Question 1. Describe the systematic position of man in the animal kingdom.
Man belongs to the phylum Chordates, the subtype Vertebrates, the class Mammals, the subclass Placentals, the order Primates, the suborder Humanoid (anthropoids-Higher apes) primates, the superfamily of the Greater narrow-nosed monkeys, the family Hominid (People), the only genus Homo (Homo) with the only species Homo sapiens (Homo sapiens).
In addition to the suborder of anthropoids, lemurs and tarsiers are also classified as primates.

Question 2. Indicate the signs of a person as a representative of the class of mammals.
Humans can be classified as Mammals on the following grounds:
seven cervical vertebrae;
hairline, sweat and sebaceous glands of the skin;
well developed lips and muscular cheeks;
diaphragm and alveolar lungs;
auricle and three auditory ossicles of the middle ear;
one aortic arch (left) and non-nuclear erythrocytes;
warm-bloodedness;
mammary glands, care of offspring;
similarities in embryonic development.

Question 3. What features are common to humans and great apes?
Human beings are related to great apes (pongids) by the large size of the body, the absence of a tail and cheek pouches, the good development of mimic muscles, and the similar structure of the skull and skeleton in general. In addition, blood groups and the Rh factor, similarity of chromosomes (out of 23 chromosomes, 13 are similar to chimpanzees), various diseases, a long gestation period and a long prepubertal (pre-reproductive) period are common to humans and great apes. They are also united by a high level of development of higher nervous activity, the ability to learn quickly, the ability to use tools, a good memory, and rich emotions. As an example, we can cite experiments on teaching deaf-mutes to great apes, during which gorillas and chimpanzees learned up to 200-300 sign words. The human and chimpanzee genomes are 98.5% identical.

Question 4. List the structural features that are unique to humans.
There are differences between humans and animals.
Man is a social being that produces tools and uses them to influence nature. A person has a highly developed brain, has consciousness, thinking, articulate speech and a number of anatomical features that have arisen in connection with labor activity that is characteristic only of a person. The differences are related to the direction of evolution. Man and great apes are two branches of the order of primates, which in relatively recent times have separated from the common pedigree trunk.
It is typical for a person:
1. Adaptation to upright posture. The spine acquired an S-shaped curvature, the foot has a domed shape. These are the main devices that provide shock absorption and shock absorption of the body when walking, jumping, which is important for protecting the brain. The big toe acts as a support. The pelvis is wider, it takes on the pressure of the organs in an upright position. The chest is flat, laterally compressed, due to the pressure that the internal organs exert on the ribs, due to the horizontal position of the torso when walking. The brain part of the skull has increased and prevails over the front. There are no superciliary ridges. The jaws and chewing muscles are less developed. In the lower part of the body, the gluteal, quadriceps, gastrocnemius, soleus muscles are especially developed. The consequences of upright walking are associated with a limitation in the speed of movement, hypertension, an immobile sacrum, dilated veins in the legs, and osteochondrosis.
2. The presence of a flexible hand - an organ of labor adapted to complex movements. The human hand is specialized as a grasping organ, the thumb is well movable. The human arms are shorter than the legs.
3. Well developed brain. A person has highly developed temporal, frontal and parietal lobes, where the main centers of higher nervous activity are located. The surface of the brain is 1250 cm2. The surface of the cortex in the frontal region is twice that of higher monkeys. Characterized by the appearance of speech, abstract thinking, consciousness.
4. Hairless skin has become a gigantic receptor field capable of bringing additional information to the brain. This was a factor in the intensive development of the brain. The "baldness" of the skin is the last biological prerequisite for the formation of man as a creative social being.

Question 5. What
An increase in the size and complexity of the structure of the brain provided a person with the opportunity to develop many functions, such as highly organized nervous activity, the ability to learn, the presence of a large amount of memory and complex emotions, speech. They also contributed to the emergence of abstract thinking and the ability to work. The centers associated with the sense organs provide the finest analysis of visual and auditory information, which allows us to perceive and understand facial expressions and speech. The motor centers of the brain carry out extremely precise and efficient control of the muscles of the fingers, vocal cords, etc. In many respects, it was the development of the brain that allowed a person to reach the high stage of evolutionary development that he now occupies.

