Chapter 1.a

December 2, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

MAN, ONE OF THE EVOLVING SPECIES

Let’s have a look around us; let’s observe the environment, with all the fantastic animals that flanked us in the wonderful journey of life and then let’s try to understand the role of man in the complex carousel of nature.
To succeed, we need to have a basic knowledge on the concept of biological species and on the theory of evolution, then stop and reflect with a deeper knowledge on the nature of human beings.

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1.a.1 – What do we mean with species?

December 3, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

leone

What do we mean with species?

The term species is synonymous with variety, gender, type, but in biology has taken a precise and technical meaning of fundamental importance to become one of the basic concepts of modern biology.
Men see living around them so many varieties of animals and it can be observed that these animals generate cubs of their own kind by mating with their own kind; horses generate other horses, dogs other dogs, etc.., just as men generate other men. The plants, animals and men who die are therefore replaced by the new born, generation after generation, in an endless cycle that, like the cycle of seasons, is repeated always equal to itself, forming an extremely stable picture.
Every form of life appears therefore as a manifestation of the many and immutable laws of nature, which form a smooth and reassuring context; bear with patience every winter knowing that then inevitably spring comes, as after the night a new day will come, after a thunderstorm, the calm will return etc.. and the repetition of the events thus infuses security to the extent that allows to provide that the hardships sooner or later certainly will end and good things will return.
Likewise, you can observe that mixed mating (between different kinds) will not take place or do not generate children; anyway, considering the domestic varieties, sometimes this happens: If we look at the many breeds of dogs, we can in fact note how these have the opportunity to cross; two groups of dogs of different races, placed in the same pen, form mixed couples that generate puppies with mixed physical characteristics. Once grown, these puppies also form couples, mating both among themselves and with the original groups and, after several generations, the peculiar characters of a race will also present in the other descendants and vice versa, there will be no more two groups distinguishable for their appearance but one group born from the merger of the first two; by farming chickens and pigeons instead, this won’t happen. The same phenomenon happens even in a forest or in another natural environment, in the presence of different varieties with the possibility of intercrosses in reproduction.
If we call “races” the varieties with the possibility of intercrosses and we call the other “species”, we can therefore say that in the same environment cannot coexist for long time two or more different races because the same tend to combine giving rise to a single genre. In a single natural environment therefore we can only find different species, which differ from the races for their inability to interbreed, regardless of the appearance of their physical characteristics; this is a general rule by definition, valid for all species of animals we see around us; they are separated from the point of view of reproduction and are kept separated by nature and therefore it is not just a question of appearance or a simple human convention.
The stable repetitiveness of species, both for animals and plants, is possible thanks to a reproductive isolation, which is the reason why biology bases the concept of species on the reproductive capacity. Giving therefore the name “horse” to a given reference animal, will also be horses all the animals that can inbreed with it (or who appear like it, even though of the same sex) to generate other horses, able in turn to repeat the cycle of reproduction. Are excluded all other animals, including donkeys that can generate with horses only sterile offspring.
Still using the example of the many breeds of dogs, it is often possible to find some of them with enormous physical differences, but to continue on existing in a distinct manner, they must be kept separate, otherwise they would intercross. The existence in nature of different races of the same species is therefore due to the fact that these races live in different regions, separated by a long distance, by a mountain range or by the sea, as well as domestic races are kept separate in different farms or by a simple fence.
Since the concept of species is linked to stability, immutability in succession of generations, one can understand the difficulty, even in the absence of religious dogmas, to accept the idea that the various forms of life can change over time.

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   BREED,   SPECIES

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1.a.2 – Is an evolution of species possible over time?

December 4, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

giraffa

Is an evolution of species possible over time?

The modern theory of evolution says that with the elapse of many thousands years, living species can change and give rise to new species; this means that this theory denies that species are fixed and immutable as it appears in everyday life. These changes are anyway  so slow to be perceptible only in a few millennia and then, in similar time intervals, the species can almost always be regarded as fixed and immutable as they appear in everyday life. The immutability of species is therefore a valid but relative concept, as its validity is limited to some centuries or millennia, i.e. periods that exceed the lives of dozens of subsequent generations of men, who will not perceive these changes, neither from experience inherited by forefathers or by direct experience.
The generation of a new species occurs when, among the many changes that happen over time, there is one that impels the intercross with the original species.
The current theory of evolution has its basis on two pillars, two phenomena both necessary for the evolution of species: natural selection and genetic mutation.

