Great apes, or ( Hominoidae) is a superfamily of primates, which includes 24 species. Although people treat Hominoidea, the term "ape" does not apply to humans and describes non-human primates.
Classification
Apes are classified in the following taxonomic hierarchy:
- Domain: ;
- Kingdom: ;
- Type: ;
- Class: ;
- Squad: ;
- Superfamily: Hominoids.
The term ape refers to a group of primates that includes the families: hominids (chimpanzees, gorillas, orangutans) and gibbons. Scientific name Hominoidea refers to apes (chimpanzees, gorillas, orangutans, gibbons) as well as humans (i.e., it ignores the fact that humans prefer not to call themselves apes).
The gibbon family is the most diverse, with 16 species. Another family, the hominids, is less diverse and includes: chimpanzees (2 species), gorillas (2 species), orangutans (3 species) and humans (1 species).
Evolution
The record is incomplete, but scientists believe that ancient hominoids diverged from the apes between 29 and 34 million years ago. The first modern hominoids appeared about 25 million years ago. Gibbons were the first group to diverge from other groups, about 18 million years ago, followed by the lineage of orangutans (about 14 million years ago), and gorillas (about 7 million years ago).
The most recent split occurred between humans and chimpanzees about 5 million years ago. The closest living relatives of hominoids are the Old World monkeys, or marmosets.
Environment and habitat
Hominoids live throughout the Western and Central regions, as well as in the Southeast. Orangutans are found only in Asia, chimpanzees inhabit Western and Central Africa, gorillas are common in Central Africa, and gibbons live in Southeast Asia.
Description
Most hominoids, with the exception of humans and gorillas, are skilled as well as flexible climbers. Gibbons are the most agile arboreal primates of all hominids. They can jump along branches, moving quickly and efficiently through trees.
Compared to other primates, hominoids have a lower center of gravity, a shortened spine relative to their body length, a wide pelvis, and a broad chest. Their overall physique gives them a more upright posture than other primates. Their shoulder blades are located on their back, allowing for a wide range of motion. Hominoids also do not have a tail. Together, these characteristics give hominoids a better balance than their closest living relatives, the Old World monkeys. Hominoids are therefore more stable when standing on two legs or swinging their limbs, and hanging from tree branches.
Hominoids are very intelligent and capable of problem solving. Chimpanzees and orangutans make and use simple tools. Scientists studying orangutans in captivity have noted the primates' ability to use sign language, solve puzzles, and recognize symbols.
Nutrition
The diet of hominoids includes leaves, seeds, nuts, fruits and a limited number of animals. Most species, but fruits are the preferred food. Chimpanzees and orangutans primarily eat fruit. When gorillas lack fruit at certain times of the year or in certain regions, they feed on shoots and leaves, often bamboo. Gorillas are well adapted to chew and digest such a low-nutrient food, but these primates still prefer fruit when it is available. Hominoid teeth are similar to those of Old World monkeys, although they are especially large in gorillas.
Reproduction
Gestation in hominoids lasts from 7 to 9 months and results in the birth of one offspring or, less commonly, two. The cubs are born helpless and require care for a long time. Compared to most other mammals, hominoids have a surprisingly long period of breastfeeding. In most species, full maturity occurs at the age of 8-13 years. As a result, females typically give birth only once every few years.
Behavior
Like most primates, hominoids form social groups, the structure of which varies among species. Gibbons form monogamous pairs. Orangutans are an exception to the social norm of primates; they lead a solitary life.
Chimpanzees form groups that can number from 40 to 100 individuals. Large groups of chimpanzees break up into smaller groups when fruit becomes less available. If small groups of dominant male chimpanzees go off to find food, the females will often copulate with other males in their group.
Gorillas live in groups of 5 to 10 or more individuals, but they remain together regardless of the availability of fruit. When fruits are difficult to find, they resort to eating leaves and shoots. Because gorillas stay together, the male is able to monopolize the females in his group. This fact is associated with more in gorillas than chimpanzees. In both chimpanzees and gorillas, groups include at least one dominant male, with females leaving the group in adulthood.
Threats
Many hominoid species are endangered due to extermination, poaching, and hunting for bushmeat and skins. Both chimpanzee species are critically endangered. Gorillas are on the verge of extinction. Eleven of the sixteen gibbon species are becoming extinct.
CONTROL TESTING AT THE RESULTS OF THE 3RD QUARTER
Grade: ninth
Program by I.N. Ponomareva
For each question, choose ONE correct answer.
1.Which hypothesis states that life on Earth was brought from space?
1) in the hypothesis of biochemical evolution
2) in the stationary state hypothesis
3) in the genetic hypothesis
4) in the panspermia hypothesis
2.What are coacervates?
1) nucleic acid complexes
2) protein complexes
3) fat complexes
4) spontaneously concentrating complexes of primary organic substances
3.What are the names of organisms that feed on ready-made organic substances?
1) protobionts
2) chemotrophs
3) heterotrophs
4) autotrophs
4.Which organisms capable of photosynthesis are the most ancient?
1) viruses
2) plants
3) green euglena
4) cyanobacteria
5.What are the names of organisms that themselves synthesize organic substances from inorganic ones?
1) autotrophs
2) heterotrophs
3) protobionts
4) chemotrophs
6.What is the largest unit of geological chronology called?
1) era
2) period
3) era
4) century
7.Which animals were the first to master land?
