Example of evolutionary theory

Evolutionary Perspective in Psychology: Principles and Examples

In the eternal quest to understand human behavior, does evolutionary psychology provide the missing link? Darwin may have approved.

You do the things you do for a multitude of reasons. Your childhood relationships, the challenges you’ve faced, and the chemical processes in your body are among the things that can influence your behaviors.

Evolutionary psychology adds ancestral traits to the equation.

The evolutionary theory says that the habits and cognitive traits that helped your ancestors survive have likely been passed down through the generations until making their way to you.

The evolutionary perspective in psychology is a purely theoretical approach. It allows for the assumption that many of your core behaviors and ways of processing information are a result of evolution.

Evolutionary psychology is partly based on Charles Darwin’s theory of evolution.

The theory was introduced in his 1859 book “On the Origin of Species. ”

In sum, Darwin theorized that within a given population, specific traits are more helpful than others when it comes to the survival of the species. This is referred to as natural selection.

Traits that increase the chance of survival are more likely to be genetically passed on to future generations. This creates a process where undesirable traits are more likely to fade over time, while desirable traits carry on strongly.

For example, at some point, foxes with longer legs were able to escape predators more easily. As the shorter-legged foxes fell prey, only the long-legged foxes lived on to reproduce and pass on their genetic characteristics to their offspring. Over time, most or all foxes developed longer legs.

Evolutionary psychology applies this premise to human thinking and behavior.

Evolutionary psychology versus evolutionary biology

Evolutionary biology is the process of passing down biological traits. It’s the fox with long legs that escapes its predators. Evolutionary psychology is the natural selection of beneficial cognitive traits passed down through the generations.

According to Ellie Borden, a registered psychotherapist from Oakville, Ontario, the two concepts meet when biology factors into psychology and vice versa.

As a species improves biologically, for example, it may be more inclined to make new psychological conclusions. Similarly, the more mental tools a species develops, the more likely these may be to influence its biology.

Principles of evolutionary psychology

Leda Cosmides and John Tooby, two of the most influential evolutionary psychologists, outlined six core tenants of evolutionary psychology in a 2005 paper.

Tenet 1

Your brain’s purpose is to analyze information from the environment like a computer would process information. The brain is a physical system, and its pathways to process information are fine-tuned through natural selection.

“Pathways” refers to the connections between brain cells, or neurons, that allow messages to travel from one region of the nervous system to another.

In other words, a pathway is a group of neurons working together to get something done, like moving your feet to walk or turning the page when you’re reading.

Neural pathways are essential to learning but also to repeating behaviors you’ve already learned.

When you do something you’ve never done before, you have no pathway for that specific behavior. As you engage in the behavior, neurons start to get together and pass the message. The pathway becomes stronger the more you repeat the behavior, and it becomes easier or more likely for you to do the behavior.

Tenet 2

Your behaviors are a response to the information your brain has gathered from both its internal and external environment.

This suggests that understanding your behavior means understanding how you process information, as well as understanding your thought pathways or patterns.

Tenet 3

The pathways your brain has created from gathering and processing information have been influenced over time by ancestral environments. These evolutionary thought processes have roots in two main goals: survival and reproduction.

Tenet 4

Some evolutionary behaviors may hold no benefit in current environments. But, since cognitive programming may come from your ancestors, it may still contribute to handling modern-day challenges.

Tenet 5

The brain has many evolutionary pathways, each one intended to solve a particular problem your ancestors faced.

The more diverse your pathways, the more challenges you’re able to overcome.

In other words, you may have pathways in your brain that have not been created by your behaviors but come from the behaviors and experiences of your ancestors.

Tenet 6

Each of your preprogrammed pathways allows your brain to categorize your individual experiences.

You’re able to compare, analyze, recognize patterns, and develop concepts based on the framework you’ve inherited.

An example

In an ancient community, empathy may have allowed for a greater understanding of others, contributing to stronger relationships and more cooperation to ensure everyone’s well-being.