 

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1.a.3 – What is the role of natural selection in the evolution of species?

December 5, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

mimetico

What is the role of natural selection in the evolution of species?

To understand the concept of natural selection we should start by noting that, like human beings, specimens of an animal species have many individual characteristics and therefore are not perfectly equal to one another. The elements in common are distinctive of species, others are peculiar to the individual (for example, among equines, white coat with black stripes characterizes the species of zebras, but two zebras can be distinguished for the different height, different strength, difference in quality of teeth etc.).. Another fundamental and easily observed phenomenon is that some of the individual features can be inherited.
The variability of individual characteristics and their inheritance are objective facts always exploited by farmers to select particularly valuable breeds of livestock. Specimens with distinctive features considered positive are isolated from others and made inbreed between them; those cubs who inherit the desired qualities will remain in the group while the others  will be sent away. This way, the positive characteristics will be increasingly common in the group and, after a number of generations, the distinctive elements of a few individuals shall have become common features of the whole group, now become a variety of their particular species.
The animals in their environment form a sort of natural breeding in which each individual has numerous special features that can be transmitted to the offspring. Some quality of individual animal can, in a special environment, increase the survival of his offspring, compared to their own kind; these characters, generation after generation, will inevitably spread in the population and become common to the entire population itself, forming a new variety. This phenomenon is called natural selection.
It is important to note that, to spread the distinctive elements of an individual, it is not necessary that all the others are either eliminated or being prevented from reproducing: just their reproduction has less success, i.e., there will be a minor number of offspring able to reproduce. In nature the role of breeder is done by the environment, since they are the characteristics of the same to determine the probability of reproductive success. This is exactly the same for plants and fungi.

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1.a.4 – How mutations happen in the evolution of species?

December 6, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

dna

How mutations happen in the evolution of species?

The individual characteristics are inherited through the genes, chemical entities present in the cells, including those intended for the reproduction of the body. To the total number of genes, also called genetic heritage, correspond all the individual inheritable physical characteristics.
The genes are linked to one another in a long chain forming  the DNA molecule. This molecule has the ability to replicate, thus duplicating the genes as well. It is possible, although it is a rare phenomenon, that a mistake occurs in that duplication and this leads to the modification of a gene. Mutations can be also caused by physical or chemical agents as external radiation, viruses and other things that are called mutagen. The alteration of a gene is called mutation and may result in the emergence of a new individual feature.
The structure of an organism is a very complicated architecture in which an arbitrary change of a gene can have the most disparate effects; it will be disastrous if compromises the functioning of a gene that plays a strategic and fundamental role (like genetic diseases), while the effects will be less deleterious if the mutated gene has a more marginal role, up to the case when no harmful effect is there, as it may be the case of the emergence of a new nuance of eye color. The genetic characteristics of an organism are enormously numerous as well as the possible mutations, including those harmless. These mutations, just because harmless, will not be eliminated by natural selection and therefore roll over time giving rise to great variability of individual characters (almond eyes, protruding cheekbones, receding chin, taurine neck etc.). The greater the variety is, the greater will be the chance that some feature is useful in the event of an environmental change (for example, the color of the skin, hair and eye for men who have colonized the northern regions of the planet).
It should be noted that mutations play a key role in the evolution of species as natural selection provide the material to work on. Without mutations, natural selection tends only to standardize the most of existing genetic heritage without further changes. On the other hand, we can say that without selection even natural mutations alone could not lead to the phenomenon of  evolution of species, but only to an increase in individual genetic variability with new purely random combinations.

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   DNA,   GENE,  MUTATION,  RADIATION,  VIRUS

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1.a.5 – How a new species appears?

December 7, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

pinguino

How a new species appears?