1) dinosaurs
2) turtles
3) crocodiles
4) Cancerscorpios
8. How many eras are there in the history of the development of our planet?
1) five
2) six
3) seven
4) eight
9.Which era continues at the present stage of the Earth’s development?
1) Proterozoic
2) Paleozoic
3) Mesozoic
4) Cenozoic
10.What, according to Charles Darwin, is the main driving force of evolution?
1) natural selection
2) heredity
3) artificial selection
4) variability
11.What set of individuals is considered to be the elementary unit of evolution?
1) view
2) population
3) family
4) gender
12.What teaching claimed that the origin and diversity of the world is the result of the divine will?
1) creationism
2) vitalism
3) Lamarckism
4) neo-Lamarckism
13.Which type criterion is the most accurate?
1) environmental
2) genetic
3) morphological
4) geographical
14.What phenomenon did Charles Darwin explain the emergence of different types of finches on the Galapagos Islands?
1) microevolution
2) macroevolution
3) allopatric speciation
4) sympatric speciation
15.What process refers to biological regression?
1) increase in the number of species
2) increase in the area of distribution of the species
3) increasing the adaptability of individuals to environmental conditions
4) decrease in the adaptability of individuals to the environment
16.Which process does NOT belong to aromorphoses?
1) the appearance of warm-bloodedness
2) the appearance of seeds in plants
4) the emergence of the brain
1) gender
2) family
3) class
4) department
18.What refers to biological progress?
1) decrease in the number of species
2) increase in the number of species
3) decrease in the adaptability of individuals to the environment
4) reduction in the area of distribution of the species
19.Which process does NOT belong to idioadaptation?
1) the appearance of wings in birds
2) a wide variety of pollination methods in angiosperms
3) ecological differentiation of finch beaks
4) formation of protective coloring
20.What was the name of the group of apes, consisting of the earliest primates?
1) anthropoids
2) pongids
3) hominids
4) tarsiers
21.What biological feature does NOT characterize the species Homo sapiens?
1) large brain volume
2) strong jaws
3) predominance of the cerebral part of the skull over the facial part
4) upright posture
22.What were the names of the extinct arboreal apes, the ancestors of modern apes and humans?
1) hominids
2) tarsiers
3) Dryopithecus
4) pongids
23.Which scientist was the first to prove in his work that humans are related to apes?
1) C. Linnaeus
2) T. Huxley
3) J.B. Lamarck
4) Charles Darwin
24.What modern people appeared on Earth 40-30 thousand years ago and continue to live today?
1) neoanthropes
2) archanthropes
3) Neanderthals
4) paleoanthropes
25.How is the word “australopithecus” translated from Latin?
1) Australian monkey
2) the oldest monkey
3) ape
4) southern monkey
26.Fossil remains of which ancient person were found near Beijing?
1) Pithecanthropus
2) paleoanthropa
3) Sinanthropa
4) Australopithecus
27.How many main races exist today?
1) two
2) three
3) four
4) five
28.Which morphological feature does NOT characterize the Mongoloid race?
1) flattened face shape
2) narrow palpebral fissures
3) noticeable cheekbones
4) straight or wavy soft hair
29.Which human race does NOT exist?
1) Americanoid
2) Caucasian
3) Mongoloid
4) Negroid
30.What did the most ancient and ancient people do during the long period of anthropogenesis?
1) cattle breeding
2) gathering and hunting
3) gardening
4) agriculture
KEY
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When preparing the testing, material from the manual Testing and Measuring Materials was used. Biology: 9th grade / comp. I.R.Grigoryan. – M.: VAKO, 2011.
The most developed, most intelligent monkeys are anthropoids. That’s how the word begs to be called – humanoid. And all because they have a lot in common with our species. We can talk about apes a lot, for a long time and with passion, simply because they are really close to our species. But first things first.
There are 4 types of these animals:
- gorillas,
- orangutans,
- chimpanzee,
- bonobos (or pygmy chimpanzees).
Bonobos and chimpanzees are very similar to each other, but the remaining two species are not at all similar to each other or to chimpanzees. However, all great apes There are many similarities, for example:
- they have no tail,
- similar structure of the hands of the upper limbs and human hands,
- the volume of the brain is very large (at the same time, its surface is full of grooves and convolutions, and this indicates a high level of intelligence of these animals)
- there are 4 blood groups,
- In medicine, bonobo blood is used for transfusion to a person with a suitable blood type.
All these facts indicate the “blood” relationship of these creatures with people.
Both species of gorillas and chimpanzees live in Africa, and this continent, as you know, is considered the cradle of all humanity. The orangutan, according to scientists, our most genetically distant relative among the great apes, lives in Asia.
common chimpanzee
Chimpanzee social life
Chimpanzees usually live in groups, with an average of 15-20 individuals. The group, which is headed by one male leader, also includes females and males of all ages. Groups of chimpanzees occupy territories, which the males themselves protect from incursions by neighbors.
In places where there is enough food for a group to live comfortably, chimpanzees lead a sedentary lifestyle. However, if there is not enough food for the entire group, then they wander over fairly long distances in search of food. It happens that the territories of residence of several groups overlap. In this case, they unite for some time. It is interesting that in all conflicts the advantage goes to the group that contains more males and which, therefore, turns out to be stronger. Chimpanzees do not create permanent families. This means that any adult male has the right to freely choose his next girlfriend from among the adult females, both from his own group and from the group that has joined.
