Scientists at the University of Liverpool came to the conclusion that our ancestors developed even before they abandoned the arboreal lifestyle and switched to living on the ground. The sensational discovery led the researchers to another important conclusion: according to British biologists, walking on two legs has always been a feature of the behavior of great apes, and human ancestors never went through the stage of walking on all fours.
For decades, anthropologists have been convinced that bipedalism is a unique quality of Homo sapiens and its closest ancestors, Homo habilis (handy man) and Homo erectus (upright man). However, scientists studying the behavior of the only great arboreal monkeys - orangutans living on the island of Sumatra - found they had the same ability. True, orangutans use the vertical position of the body to move not on the ground, but along the branches of trees.
“There are a lot of hypotheses for the origin of bipedal walking (bipedia), - Vitaly Kharitonov, a leading researcher at the Institute and Museum of Anthropology at Moscow State University, told our publication. - In accordance with one of them, the complex of anatomical abilities necessary for walking upright developed in the ancestors of man after he changed his habitat: he switched from an arboreal lifestyle to a terrestrial one. According to another point of view, our ancestor really could have learned to walk upright already during his life in the trees. These are two alternative hypotheses. It is only possible to accurately indicate the time when the transition to bipedia took place: today, the antiquity of Australopithecus, which are the first members of our evolutionary trunk, according to archaeological finds, reaches 6-7 million years. The bones of Australopithecus that lived in this era already have features associated with upright walking. However, it was probably episodic: the ancient Australopithecus mostly moved on four legs, but if necessary, they could stand only on their hind limbs. “It is quite possible that bipedal locomotion occurred earlier, but the transition of Australopithecus to bipedia as the preferred mode of movement begins precisely 6-7 million years ago,” says Mr. Kharitonov. “And already 2-3 million years ago, in African Australopithecus, all the signs necessary for bipedia were combined into a single anatomical complex.”
The orangutans, whose behavior was observed by scientists at the University of Liverpool, hold their torso upright, and moving along flexible branches that are elastic, like soft soil, grab them with their toes. From falling, the monkey is insured by the forelimbs, with which the orangutan clings to high branches. This, apparently, is the best way for orangutans to move along the branches.
“All anthropoid primates are prone to upright walking, - The reason lies in the living conditions: in the open spaces of the savannah, the primate cannot hide from a predator with the same ease as in the rainforest. The presence of permanent danger required a number of sociobiological adaptations from primates: this includes not only upright posture, but also social communication skills, which later gave rise to first non-verbal, and then verbal speech.
“Upright walking is very effective in a number of its qualities,” says Vitaly Kharitonov. - Firstly, in the conditions of the African savannah, this method makes it possible to get away from overheating: the area on which the sun's rays fall becomes smaller. Secondly, the presence of free forelimbs allows the female to carry the cub. Thirdly, the review of a bipedal animal is much greater than that of a quadrupedal one: standing on two legs, the monkeys learned to notice a predator from a distance.”
Most likely, Australopithecus already used tools: sticks, clubs, stones, large animal bones. True, they still did not know how to make them: these distant ancestors of man only picked them up in nature, but they could not process them at all. That is why there are no traces of artificial processing on the finds of this era.
“The theory about the development of upright walking during the life of primates on trees has the right to life,” Sergey Vasilyev, head of the laboratory of anthropology at the Institute of Ethnology and Anthropology of the Russian Academy of Sciences, told RBC daily. “It’s not for nothing that many modern primates are able to stand on their hind legs.” There is a third, very plausible version of the development of bipedia: our ancestral form, which preceded the bipedal primates, did not move on four limbs, but in the same way as the modern apes of Africa - they stand on two hind limbs, leaning on the ground only with their fingers hands, with which they seem to help the legs. In accordance with this hypothesis, a similar mode of movement was the starting point for our ancestors.
“There is also a fourth hypothesis that has been very fashionable lately,” notes Vitaly Kharitonov. - According to her, our predecessors, who experienced a constant need for water, often entered the reservoirs, involuntarily straightening up to keep their heads above the surface. Since the food found in water bodies is shellfish, fish, etc. - was an important part of the diet of our ancestors, primates gradually switched to upright walking.
Most anthropologists still believe that the skills of vertical walking developed in humans precisely when our ancestors descended from the trees in connection with
In the process of human evolution, signs of upright posture gradually formed: a balanced head position, an S-shaped spine, an arched foot, a wide pelvis, a wide and flat chest, massive bones of the lower extremities, and the orientation of the shoulder blades in the frontal plane. The S-shaped spine is a kind of shock absorber for axial loads.
As you know, there is an forward bend in the cervical region - cervical lordosis, a back bend in the thoracic region - thoracic kyphosis, an anterior bend in the lumbar region - lumbar lordosis. Due to the natural curves, the strength of the spine to axial load increases. With sudden and excessive loads, the spine, as it were, "folds" into an S-shape, protecting the discs and ligaments of the spine from injury, and then straightens out like a spring.
The upright skeleton allows humans to move, unlike other animals, on two legs, transferring weight from the heel to the forefoot, which turns each step into a balancing exercise. The load is transferred through the tibia. The fulcrum is on the toe. The force is created by the Achilles tendon, which, when the calf muscles contract, raises the heel. The arches of the foot “extinguish” inertial loads upon landing, which reach up to 200% of body weight. Natural, balanced head posture allows the long axes of the orbits to be facing forward. This is a distinguishing feature of a person from his anthropoid "brothers", in which the head is suspended on the occipital muscles (anthropologists determine the position of the head by the structure of the base of the skull and cervical vertebrae).
The balanced position of the head eliminates the stretching of the posterior ligaments of the neck and the need for constant tension of the muscles of the neck, mainly, unlike animals, the muscles of the upper trapezium. In the process of historical development, mankind has passed a difficult path.
Signs of upright walking: balanced head position, S-shaped spine, arched foot, wide pelvis, wide and flat chest, massive bones of the lower extremities, orientation of the shoulder blades in the frontal plane.