As empathy continued to be a beneficial trait practiced by one generation and the next, it eventually made its way to you.

Now, when you’re faced with the choice of helping someone or turning away, your evolutionary inclination toward empathy may encourage you to put yourself in other people’s shoes and help.

Fear of predators

If you’re naturally wary of bears and wolves, it may be because your ancestors quickly learned the consequences of not avoiding these animals in the wild.

Partner selection preferences

Reproduction and survival are interlinked.

Back in the day, choosing a partner most likely meant picking someone who displayed specific behaviors and traits that protected and supported the survival of the community and offspring.

Evolutionary psychology would say that your current partner selections may be influenced by the choices that your ancestor clan tended to repeat more often.

Dislike of dishonesty

Why is dishonesty so distasteful? Maybe because trust was important in a primitive community where people had to rely on one another to survive.

If someone can’t trust you, they might be less likely to share with you or offer you social support.

Feeling anxious

Borden indicates that evolutionary psychology can account for certain negative emotions, like anxiety.

“Sometimes, certain experiences passed down from generations and growing up in a certain culture can more greatly influence these genetic dispositions,” she says. “This is why some individuals may have higher levels of anxiety.”

An example of this may be growing up in a culture that has a long history of unpredictability or facing greater dangers. You may find you’re naturally more anxious, wary, and reserved even though you may not have experienced anything personally. Anxiety may have become a protective trait to face unpredictability.

The goal of evolutionary psychology isn’t to explain mental health conditions. But, it can offer insight into why you might be more likely to develop certain challenges.

As Borden explains, evolutionary psychology may make you naturally inclined to certain traits, like being reserved or anxious. These inclinations may influence your behaviors and thoughts, which in turn could make you more likely to develop certain symptoms.

Dr. Michael J. McGrath, a licensed psychiatrist in Kailua-Kona, Hawaii, says phobias are one of the best ways to explore the evolutionary perspective on mental health.

Many phobias can be traced back to survival-oriented fears, he says.

“It is thought that these phobias are influenced in part by evolution,” he explains. “For example, it is beneficial for humans to be afraid of spiders, as some are poisonous. With a phobia, however, the fear is quite extreme.”

Another example he gives is achluophobia, the intense fear of darkness.

“It would make sense from an evolutionary perspective for humans to fear darkness, as we don’t see as well at night, and that makes us more vulnerable to predators,” says McGrath.

Evolutionary psychology is a theory that, at times, has been the source of critique and debate in the scientific community.

A 2010 paper from researchers at the University of Texas at Austin mentioned these primary concerns about the evolutionary perspective in psychology:

It may be difficult to test, prove, or even accurately know what ancient human habits were and how they translate to modern behaviors.
Evolutionary psychology contradicts domain-general rationality, which states that behaviors are the result of in-the-moment critical thinking.
Contrary to many modern theories, it implies that the mind is not a blank slate at birth that can be completely molded and shaped through personal experience.
Cultural phenomena, such as a transfer of beliefs or ideals through generations, are not well-explained in the original framework of evolutionary psychology and require more research.

Evolutionary psychology looks at how the behavioral habits of your ancestors may influence your behavior.

Just as the biological evolution theory suggests your physical and biological traits are a result of the challenges your ancestors faced, psychological evolution suggests cognitive traits that were key to survival were also passed down from generation to generation.

Some questions remain about the application of the evolutionary perspective in psychology.

Darwin's Theory of Evolution: Definition & Evidence

When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works.

The hominin wall at the Natural History Museum of Utah in Salt Lake City. (Image credit: Copyright NHMU/Credit: Mark Johnston)

The Theory of Evolution by natural selection was first formulated in Charles Darwin's book "On the Origin of Species " published in 1859. In his book, Darwin describes how organisms evolve over generations through the inheritance of physical or behavioral traits, as National Geographic explains. The theory starts with the premise that within a population, there is variation in traits, such as beak shape in one of the Galapagos finches Darwin studied.