After an 8-month gestation period, a female chimpanzee gives birth to one absolutely helpless baby. Up to a year of life, the female carries the baby on her stomach, after which the baby independently transfers to her back. For as long as 9-9.5 years, the female and the cub are practically inseparable. His mother teaches him everything she knows, shows him the world around him and other members of the group. There are cases when teenagers are sent to their own “kindergarten”. there they frolic with peers under the supervision of several adults, usually females. When the baby turns 13 years old, the chimpanzee enters adulthood and begins to be considered independent members of the pack. At the same time, young males begin to fight for leadership,
Chimpanzees are quite aggressive animals. Conflicts often occur in the group, which even escalate into bloody fights, which often end in death. Apes are able to establish relationships with each other through a wide range of facial expressions, gestures and sounds with which they convey their approval. These animals express friendly feelings through picking each other's fur.
Chimpanzees get their food in the trees and on the ground, feeling in their place in both places. Their food includes:
- plant food,
- insects,
- small living creatures.
In addition, hungry chimpanzees as a whole group can go out hunting and capture, for example, a gazelle for shared food.
Skillful hands and a smart head
Chimpanzees are extremely smart, they are able to use tools, deliberately selecting the most convenient tool. They are even capable of improving it. For example, to climb into an anthill, an ape uses a twig: it selects a twig of appropriate size and optimizes it by tearing off the leaves on it. Or, for example, they use a stick to knock down a tall growing fruit. Or to hit an opponent with it during a fight.
To break a nut, the monkey places it on a flat stone specially selected for this purpose, and uses another sharp stone to break the shell.
To quench their thirst, the chimpanzee uses a large leaf and uses it as a scoop. Or he makes a sponge from a pre-chewed leaf, dips it in a stream and squeezes the water into his mouth.
When hunting, great apes can stone a victim to death; a hail of cobblestones will await a predator, for example, a leopard, who dares to hunt these animals.
In order not to get wet when crossing a pond, chimpanzees are able to build a bridge from sticks, and they will use wide leaves as an umbrella, fly swatter, fan and as toilet paper.
Gorilla
Good giants or monsters?
It is not difficult to imagine the feelings of the person who first saw a gorilla in front of him - a humanoid giant, frightening aliens with menacing screams, beating himself in the chest with his fists, breaking and uprooting young trees. Such encounters with forest monsters gave rise to terrible stories and tales about the fiends of hell, whose superhuman strength poses a mortal danger, if not for the human race, then for its psyche.
Unfortunately, this is not an exaggeration. Such legends, which pushed the public to the fact that these humanoid creatures began to be treated too incorrectly, at one time caused an almost uncontrolled, panicky extermination of gorillas. The species was threatened with complete extinction if it were not for the work and efforts of scientists who took under their protection these giants, about whom in those years people knew almost nothing at all.
As it turned out, it seemed these creepy monsters are the most peaceful herbivores who eat only plant foods. Besides they are almost completely non-aggressive, but demonstrate their strength and, even more so, use it only when there is real danger and if someone comes to their territory.
Moreover, to avoid unnecessary bloodshed, gorillas try to scare off offenders, it doesn’t matter whether it’s another male, a ruler of another species, or a human. Then all possible means of intimidation come into play:
- screams,
- pounding your chest with your fists,
- breaking down trees, etc.
Features of the life of a gorilla
Gorillas, like chimpanzees, live in small groups, but their numbers are usually smaller - 5-10 individuals. Among them there is usually the head of the group - the eldest male, several females with cubs of different ages and 1-2 young males. The leader is easy to recognize: It has silver-gray fur on its back.
By the age of 14, the male gorilla becomes sexually mature, and instead of black fur, a light stripe appears on his back.
An already mature male is enormous: he is 180 cm tall and sometimes weighs 300 kg. The one of the silver-backed males who turns out to be the eldest becomes the leader of the group. The care of all family members is entrusted to his powerful shoulders.
The main male in the group gives signals to wake up at sunrise and to sleep at sunset, he himself chooses the path in the thickets along which the rest of the group will go in search of food, regulates order and peace in the group. He also protects all of his people from impending dangers, of which there are many in the rainforest.
The younger generation in the group is raised by their own mothers. However, if the baby suddenly becomes orphaned, then it is the leader of the pack who takes them under his wing. He will carry them on his back, sleep next to them and make sure that their games are not dangerous.
When protecting orphan cubs, the leader may even fight with a leopard or even with armed people.
Often the capture of a baby gorilla entails not only the death of its mother, but also the death of the leader of the group. The remaining members of the group, deprived of protection and care, young animals and helpless females also stand on the edge of the abyss if one of the single males does not take responsibility for the orphaned family.
Orangutans
Orangutan: features of life
"Orangutan" is translated from Malay as "man of the forest". This name refers to large apes that live in the jungles of the islands of Sumatra and Kalimantan. Orangutans are one of the most amazing creatures on earth. They differ in many ways from other apes.
Orangutans are arboreal. Even though their weight is quite significant, 65-100 kg, they climb trees remarkably well even at a height of 15-20 m. They prefer not to go down to the ground.
Of course, due to the weight of their body, they cannot jump from branch to branch, but at the same time they are able to confidently and quickly climb trees.
Orangutans eat almost around the clock, eating
- fruit,
- foliage,
- bird eggs,
- chicks.