With the development of civilization, the requirements for the musculoskeletal system have changed. If the ancient people were either in a vertical or horizontal position (hunted, gathered, fought, lay down, resting), then already in the 17th century 10% of the population performed sedentary work. In the 21st century, the number of such workers has increased to 90%. In the process of evolution, a person stopped adapting to the environment and began to adapt the environment to himself, and this could not but affect his posture. The invention of a bench, a chair (this is probably the 15th century) significantly changed the biomechanics of a person, a new problem appeared - “the posture of a person sitting on a chair”. A modern person spends most of his time sitting at work, at home, in transport, working, studying, relaxing, waiting, eating.
The “sitting” position, optimal for office work and training, is a severe test for the musculoskeletal system. It is in this position that posture most often suffers. It is a long sitting posture that causes back pain, and the cause of various diseases. The 18th century is the century of mass schooling. This progressive historical process also has a downside. According to the Russian Institute of Pediatric Orthopedics, 40-80% of children have posture disorders, and 3%-10% of them have various curvature of the spine, the so-called school scoliosis.
With the development of civilization, the content, organization and methods of human labor change. Office workers are a new mass profession, whose number is more than 60% of the total working population. The need for long-term adherence to a sitting working posture (working at a computer, with documents, with clients) leads to an increase in the number of diseases of the musculoskeletal system of the adult population. The number of such diseases is steadily growing, they are getting younger, and this trend is likely to continue in the foreseeable future.
One of the most important questions in the problem of the origin of man is which of the modes of movement of primates was a prerequisite for bipedal walking.
Charles Darwin believed that our ancestors were tree animals.
One of the theories - "brachiator" - believed that only brachiation could lead to a good development of the collarbone, to a wide chest, to the ability of supination and pronation of the limbs. According to this theory, the common ancestor of hominids and pongids was a brachiator.
Proponents of another theory - originally four-legged walking - considered the similarity of the hands of a monkey and a person to be convergent: both work and climbing on branches led, according to these researchers, to the same result. Studying the features of the foot in humans, monkeys and other mammals - hedgehog, rat, marmot, etc. - they believed that the human foot is closest to the macaque foot type, i.e. man did not have adaptations for either brachiation or jumping, as Jones Wood, a supporter of the origin of man from the tarsier, bypassing the ape stage, believed.
Brachiation is now regarded as an extreme adaptation to an arboreal lifestyle.
One of the theories is the theory of cruration: according to it, bipedal walking was preceded by walking along the branches in a half-upright position (cruration). Some authors believe that the human ancestor could at the same time rely on his fingers, as do modern large apes, other authors consider vertical climbing important for the emergence of bipedalism.
It should be noted that none of the proponents of the arboreal stage meant exclusively arboreal life. With all the adaptability of the foot to ground movement, it retains the features of the arboreal locomotion of its ancestors, for example, there is a muscle that abducts the first toe. The ability to abduct the first finger is developed in many climbing mammals, for example, in rats, marsupials, and some rodents. One of the prerequisites for the development of upright walking may have been upright sitting, which is characteristic of all primates.
Paleontological data do not provide sufficient material to resolve this discussion. Egyptopithecus was probably a quadrupedal tree monkey, similar to the howler monkey, he hung from the branches with his hands and feet. Dryopithecus, proconsul, pliopithecus have a generalized skeleton similar to broad-nosed, thin-bodied and great apes. The structure of their shoulder joint shows great freedom of the hand. Their locomotion could also include brachiation. It is believed that the group of Miocene hominoids was heterogeneous in the development of locomotion, pliopithecus was an arboreal quadruped, proconsul was a semi-brachiator, and dryopithecus walked on the joints of the forelimbs. Miocene hominoids show signs of straightening of the body, but only initial signs. In some later forms - for example Oreopithecus - a more upright position of the body is observed. This is evidenced by five massive lumbar vertebrae, the structure of the upper end of the thigh, the large width of the ilium, and other signs. In the forelimb there were also signs of brachiation - movement on the hands: this is the lengthening of the forelimb, the mobility of the carpal joint, the curvature of the phalanges and metacarpus. Modern pongids have retained the brachiator complex. The ability of the arms to span up to 180 degrees, to wide pronation and supination, and the grasping type of the hand with opposition of the first finger are important arguments in favor of the arboreal stage of primates.
In the process of anthropogenesis, the traits of brachiatoric specialization could be forced out, but they still remained in the early Australopithecus. Their forelimbs are longer than their hind ones, the toe phalanges are long and curved, and they are similar in skeletal structure to the great apes.
The ability to straighten the body position is one of the main features of primates. According to some assumptions, the original type of locomotion was vertical clinging and jumping. All modern primates, when sitting, take a straightened position of the body, and many are capable of vertical forms of movement, including bipedalism, this ability is especially well expressed in great apes, in which the supporting role of the hind limb increases. However, the bipedal locomotion of great apes is the bipedal locomotion of a four-legged animal standing on two legs. At the same time, the body is tilted forward, the spine is curved, and there is no lumbar lordosis. When the body is straightened, it throws back along with the pelvis. The lower limbs are bent at the knee joints, there is no rotational movement of the pelvis, and the body seems to roll over with each step.
http://answer.mail.ru/question/13315969
http://www.examens.ru/answer/8/9/680.html
http://www.sunhome.ru/journal/16241
http://medbiol.ru/medbiol/antrop/00010554.htm
Option number 1.
1. In the human brain, unlike the brain of mammals, there are centers
B) sense of smell
B) hearing
D) movement coordination
2. Man belongs to the class of mammals, since he has
A) breathing is carried out with the help of the lungs
B) blood flows through two circles of blood circulation
IN) forebrain includes two hemispheres
D) the development of the embryo occurs in the uterus
3. The transition of human ancestors to upright posture contributed
A) hands free
B) the appearance of conditioned reflexes
B) the development of a four-chambered heart
D) increased metabolism
4. How does the human skull differ from the skull of the great ape?
A) the presence of the facial and brain sections
B) a large volume of the brain
B) the location of the eye sockets and superciliary arches
D) the method of connecting the parietal and temporal bones
5. Who are referred to as ancient people?
A) Neanderthal
B) Pithecanthropus
B) synanthropus
D) Cro-Magnon
6. What is the similarity between Homo habilis and Australopithecus?
A) brain volume 1200 cm 3
B) speech is developed
B) upright posture
D) the ability to make tools
7. What underlies racial differences?
A) mental ability
B) social opportunities
C) biological hereditary differences
D) level of evolutionary development
8. What is the similarity between humans and great apes?
A) arched foot
B) abstract thinking is developed
C) no facial hair
D) 4 bends of the spine
9. What is the difference between ancient people and ancient people?
A) use fire
B) made tools
B) upright posture
D) speech in the form of babbling
10. Which of the signs of a person refers to rudiments?
A) muscles that move the ear
B) thick body hair
D) strongly developed fangs
11. Describe the oldest people.
Option number 2.
