accumulate and form more complex structures which, by definition, have more parts that can then be modified.
Every species, including man, has thus behind its own history a long path, made up of all species that have preceded evolving one by the another.
ROYAL BOX
NIELS STEENSEN 
1.b.2 – How did the transition from matter to life happen?
How did the transition from matter to life happen?
The beginning of the solar system and the formation of Earth are dated back to around 4.5 billion years ago and it is estimated that it took about a billion years to gradually develop all the conditions necessary for the emergence of life.
Originally, what we today call planet Earth was a sphere of burning melted lava; this sphere was placed at a very convenient distance from the Sun: far enough so that the process of cooling and condensation could take place and at the same time close enough to prevent atmospheric gases to remain frozen.
Earth also had a size sufficient to retain a gaseous atmosphere and contained the chemical elements fundamental to the emergence of life.
After 500,000 years of gradual cooling, the steam that filled the atmosphere condensed and for thousands of years torrential rains fell on Earth and formed the oceans. During the period of cooling, carbon, the chemical element essential to life, quickly combined with hydrogen, oxygen, nitrogen, sulphur and phosphorus and generated an immense variety of chemical compounds. These six elements are still today the major chemical constituents of all living organisms.
The latest research on the origin of life are not based anymore on sudden and particular events such as an extremely powerful lightning or the insemination by molecules flown from meteorites; this research studies today the evolution of living systems as systems capable of self organization; it is then considered that the environment, formed on Earth in those bygone days, has encouraged the formation of complex molecules, that some of them became catalysts of a series of chemical reactions and that these gradually led to the formation of cell structures.
The astrophysics and geology indicate that, at that time, the appearance of Earth should have been very different from now, particularly in the chemical composition of the atmosphere and seas.
Then as now, the planet could look like a patchwork of environments, different for temperature, humidity, soil type, altitude or depth, chemical concentration of the various substances present in water or soil etc. ..
Modern biochemistry explains that in such conditions are formed molecules, called organic, which combining with each other become the bodies of living beings; furthermore, in a supportive environment, that even in remote eras could have been found somewhere on Earth, these molecules spontaneously react with each other, forming more complex compounds, accumulate and reach the right concentration for life. We must consider that these compounds are made of a large number of atoms and this leads to countless number of possible varieties; in this variety, over the millennia, it is plausible that have appeared specific molecules able to cause many chemical reactions still essential for living beings, and other molecules, known today, capable of producing copies of themselves.
Such molecules are thus able to reproduce, that means to be born by their own kind, and like all other molecules can disgregate and then die, showing therefore the main peculiarities of living beings.
There are also two other characteristics typical of living beings: a wide variety of different characters able to promote or less the reproductive process and the possibility of mutations, that is enough to start biological natural selection and evolution.
For the continuation of the history of life, a great importance had the development of two characteristics: the membranes and the use of DNA. The membranes, that still surround our cells, have a very simple basic chemical structure and were the product of one of the many above chemical reactions. These membranes form spontaneously microscopic bubbles, inside of which it is created a protected environment that maintains the right chemical concentration for the vital processes of the complex community of living molecules.
These processes, increasingly complex, began to be managed using chains of amino acids that with time, mutation after mutation, formed the DNA.
These structures, which become very complicated, had at their turn all the characteristics typical of the living beings, and they still exist today in a thousand forms and are generically called bacteria.
FURTHER INFO
AMINO ACIDS, ASTROPHYSICS, ATOM, BACTERIA, BIOCHEMISTRY,
CATALYSIS, CELL, GEOLOGY, METEORITE,
MOLECULE, CHEMICAL REACTION
ROYAL BOX
ALEKSANDR IVANOVIC OPARIN
1.b.3 – What have been the next forms of life?
What have been the next forms of life?
The study of genetics leads us to think that all forms living today are descendants from a single common ancestor; all cells of all known organisms base in fact their operation on the same type of molecule, the DNA, which incorporates the same encrypted language: the genetic code.
This ancient ancestor, presumed similar to the existing bacteria, subject to different environmental conditions, adapted itself under the circumstances and gave rise to new species; these species have also done the same, producing always evolving chains ready for new branches.