In the evenings, orangutans build their homes, and each one has his own place, where they settle down for the night. They sleep holding a branch with one of their paws so as not to fall down in their sleep.
Every night, orangutans settle down in a new place, for which they again build a “bed” for themselves. These animals practically do not form groups, preferring a solitary life or life in pairs (mother - cubs, female - male), although there are cases when a pair of adults and several cubs of different ages form almost a family.
The female of these animals gives birth to 1 cub. His mother takes care of him for about 7 years, until he is old enough to live independently.
Until the age of 3, a baby orangutan feeds only on its mother’s milk, and only after this period does the mother begin to give it solid food. She chews the leaves for him, thus making a vegetable puree for him.
She prepares the baby for adult life, teaching him to climb trees correctly and build a place to sleep. Baby orangutans are very playful and affectionate, and they perceive the entire process of education and training as an entertaining game.
Orangutans are very savvy animals. In captivity, they learn to use tools and are even able to make them themselves. But in conditions of free life, these apes rarely use their abilities: the incessant search for food does not give them time to develop their natural intelligence.
Bonobos
The bonobo, or pygmy chimpanzee, is our closest relative
Few people know about the existence of our closest relative, the bonobo. Although the set of genes in the dwarf chimpanzee coincides with the set of human genes by as much as 98%! They are also very close to us in the basics of social-emotional behavior.
They live in Central Africa, northeast and northwest Congo. They never leave tree branches and move on the ground very rarely.
Characteristic behavioral features of this species are joint hunting.. They can wage war among themselves, then the presence of power politics is revealed.
Bonobos have no sign language, so characteristic of other creatures. They give each other vocal signals and they are very different from the signals of the second type of chimpanzee.
The bonobo's voice consists of high, harsh and barking sounds. For hunting they use various primitive objects: stones, sticks. In captivity, their intellect gets the opportunity to grow and express itself. There, they become real masters in mastering objects and inventing new ones.
Bonobos do not have a leader like other primates. A distinctive and characteristic feature of pygmy chimpanzees is that at the head of their group or the whole community is a female.
Females stay in groups. They also include cubs and juveniles up to 6 years of age. The males stay away, but not nearby.
It is interesting that almost all aggressive outbursts in bonobos are replaced by elements of mating behavior.
The fact that females dominate among them was revealed by scientists in an experiment when combined with groups of monkeys of both species. In bonobo groups, females are the first to eat. If the male does not agree, then the females join forces and expel the male. Fights never occur during eating, but mating always occurs just before eating.
Conclusion
As many wise books claim, animals are our smaller brothers. And we can say with confidence that apes are our brothers - our neighbors.
Great apes or hominoids are a superfamily that includes the most highly developed representatives of the order of primates. It also includes man and all his ancestors, but they are included in a separate family of hominids and will not be discussed in detail in this article.
What distinguishes an ape from a human? First of all, some features of the body structure:
The human spine bends forward and backward.
The facial part of the ape's skull is larger than the brain.
The relative and even absolute volume of the brain is significantly less than that of humans.
The area of the cerebral cortex is also smaller, and the frontal and temporal lobes are also less developed.
Apes do not have a chin.
The chest is round and convex, while in humans it is flat.
The monkey's fangs are enlarged and protrude.
The pelvis is narrower than that of a human.
Since a person is erect, his sacrum is more powerful, since the center of gravity is transferred to it.
The monkey has a longer body and arms.
The legs, on the contrary, are shorter and weaker.
Monkeys have a flat grasping foot with the big toe opposed to the others. In humans, it is curved, and the thumb is parallel to the others.
Humans have virtually no fur.
In addition, there are a number of differences in thinking and activity. A person can think abstractly and communicate using speech. He has consciousness, is capable of summarizing information and drawing up complex logical chains.
Signs of great apes:
large powerful body (much larger than that of other monkeys);
absence of a tail;
lack of cheek pouches
absence of ischial calluses.
Hominoids are also distinguished by their way of moving through trees. They do not run along them on all fours, like other representatives of the primate order, but grab branches with their hands.
Skeleton of apes also has a specific structure. The skull is located in front of the spine. Moreover, it has an elongated front part.
The jaws are strong, powerful, massive and adapted for gnawing solid plant food. The arms are noticeably longer than the legs. The foot is grasping, with the big toe set to the side (like on a human hand).
Great apes include, orangutans, gorillas and chimpanzees. The first are separated into a separate family, and the remaining three are combined into one - pongidae. Let's take a closer look at each of them.
The gibbon family consists of four genera. All of them live in Asia: India, China, Indonesia, on the islands of Java and Kalimantan. Their color is usually gray, brown or black.
Their sizes are relatively small for anthropoid apes: the body length of the largest representatives reaches ninety centimeters, weight - thirteen kilograms.
Lifestyle – daytime. They live mainly in trees. They move uncertainly on the ground, mostly on their hind legs, only occasionally leaning on their front legs. However, they go down quite rarely. The basis of nutrition is plant food - fruits and leaves of fruit trees. They may also eat insects and bird eggs.
Pictured is a gibbon ape
Gorilla is very great ape. This is the largest representative of the family. The height of a male can reach two meters, and weight – two hundred and fifty kilograms.
These are massive, muscular, incredibly strong and resilient monkeys. The coat color is usually black; older males may have a silver-gray back.