Man is the only living Earth species from the human family. At the heart of modern ideas about the origin of man is the concept of his animal origin. Therefore, according to all common morphophysiological features, the place of man in the system of the animal world is determined.

1. The presence of an axial skeleton during embryogenesis - a chord, a hollow neural tube, gill slits in the pharynx, bilateral symmetry of the body - signs characteristic of chordate type.

2. The development of the spinal column, the presence of a developed brain, two pairs of limbs, a heart on the ventral side of the body, the formation of the skull and jaw apparatus - signs subtype Vertebrates.

3. The presence of a diaphragm, mammary glands, differentiated teeth, auditory ossicles in the middle ear, auricles, hairy skin containing sweat and sebaceous glands, warm-bloodedness, a four-chambered heart are signs of a class Mammals.

4. Intrauterine development of the fetus, the presence of the uterus and placenta - signs subclass Placental.

The forelimbs are grasping type, the first finger is opposed to the rest, the presence of nails, one pair of nipples of the mammary glands, the location of the eyes in the same plane (volumetric vision), the change of milk teeth to permanent ones, etc. - signs of the Primate order.

6. The primate order is divided into several families, including the lower broad-nosed and higher narrow-nosed monkeys and family of people.

Based on these and other data, the systematic position of a person is determined:

Type: Chordata,

Subtype : Vertebrates (Vertebrata),

Class: Mammals (Mammalia),

Subclass: Placental (Placentalia),

Order: Primates (Primates),

Suborder: Narrow-nosed monkeys (Catarrini),

Family: Humans (Hominidae),

Genus: Man (Homo),

Species: Homo sapiens.

Age features and constitutional variants in humans.

Each person is morphologically unique, since the hereditary program implemented in his ontogenesis is unique, and the environmental conditions that control the implementation of the genotype (the totality of all genes in an individual) into a phenotype (the totality of all traits in an individual) are also specific. Among morphological individuals, certain types can be distinguished according to the principle of similarity, i.e. generalized variants of variability.

The variability of the body structure is established by interpopulation, intrapopulation and individual comparisons. It is both geographical and historical. The variability of structures, especially body size, depends on the genotypic features that arise during migrations and mixing of the population, and on changes in environmental conditions. Differences in size and build, in skin color and other features between the inhabitants of different continents of the globe are well known and attracted the attention of anthropologists as early as the end of the 18th century. In recent decades, immunological, biochemical and genetic research has significantly expanded our knowledge in this area.

People differ from each other in many aspects and form very diverse groups scattered throughout the globe. In addition, people speak different languages, obey different laws, have different customs and beliefs, and differ greatly in character and professional activities. Social differences can be as important as biological ones.

Features of culture are transmitted from generation to generation due to training and living conditions in a particular social environment, and not according to the laws of biological heredity. They can change much faster than traits encoded in the genome and regulated by natural selection. Nevertheless, the ability to master the language or cultural heritage of a society undoubtedly depends both on the characteristics of the brain and on higher nervous activity that develops according to biological laws.

The growth and development of an organism is the result of many metabolic processes and cell reproduction, an increase in their size, processes of differentiation, shaping, etc. There are two types of morphological studies of the growth process in humans: longitudinal and transverse. In longitudinal studies (individualizing method), the same children are measured annually or several times a year for a number of years. In cross-sectional studies (generalizing method), children of different ages are examined in a short period of time. This creates an average picture of growth processes for a given group, and establishes norms for each age.

The concept of ontogenesis (individual development) includes the whole set of successive changes in the body from the stage of a fertilized egg to old age and death. The entire full cycle of individual development is divided into two periods: prenatal (intrauterine) and postnatal (extrauterine). The prenatal period is divided into two: embryonic and fetal (fetal). Three periods are distinguished in postnatal development: juvenile (from birth to puberty), mature (adult sexually mature state), and the period of old age ending in natural death (Table 2).

Table 2. Scheme of periodization of human ontogeny

The division of ontogenesis into age periods in children reflects the stages of maturation of a number of systems: bone, nervous, and sexual. Man differs from other species, including primates, by a relatively longer period of childhood. During this period, not only the physical development of the organism takes place, but also the formation of the personality: in the conditions of the collective, various paths of social inheritance are carried out.