1. Signs of what race are a high and long nose, skin with a small amount of melanin, thin lips, and well-developed facial hair in men?
A) australoid
B) Caucasian
B) mongoloid
D) negroid
2. What is NOT considered a human rudiment?
A) the remainder of the third century
B) appendix
B) multitasking
D) wisdom teeth
3. In humans, the front limbs are of a grasping type (the first finger is opposed to the rest), like everyone else
A) chordates
B) mammals
B) placental
D) primates
4. Which of the signs of a person refers to atavism?
A) appendix
B) wisdom teeth
D) third eyelid
5. The first representatives of the species Homo sapiens
A) driopithecus
B) australopithecines
B) Neanderthals
D) Cro-Magnons
6. Man as a biological species arose as a result of:
A) social evolution
B) the evolution of the organic world
C) development of the ability to work
D) the appearance of rational activity
7. Neanderthal was able to:
A) hunting with a bow
b) speak well
B) produce bronze
D) keep the fire going
8. The distant ancestors of primates are:
A) insectivores
B) rodents
B) oviparous
D) bats
9. Walking upright with support on hands was typical for:
A) Australopithecus
B) Pithecanthropus
B) synanthropus
D) Neanderthal
10. Modern people include:
A) Cro-Magnon
B) Australopithecus
B) Pithecanthropus
D) Neanderthal
11. What is the difference between man and great apes?
Test on the topic "The origin of man."
Option number 3.
1. The most ancient people include:
A) Cro-Magnon
B) Australopithecus
B) Pithecanthropus
D) Neanderthal
2. A skilled person refers to:
A) ancient people
B) ancient people
B) ape people
D) new people
3. All types of human activity are classified as factors
A) abiotic
B) biotic
B) anthropogenic
D) periodic
4. Man, unlike mammals
A) is excitable
B) has a cerebral cortex
C) think abstractly
D) is irritable
5. Man, like great apes, has
A) 4 blood groups
B) arched foot
C) brain volume 1200-1450 cm3
D) S-shaped spine
6. What part of the human upper limb has changed most dramatically in the course of its evolution?
A) shoulder
B) forearm
B) a brush
D) scapula
7. Bipedalism in human ancestors contributed
A) hand free
B) the appearance of speech
B) the development of a multichambered heart
D) increased metabolism
8. Social factors of evolution played a decisive role in the formation of human
A) flattened chest
B) upright posture
B) articulate speech
D) S-curves of the spine
9. In the early stages of human evolution, under the control of biological factors, the formation of
A) features of its structure and activity
B) articulate speech
B) labor activity
D) thinking, developed consciousness
10. The presence of a tail in a human embryo on early stage development shows
A) the resulting mutations
B) manifestation of atavism
B) violation of the development of the fetus in the body
D) there is no correct answer
11. Describe the ancient people.
Test on the topic "The origin of man."
Option number 4.
1. Under the influence of biological and social factors, the evolution of ancestors took place
B) a person
B) mammals
D) reptiles
2. Which of the listed signs of a person is classified as atavism?
A) the birth of a person with an elongated tail
B) division of the body into sections
B) differentiation of teeth
D) the presence of breast and abdominal cavity body
3. In the process of evolution in humans, under the influence of biological factors, the formation of
A) work needs
B) developed consciousness
D) arched foot
4. Man in the system of the organic world
A) is a special order of the class of mammals
B) stands out in a special kingdom, including the most highly organized living beings
C) represents a special species that is included in the order of primates, the class of mammals, the kingdom
animals
D) is an integral part of human society and is not related to the system
organic world
5. Man belongs to the class of mammals, since he has
A) internal fertilization
B) pulmonary respiration
B) four-chambered heart
D) there is a diaphragm, sweat and mammary glands
6. The action of only biological factors of evolution cannot explain the appearance in humans
A) convolutions in the forebrain
B) consciousness
B) high arch of the foot
D) S-shaped spine
7. The development on the body of individual people of a large number of nipples in the mammary glands - an example
A) aromorphosis
B) regeneration
B) atavism
D) idioadaptation
8. The driving forces of anthropogenesis should not be attributed
A) struggle for existence
B) social lifestyle
B) hereditary variability
D) modification variability
9. What was the significance of the blacks' acquisition of dark skin?
A) increased metabolism
B) adaptation to life in a marine climate
C) protection from ultraviolet rays
D) improvement of the respiratory function of the skin
10. In humans, due to upright posture
A) the arch of the foot has formed
b) claws turned into nails
B) the phalanges of the fingers are fused
D) the thumb is opposed to the rest
11. What evidence is there for the origin of man from animals?
Test on the topic "The origin of man."
Option number 5.
1. In the human skeleton, unlike the great apes, there is an increase
A) brain region of the skull
B) the facial part of the skull
B) cervical spine
D) caudal spine
2. . Man and great apes
A) have abstract thinking
B) able to work
B) have similar blood types
D) lead a social life
3. An increase in the size of the brain region of the human skull in comparison with the facial one contributed to
A) the development of thinking
B) the development of a terrestrial lifestyle
B) reduction of hairline
D) eating animal food
4. For humans, as well as for other mammals, live birth, feeding of young with milk is characteristic, which indicates
A) about a higher level of human development
B) about divergent evolution
C) about the development of the class Mammals in the process of evolution
D) about the relationship between humans and mammals
5. The main factor of anthropogenesis is:
A) social life
B) labor
B) speech
D) rational activity
6. The ability to manufacture the simplest tools appeared for the first time in:
A) driopithecus
B) Ramapithecus
B) australopithecines
D) Neanderthals
7. Who had the most developed chin protrusion:
A) Pithecanthropus
B) synanthropus
B) Neanderthal
D) Cro-Magnon
8. What do not belong to the social factors of human evolution:
A) speech
B) upright posture
B) labor
D) consciousness
9. Which of the following signs of people are classified as rudiments:
A) multitasking
B) the presence of a tail
C) the remainder of the third century
D) excessive body hair.