When in evolution appears a mutation that prevents the possibility of crossing with the original species, it is passed a point of no return, a point after which there can be no longer the genetic mixing. This reproductive isolation, leads to the formation of a new species: it is not due to physical or geographical barriers but it is physiological, is part for the intrinsic nature of the species.
This can happen in many ways, for example, two people of the  same species, separated in different regions, can develop mutations that lead to the creation of two separate races. Then if the race of the first region develops a ritual of courtship incompatible with the other members of the second region, these latter will always be discarded in case of encounter. Another case occurs when the two races develop a physical shape too different; think of the difference in size between a St. Bernard dog and a Chihuahua dog that makes mating mechanically impossible.
The most important case is however the one due to genetic causes, that is when the accumulation of several mutations makes the fusion of DNA of two individuals increasingly difficult, until the total incompatibility is reached, causing sterility of the offspring or its failure to develop.

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1.a.6 – Is there a kinship among all species?

December 8, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

GORILLA RID  Fotolia_5005909_XSIs there a kinship among all species?

When a species is divided in two or more species, we can say that the new forms appeared descend from the first as the children are descended from their parents. This way it is highlighted a kind of kinship between species which, as human beings, may arise from each other, have a common ancestor, belonging to a very large family and form dynasties with also very complicated genealogical trees. Generally, the more distant the relationship is, the greater are the physical differences that appear, as a result of the sum of many mutations; with a reverse reasoning, as more are similarities, the closer we expect the kinship to be. With this criterion, it is easy to establish that a gorilla is a closer relative of man than it is of a horse and that this, in turn, has a closer kinship with man than with a hawk.
All this shows that man is not derived from present monkeys as well as a given individual is not derived from a cousin; the human  species and that of gorillas, today coexisting, result from an ancestor of both species as well as two cousins descended by a pair of grandparents in common.

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1.a.7 – The adaptation is subject to environmental context?

December 9, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

falco

The adaptation is subject to environmental context?

For adaptation we mean the sum of changes that a species undergoes because of natural selection in a given environment.  Natural selection favors the mutations that promote the survival of future generations, who consequently will be better fit to live in that environment. A classic example of adaptation is the development of a thick, warm fur in a region having very cold climate, or the development of long fast legs to escape predators.
Adaptation is always related to a certain environment because this determines the chances of survival and therefore the natural selection. However, a positive change in a certain context may also prove to be useful in other circumstances: for example hands, that the first monkeys used to cling to branches and to collect fruits, were then used by men to build instruments of all kinds, to write and to drive a car; another example is the stratum of fat, developed to deal with periods of famine and then became a protection against the cold for animals of polar regions. In these cases, we talk about pre-adaptation, as if they were an early adaptation, but in fact these are fortunate combinations which are anyway of great importance for the evolution, because increase the chances of adaptation to new environments, as well as to meet new needs and exploit new resources. In general, the evolution progresses by small steps but cannot create from scratch the new organs: it can only modify the existing ones, which therefore constitute a pre-adaptation, that is a basis for future developments.
In any stable environment, which does not change over time, positive mutations would sum up to exhaust all possibilities; over time, the appearance of new positive changes would increasingly become less likely and the different species would  find themselves in a sort of state of equilibrium given by the maximum adaptation to their environment.
The evolution is slow, gradual, but not uniform; often presents a variable speed precisely because of stability or instability of the environment. A situation of perfect stability is also very unlikely, in fact every mutation of any species is actually a small or large environmental change and thus the evolution will not stop ever, even without considering geological and climatic changes.

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1.a.8 – Progress and development: two terms to be distinguished?

December 10, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

treno

Progress and development: two terms to be distinguished?

With the term progress it is generally meant an improvement, namely a change that brings some benefits: in fact we speak of economic, technological progress etc…
If we talk instead of evolution, it refers to a gradual change over time, not necessarily beneficial, for example the evolution of a disease, a storm, the phases of the moon.
Since the biological evolution is a gradual change that involves always some benefit for the survival of the species (or the offspring) such as a greater capacity to provide food, to protect the offspring, to escape predators, we may ask why it is defined evolution and not biological progress.
The main reason is that natural selection favors those changes that offer an immediate advantage in the environment in which the species lives, but often these changes are valid only in that environment, for example, it is good to develop a thick fur in a very cold climate, but if it warms, the same fur will become a problem. The biological progress is therefore related to a given environment, limited to this and is more precisely defined as adaptation, while the biological evolution never stops and is indeed stimulated by environmental changes.
To a continuous evolution does not match then a continuous progress, so it is good not to confuse the two concepts.