According to the theory, individuals with traits that enable them to adapt to their environments will help them survive and have more offspring, which will inherit those traits. Individuals with less adaptive traits will less frequently survive to pass them on. Over time, the traits that enable species to survive and reproduce will become more frequent in the population and the population will change, or evolve, according to BioMed Central . Through natural selection, Darwin suggested, genetically diverse species could arise from a common ancestor.

Darwin did not know the mechanism by which traits were passed on, according to National Geographic. He did not know about genetics, the mechanism by which genes encode for certain traits and those traits are passed from one generation to the next. He also did not know about genetic mutation, which is the source of natural variation. But future research by geneticists provided the mechanism and additional evidence for evolution by natural selection

What is natural selection?

Darwin chose the term "natural selection" to be in contrast with "artificial selection," in which animal breeders select for particular traits that they deem desirable. In natural selection, it's the natural environment, rather than a human being, that does the selecting.

Put simply, the theory of evolution by means of natural selection can be described as "descent with modification," said Briana Pobiner , an anthropologist and educator at the Smithsonian National Museum of Natural History in Washington, D.C., who specializes in the study of human origins. The theory is sometimes described as "survival of the fittest," but that characterization can be misleading, Pobiner said. Here, "fitness" refers not to an organism's strength or athleticism but rather its ability to survive and reproduce.

Natural selection can alter a species in small ways, causing a population to change color or size over the course of several generations, according to The Natural History Museum . When this process happens over a relatively short period of time and in a species or small group of organisms, scientists call it "microevolution."

Archaeopteryx, shown here in this illustration, is considered the first bird-like dinosaur on record, dating to about 150 million years ago during the Jurassic period.

(Image credit: Leonello Calvetti/Getty Images)

But when given enough time and accumulated changes, natural selection can create entirely new species, a process known as "macroevolution," according to Derek Turner and Joyce C. havstad in "The Philosophy of Macroevolution ." This long-term process is what turned dinosaurs into birds, amphibious mammals (such as an animal called Indohyus) into whales and a common ancestor of apes and humans into the people, chimps and gorillas we know today.

Darwin also described a form of natural selection that depends on an organism's success at attracting a mate — a process known as sexual selection, according to Nature Education . The colorful plumage of peacocks and the antlers of male deer are both examples of traits that evolved under this type of selection.

How did whales evolve?

One of the best examples scientists have of natural selection, is the evolution of whales. By using Darwin's theory as a guide, and understanding how natural selection works, biologists determined that the transition of early whales from land to water occurred in a series of predictable steps.

The evolution of the blowhole, for example, might have started with random genetic changes that resulted in at least one whale having its nostrils farther back on its head, according to Phys.org .

The whales with this adaptation would have been better suited to a marine lifestyle, since they would not have had to completely surface to breathe. Such individuals were more successful and had more offspring. In later generations, more genetic changes occurred, moving the nose farther back on the head.

Other body parts of early whales also changed. Front legs became flippers. Back legs disappeared. Their bodies became more streamlined, and they developed tail flukes to better propel themselves through water, according to the Natural History Museum .

Even though scientists could predict what early whales should look like, for a long time they lacked the fossil evidence to back up their claim. Creationists viewed this absence, not just with regard to whale evolution but more generally, as proof that evolution didn't occur, as pointed out in a Scientific American article .

This illustration shows the semiaquatic "god of death" whale, called Phiomicetus anubis, that lived about 43 million years ago in what is now Egypt. (Image credit: Illustration by Robert W. Boessenecker)

However, since the early 1990s, scientists have found evidence from paleontology, developmental biology and genetics to support the idea that whales evolved from land mammals. These same lines of evidence support the theory of evolution as a whole.

In the first edition of "On the Origin of Species," Darwin speculated about how natural selection could cause a land mammal to turn into a whale. As a hypothetical example, Darwin used North American black bears (Ursus americanus), which were known to catch insects by swimming in the water with their mouths open, according to the Darwin Correspondence Project .