The growth process proceeds unevenly, periods of rapid growth are replaced by periods of its slowdown. The most intensive growth is observed in the first year of life, when the child's body length increases by 23-25 ​​cm. The second growth spurt occurs from 11-12 years old in girls and 13-14 years old in boys to 16-17 years old. The increase in body length is 7-8 cm per year. With the same regularity, there is an increase in body weight.

Over the past 100-150 years, in many European populations, in Mongoloid groups, among US blacks, in some South African countries, there has been an acceleration of somatic development and physiological maturation of children and adolescents (acceleration - from Latin acceleratio - acceleration). Acceleration manifests itself already at the stage of intrauterine development (an increase in the length and weight of the body of newborns). At an earlier age, milk teeth erupt, the average body length of people has increased significantly over the past 100 years. According to the main criteria of morphological maturity - skeletal and dental age, somatic and puberty - the advance reaches up to 12 years. Body length in newborns increased by an average of 0.5-1.0 cm, in preschoolers - by 10-12 cm, in schoolchildren - by 10-15 cm. -2 years earlier. The pubertal growth spurt occurs earlier, but ends earlier. Stabilization of the length and proportions of the body now usually occurs by the age of 16-17 in women and 18-19 in men, while earlier this was noted at 20-22 and 22-25 years, respectively.

Acceleration as a whole is heterogeneous in etiology and not quite unambiguous in its manifestations, a process that has both positive and some negative sides. Among them are the difficulties of the formation of the personality due to the discrepancy between the rates of biological and social development.

Among the most significant phenomena in the individual development of modern mankind is also the lengthening of average life expectancy in many countries and the redistribution of the age composition of populations associated with it. The number of elderly and senile people is increasing. Indicator of the level of "demographic old age", i.e. the proportion of people over 60 years old, in almost all economically developed countries, now exceeds 12%. This phenomenon is an important biological, medical and socio-economic problem.

Aging is a universal and natural biological process, characterized by gradualness, timing and steady progression, leading to a decrease in the adaptive capacity, viability of the individual and ultimately determining life expectancy.

The manifestations of aging are diverse and affect all levels of organization: from the molecular to the systems of self-regulation of the whole organism. Determination of biological age during aging is necessary for solving socio-hygienic, clinical, experimental and gerontological problems, in assessing the effectiveness of measures to prolong active longevity.

Sex differences in life expectancy to a certain extent depend on the reliable operation of the genetic apparatus. Women live longer than men, but the "champions" of longevity are more often men. Individual life expectancy is the result of a complex interaction of many factors.

Aging is the result of natural selection. The maximum duration of life over the past 100 thousand years has increased by an average of 14 years, the rate of aging has decreased by 20%. It is possible that an increase in heterozygosity as a result of mixing different populations played a certain role in this. In the modern era, the problem of “pushing back” the main diseases that affect aging and life expectancy, slowing down the processes of biological, psychological and social involution, is of greatest importance. prolongation of active longevity.

When describing the main morphological features of a person in different age periods, as a rule, average indicators are used. However, as mentioned above, there are individual fluctuations in the processes of growth and development, which served as the basis for the introduction of the concept of "biological age". In a significant proportion of children, the biological and chronological (calendar) age coincide. However, there are children and adolescents whose biological age is ahead of chronological or behind it.

Various morphological, physiological, biochemical, immunological, molecular genetic, and, to a lesser extent, psychological indicators can be used as criteria for biological age. The main criteria of biological age are: 1) maturity, assessed by the degree of development of secondary sexual characteristics; 2) skeletal maturity (the order and timing of ossification of the skeleton); 3) dental maturity (terms of eruption of milk and permanent teeth).

Recently, indicators of the maturity of individual physiological systems of the body, as well as age-related changes in the microstructures of various organs, have been used to assess biological age.

Biological age is assessed by comparing the relevant indicators of the development of the examined individual with the standards characteristic of a given age, gender and ethnic group. As a rule, several indicators are used in combination.

Despite the general scheme of the structure, people also differ significantly in physique, i.e. by its constitution. The doctrine of the human constitution has a long history (Hippocrates, Galen). At present, the concept of the constitution includes not only morphological, but also physiological features of the body, its reactivity, resistance to pathogenic factors, features of metabolic processes associated with the influence of the nervous and endocrine systems. The widest and deepest development of the doctrine of the human constitution was carried out in the first half of the twentieth century (Krylov V.P., Seago, Krechmer E., Pavlov I.P., Roginsky Ya.Ya., Akinshchikova, Shevkunenko V.N. and Geselevich A .M., Chernorutsky M.V., Bogomolets A.A., Bunak V.V., Sheldon W. and others). In world constitutional science, there are several approaches to determining the constitution: somatopsychological, physiological, genetic, mixed.