One of the first activities of bacteria was the fermentation, which is the decomposition of sugars to create the necessary energy to all cellular processes; such process allowed the bacteria to live thanks to chemicals existing in the land and water. Some of these bacteria developed a capacity of the greatest importance: to absorb nitrogen from air and transform it into various organic compounds. Nitrogen is a component of protein present in every cell and even today all living organisms, to survive, depend on the bacteria that fix nitrogen.
The bacteria also developed photosynthesis, a process that became the source of primary energy for life, although very different from that practiced by the current plants. All these survival strategies allowed the bacteria not only to live and evolve, but also to begin to alter the environment, maintaining, through their adjustment processes, the conditions for the development of life.
A new type of bacteria at some point developed a new process of photosynthesis capable of extracting hydrogen from water, releasing oxygen in the air. But this oxygen became at some point too much; oxygen pollution produced, approximately two billion years ago, an unprecedented disaster and the whole bacterial organization had to reorganize in order to survive.
The crisis of oxygen started an evolutionary process that brought to the appearance of cyanobacterial, who used their oxygen, the harmful substance, through aerobics respiration, based on the consumption of that element. Life was forever changed and so the environment in which evolving; the amount of free oxygen in the atmosphere stabilized to 21 per cent and it is to be noted that if this value would go below 15 percent, nothing would burn and bodies, unable to breathe, would die; above 25 percent instead everything would burn, combustion would be spontaneous and the flames would swallow the Earth. From millions of years the community of bacteria and their descendants maintain oxygen in the quantity ideal for the life of plants and animals.
It should be noted that not always living beings can adapt to various situations that arise; in that case their chain stops, which means that not only there will not have new species, but also the old one can disappear, that is to extinct.
The enormous variety of life forms has made it impossible that all the species would extinct for inability to adapt; among many species there are always many who manage to survive and to further differentiate. This is demonstrated by the fact that bacteria not only still exist in large numbers and in every part of the planet, but they also produced new forms of life, so complex and so different from them, to be classified as separate groups; among these, there are the protistis, beings formed by a single cell like bacteria, but with a nucleus containing the DNA and other internal structures managing the activities of the cell; this structure is also that of cells that make up our body and the body of every animal or plant.
Encouraged by genetic studies, it is considered therefore that all living beings formed by many cells, called multicellular, derived from these beings, and every form of life visible to the naked eye can therefore be seen as a huge and complicated colony of protists.
FURTHER INFO
CYANOBACTERIA, GENETIC CODE, ORGANIC COMPOUND,
FERMENTATION, PHOTOSYNTHESIS, GENETICS, PROTEIN, PROTIST
ROYAL BOX
JAMES DEWEY WATSON
1.b.4 – What the evolution of plants has been?
What the evolution of plants has been?
The progenitors of the plants looked like algae, that live in deep waters and were illuminated by the sun; their habitat sometimes dried and, at the end, some of they found ways to survive turning into plants living on the ground. Originally those plants were similar to mosses, had not either branches or leaves, but with the production of a new material in cell walls, called lignin, they develop the stems and branches, as well as the vascular systems to absorb water from roots. To resist drought, which was a constant threat in the new terrestrial environment, plants closed their embryos in seeds to protect them while they waited to find the appropriate moisture conditions to develop.
During a period from 350 to 250 million years ago, while the first land animals, the amphibians, evolved into reptiles and dinosaurs, lush tropical forests of “Ferns with seeds” covered extended regions of the planet. When, about 200 million years ago, glaciers formed on many continents, the ferns with seeds were replaced by evergreen conifers that could withstand the cold. Approximately 125 million years ago appeared the first plants with flowers, whose seeds were encased in fruit. From the outset, these plants have coexisted and they have evolved together with animals that ate the fruit and that disseminated in return the seeds not digested.
FURTHER INFO
ALGAE, PINOPHYTA, EMBRYO, FERN, HABITAT, LIGNIN, MOSS
ROYAL BOX
RICHARD VON WETTSTEIN
1.b.5 – Are fungi different from plants?
Are fungi different from plants?
In addition to plants, other types of multicellular organisms reached the shore: fungi. These, while look like plants, are completely different from them and are part of a separate “kingdom”. They appeared more or less 300 million years ago and developed together with plants, because they depend for the absorption of nitrogen by a tiny fungus that is in their roots. The mushrooms, visible or hidden, are however essential for the existence of forests.