10. Homo sapiens differs from other types of people:
A) the ability to make tools
B) development of care for offspring
C) fuel and clothing use
D) the emergence of science and art
11. Describe the new people.
Test on the topic "The origin of man."
Option number 6.
1. Who studied the social factors of anthropogenesis:
A) Engels
B) Darwin
B) Lamarck
D) Linnaeus
2. Which of the fossil forms belongs to the genus Homo?
A) driopithecus
B) Australopithecus
B) synanthropus
D) chimpanzee
3. Embryological proof of the origin of man from animals are:
A) second signaling system
B) the similarity of embryos in the early stages
B) atavisms
D) rudiments
4. Modern man refers to the species:
A) monkey man
B) a skilled person
B) Neanderthal man
D) there is no correct answer
5. Articulate speech is well developed in a Human:
A) skilled
B) upright
B) Neanderthal
D) reasonable
6. Humans, unlike the great apes, have
A) work activity
B) four-chambered heart
B) caring for offspring
D) 4 blood types
7. Does not apply to biological factors of human evolution
A) struggle for existence
B) developed thinking
B) natural selection
D) hereditary variability
8. Thanks to the social way of life of human ancestors
A) there was a speech
B) an S-shaped spine appeared
B) free hand
D) upright posture appeared
9. The evolution of the most ancient apes along the path of adaptation to a terrestrial way of life was determined
A) the ability to run fast
B) three-dimensional vision, developed ability to orientate
B) no tail
D) shortened facial part of the skull
10. Anatomical and morphological changes associated with upright posture in human ancestors include
A) speech
B) developed thinking
B) social life
D) arched foot
11. What features appeared in a person in connection with upright walking?
1. Features of the skeleton, peculiar only to humans
A) the presence of clavicles
B) the presence of a chin protrusion
B) lightening the mass of the bones of the upper limbs
D) the presence of five-fingered limbs
D) S-shape of the spinal column
E) arched foot
2. In connection with upright posture in humans
A) the upper limbs are released
B) the foot becomes arched
C) the thumb is opposed to the rest
D) the pelvis expands, its bones grow together
D) the brain region of the skull is smaller than the facial
E) hair loss
3. The human skeleton, unlike the skeleton of mammals, has
A) straight spine without bends
B) chest, compressed in the dorsal-abdominal direction
B) chest, laterally compressed
D) S-shaped spine
D) arched foot
E) massive facial part of the skull
4. What is the similarity between the human skeleton and the skeletons of mammals?
A) the spine has five sections
B) the foot has an arch
B) the brain region of the skull is larger than the facial
D) there are paired articular limbs
D) there are seven vertebrae in the cervical region
E) the shape of the spine is S-shaped
5. In humans, unlike mammals
A) the body is vertical
B) the spine does not have bends
B) the spine forms four smooth curves
D) the chest is expanded to the sides
D) the chest is compressed from the sides
E) the facial part of the skull prevails over the brain
6. Man, unlike animals
A) affects the environment in the process of life
B) has an S-shaped spine
B) forms different populations
D) has the first signal system
D) has a second signaling system
E) creates and uses tools
7. What features of mammals are NOT characteristic of humans?
A) the presence of a diaphragm
B) the presence of undercoat
B) the presence of seven cervical vertebrae
D) tail section of the body
D) movable auricle
E) alveolar lung
8. Man, unlike animals
A) has a cerebral cortex
B) forms various natural populations
B) has a second signaling system
D) can create an artificial habitat
D) has the first signal system
E) can create and use tools
Stanislav Vladimirovich Drobyshevsky
Scientific Editor of ANTROPOGENESIS.RU, Ph.D., Associate Professor of the Department of Anthropology, Faculty of Biology, Lomonosov Moscow State University Lomonosov
Retrieving link
Especially for the portal "Anthropogenesis.RU".
Author's project by S. Drobyshevsky. The e-book will give readers basic information about what is known modern science about the ancient genealogy of man.
Its complex is determined by the following main features.
Location of the foramen magnum: from left to right - gorilla, sahelantrop, African Australopithecus, Homo ergaster, modern man.
http://warrax.net/85/m1.html
From left to right - the pelvis: man, australopithecine afar, ardipithecus ramidus, chimpanzee.
Position of the foramen magnum- in erectus, it is located in the center of the length of the base of the skull, it opens down; in tetrapods - in the back of the base of the skull, turned back. Accordingly, the base of the skull is shortened in bipeds and elongated in tetrapods. A variant of the intermediate type is already known in Sahelanthropus tchadensis about 6-7 million years ago, and a typical bipedal type was found in Ardipithecusramidusramidus 3.9-4.4 million years ago.
The structure of the pelvis- In upright pelvis wide and low; in tetrapods, the pelvis is narrow, high, and long. An intermediate variant is found in Ardipithecus ramidus 4.4 million years ago. The bipedal variant has been known since Australopithecus afarensis 3.2 million years ago.
The structure of the long bones of the legs- erect legs are long hip joints strongly separated from each other due to the large width of the pelvis, and the knees are brought together, so that the femurs, when viewed from the front, are tilted, and the bones of the lower leg are vertical, the feet are brought together, when viewed from the side, the knees are straightened; in quadrupedal primates, the arms are longer than the legs, the knees are spread apart with a “wheel” and are always half-bent, the feet are spaced apart from each other, so that when walking bipedally, the monkey moves very awkwardly, sideways, compensating for instability with strong lateral body oscillations. Both variants correspond to certain characteristic shapes of the knee and ankle joints. bipedal structure thigh bones known from Orrorin tugenensis 6.2 million years ago.
Foot of Homo habilis.
Paleontological Museum, Moscow.