According to modern concepts , the constitution is a set of morphological and functional features of an organism, which has developed on the basis of a hereditary program under the influence of modifying environmental factors and determines its reactivity.

In medicine, the classification proposed by M.V. Chernorutsky, which includes three types:

1) hypersthenic - massive, well-fed people, characterized by a relatively long torso and short limbs;

2) normosthenic - with normal average development of the bone and muscle system, moderate fat deposition;

3) asthenic - with a narrow chest, weak fat deposition, weak muscles, narrow bones.

The American anthropologist W. Sheldon (1940) based the classification on the theory of the development of all body systems from three germ layers. Accordingly, he identified three tissue components of the constitution: ectomorphic, mesomorphic and endomorphic. The ectomorphic component consists of organs that develop from the ectoderm (skin epithelium, nervous system, etc.). The mesomorphic component is bone tissue, skeletal muscles, connective tissue, etc. The endomorphic component is made up of organs that develop from the endoderm (epithelium of the alimentary canal, liver, pancreas, etc.).

The development of each component is evaluated in points from 1 to 7. The sum of points can vary from 9 to 13, a set of three digits is the somatic type (somatotype) of a person. Score 1 corresponds to the least severity of the component, score 7 to the maximum severity.

The extreme endomorphic variant (7-1-1) is characterized by rounded spherical shapes, a tendency to obesity, and a relative predominance of the anterior-posterior dimensions of the body (including the chest and pelvis) over the transverse ones. He has a relatively large liver, spleen and intestines.

The extreme mesomorphic variant (1-7-1) corresponds to the description of the muscular or normosthenic type.

The extreme ectomorphic variant (1-1-7) corresponds to the description of the asthenic type.

By definition of W. Sheldon, the somatotype remains constant throughout life: the appearance, body size change, but not the somatotype. When determining the somatotype, it is better to examine people aged 20-25 years with a normal diet. The scoring is carried out anthroposcopically according to specially made photographs and can be supplemented by measurements of the diameters and longitudinal dimensions of the body.

The idea put forward by E. Kretschmer about the connection between physique and temperament was further developed in the work of W. Sheldon. He singled out three components in the description of temperament, corresponding to the three components of the constitution.

Viscerotonia corresponds to the endomorphic component: natural relaxed posture, ease in communication and expression of feelings (extraversion), craving for people in difficult periods of life, smooth mood swings.

The ectomorphic component is characterized by stiffness of posture, emotional restraint, secrecy, great resistance to the action of alcohol and other depressants, craving for loneliness in difficult periods of life.

The mesomorphic component corresponds to somatotonia: confidence in movements and posture, extraversion, alcohol can lead to aggressive manifestations, craving for action in a difficult moment.

However, it is impossible to correlate any of the mental properties of a person with bodily features. In the individual-psychic properties of the personality, two sides are distinguished: dynamic and meaningful. The content side is formed on the basis of the individual experience of the individual, on the basis of education, the assimilation of the moral and ethical values ​​of society, traditions, customs, and scientific information. This side of the personality is not related to the type of constitution.

The dynamic side is largely associated with the innate individual typological features of higher nervous activity.

Various hypotheses have been put forward to explain the existence of a certain relationship between the constitution and temperament. According to genetic theory, the genes that determine body features have a pleiotropic (i.e., multiple) effect, influencing the development of the endocrine glands and the nervous system that determine the biological characteristics of temperament. The external environment, including the social environment, is also important, especially in the early stages of development, when the child is aware of his natural abilities in comparison with his peers and subsequently realizes them.

Doctors have long noted that constitutional features are of some importance in the predisposition of people to various diseases. For example, people with a pronounced ectomorphic component and a relatively low weight are more likely to experience tuberculosis and its more severe course. Asthenics have a relatively higher risk of stomach and duodenal ulcers, vegetative-vascular dystonia.

Anthropological data must be taken into account in the orientation of the choice of sports specialization, especially for children. Features of a certain constitutional predisposition of temperament, emotional sphere must be taken into account in professional orientation for the most effective use of inclinations for a particular type of activity.