They live in African forests and mountains. They prefer to be on the ground, on which they walk mainly on four legs, only occasionally rising to their feet. The diet is plant-based and includes leaves, grass, fruits and nuts.
Quite peaceful, they show aggression towards other animals only in self-defense. Intraspecific conflicts occur, for the most part, between adult males over females. However, they are usually resolved by demonstrating threatening behavior, rarely even leading to fights, much less murder.
Pictured is a gorilla monkey
Orangutans are the rarest modern apes. Currently, they live mainly in Sumatra, although previously they were distributed throughout almost all of Asia.
These are the largest of the monkeys, living mainly in trees. Their height can reach one and a half meters, and their weight can reach one hundred kilograms. The coat is long, wavy, and can be of various shades of red.
They live almost entirely in trees, not even coming down to drink. For this purpose, they usually use rainwater that accumulates in the leaves.
To spend the night, they make nests in the branches, and build a new home every day. They live alone, forming pairs only during the breeding season.
Both modern species, Sumatran and Climantan, are on the verge of extinction.
In the photo there is an orangutan monkey
Chimpanzees are the smartest primates, apes. They are also the closest relatives of humans in the animal world. There are two types of them: ordinary and dwarf, also called. Even the normal size is not too big. The coat color is usually black.
Unlike other hominoids, with the exception of humans, chimpanzees are omnivores. In addition to plant foods, they also eat animals, obtaining them by hunting. Quite aggressive. Conflicts often arise between individuals, leading to fights and death.
They live in groups, the average number of which is ten to fifteen individuals. This is a real complex society with a clear structure and hierarchy. Common habitats are forests near water. Distribution: Western and central part of the African continent.
Pictured is a chimpanzee monkey
Ancestors of great apes very interesting and varied. In general, there are much more fossil species in this superfamily than living ones. The first of them appeared in Africa almost ten million years ago. Their further history is very closely connected with this continent.
It is believed that the line leading to humans separated from the rest of the hominoids about five million years ago. One of the likely candidates for the role of the first ancestor of the genus Homo is considered Australopithecus - great ape, who lived more than four million years ago.
These creatures contain both archaic characteristics and more progressive, already human ones. However, there are much more of the former, which does not allow Australopithecines to be classified directly as humans. There is also an opinion that this is a side, dead-end branch of evolution that did not lead to the emergence of more developed forms of primates, including humans.
But the statement that another interesting human ancestor, Sinanthropus - great ape, is already fundamentally wrong. However, the statement that he is the ancestor of man is not entirely correct, since this species already clearly belongs to the genus of humans.
They already had developed speech, language and their own, albeit primitive, culture. It is very likely that Sinanthropus was the last ancestor of modern homo sapiens. However, the possibility is not excluded that he, like Australopithecus, is the crown of a side branch of development.
Key questions
What is evolution and what is the proof of its existence?
To us and from whom did man come?
Why did one animal species have to undergo such rapid evolution over the last century?
In 1831, Charles Darwin set off on a voyage on the Beagle as a naturalist. When he set out, he shared the common belief that every existing species is unique and permanent and that worldwide catastrophes destroyed previous populations, the evidence of which was preserved in the form of fossil remains, and new species arose in their place.
Returning from his trip almost five years later, Darwin already had a different opinion. He became convinced that organisms evolve slowly, and that fossils - the ancestors of existing forms - provide partial evidence of this process.
What made Darwin change his idea of the origin of life? During his trip around the world on the Beagle, Darwin collected facts indicating the evolution of species. Of course, these facts were not so numerous compared to the striking and convincing examples that evolutionists have discovered over the past 100 years or more. However, Darwin saw a lot and did a lot based on what he saw, which will be the subject of discussion in this and subsequent chapters.
19.1. Evolution is a change in the heritable phenotypes (inherited manifestations of traits) of individuals in a population
Evolution is a special type of change that can only occur in a group of organisms. An individual does not evolve.
Evolution happens within populations, which can be defined as a group of organisms of the same species living in a more or less limited area.
The process of evolution consists of changing the inherited phenotype, i.e. the external manifestation of the hereditary characteristics of the organism, such as color, size, biochemical composition, speed of development, behavior, etc.
Evolution in a population can occur even if evolutionary changes do not appear in a particular individual. An adult gray butterfly does not become black, just as a bacterium does not become resistant to a drug, but one of the offspring of a gray butterfly may turn out to be black, etc. A population consists of different individuals at different times, and therefore it reflects general changes that have occurred over many years. generations. If a population is examined twice over a long period of time, and if it turns out that during this period new phenotypes have appeared in the population that can be transmitted to future generations, then we can say that evolution has occurred in the population (Fig. 19-1).
19.2. As a rule, information about previous populations exists only in the form of fossil remains.
Because noticeable evolutionary change usually occurs after thousands or millions of years, evolution can be traced by comparing modern populations with ancient ones that are only partially preserved as fossils. We cannot be sure that the fossils we find are typical representatives of their populations, but our knowledge of the fossilization process suggests that they are so. The close correspondence between individual fossils and the populations they represent is clearly demonstrated when a living “fossil”—a living representative of a supposedly extinct fossil group—is discovered.
For example, the lobe-finned fish Latimeria belongs to an ancient subfamily of fish that for a long time we knew about only from the presence of fossil remains. Scientists believed that all species of lobe-finned fish became extinct 75 million years ago. But in 1939, a live cross-finned fish was caught in the waters of the Malagasy Republic at great depths, followed by others.