FURTHER INFO
FUNGI
ROYAL BOX
HEINRICH ANTON DE BARY
1.b.6 – What are the characteristics of animals?
What are the characteristics of animals?
The multicellular bodies are divided into fungi, plants and animals; these latter are those who, for living, must feed on other living beings and are generally capable of moving. It is estimated that the appearance of the first animals dates back to around 700 million years ago and that all derive from a common ancestor; this ancestor should have been a complex colony of protists, perhaps similar to the current sponges, whose cells still enjoyed considerable autonomy. Even today the embryos of all animals, including humans, begin their development with a structure of this type, then start the process of differentiation and specialization of cells, that are divided into two or three layers: internal, external and intermediate, from which then derive all our tissues.
The construction of our body seems to retrace its evolutionary history; in fact the comparative anatomy, the fossil remains and genetic comparisons, show us that most known animal descended from a common ancestor, which body was divided into three main layers of cells: an outer protective layer, which in subsequent forms gives rise to skin, the sense organs and nervous system, an internal layer with digestive functions that then gives rise to all organs of the digestive system, and an intermediate layer from which will have origin bones, muscles, blood and the genital apparatus. The other animals descended from another branch, even more ancient, whose body structure was based on only two initial layers.
This ancient ancestor gave rise to many large families such as crustaceans, mollusks, insects, starfish and fish.
FURTHER INFO
ANATOMY, FOSSIL, SPONGE
ROYAL BOX
ANDREAS VAN WESSEL
1.b.7 – How to identify vertebrates?
How to identify vertebrates?
Fishes belong to a group of animals characterized by a symmetrical physical conformation, compared with a central axis; along that axis has set a rigid structure , which supports muscles, which in turn allows to swim in a sinuous manner. In fish and all their descendants, the spine is made up of a series of rings called vertebrae, resulting in the new name of the vertebral column and in the name of the group of animals who are gifted with this vertebral column, precisely the vertebrates.
At a distant age, freshwater fish have originated the group of amphibians. The first insects reached the mainland in the same period of amphibians, that is about 400 million years ago. The amphibians are specialized in the life out of the water, where they must return to spawn. Even today all amphibians seek freshwater to lay their eggs and drink, tolerating brackish water.
From amphibious then descended reptiles, which have developed the ability to lay down their eggs on land and lost the ability to breathe in water, so that the aquatic reptiles must return to the surface to breathe and should even reach the mainland to lay their eggs.
From reptiles, about 200 million years ago, have also independently arisen two large families: the birds and mammals.
The birds are distinguished by having the body covered with feathers and from having two front limbs as wings that allow almost all species to fly; mammals instead have the skin covered with hair and are predominantly soil or tree animals; they feed their little ones with milk secreted from breast and hence their name.
All vertebrates have the following characteristics: a spine with a skull to one end, a brain contained and protected by the skull and ribs as support for muscles and protection of internal organs; also almost all have a jaw with teeth, four limbs and a tail. From the anatomical point of view the human being is therefore a typical vertebrate and in particular a mammal.
THE FORM
VERTEBRATES
1.b.8 – Monkeys are really our kin?
Monkeys are really our kin?
The monkeys are a group of mammals specializing in life on trees; almost all their species therefore live mainly on trees, leading diurnal life and omnivorous diet; also very important for understanding human nature, almost all live in flocks. The monkeys have prehensile hands and feet to grasp the branches of trees, and often in the American variety, the tail is also prehensile. The hands in particular are used to bring food to their mouths, for cleaning the hair, to care for the offspring; some species also use them to build shelters from the rain, a place to sleep and some simple tools.
If we do a thorough examination, monkeys have great similarities with men, both physical and behavioral, and there are no more doubts that by the family of great apes, such as gorillas and chimpanzees, derived about 6 million years ago that of hominids from which the man of today had origin.
ROYAL BOX
JANE GOODALL
1.b.9 – Are the hominids our ancestors?
Are the hominids our ancestors?