INTRODUCTION

The purpose of this control work is to identify the meaning of the origin of man, the features of this problem.

In connection with the goals set, the following tasks were identified: determining the position of man in the system of the animal world, considering the evolution of primates, stages and the current stage of human evolution.

The relevance of the problem of natural science of the origin of man is associated with the most important role in the worldview of people, in our ideas and understandings of the world. By solving the problem of the origin of man, it would be possible to solve many of the problems of mankind, such as genetic diseases, immortality, and others.

The beginnings of evolutionary ideas about the origin of man are already in the works of ancient philosophers. In the eighteenth century K. Linnaeus places man in the order of primates along with the lemur and the monkey. Lamarck believed that man descended from ape-like ancestors who switched from climbing trees to walking on the ground.

Darwin's The Descent of Man and Sexual Selection was a major development in understanding the history of man as a species. This work dealt a crushing blow to the idea of ​​man as a product of divine creation.

The position of man in the system of the animal world

In the embryonic development of a person there are features characteristic of all representatives of the Chordata type: this is a notochord, a neural tube on the dorsal side of the embryo, gill slits in the pharynx. The development of the spinal column, the presence of two pairs of limbs, the location of the heart on the ventral side of the body determine whether a person belongs to the vertebrate subtype. A four-chambered heart, a highly developed cerebral cortex, warm-bloodedness, mammary glands, hair on the surface of the body, three types of teeth (molars, fangs, incisors) indicate that a person belongs to the class of mammals.

The development of the fetus in the mother's body and its nutrition through the placenta is characteristic of the placental subclass. Features such as grasping limbs (the first finger is opposed to the rest), fingernails, one pair of mammary nipples, well-developed clavicles, replacement of milk teeth with permanent ones during ontogenesis, the birth, as a rule, of one cub determine the position of a person in the order of primates. .

Reduction of the caudal spine, appendix, a large number of convolutions on the cerebral hemispheres, four main blood groups (A, B, O, AB), the development of facial muscles and a number of other signs - all this makes it possible to classify a person as a suborder of great apes.

The animal origin of man is confirmed by a number of properties indicating that man is the result of a long evolution of vertebrates.

In the embryonic period of development, a two-chambered heart, six pairs of gill arches, and a tail artery are laid in the human embryo - signs of fish-like appendages. From amphibians, man inherited the swimming membranes between the fingers, which are present in the embryo.

Weak thermoregulation in newborns and children under 5 years of age indicates the origin of animals with variable body temperature. The fetal brain is smooth, without convolutions, as in the lower mammals of the Mesozoic era.

A six-week-old fetus has several pairs of mammary glands. The tail section of the spine is also laid, which then turns into the coccyx.

Thus, the main features of the structure and embryonic development clearly determine the position of the species Homo sapiens in the class of Mammals, the order of Primates, the suborder of anthropoid apes.

However, a person has specific (that is, inherent only to him) features: upright posture, highly developed muscles of the lower extremities, a foot with a strongly developed first toe, a movable hand, a spine with four bends, the location of the pelvis at an angle of 60 ° to the horizontal, very large and voluminous the brain, the large size of the brain and the small size of the facial skull, binocular vision, limited fertility, the shoulder joint, which allows movements with a swing of almost 180 °, and some others. These features of the structure and physiology of man are the result of the evolution of his animal ancestors.

Taxon- a classification unit in the taxonomy of plant and animal organisms.

The main evidence of the origin of man from animals is the presence in his body of rudiments and atavisms.

Rudiments- these are organs that have lost their significance and function in the process of historical development (evolution) and remained in the form of underdeveloped formations in the body. They are laid down during the development of the embryo, but do not develop. Examples of rudiments in humans can be: coccygeal vertebrae (remains of the skeleton of the tail), appendix (process of the caecum), body hair; ear muscles (some people can move their ears); third eyelid.

atavisms- this is a manifestation, in individual organisms, of signs that existed in individual ancestors, but were lost in the course of evolution. In humans, this is the development of the tail and hair on the whole body.