Photo: A. Sokolov
The structure of the foot- in upright walkers, the longitudinal and transverse arches (lifts) of the foot are expressed, the fingers are straight, short, the thumb is not laid aside and is inactive; in tetrapods, the foot is flat, the fingers are long, curved, movable, the thumb has a grasping function, it can be strongly retracted to the side, which is reflected in the greater length of its muscles and the characteristic shape of the joints. Ardipithecus ramidus 4.4 million years ago has arches, but the toes are long and curved, and the big toe is able to flex far to the side. In the foot of Australopithecus anamensis 4.1 million years ago, judging by the structure of the tibia, the thumb was inactive. In Australopithecus afarensis 2.5-3.9 million years ago, the arches of the foot are well defined, the thumb could be slightly opposed to others, but much weaker than in modern monkeys, the footprint was almost like modern man. In the foot of Australopithecus africanus and Paranthropus robustus, the thumb was strongly abducted from the others, the fingers were very mobile, the structure is intermediate between apes and humans.
Features of bipedalism
All Australopithecus toes were quite long and curved. In Homo habilis, the foot is flattened, without a pronounced arch, but the fingers are straight, short, and the thumb is fully adducted to the rest.
The structure of the hands- in fully erect hominids, the hands are not adapted for walking on the ground or climbing trees, the arms are short, the phalanges of the fingers are straight; different primates have numerous morphological adaptations to clinging to branches (including variants with a reduction of the thumb or other fingers, or with the fusion of fingers into a single "hook"), and in higher anthropoids - to walking on the ground relying on the phalanges of bent fingers (including a special skewness of the articular surface radius). Traits of adaptation for walking on the ground or climbing trees are found in Australopithecus Orrorintugenensis, Ardipithecuskadabba, Ardipithecusramidus, Australopithecusanamensis, Australopithecusafarensis, Australopithecusafricanus, Paranthropusrobustus and even Homohabilis. In particular, it is possible that Australopithecusanamensis often moved on all fours, relying on the phalanges of bent fingers.
The structure of the spine- in erect walkers, the spine is oriented vertically and has characteristic curves - lordosis forward and kyphosis backward, the size of the vertebrae naturally increases from top to bottom, the sacrum is wide and short; tetrapods do not have cervical and lumbar lordosis, and the size of the vertebrae does not differ so regularly, the sacrum is narrow and long. The australopithecines Australopithecusafarensis and Australopithecusafricanus probably had curves like those of modern humans, but some details of the structure of the vertebrae (for example, the elongation of the body of the vertebrae from front to back) bring them closer to monkeys. The structure of the sacrum in known Australopithecus - starting with Ardipithecusramidus and Australopithecusafarensis - is typically hominid.
Back: What makes us different from monkeys? Unique features of a person
Level A assignments.
Choose one correct answer from the four given.
A1. The belonging of a person to the class Mammals is evidenced by
4) hairline and live birth
A2. The person is assigned to the group
2) Primates
A3. vestige of a man
1) appendix
A4. Ancestral home of man
4) East Africa
A5. Anatomical sign of a person associated with upright posture
2) spring foot
A6. Human evolution is characterized
3) the unity of action of biological and social factors
A7. The common ancestor of great apes and humans is
3) driopithecus
A8. Refers to modern man
3) Cro-Magnon
A9. Refers to the ancient people
3) Australopithecus
A10. The biological factor of human evolution is
4) natural selection
A11. The human ancestor is
4) none of the listed monkeys
A12. Man is different from all other animals
3) the presence of a second signal system
Level B assignments.
Choose three correct answers from the six given.
II. new material
Arboreal adaptations in ancestral primates and modern great apes
2) all limbs have five fingers
4) strong development of the motor parts of the brain
6) strong development of the shoulder girdle
AT 2. Human Distinctive Features (Compared to Great Apes)
1) chin protrusion on the lower jaw
2) foot with a strong developed big toe, having arches
4) relatively strong development of the brain skull
AT 3. Evidence from comparative embryology proving the animal origin of man
2) appendix caecum
3) two-chamber heart in a two-week-old embryo
Match the contents of the first and second columns.
AT 4. Establish a correspondence between the characteristics of a person and the systematic group for which they are characteristic.
A) sweat and sebaceous glands of the skin
B) neural tube on the dorsal side of the body
B) the heart is on the ventral side of the body
D) the presence of the collarbone
D) non-nuclear erythrocytes
E) expanded terminal phalanges of fingers with nails
SYSTEMATIC GROUP
1) signs indicating that a person belongs to the type Chordates
2) signs indicating that a person belongs to the class Mammals
3) signs indicating that a person belongs to the order Primates
AT 5. Establish a correspondence between the signs and the group to which they belong.
SIGNS
A) coccyx
B) remnants of the nictitating membrane of the eye
C) extra pores of the mammary glands
D) appendix of the caecum
D) continuous hairline on the face
E) muscles of the auricle
1) vestigial organs
2) atavisms
AT 6. Establish a correspondence between the factors of the historical development of a person and the group to which they belong.
A) mutational variability
B) labor activity
B) natural selection
D) isolation
D) genetic drift
E) social lifestyle
1) biological factors
2) social factors
AT 7. Establish a correspondence between the signs and the races for which they are characteristic.
SIGNS
A) epicanthus
B) curly hair
B) narrow eyes
D) a narrow, strongly protruding nose
D) wide cheekbones
E) thick lips
1) Australo-Negroid
2) polyloid
3) Caucasian
Set the correct sequence of biological processes, phenomena, practical actions.
AT 8. Establish the sequence of stages of the appearance and evolution of man, starting with the most ancient.
A) Pithecanthropus
B) Cro-Magnon
B) driopithecus
D) Australopithecus
D) Neanderthal
AT 9. Determine the systematic position of man as a biological species by arranging the taxa in the required sequence, starting with the species.
A) man
B) primates
B) a reasonable person
D) mammals
E) vertebrates
G) placental
H) chordates
Features of bipedalism
In the process of human evolution, signs of upright posture gradually formed: a balanced head position, an S-shaped spine, an arched foot, a wide pelvis, a wide and flat chest, massive bones of the lower extremities, and the orientation of the shoulder blades in the frontal plane. The S-shaped spine is a kind of shock absorber for axial loads.
As you know, there is an forward bend in the cervical region - cervical lordosis, a back bend in the thoracic region - thoracic kyphosis, an anterior bend in the lumbar region - lumbar lordosis. Due to the natural curves, the strength of the spine to axial load increases. With sudden and excessive loads, the spine, as it were, "folds" into an S-shape, protecting the discs and ligaments of the spine from injury, and then straightens out like a spring.