It is clear from Figure 19-2 that the phenotype of this fish, reconstructed from fossil evidence, is remarkably similar to that of its modern relatives. Examples like these allow scientists to use fossil material with confidence.
For reference
Each element has several varieties called isotopes. Isotopes differ in that their atoms contain different numbers of neutrons. Because the atomic mass of an element is approximately the sum of its protons and neutrons, isotopes of the same element have different atomic masses. To designate isotopes of the same element, their atomic mass (rounded to the nearest whole number) is written to the left and slightly above the element's sign. For example, 14 C is a radioactive isotope of carbon. Other isotopes of carbon are stable (non-radioactive), for example 12 C. Each radioactive isotope of any element is characterized by a certain half-life.
19.3. The age of fossils is most often determined by studying the radioactive substances they contain.
Radioactive substances break apart and are converted into other substances. For example, radioactive uranium decays into lead and helium (a persistent gas), radioactive potassium turns into argon (a persistent gas) and ordinary calcium, radioactive carbon turns into nitrogen, etc.
Some radioactive transformations occur within a few hours, others over several years, and some over eons. Over 456 billion years, only half of a certain amount of 238 U (an isotope of uranium) will turn into lead and helium. The period required for the decay of half a given amount of a substance is called half-life. Each radioactive substance has a certain half-life. If the half-life is known, it can be used to determine the age of rocks and the fossil remains they contain. For example, when the isotope of uranium 238 U weighing 1.0 g decays to 0.5 g in 456 billion years, 0.4 g of lead is formed (the rest of the mass is converted into helium and nuclear energy). After another 456 billion years, only 0.25 g of uranium will remain, but the amount of lead will increase to 0.6 g. To determine the age of a rock, the relative content of uranium and lead in it is measured. The greater the amount of uranium relative to lead, the younger the rock.
The half-life of the uranium isotope 238 U is too long to be used in determining the age of later fossils. The half-life of the uranium isotope 235 U is 713 million years. And the potassium isotope 40 K turns into the argon isotope A, having a half-life of 13 billion years. These half-lives are quite useful for determining the age of many fossils.
Another useful isotope is the 14 C isotope of carbon. It is present along with ordinary carbon in all living organisms in the form of a small but constant fraction of living tissue. Like all radioactive elements, it decays constantly. But while the organism lives, the amount of radioactive carbon in it is replenished as it decays. After the death of the organism, the content of 14 C relative to the total amount of carbon in dead tissues begins to decrease. In fact, in 5570 years there will be half as much left. Therefore, comparing the amount of ordinary carbon with the amount of radioactive carbon allows us to date the most recent fossils, as well as teeth, bones, wood remains and charcoal, dating back 10,000 years.
In general, the "repertoire" of radioactive tests now covers the entire period of life on Earth. Thus, the age of most fossils can now be determined more accurately than ever before.
19.4. To study human evolution, that is, the divergence between hominids (humans) and pongids (apes), it is necessary to consider the differences between them
Since there are people who do not want to admit that the process of evolution involves man, we have chosen him as an example of evolution, although many other organisms could serve as good or even better examples, especially those whose remains are preserved in places where decomposition is under the influence of bacteria was minimal.
The reconstruction of human evolution should begin with a study of the differences between humans and great apes. Knowing them, we will know what to look for to establish common ancestors or "missing links." There are relatively few anatomical differences between apes and humans. The human brain is much larger, and the forehead is higher. The jaws are shorter than those of monkeys, and the face, on which the nose protrudes, is flatter. Human teeth are arranged in the jaws in a gracefully curved arc called the dental arch. In monkeys, the dental arch is whiter rectangular than arched. Some teeth in monkeys are separated by a relatively large distance, while in humans the teeth touch each other. In addition, the canines, or eye teeth, in humans are no longer than the other teeth; in monkeys they are longer and resemble teeth.
Human - bipedal vertically walking creature. The method of movement of monkeys is called brachiation; they throw their bodies from tree to tree, clinging to branches with their hands. Since man is a bipedal creature, he differs from apes in that he has: 1) a wide cup-shaped pelvis; 2) large muscular buttocks; 3) a fairly powerful heel; 4) long kogi; 5) arched foot; 6) S-shaped spine; 7) foramen magnum (a large hole at the base of the skull through which the spinal cord passes), facing downwards, and not backwards, as in monkeys (Fig. 19-3). There are other differences, such as the relative absence of hair and Priapus bone(bones of the penis) in humans.
Since bones are easily fossilized, we can hope that we will be able to fully trace the evolutionary differences in the skeleton of humans and great apes. However, there are significant differences between humans and apes that are not subject to fossilization: human puberty lasts longer (17 years in humans, 8-10 years in monkeys); 2) a person can be left-handed or right-handed; 3) people unite in large groups and use complex means of transmitting thoughts, signs and abstract concepts to each other; 4) humans are able to produce offspring throughout the year, while monkeys reproduce at certain periods/However, there is one, “non-skeletal” difference that is “fossilized” very well. People create tools that shape and reflect their complex culture.
There are more similarities between humans and apes, but not many differences. They have many common anatomical and biochemical features. For example, neither humans nor apes are capable of synthesizing vitamin C and do not have tails.