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THE POINTS OF VIEW
lente_ingrandimento SOCIAL PROGRESS
Progresso ed evoluzione

ABSTRACTS
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n. 2 – PROGRESS AND EVOLUTION 

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Chapter 1.b

December 11, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

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.

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1.b.1 – Is it important to know the evolutionary history?

December 12, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

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.

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1.b.2 – How did the transition from matter to life happen?

December 13, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

chimico

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.

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1.b.3 – What have been the next forms of life?

December 14, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

cellule

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.

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1.b.4 – What the evolution of plants has been?

December 15, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

alghe

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.

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1.b.5 – Are fungi different from plants?

December 16, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

funghi

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.

 

 

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1.b.6 – What are the characteristics of animals?

December 17, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

pesce

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.

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1.b.7 – How to identify vertebrates?

December 18, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

colonna

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.

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1.b.8 – Monkeys are really our kin?

December 19, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

scimpanzé

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.

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1.b.9 – Are the hominids our ancestors?

December 20, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

utensile

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.

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1.b.10 – What is the chronologic position of man in the environment?

December 21, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

clessidra

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.

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1.b.11 – What is the astronomical collocation of man environment?

December 22, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

universo

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.

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  COSMOLOGY,  GALAXY,  SOLAR SYSTEM,  UNIVERSE

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Chapter 1.c

December 23, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

HUMAN NATURE

Let’s have a look inside ourselves; let’s commit to apply the acquired knowledge for understanding the nature of human beings.
It is a theme to which it is normally given a value of insuperable complexity, if not mysticism, which discourages or even frightens any solution. To reassure the hearts and simplify the work, we need to learn knowledge related to evolutionary strategies, with particular reference to the winning ones peculiar to man

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1.c.1 – What are the evolutionary strategies?

December 24, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

canguro

What are the evolutionary strategies?

The living beings adapt to the environment in which they live to meet their needs of survival. These exigencies can be seen as problems to solve, problems whose solution lies in a reply of adaptation, i.e. in development of appropriate strategies through the biological evolution.
Among the fundamental evolutionary strategies, we must remember the following: symbiosis, group, specialization and sexuality.

 

 

 

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1.c.2 – Is symbiosis an important evolutionary strategy?

December 25, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

lichene

Is symbiosis an important evolutionary strategy?

When the individuals of two different species live together to obtain a mutual benefit, it is realized a phenomenon of fundamental importance defined symbiosis. This relation is sometimes so close that the two units end with forming a single body; is the case of lichens, which are bodies formed from the merger of a mushroom with a colony of unicellular algae; the fungus provides nourishment for algae, water and minerals, and support for better lighting and ventilation, while the algae in turn feed the fungus with the organic molecules produced through photosynthesis.
An example of symbiosis in the animal world is given by the Egyptian trochilus and the Nile crocodile: the trochilus is a bird that feeds cleaning the teeth of the crocodile from annoying residues of food, getting in return protection and food.
The examples of symbiosis are very numerous and some of them have obtained a great success; we can recall the symbiotic relationship between plants and fungi living in their roots that allows plants to absorb  phosphorus and nitrogen, indispensable to their metabolism, while plants allow mushrooms to eat their own sap.
Symbiosis is one of the oldest evolutionary strategies. We have seen how one of the fundamental steps in evolution of living beings is given by the appearance of protists, i.e. bodies that are distinct from bacteria by a much more complex internal structure. This structure is formed by a nucleus that joins with other parties, isolated from internal membranes and thus distinct, which, by carrying out specific functions, represent the real internal organs. Some of these organs, the mitochondria, have within them their own DNA molecule, and then a genetic heritage that reveals their true nature: they are the descendants of ancient bacteria able to use the waste products of other chemical cellular reactions to feed themselves and derive the energy necessary for life; the above is carried out with a much higher efficiency than that of the cell their host. Over time, these bacteria have become the power plant of the cell, obtaining in change a constant and secure source of nourishment.
A similar situation is in the case of chloroplasts present in the cells of all plants: they are the evolution of ancient bacteria able to carry out photosynthesis.
It is crucial to know that the mitochondria are also present in the cells of all animals and also in humans.
This is a symbiotic strategy that led to evolutionary success of protists.
The idea of creating new life forms through the merger of different species Is called symbiogenesis, and it is now clear that it has played an important role in evolution, since it allowed to combine the capabilities developed and improved by different species of bacteria (such as the use of sunlight and oxygen as a source of energy) with those of autonomous movement peculiar to complex cells. This way, chances of survival otherwise unthinkable were seized.
The symbiosis may seem a survival strategy far away from the life of human beings, but reality is quite different. For example, in human intestines, as in that of many other animals, there are colonies of bacteria that help us in digestion and in the defense from infections, having in change a safe and easy nourishment. The number of such bacteria gives us an idea of the vastness of the phenomenon: we know more than 400 different species of them.
We must also remember that every cell of the human body, like those of all animals, contains a large number of mitochondria and is thus in turn a symbiotic body . The symbiosis is therefore essential to our lives.