The group of hominids began its history adapting to a life on the ground, probably because of a climate change that made the forest recede in proximity to some of major lakes in Africa. The drastic environmental change drove the great apes to adapt to a more terricolous life, considering the scarcity of trees. They withdrew together with the forest, perhaps to stay near the lakes since, with an increasingly arid climate, the water had become an increasingly valuable good. Some have hinted the hypothesis that hominids adapted to a life style similar to that of hippos while retaining the omnivorous diet of monkeys.
The hominids are divided into two main groups: the australopitechus, which is the oldest kind, and the genus homo, appeared about 2 million years ago, which also includes today man. The latest hominids present a progressive reduction of bulging eye sockets and jaw associated with an increase in production of tools. There is evidence that the homo erectus, one of the oldest species of the genus homo, already used the fire and therefore such use is not a discovery of our species.
From homo erectus, about 800 thousand years ago, developed the homo antecessor, which disseminated in Africa, Middle East and Europe, where at its turn gave origin to various species; about 600 thousand years ago generated the homo of Heidelberg, which then became the man of Neanderthal; about 200 thousand years ago, in Africa, the homo antecessor gave rise to the current man, defined Homo sapiens.
FURTHER INFO
AUSTRALOPITHECUS, HOMO ERECTUS, HOMO NEANDERTHALENSIS,
HOMO SAPIENS
ROYAL BOX
LOUIS LEAKEY
1.b.10 – What is the chronologic position of man in the environment?
What is the chronologic position of man in the environment?
Speaking of the history of life, we have seen periods of millions, hundreds of millions or billions of years. These periods very far from our perception, are difficult to conceive and it is difficult to give them the due weight. Let’s try to realize this concept with the following example:
80 years approximately average life;
5,000 years approximately of history more or less known;
200,000 years approximately of existence of current man
(homo sapiens);
4,500,000,000 years approximately of life on the planet Earth.
By writing these figure in columns, we can have an initial perception of how recently man has appeared on earth, but how long is four billions and five hundred millions of years? This is a figure so large to have difficulty even in reading it, a figure that surely we cannot perceive in relation to our life.
To make more comprehensible the time of our planet, a curious game can be done that relates life on Earth to a day, which is the unit with which we are familiar:
00:00 hours the planet Earth is formed;
around 04:00 p.m.: the first protists;
around 08:00 p.m.: the first aquatic animals;
around 10:00 p.m.: the first terrestrial animals;
around 11:00 p.m.: the first mammals;
around 11:40 p.m.: the appearance of the first prosimians;
around 11:53 p.m.: the appearance of the first great apes;
around 11:58 p.m.: the appearance of the first hominids;
around 11:59:54 p.m.: appearance of the homo sapiens;
around 11:59:59:94 p.m.: the birth of Christ.
Before this game, certainly none of us would have assumed that the prehistory began about six seconds before midnight and that the era “after Christ” of current calendars is a small fraction in hundredths of a second.
All the existence of humanity is only a wink of an eye compared to the history of Earth and the modern era itself is only a thousandth part of human history.
ROYAL BOX
WILLARD FRANK LIBBY
1.b.11 – What is the astronomical collocation of man environment?
What is the astronomical collocation of man environment?
The man then, for a microscopic period, lives and interacts with the surrounding environment of planet Earth, but this in turn is part of more complex systems:
– planet Earth is positioned in the solar system, i.e. an assembly of celestial bodies who suffer the gravitational attraction of the Sun. In the solar system there are eight planets with their satellites, some tens of thousands of asteroids, a massive number of comets and countless meteorites;
– the solar system is located, along with at least another 200 billion stars in the galaxy, In the Milky Way;
– the Milky Way, together with at least thirty other galaxies, is part of the Local Group. This definition seems bizarre in relation to the inordinate size of that group, but is instead significant, compared to the immensity of the Universe.
Cosmology is the science that seeks to understand the Universe as a whole, with the widest possible scale. The developments of physics and astronomy and the increasingly advanced technology can extend more and more the cosmic horizon, but what is currently known is already more than enough to be aware of the fact that man environment, the planet Earth, is practically a speck of dust in the immensity of cosmos.
FURTHER INFO
COSMOLOGY, GALAXY, SOLAR SYSTEM, UNIVERSE
ROYAL BOX
MIKOLAJ KOPERNIK 
ABSTRACTS
n. 4 – PLACEMENT OF THE EARTH