The upright skeleton allows humans to move, unlike other animals, on two legs, transferring weight from the heel to the forefoot, which turns each step into a balancing exercise. The load is transferred through the tibia. The fulcrum is on the toe. The force is created by the Achilles tendon, which, when the calf muscles contract, raises the heel. The arches of the foot “extinguish” inertial loads upon landing, which reach up to 200% of body weight. Natural, balanced head posture allows the long axes of the orbits to be facing forward. This is a distinguishing feature of a person from his anthropoid "brothers", in which the head is suspended on the occipital muscles (anthropologists determine the position of the head by the structure of the base of the skull and cervical vertebrae).
Human foot: the miracle of bipedalism
The balanced position of the head eliminates the stretching of the posterior ligaments of the neck and the need for constant tension of the muscles of the neck, mainly, unlike animals, the muscles of the upper trapezium. In the process of historical development, mankind has passed a difficult path.
Signs of upright walking: balanced head position, S-shaped spine, arched foot, wide pelvis, wide and flat chest, massive bones of the lower extremities, orientation of the shoulder blades in the frontal plane.
With the development of civilization, the requirements for the musculoskeletal system have changed. If the ancient people were either in a vertical or horizontal position (hunted, gathered, fought, lay down, resting), then already in the 17th century 10% of the population performed sedentary work. In the 21st century, the number of such workers has increased to 90%. In the process of evolution, a person stopped adapting to the environment and began to adapt the environment to himself, and this could not but affect his posture. The invention of a bench, a chair (this is probably the 15th century) significantly changed the biomechanics of a person, a new problem appeared - “the posture of a person sitting on a chair”. A modern person spends most of his time sitting at work, at home, in transport, working, studying, relaxing, waiting, eating.
The “sitting” position, optimal for office work and training, is a severe test for the musculoskeletal system. It is in this position that posture most often suffers. It is a long sitting posture that causes back pain, and the cause of various diseases. The 18th century is the century of mass schooling. This progressive historical process also has a downside. According to the Russian Institute of Pediatric Orthopedics, 40-80% of children have posture disorders, and 3%-10% of them have various curvature of the spine, the so-called school scoliosis.
With the development of civilization, the content, organization and methods of human labor change. Office workers are a new mass profession, whose number is more than 60% of the total working population. The need for long-term adherence to a sitting working posture (working at a computer, with documents, with clients) leads to an increase in the number of diseases of the musculoskeletal system of the adult population. The number of such diseases is steadily growing, they are getting younger, and this trend is likely to continue in the foreseeable future.
One of the most important questions in the problem of the origin of man is which of the modes of movement of primates was a prerequisite for bipedal walking.
Charles Darwin believed that our ancestors were tree animals.
One of the theories - "brachiator" - believed that only brachiation could lead to good development of the collarbone, to a wide chest, to the ability to supinate and pronate the limbs. According to this theory, the common ancestor of hominids and pongids was a brachiator.
Proponents of another theory - originally quadrupedal walking - considered the similarity of the hands of a monkey and man to be convergent: both work and climbing on branches led, according to these researchers, to the same result. Studying the features of the foot in humans, monkeys and other mammals - hedgehog, rat, marmot, etc. - they believed that the human foot is closest to the type of macaque foot, i.e. man did not have adaptations for either brachiation or jumping, as Jones Wood, a supporter of the origin of man from the tarsier, bypassing the ape stage, believed.
Brachiation is now regarded as an extreme adaptation to an arboreal lifestyle.
One of the theories is the theory of cruration: according to it, bipedal walking was preceded by walking along the branches in a half-upright position (cruration). Some authors believe that the human ancestor could at the same time rely on his fingers, as do modern large apes, other authors consider vertical climbing important for the emergence of bipedalism.
It should be noted that none of the proponents of the arboreal stage meant exclusively arboreal life. With all the adaptability of the foot to ground movement, it retains the features of the arboreal locomotion of its ancestors, for example, there is a muscle that abducts the first toe. The ability to abduct the first finger is developed in many climbing mammals, for example, in rats, marsupials, and some rodents. One of the prerequisites for the development of upright walking may have been upright sitting, which is characteristic of all primates.
Paleontological data do not provide sufficient material to resolve this discussion. Egyptopithecus was probably a quadrupedal tree monkey, similar to the howler monkey, he hung from the branches with his hands and feet. Dryopithecus, proconsul, pliopithecus have a generalized skeleton similar to broad-nosed, thin-bodied and great apes. The structure of their shoulder joint shows great freedom of the hand. Their locomotion could also include brachiation. It is believed that the group of Miocene hominoids was heterogeneous in terms of the development of locomotion, Pliopithecus was an arboreal quadruped, Proconsul was a semi-brachiator, Dryopithecus walked on the joints of the forelimbs. Miocene hominoids show signs of straightening of the body, but only initial signs. In some later forms - for example Oreopithecus - a more upright position of the body is observed. This is evidenced by five massive lumbar vertebrae, the structure of the upper end of the thigh, the large width of the ilium, and other signs. In the forelimb there were also signs of brachiation - movement on the hands: this is the lengthening of the forelimb, the mobility of the carpal joint, the curvature of the phalanges and metacarpus. Modern pongids have retained the brachiator complex. The ability of the arms to span up to 180 degrees, to wide pronation and supination, and the grasping type of the hand with opposition of the first finger are important arguments in favor of the arboreal stage of primates.
In the process of anthropogenesis, the traits of brachiatoric specialization could be forced out, but they still remained in the early Australopithecus. Their forelimbs are longer than their hind ones, the toe phalanges are long and curved, and they are similar in skeletal structure to the great apes.
The ability to straighten the body position is one of the main features of primates. According to some assumptions, the original type of locomotion was vertical clinging and jumping. All modern primates, when sitting, take a straightened position of the body, and many are capable of vertical forms of movement, including bipedalism, this ability is especially well expressed in great apes, in which the supporting role of the hind limb increases. However, the bipedal locomotion of great apes is the bipedal locomotion of a four-legged animal standing on two legs. At the same time, the body is tilted forward, the spine is curved, and there is no lumbar lordosis. When the body is straightened, it throws back along with the pelvis. The lower limbs are bent at the knee joints, there is no rotational movement of the pelvis, and the body seems to roll over with each step.
http://answer.mail.ru/question/13315969
http://www.examens.ru/answer/8/9/680.html
http://www.sunhome.ru/journal/16241
http://medbiol.ru/medbiol/antrop/00010554.htm
Scientists at the University of Liverpool came to the conclusion that our ancestors developed even before they abandoned the arboreal lifestyle and switched to living on the ground. The sensational discovery led the researchers to another important conclusion: according to British biologists, walking on two legs has always been a feature of the behavior of great apes, and human ancestors never went through the stage of walking on all fours.