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1.c.3 – What is the use of living in a group?

December 26, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

branco

What is the use of living in a group?

An old and well-known proverb tells us that unity is strength. This principle is been exploited not only with the symbiosis of different kinds, but also through alliances and cohabitation between members of the same species. These, rather than living isolated, can meet in groups with multiple advantages: in a group, predators can encircle the prey, the prey in the flock can better defend themselves from predators; together can carry out activities otherwise impossible, for example, the ants may build huge anthills only through cooperation.
The strategy group is very old and, as in the case of symbiosis, may be so extreme as leading to formation of a single body; it is apparently successful in the first multicellular beings, descendants from colonies of unicellular organisms, so closely associated with their group that they cannot live without it.

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1.c.4 – What’s the use of specialization?

December 27, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

chirurgo

What’s the use of specialization?

The species coexisting in a given environment can all be seen as a great and numerous community that tries to exploit all possible resources in order to perpetuate life.
Considering that the same structure cannot be suitable for all applications, in order of making the best use of various resources (that could be the different sources of nourishment), it was necessary to generate a growing variety of species, each specialized in conducting a particular lifestyle that takes advantage of special resources or favorable conditions. In this communities of species, called ecosystem, every form of life carries out a particular role as an actor in a drama. Surviving therefore means to obtain one of the available roles; this place is often defined as ecological niche.
A similar phenomenon occurs in the community formed by a single species, because, in order to make the best use of every chance of survival for the group, this forms inside of itself a populations specialized in performing a given activity. If we take as example an anthill, we can see that there are worker ants, warrior ants and a king and a queen for breeding purposes.
The same process was developed with the first multicellular beings, whose cells have specialized forming different tissues. The great anatomical complexity of the other animals is then due to the phenomenon of specialization.

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1.c.5 – Sexuality leads to genetic mixing?

December 28, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

famiglia

Sexuality leads to genetic mixing?