19.5. Possible common ancestors of modern apes and humans are the extinct arboreal apes that lived approximately 15-30 million years ago
15 million years ago neither modern apes nor humans existed. Fossil remains of ape-like primates have been found, which appear to be their common ancestors. The age of these fossils is approximately 15-30 million years. However, the remains of these ancient fossils are very scarce. Most often this is only a part of the jaw, sometimes just one tooth, less often - finds approaching a complete skeleton. Of greatest interest for our discussion are the fossils belonging to the group Dryopithecus, an arboreal ape (Fig. 19-4), whose remains have been found in Africa, India, and Europe. They are the likely ancestors of great apes such as the gorilla and chimpanzee, and appear to be closely related to human ancestors.
The pelvis of Dryopithecus was adapted for walking on four legs, but its size was smaller than that of modern chimpanzees and gorillas. Their legs were not as long as those of humans, and their arms were shorter than those of chimpanzees or orangutans. Some Dryopithecus have canines (eye teeth) larger than those of humans, but smaller than those of modern apes. Human canine roots are larger than seems necessary. This suggests that our ancestors had larger fangs. There are also similarities between the molars of humans and Dryopithecus.
The dentition of Dryopithecus varies, as they belonged to several different families, genera and species. Most dryopithecines had teeth similar to those of monkeys, but some are also known that had a more rounded dental arch, relatively small fangs and other features similar to human teeth. Elwyn Simons united humanoid forms under a common name Ramaptihecus punjabicus.
These fossils lived in Africa and India, and possibly in areas in between. They lived about 14 million years ago, as determined by potassium-to-argon dating done at the site where one was discovered by the late Lewis Leakey.
Leakey and Simone disagreed about the names of some ape-like fossils, but they shared the same interpretation of their origin, namely that 12-14 million years ago, animals that showed signs of developing the ape-like features that we see in modern pongids lived in warmer climes Old World.
Together with them there was a group of primates very similar in appearance, whose teeth had a clear resemblance to human teeth. (Simonet called them Ramapithecus.) Leakey formally separated these humanoid-jawed individuals from the Dryopithecus group and classified them as hominids.
Extremely important information was obtained from the discovery of the remains of a fossil Ramapithecus, known as the Calcutta jaw. They show that the period of maturation of Ramapithecus, in contrast to Pongida, was very long, just like in humans. The lower jaw contains all three molars, but with very different wear. The first is heavily worn, the second is only moderately worn, the third is almost completely unworn. This differential wear of molars is observed in humans and fossil humans (including Australopithecus), but is never observed in apes. According to Simons, the third molar, or wisdom tooth, is a sign of maturity in all humans and apes. It appears after the development of the skeleton and puberty of the body are completed. In apes, which have a short period of maturation, the molars appear quickly one after another and therefore they are almost equal in the degree of wear. In humans, the first molar erupts at approximately the same chronological age as in monkeys, but the second appears somewhat later, and the third much later than in monkeys. Therefore, in a person who has reached maturity, the third molar is completely new, and the first is worn out, which is also characteristic of the fossil Ramapithecus.
If all this is confirmed by further findings, the picture of human evolution will appear as follows:
1) The first apes evolved from Old World monkeys that gradually lost their tails. These apes then diverged into forms that appear to be the ancestors of Dryopithecus and Gibbons (Gibbons are a separate family of Apes). 2) 15-20 million years ago, Dryopithecus diverged into a) forms from which humans would later emerge ( Ramapithecus), and b) the forms from which modern pongids will arise ( Dryopithecus).
19.6. A closer ancestor to humans appears to have been Australopithecus.
About 2, and perhaps even 3 or 4 million years ago, hominids not only existed, but their anatomy was very similar to that of humans. Even their heads had a number of features characteristic of humans. The teeth were almost the same as those of humans, with the exception of the molars, which were larger in size, and the jaws were somewhat smaller than those of Dryopithecus.
R. A. Dart, the first to discover these hominids, did not immediately mistake the small skull he found for a hominid skull, although he drew attention to the fact that the teeth and jaws had many features characteristic of hominids (Fig. 19- 5, B, C). So he called his find Australopithecus africanm.
In 1936, ten years after Dart's discovery, Robert B. Broom discovered the pelvic bones of an Australopithecus (Fig. 19-5, A). Apart from minor details, their shape clearly resembled the familiar shape of human bones, proving that Australopithecus walked upright.
This was not entirely unexpected, since the foramen magnum of the fossil found by Dart was directed downwards, which also indicated an upright position of the body. Additionally, many other anatomical details of the skeleton indicated that Australopithecus was more of a mini-brained human than anything else.
In the late 1950s, Lewis Leakey's wife, Dr Mary Leakey, discovered the most astonishing of all finds: the skeletal remains of an Australopithecus, along with stone tools of the earliest known type.
Based on the radioactive decay of potassium, it was established that the age of the remains is 1.75 million years, i.e. this proved that A. africanm created tools.
19.7. Gradually A. africanus evolved into a form called A. habilis, which in turn gave rise to Homo erectus about a million years ago
Although the Leakeys have produced the largest number of finds tracing the transformation of Australopithecus africanus into Homo erectus in Tanzania (partly aided by the Tanzanian climate), Homo erectus was first discovered by the Danish physician Eugene Dubois in Java in 1891.