The historical past of people

The first people on earth. The name of the ape-man - Pithecanthropus was given to one of the earliest finds made in the 19th century in Java. For a long time, this find was considered a transitional link from apes to humans, the first representatives of the hominin family. These views were promoted by morphological features: a combination of modern-looking bones of the lower limb with a primitive skull and intermediate brain mass. However, the Pithecanthropes of Java are a fairly late group of hominids. Starting from the 20s of the twentieth century and up to the present, an important discovery has been made in southern and East Africa: the remains of bipedal Plio-Pleistocene primates (from 6 to 1 million years) have been found. They marked the beginning of a new stage in the development of paleontology - the reconstruction of these stages of hominin evolution on the basis of direct paleontological data, and not on the basis of various indirect comparative anatomical and embryological data.

The era of the bipedal apes australopithecines. The first Australopithecus of East Africa, the Zinjanthropus, was discovered by the spouses L. and M. Lika. The most striking distinguishing feature of Australopithecus is upright walking. This is evidenced by the structure of the pelvis. Bipedal locomotion is one of the oldest acquisitions of man.

The first representatives of the human race in East Africa. Along with the massive Australopithecus, other creatures lived in East Africa 2 million years ago. This became known for the first time when the following year after the discovery of Zinjanthropus, the remains of a miniature hominid were discovered, whose brain volume was no less (and even more) than that of Australopithecus. It was later revealed that he was a contemporary of the Zinjanthropus. The most important discoveries were made in the lowest layer dating back 2-1.7 million years. Its maximum thickness is 40 meters. The climate, when this layer was laid, was more humid and its inhabitants were zinjantrop and prezinjantrop. The latter did not last long. In addition, stones with traces of artificial processing were also found in this layer. Most often it was a pebble ranging in size from a walnut to 7–10 cm, with a few chips of the working edge. Initially, it was assumed that Zinjantrops were able to do this, but after new discoveries it became obvious: either the tools were made by a more advanced prezinjantrop, or both inhabitants were capable of such initial stone processing. The emergence of a clamp with a full opposition of the thumb must have been preceded by a period of predominance of a forceful grip, when the object was raked in a handful and clamped in the hand. Moreover, it was the nail phalanx of the thumb that experienced especially strong pressure.

Background of anthropogenesis.The common ancestors of great apes and humans were gregarious narrow-nosed monkeys that lived on trees in tropical forests. The transition of this group to a terrestrial way of life, caused by a cooling of the climate and the displacement of forests by steppes, led to upright walking. The straightened position of the body and the transfer of the center of gravity caused the replacement of the arched spinal column with an S-shaped one, which gave it flexibility. A vaulted springy foot was formed, the pelvis expanded, the chest became wider and shorter, the jaw apparatus was lighter, and most importantly, the forelimbs were freed from the need to support the body, their movements became freer and more varied, their functions became more complicated. The transition from the use of objects to the manufacture of tools is the boundary between ape and man. The evolution of the hand followed the path of natural selection of mutations useful for work. Along with bipedalism, the most important prerequisite for anthropogenesis was the herd way of life, which, with the development of labor activity and the exchange of signals, led to the development of articulate speech. Concrete ideas about the surrounding objects and phenomena were generalized into abstract concepts, mental and speech abilities developed. Higher nervous activity was formed, and articulate speech developed.

Stages of human development. There are three stages in human evolution: ancient people, ancient people and modern (new) people. Many populations of Homo sapiens did not replace each other sequentially, but lived simultaneously, fighting for existence and destroying the weaker ones.

Modern people. The emergence of people of the modern physical type occurred relatively recently (about 50 thousand years ago), who were called Cro-Magnons. Increased brain volume (1 600 cm 3), well-developed articulate speech; the construction of dwellings, the first rudiments of art (rock painting), clothing, jewelry, bone and stone tools, the first tamed animals - all indicate that a real person finally separated himself from his bestial ancestors. Neanderthals, Cro-Magnons and modern humans form one species - Homo sapiens. Many years passed before people moved from the appropriating economy (hunting, gathering) to the producing economy. They learned how to grow plants and tame some animals. In the evolution of the Cro-Magnons, social factors were of great importance, the role of education and the transfer of experience grew immeasurably.