Sexuality is a strategy that allows to reuse the genes already available through a different association. The result is similar to that of a mutation but, unlike this, regularly occurs in every reproduction act. The advantage may be insignificant for the individual, but is crucial for the species and its future evolution: by mating occurs fertilization of the egg in which the mother genes recombine with those of the father; thus the descendants of an individual will be able to exploit the positive mutations arising in the other parent, bringing the benefits of evolution arising from different sources; with this procedure we obtain something similar to what symbiosis achieved by combining the different capabilities of different species. The new combinations can also be negative and, in order to diffuse only the positive ones, the intervention of natural selection is necessary. Similar considerations were made even talking about the phenomenon of mutations but, unlike this, which is slow because based on rare events, the phenomenon of sexual reproduction creates new combinations at each new birth and then generates a much higher number of variants. The result of this phenomenon is a much greater capacity and speed of adaptation and this is the great advantage of evolutionary sexuality: it is no coincidence that virtually all animals and plants that we see around us use this technique.
The phenomenon of sexuality joins that of specialization and the result is that in reproduction both parents play different roles; since for playing different roles, different characteristics are necessary, the evolution has led to the creation of two types of sex: male and female.
It seems that the protists have been the first beings, with unicellular nucleus and internal organs, to develop sexuality and, since then, the strategy was no more abandoned. From a greater capacity and speed of adaptation has resulted a faster evolution and diversification.
The appearance of the first unicellular beings with sexual reproduction occurred around one billion and a half years ago and this corresponds, as we have seen, to h. 16:00 on our evolutionary day. Before then, only the bacteria had developed, who reproduce themselves by scission, i.e. asexually; evolution, for almost three quarters of history of the Earth, has produced thus only the bacteria, while with the advent of the first protists, in the last quarter or so, all the forms that we know, and those extinct too, have developed. This incredible acceleration is due to the development of sexuality. It is therefore reasonable to assume that evolution has a natural tendency, irregular and tied to random events, both in terms of adaptability that results in the production of individual variations, and in terms of speed of adaptation i.e. the production of new species. 

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1.c.6 – The egg is an organic shuttle?

December 29, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

uova

The egg is an organic shuttle?

Sometimes it happens that living organisms are in the need to colonize an environment quite different from the original, so different to be prohibitive for survival. Often there are no alternatives to death but some species have been successful in the enterprise, thanks to a simple but ingenious strategy: to create a protection around them, a sort of housing within which preserving or reproducing a portion of the original environment.
This is what vertebrates did passing from the oceans to the mainland; Indeed, their skin became a waterproof casing that prevented a rapid dehydration and that kept inside an environment favorable to life of their cells. Even today the salt concentrations in the blood and other body fluids of mammals, as the sweat and tears, are very similar to the ocean, that is that environment that was our first cradle, which we have abandoned about 400 million years ago, but that we still carry inside us.
The same strategy was used to allow the development of their offspring: eggs of reptiles and birds, and the uterus of mammals, reproduce the wateriness, the hydrostatic drive and salinity of the original water.
This technique is perhaps the oldest of all: it is in fact assumed that inside the cell membrane of bacteria, as inside the nucleus of some more complex cells, an environment similar to that in which life was born is reproduced.
It is a simple, essential and ancient technique but always valid; it is actually the same as we men use when we build submarines and space ships, which are large containers of a portion of Earth environment, with air for breathing and controlled temperature, which can travel in environments for us uninhabitable.

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1.c.7 – Perception and response: an important sequence?

December 30, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

percezione

Perception and response: an important sequence?

Even living in the same environment, we can find in very different situations: shifting from day to night and vice versa;  from warm to cold, from drought to rain; from insulation to the company, and predators can become preys. The life depends on these environmental changes and all the bodies, in some way, react to these stimuli. For reaction is therefore meant the creation of a change and this change may be physiological, as the reaction of the immune system in the presence of an infection, or behavioral, as a quick flight in presence of a predator. When a stimulus of the outside world leads to a consequent reaction, one can say that the stimulus was perceived; i.e. a signal that triggered a response was somehow received.
Considering the obvious and vital importance of this process, it is immediately understood how, during evolution, a myriad of systems for perceiving any sort of stimuli and to respond to them with a speedy reaction, has developed.
The unicellular beings are already able to respond to a wide variety of chemical and physical stimuli: for example, when they are in contact with nutrients, they produce the enzymes necessary for their absorption.
Even the plants are sensitive to different types of chemical and physical stimuli; their activities, for example, change from day, during which produce the substances they need through photosynthesis, to night, during which such activity stops. Plants are moreover able to do much more: it was found that in the presence of an invasion by pests, some plants not only have a chemical reaction of defense, but also emit in the air substances that, perceived by the other plants, activate their defenses enabling them to anticipate the attack. It is therefore a genuine chemical communication consisting of stimuli and appropriate reactions.
In the animal world, where for surviving it is necessary to identify a prey or a predator, the greater need to perceive and react led to the formation of the sense organs and nervous system. Thanks to the bodies specialized in the perception of certain stimuli, the animals manage to locate their prey or their predators, feel the presence of their own kind and many other things. Very early in their history, animals have developed a system to manage the amount of information from their senses and to give a comprehensive interpretation: this is the nervous system, which is formed by neurons, very specialized cells capable of transmitting electrochemical signals at high speed to one another.
The neurons form in the body real communication channels, through which the stimuli perceived by the senses are transmitted to the brain, that is a sort of centre of coordination determining the most appropriate reaction. This latter, in some cases, may necessarily result in a given motion.
The brain then manages the sensations and accordingly guides the movements of the body, but also performs many other functions; among them, two have a fundamental importance: memory and learning.