Du Bois suggested that Java was the place to look for the "missing link." Having gone there, he found what he was looking for! The species he discovered is now found in most tropical and temperate zones of the Old World. However, his luck remains amazing to this day. For 40 years, other expeditions tried unsuccessfully to repeat his discovery.
At first, Dubois's find was called Pithecanthropus erectus(upright ape-man), but now this species has received the name Homo erectus(upright person).
Anatomical changes in Homo erectus observed mainly in the skull.
The size of his brain approached the size of the brain of a modern person. And some representatives of H. erectus had the same brain as some modern H. sapiens with a small brain volume.
Speaking about the volume of the human brain, it should be noted that the most famous H. sapiens with a small skull size was the French writer Anatole France, whose skull volume was only 1017 cm 3 with an average volume of 1350 cm 3. Thus, this does not mean that H. erectus was a weak-minded creature. The tools he made testify to his extraordinary abilities and technical skill.
H. erectus appears to have had other behavioral similarities to modern humans: several H. erectus skulls have been found carefully opened, as if their contents had been eaten during a cannibal feast or ritual.
19.8. The increase in the volume of the human brain over the past 2 million years is one of the most rapid evolutionary changes
Now there is a whole series of fossil skulls found that allow us to carefully trace the path from A. africanus with a mini-brain to H. sapiens. Although brain growth occurred in relatively small steps, it represents one of the most rapid evolutionary changes in the history of life on Earth. In less than 2 million years, the average volume of the hominid brain more than doubled. This is an exceptional speed compared to the normal rate of evolution. For example, the evolution of the horse from its dog-sized ancestors to its modern form took place over 60 million years.
The volume of the human brain is no longer increasing, and the pH appears to have remained that way for almost 250,000 years. In fact, N. sapiens neanderthalensis(Neanderthal man, a race of our species that “flourished” during the last ice age) the brain volume was on average 100 cm 3 larger than that of modern humans. It is likely that the brain is no longer enlarging because the already large size of the newborn's head barely allows it to fit through the mother's pelvis, which must expand slightly during labor to allow the baby to be born. But perhaps there were other, even more important reasons.
19.9. The evolution of Homo erectus into Homo sapiens ended about 300,000 years ago
Paleontologists believe that N. erectus evolved into Homo sapiens about 300,000 years ago, but they admit that this figure is somewhat arbitrary. The evolution of human anatomy, behavior and physiology, that is, the human phenotype, is a gradual process. It continues to this day.
19.10. There is actual evidence of the evolution of one butterfly species within the last 100 years or more
The first documented observation of evolution concerned butterflies, which developed black coloration as the forest environment in which they lived became more complete.
Even in Darwin's youth, almost all British Biston betularia butterflies were mottled, pale gray and white. A black form of Biston betularia also existed, but was rare. We know this because it was highly sought after by collectors. And now the forests of Birmingham in England are full of them, and they are as common as they once were rare. Evolution has occurred in our time.
Modern biologists noticed that the black form was common in areas east of large industrial centers such as Birmingham, and, knowing that in England the winds usually blow from west to east, they suggested that the smoke and soot from factories and factories somehow influenced the formation of the black form. British biologist
H. B. D. Kettlewell noticed that in forests where there were black butterflies, the trees were black and sooty, and in forests where there were still many gray and white spotted butterflies, the old "typical form ", - relatively clean. The trunks in these forests were covered with variegated gray-white lichen. He found that the black color in butterflies is associated with natural pigmentation and is inherited, like the typical spotted form.
Kettlewell suggested that since birds are the most dangerous enemies of butterflies, the more visible a butterfly was sitting on a tree trunk, the more likely it was to be seen and eaten. Therefore, the spotted butterfly was relatively safe on a trunk covered with lichen, and the black butterfly on a trunk covered with soot (Fig. 19-6). To test his hypothesis, Kettlewell bred butterflies of both forms and released them into clean and smoky forests. Before releasing them, he painted a dot under the wing of each butterfly. Kettlewell released 799 butterflies into lichen-covered forests and after 11 days captured 73 butterflies with his mark.
Spotted butterflies were more likely to survive among lichen-covered trees. Over an 11-day period, each spotted butterfly was approximately 2.9 times more likely to persist than a black butterfly.
In smoky forests, the black form of butterflies had an advantage. Here the experiment was carried out 2 times. In 1953, 27.5% of black butterflies were caught in 11 days, but only 13% of spotted ones. During this period, the survival rate of black butterflies was 2.1 times higher than that of spotted butterflies. In 1955, the survival rate of black butterflies was again 2.1 times higher.
Kettlewell used filming to record the actions of birds given the opportunity to catch one of two species of butterfly sitting in a tree in front of them. In Birmingham, birds were much less likely to spot black butterflies. For example, redstarts ate 43 spotted and only 15 black butterflies in two days. In clean forests it was the other way around. The gray flycatcher ate 81 black butterflies and 9 spotted ones. Filming showed that it was not easy for birds to see spotted butterflies against a spotted background of lichen and black butterflies against a dark background of soot. Not surprisingly, in the smoky environment, about 100 species of butterflies began to take on dark colors.
There are other cases of observable evolution known to science, many of which are caused by our radical interventions in nature. One of them is the acquisition of resistance to DDT by mosquitoes. Another case is the acquisition of antibiotic resistance by infectious bacteria. These examples, as well as fossil evidence, confirm the fact of evolution. Thus we arrive at the next question: what causes biological evolution?