For decades, anthropologists have been convinced that bipedalism is a unique quality of Homo sapiens and its closest ancestors, Homo habilis (handy man) and Homo erectus (upright man). However, scientists studying the behavior of the only great arboreal monkeys - orangutans living on the island of Sumatra - found they had the same ability. True, orangutans use the vertical position of the body to move not on the ground, but along the branches of trees.
“There are a lot of hypotheses for the origin of bipedal walking (bipedia), - Vitaly Kharitonov, a leading researcher at the Institute and Museum of Anthropology at Moscow State University, told our publication. - In accordance with one of them, the complex of anatomical abilities necessary for walking upright developed in the ancestors of man after he changed his habitat: he switched from an arboreal lifestyle to a terrestrial one. According to another point of view, our ancestor really could have learned to walk upright already during his life in the trees. These are two alternative hypotheses. It is only possible to accurately indicate the time when the transition to bipedia took place: today, the antiquity of Australopithecus, which are the first members of our evolutionary trunk, according to archaeological finds, reaches 6-7 million years. The bones of Australopithecus that lived in this era already have features associated with upright walking. However, it was probably episodic: the ancient Australopithecus mostly moved on four legs, but if necessary, they could stand only on their hind limbs. “It is quite possible that bipedal locomotion occurred earlier, but the transition of Australopithecus to bipedia as the preferred mode of movement begins precisely 6-7 million years ago,” says Mr. Kharitonov. “And already 2-3 million years ago, in African Australopithecus, all the signs necessary for bipedia were combined into a single anatomical complex.”
The orangutans, whose behavior was observed by scientists at the University of Liverpool, hold their torso upright, and moving along flexible branches that are elastic, like soft soil, grab them with their toes. From falling, the monkey is insured by the forelimbs, with which the orangutan clings to high branches. This, apparently, is the best way for orangutans to move along the branches.
“All anthropoid primates are prone to upright walking, - The reason lies in the living conditions: in the open spaces of the savannah, the primate cannot hide from a predator with the same ease as in the rainforest. The presence of permanent danger required a number of sociobiological adaptations from primates: this includes not only upright posture, but also social communication skills, which later gave rise to first non-verbal, and then verbal speech.
“Upright walking is very effective in a number of its qualities,” says Vitaly Kharitonov. - Firstly, in the conditions of the African savannah, this method makes it possible to get away from overheating: the area on which the sun's rays fall becomes smaller. Secondly, the presence of free forelimbs allows the female to carry the cub. Thirdly, the review of a bipedal animal is much greater than that of a quadrupedal one: standing on two legs, the monkeys learned to notice a predator from a distance.”
Most likely, Australopithecus already used tools: sticks, clubs, stones, large animal bones. True, they still did not know how to make them: these distant ancestors of man only picked them up in nature, but they could not process them at all. That is why there are no traces of artificial processing on the finds of this era.
“The theory about the development of upright walking during the life of primates on trees has the right to life,” Sergey Vasilyev, head of the laboratory of anthropology at the Institute of Ethnology and Anthropology of the Russian Academy of Sciences, told RBC daily. “It’s not for nothing that many modern primates are able to stand on their hind legs.” There is a third, very plausible version of the development of bipedia: our ancestral form, which preceded the bipedal primates, did not move on four limbs, but in the same way as the modern apes of Africa - they stand on two hind limbs, leaning on the ground only with their fingers hands, with which they seem to help the legs. In accordance with this hypothesis, a similar mode of movement was the starting point for our ancestors.
“There is also a fourth hypothesis that has been very fashionable lately,” notes Vitaly Kharitonov.
Topic 4. Musculoskeletal system
According to her, our predecessors, who experienced a constant need for water, often entered the reservoirs, involuntarily straightening up to keep their heads above the surface. Since the food found in water bodies is shellfish, fish, etc. - was an important part of the diet of our ancestors, primates gradually switched to upright walking.
Most anthropologists still believe that the skills of vertical walking developed in humans precisely when our ancestors descended from the trees in connection with
bipedalism
The structural features of the human skeleton, which he acquired in the process of evolution, are associated with upright walking and the use of the upper limbs - hands - as an organ of labor.
These features are:
- The cerebral part of the skull predominates in volume over the front by 4 times, while in primates this ratio is 1:1.
- The lower jaw is arched, with a protruding chin, which is associated with the development of the muscles of the tongue and speech activity.
- The spine has 4 bends: two forward - cervical and lumbar lordosis and two back - thoracic and sacral kyphosis, thanks to which it acquired an S-shape and springs when walking.
- The mass of the vertebral bodies increases in the direction from the cervical to the lumbar, which is associated with an increase in the load on the vertebrae of the lower spine.
- The chest is flat and wide.
- The pelvis is massive, cup-shaped, supports the organs lying above it and is a support for the lower extremities.
- The bones of the upper limbs are lighter, more mobile and shorter than the lower ones. The stable position of the body is provided by the shortening of the spine. Thumb brushes are opposed to the rest.
- The bones of the foot form an arch that softens the shocks of the body when walking.
At the beginning of the week, the media reported that scientists had found an Australopithecus skeleton, which will force experts to reconsider their views on when human ancestors learned to walk confidently on two hind limbs. If the results new work are confirmed, then scientists will have to move this momentous event at least half a million years ago.
Top down
Before talking about the addition to the Australopithecus family, let us briefly recall modern ideas about the formation of human ancestors on their feet. It is believed that the branch leading to man comes from ape-like creatures that lived in trees. At some point, these creatures decided to change their place of residence and began to develop a new ecological niche - open spaces under the trees. The reasons why our ancestors descended are not entirely clear. Perhaps they lost competition for food to more agile small monkeys, and on earth they had more opportunities to get their own food.