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1.c.8 – Are memory and learning evolving strategies?

December 31, 2009 — Riccardo Sabellotti - Giacinto Sabellotti

elefanti

Are memory and learning evolving strategies?

Thanks to memory the brain is able to recognize feelings already felt and accumulate experience; when facing a new problem, every animal can react with generic, uncoordinated and random actions but certainly will remember the one that has proved to be more effective; in a subsequent and similar situation, to remind it will save time and efforts. We are facing a new form of adaptation; after genetic adaptation, which requires a large number of generations, we are now considering the intellectual adaptation, which, even if limited to a single individual and consequent to a period of apprenticeship, offers major advantages: thanks to memory and learning, animals can develop a great number of specific reactions, enabling him to swim, run, climb, fly, hunt, build lairs and many other things to be done at an appropriate time.
These faculty of the brain, already present in marine flat  worms, which are rather an archaic group, probably have developed to learn to move on the uneven seabed, but we know that they are the basis for important future developments. These abilities, which can be summed up in the term “intelligence”, were maintained in all main groups that have later evolved, and this demonstrates their importance and versatility.
These strategies, perhaps with minor modifications, have allowed the colonization of a wide variety of environments. This brilliant result is called evolutionary success.
Now let’s consider the strategies that led especially our species to the evolutionary success.

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1.c.9 – Is handling essential for man?

January 1, 2010 — Riccardo Sabellotti - Giacinto Sabellotti

mani

Is handling essential for man?

Hands and arms are much more ancient structures than we are, so much that they were already present in amphibians in an almost identical form. They are a perfect example of pre-adaptation to various functions: if in the first amphibians they were a simple point of support, in subsequent forms living on trees, the movement and mobility of the thumb have made them capable of grasping the branches so that they can climb. All mammals living on trees are able to use their hands in this way, but some of them have found other uses: the squirrels use them to bring food to their mouths, monkeys use them even for cleaning the body and to care for the offspring and finally the great apes use them to build shelters and small tools. This was possible thanks to a increasing mobility and coordination of the fingers and especially the thumb, which has evolved becoming able to precisely oppose to the tip of the forefinger.
The ability to manipulate objects has been developed further in humans, whose hands have a more square and less elongated shape compared to monkeys next to him, so that the thumb of man can reach easily and with great speed the tip of each finger; this shows how the main purpose of hands is no more to cling to branches. The number and sophistication of the instruments constructed and used by human hands has become incalculable, so that its most apparent feature is perhaps that of being a manipulator of objects. The importance of this faculty in our lives is obvious.

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1.c.10 – Socialization is found in all human major activities?

January 2, 2010 — Riccardo Sabellotti - Giacinto Sabellotti

operai

Socialization is found in all human major activities?

The socialization is a variant of the group strategy which allows members of the community to maintain its own movement autonomy. This is a strategy very common among mammals and almost universally used by monkeys; it is therefore linked to the evolutionary success of many mammals and in particular of man, who has not only inherited, but has also further developed it.
Without any particular training, a man left alone in a in a forest or grassland has less chance of survival than a monkey isolated in its environment. This demonstrates a greater degree of dependence to group, i.e. the need for an articulated socialization.
The human community, especially the most recent, have a high level of specialization with a high number of sub-groups that are dedicated to particular activities (workers, doctors, teachers etc.). This is also typical of the groups in which the link between the members is very close.
Man, a set of specialized and interacting organs, in turn consisting of symbiotic cells, has thus the need to exploit even the phenomena of the group and the specialization in their social organizations.
It is worth noting here that all the main activities of such work, protection, the search for food, etc.., occur through some form of collaboration and then through a social contact. The ancient herd of monkeys has thus evolved enlarging itself, specializing and becoming complex up to levels never seen before among mammals and, perhaps, throughout the animal kingdom. Such a development, which historically goes hand in hand with the expansion of the human population, is surely one of the bases of its evolutionary success.