Races of man

All modern humanity belongs to the same species - Homo sapiens. The unity of mankind follows from the common origin, the similarity of the structure, the unlimited interbreeding of representatives of different races and the fertility of offspring from mixed marriages. Inside view - Homo sapiens- five large races are distinguished: Negroid, Caucasoid, Mongoloid, Australoid, American. Each of them is divided into small races. Differences between races come down to features of skin color, hair, eyes, shape of the nose, lips, etc. these differences arose in the process of adapting human populations to local natural conditions. It is believed that the black skin absorbed ultraviolet rays. Narrow eyes protected from sharp solar exposure in open spaces; a wide nose cooled the inhaled air faster by evaporation from the mucous membranes, on the contrary, a narrow nose warmed the cold inhaled air better, etc.

But man, thanks to labor, quickly got out of the influence of natural selection, and these differences quickly lost their adaptive significance.

Human races began to form, it is believed, about 30-40 thousand years ago, in the process of human settlement of the Earth, and then many racial traits had an adaptive value and were fixed by natural selection in a certain geographical environment. All races of man are characterized by common species features of Homo sapiens, and all races are absolutely equivalent in biological and mental relations and are at the same level of evolutionary development.

There is no sharp border between the main races, and there are a number of smooth transitions - small races, whose representatives have smoothed out or mixed the features of the main masses. It is assumed that in the future the differences between races will completely disappear and humanity will be racially homogeneous, but with many morphological variants.

The races of man should not be confused with the concepts nation, people, language group. Different groups can be part of one nation, and the same races can be part of different nations.

The Haeckel-Muller biogenetic law states that in the embryonic development of an organism, there is a brief and rapid repetition of the phylogenetic stages of the formation of the species to which this individual belongs. Thus, the study of the stages of embryogenesis allows us to trace the history of origin and determine the systematic position of our species.

In human embryonic development there are features characteristic of all representatives of the type chordates: this is a notochord, a neural tube on the dorsal side of the embryo, gills in the pharynx. The development of the spinal column, the presence of two pairs of limbs, the location of the heart on the ventral side of the body determine whether a person belongs to the subtype Vertebrates. A four-chambered heart, a highly developed cerebral cortex, warm-bloodedness, mammary glands, hair on the surface of the body, three types of teeth (molars, fangs, incisors) indicate that a person belongs to the class Mammals.

The development of the fetus in the mother's body and its nutrition through the placenta is characteristic of the subclass Placental. Features such as grasping limbs (the first finger is opposed to the rest), fingernails, one pair of mammary nipples, well-developed clavicles, replacement of milk teeth with permanent ones during ontogenesis, the birth, as a rule, of one cub determine the position of a person in the detachment Primates.

More particular signs - reduction of the caudal spine, appendix, a large number of convolutions on the cerebral hemispheres, four main blood groups (A, B, 0, AB), the development of facial muscles and a number of others - allow us to attribute a person to a suborder Humanoid apes. The animal origin of man is confirmed by a number of properties indicating that man is the result of a long evolution of vertebrates.

In the embryonic period of development, a two-chambered heart, six pairs of gill arches, and a tail artery are laid in the human embryo - signs fish ancestors. From amphibian a person has inherited the swimming membranes between the fingers that the fetus has.

Weak thermoregulation in newborns and children under five years of age indicates the origin of animals with variable body temperature. The fetal brain is smooth, without convolutions, as in lower mammals Mesozoic era.

A six-week-old fetus has several pairs of mammary glands. The tail section of the spine is also laid, which is then reduced and turns into the coccyx. Thus, the main features of the structure and embryonic development clearly determine the position of the species Homo sapiens in the Mammals class, detachment Primates, suborder of anthropoid apes. At the same time, a person has specific features inherent only to him: upright posture, powerfully developed muscles of the lower extremities, an arched foot with a highly developed first toe, a movable hand, a spine with four bends, an angle of the pelvis at an angle of 60 ° to the horizontal, a very large and voluminous brain , large sizes of the brain and small sizes of the facial skull, binocular vision, limited fertility, a shoulder joint that allows movements with a span of almost 180 °, and some others. These features of the structure and physiology of man are the result of the evolution of his animal ancestors.

Anchor points

• Observations of human embryonic development show its relationship with primitive chordates, fish, and amphibians.
• Comparative anatomical studies reveal many similarities in humans with other members of the Mammals class.

Questions and tasks for repetition

• 1. What are the signs of a person that make it possible to classify him as a subtype of vertebrates.
• 2. Indicate the signs that determine the position of a person in the class of mammals.
• 3. What features are common to humans and great apes?
• 4. List the structural features that are unique to humans.