Surely, many readers have watched how monkeys move on the ground - this process is rather difficult for them, and in order to maintain balance, the animals are forced to rely on their front limbs. Approximately in the same way, the Australopithecus descended from the branches should have moved (it is believed that it was from them that the terrestrial period of the history of man and his ancestors began). But it is one thing to walk from tree to tree for your own pleasure, and quite another to spend 24 hours a day on the ground. In order not to starve to death in a completely unfriendly environment, Australopithecus had to learn to walk on two limbs.
Gradually, the skeleton of our ancestors began to take on a different shape: the size of the bones and the structure of the skeleton changed so that their owner could move upright for a long time. At the same time, the forelimbs of the recent inhabitants of the trees were freed, with the help of which they could more deftly obtain and eat food, and later make, first, primitive, and then more complex tools.
Most paleontologists were of the opinion that only Homo erectus, which is reflected in the very name of this type of people, which is translated from Latin as "upright man." H. erectus It is considered the direct ancestor of Homo sapiens - recently even works have appeared proving that representatives of these two species interbred with each other. The researchers believed that Australopithecus, although they descended to the ground, moved along it very awkwardly and still spent a lot of time in the trees.
Recently, a work has appeared, the authors of which, that the ability to walk upright developed in Australopithecus even before they climbed down from the trees. The researchers analyzed the footprints left by "real" bipeds and creatures that had not yet mastered the upright gait (although both were represented by people), and compared them with the footprints of the 3.6 million year old Australopithecus of Afar, found near the city of Laetoli in 1978 . The scientists came to the conclusion that the traces A. afarensis differ very little from traces of true bipeds.
This point of view was based on the analysis of the remains of Lucy, an australopithecine of the species Australopithecus afarensis, the remains of which were found in Ethiopia in 1974. Actually, it was Lucy, who lived on Earth about 3.2 million years ago, who largely determined the ideas of scientists about A. afarensis, from which the more advanced australopithecines and later humans are thought to have descended. Lucy was a miniature creature - her height was barely more than one meter, with relatively short legs and arms similar to monkey paws. After analyzing the appearance of the ancient Ethiopian, scientists concluded that A. afarensis they moved uncertainly on the ground, primarily due to short legs (it is the insufficient length of the lower limbs that does not allow modern monkeys to move on the ground as deftly as on trees). And although after the discovery of Lucy, experts found the remains of several more Afar australopithecines, which were noticeably larger than the "debutante", it was believed that A. afarensis nevertheless, they were somewhere in the middle of the path from dart frogs to walkers.
Everything is different
A recent find described in a magazine Proceedings of the National Academy of Sciences, may force scientists to reconsider their opinion about the appearance and abilities of the Afar australopithecines. Scientists discovered the first bone in 2005, 50 kilometers from the place where Lucy was found. In the next three years, experts found about 30 more bones, from which they managed to put together an approximate skeleton of a relative of Lucy - scientists came to the conclusion that the creature also belongs to the species A. afarensis and is male. His age was estimated at 3.6 million years - that is, he is 400 thousand years older than Lucy.
Paleontologists named the australopithecine Kadanuumuu, which means "big man" in the Afar language spoken in central Ethiopia. Kadanuumuu was large even by modern standards - his height ranged from 1.5 to 1.8 meters. This australopithecine's legs were much longer than Lucy's, even with their difference in height. In addition, the structure of the humerus, as well as the ribs and pelvis of Kadanuumuu, turned out to be very similar to the structure of a modern person. All representatives A. afarensis found earlier, these bones were not preserved or were poorly preserved.
According to the scientists who discovered the "big man", he moved on the ground just as well and climbed trees as badly as modern people. In particular, the researchers believe that he could stand on one leg for a long time - a skill necessary for an upright gait and inaccessible to monkeys. In other words, if we consider Kadanuumuu as a typical representative of the species, then A. afarensis much more reminiscent of representatives of the genus Homo than their tree-dwelling ancestors or modern apes, with whom Australopithecus is sometimes compared. And taking into account the age of the "big man", this conclusion means that Australopithecus mastered bipedal locomotion at least 400 thousand years earlier than it was thought.
The authors of the new work explain the contradiction with the results obtained after the analysis of Lucy's skeleton by the fact that she was a female. Australopithecus was characterized by pronounced sexual dimorphism - the difference in the appearance of males and females. Taking the Afar Lucy as a model, scientists have gone the wrong way, says one of the authors of the work, Johannes Haile-Selassie (Yohannes Haile-Selassie). "Most of the misinterpretations have to do with Lucy's size and gender," he said.
An indirect confirmation of the conclusions of the new work may be the analysis of another recent find. In October 2009 in an authoritative scientific journal Science more than a dozen articles have appeared on another recent paleontological find - Ardipithecus Ardipithecus ramidus, which many experts consider the ancestor of Australopithecus. The age of Ardi, as the find was called, is 4.4 million years, while the structure of her pelvis indicates that A. ramidus if desired, they could move relatively confidently on two limbs. That is, the prerequisites for upright walking appeared 800 thousand years before the birth of Kadanuumuu. You can read more about Ardi.
Early?
The new study aroused great interest in scientific circles, although some experts doubt the legitimacy of the conclusions made by the authors, and the main objection concerns the fundamental point of the work - the definition of the type of "big man". Scientists managed to find quite a few bones of Kadanuumuu, but they did not find a skull and teeth - extremely important elements for determining the place of a creature on the evolutionary tree.
But even if "big man" still refers to the species A. afarensis, he may well be atypical of his representative. This opinion was expressed by one of the scientists who discovered in 2006 the bones of the "child Lucy" - a three-year-old Australopithecus of Afar, named Selam. Humerus Selam ("Lucy's baby" female) resemble the bones of a baby gorilla rather than a human baby. However, it can be objected to this argument that Selam has already begun to show sexual dimorphism, although usually differences between the sexes appear at a more mature age.
Despite the criticism and not absolute reliability of scientists' arguments, Kadanuumuu is, of course, a very important find for paleontology. Due to the meager amount of data compared to other sciences, scientists are forced to build theories based primarily on assumptions and more or less logical comparisons and comparisons. Each new bone found makes these speculative conclusions a little more convincing. What can we say about almost complete skeletons.