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1.c.11 – Is word the first stone of human culture?

January 3, 2010 — Riccardo Sabellotti - Giacinto Sabellotti

libri

Is word the first stone of human culture?

To coordinate the activities in a society as complex as human is, an efficient communication system is needed.
Today we know that our movements are coordinated by a complex system of internal communication that is the nervous system, which cells use a complex electrochemical language. Similarly human beings use a complex language made of gestures, facial expressions and, above all, of words. Even in this case, it is an evolution of language used by monkeys, which use both visual signals and sounds; as previously seen for the group, also the complexity of language is considerably increased, particularly for what concerns sound signals.
We humans have in practice a different sound to indicate any type of object and action that we are able to conceive: i.e. words.  We can achieve such a miracle, through appropriate modifications of the voice refined by evolution, of being able to modulate and articulate an enormous number of sounds at high speed. The words are associated with each other to express more complex concepts and this according to conventional, very intricate rules, called grammar and syntax.
A similar evolutionary and intellectual effort leads to an exceptional ability in communication, allows to sharpen faculties uncommon in the animal world, including monkeys; this is a faculty that goes beyond the need to manage public relations: it must therefore have been developed for another purpose.
The word enables communication of complex concepts and this, if it can be unnecessary for the purpose of socialization, is indispensable in specialized work that, as we have seen, is an essential and successful peculiarity of the human being.
The purpose we mentioned before is then the formation and transmission of culture, i.e. the body of knowledge tending to increase and to become increasingly complex.

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1.c.12 – Is culture an integration to the genetic heritage?

January 4, 2010 — Riccardo Sabellotti - Giacinto Sabellotti

bicicletta

Is culture an integration to the genetic heritage?

In nature can be observed three types of behaviors:

– innate behaviors, such as the crying of babies or their attachment to maternal breast;
– discovered behaviors, or everything that we learn from direct experience, as the ability to maintain the balance;
– cultural attitudes that are learned by others, both by imitation and through teaching.

A behavior discovered from direct experience can be culturally transmitted to the others. Culture, therefore based on experience of the others, allows to overcome the limitations of personal experience.
The transmission by culture of knowledge useful to survival is a strategy often used by mammals, which spend much time to care for the offspring and teach them what is necessary.
At this point, it is important to note how in cultural heritage there are many affinities with genetic heritage:

  • survival depends on it
  • it is heritable
  • undergoes mutations
  • is subject to natural selection
  • contributes to environmental adaptation through appropriate behavior
  • evolves over time.

The cultural heritage, considering its contribution to survival, can be then reasonably regarded as an integration of the genetic heritage.
It should be remembered, however, that among these heritages there are also some significant differences:

  • Culture is not innate: it needs a period of learning; in case of premature death of parents may also be lost, but the social animals may also learn from other members of the flock, thereby balancing the loss of parents
  •  a new discovery can be transmitted to the whole community and not only to their offspring
  •  an individual can’t change its genetic heritage, but it can change the cultural heritage and may do so several times, resulting in a form of individual development.

These cultural characteristics can give to cultural evolution a speed of adaptation unthinkable for genetic evolution: mutation can spread to the entire flock within a single generation.
Man, thanks to the word and to the brain which can use it, is capable of transmitting experiences and knowledge in a very detailed and effective way. The great number of inhabitants in human communities also allows a man to manage a huge cultural heritage, and this still thanks to the phenomenon of specialization, which in human societies is not in the physical form, but cultural: a warrior ant is physically different from a worker and distinguishes itself easily to naked eye, while there is no way to distinguish a lawyer by a doctor until we don’t see them at work.
We have already established that the successful evolution of man is based on its ability in using every kind of tool that he builds himself, thanks to technology, and on a very large and specialized society; however, these pillars are based on turn on the platform of culture, which is then the basis of primary evolutionary success.

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