"I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale," he speculated.

The idea didn't go over very well with the public or with other scientists. Darwin was so embarrassed by the ridicule he received that the swimming-bear passage was removed from later editions of the book. Scientists now know that Darwin had the right idea but the wrong animal. Instead of looking at bears, he should have been looking at cows and hippopotamuses.

Other theories of evolution

Darwin wasn't the first or only scientist to develop a theory of evolution. Around the same time as Darwin, British biologist Alfred Russel Wallace independently came up with the theory of evolution by natural selection, according to the Natural History Museum . However this had little impact.

"The concept of evolution as a historical event was a hot topic among biologists and geologists prior to Darwin’s book because there was so much evidence accumulating, but I suspect biological evolution hadn’t really impinged on people outside of the academic bunker," Dr. P John D. Lambshead, a retired science research leader in marine biodiversity, ecology, and evolution at The Natural History Museum, London, told All About History Magazine . "As long as science knew of no mechanism to explain how evolution happened it could be safely dismissed as a crank idea."

Meanwhile, French biologist Jean-Baptiste Lamarck proposed that an organism could pass on traits to its offspring, though he was wrong about some of the details, according to the University of California’s Museum of Paleontology .

Like Darwin, Lamarck believed that organisms adapted to their environments and passed on those adaptations. He thought organisms did this by changing their behavior and, therefore, their bodies — like an athlete working out and getting buff — and that those changes were passed on to offspring.

Maasai giraffe browses on leaves of a tall tree in the Maasai Mara National Reserve, Kenya. (Image credit: Anup Shah/Getty Images)

For example, Lamarck thought that giraffes originally had shorter necks but that, as trees around them grew taller, they stretched their necks to reach the tasty leaves and their offspring gradually evolved longer and longer necks. Lamarck also believed that life was somehow driven to evolve through the generations from simple to more complex forms, according to Understanding Evolution , an educational resource from the University of California Museum of Paleontology .

Though Darwin wasn't sure of the mechanism by which traits were passed on, he did not believe that evolution necessarily moved toward greater complexity, according to Understanding Evolution — rather, he believed that complexity arose through natural selection.

A Darwinian view of giraffe evolution, according to Quanta Magazine , would be that giraffes had natural variation in their neck lengths, and that those with longer necks were better able to survive and reproduce in environments full of tall trees, so that subsequent generations had more and more long-necked giraffes.

The main difference between the Lamarckian and Darwinian ideas of giraffe evolution is that there's nothing in the Darwinian explanation about giraffes stretching their necks and passing on an acquired characteristic.

What is modern evolutionary synthesis?

According to Pobiner, Darwin did not know anything about genetics. "He observed the pattern of evolution, but he didn't really know about the mechanism," she said. That came later, with the discovery of how genes encode different biological or behavioral traits, and how genes are passed down from parents to offspring. The incorporation of genetics into Darwin's theory is known as "modern evolutionary synthesis."

The physical and behavioral changes that make natural selection possible happen at the level of DNA and genes within the gametes, the sperm or egg cells through which parents pass on genetic material to their offspring. Such changes are called mutations. "Mutations are basically the raw material on which evolution acts," Pobiner said.

Mutations can be caused by random errors in DNA replication or repair, or by chemical or radiation damage, according to Nature Education . Usually, mutations are either harmful or neutral, but in rare instances, a mutation might prove beneficial to the organism. If so, it will become more prevalent in the next generation and spread throughout the population.

In this way, natural selection guides the evolutionary process, preserving and adding up the beneficial mutations and rejecting the bad ones. "Mutations are random, but selection for them is not random," Pobiner said.

A molecule of DNA coiled inside a cell nucleus. (Image credit: Shutterstock)

But natural selection isn't the only mechanism by which organisms evolve, she said. For example, genes can be transferred from one population to another when organisms migrate or immigrate — a process known as gene flow. And the frequency of certain genes can also change at random, which is called genetic drift.

The reason Lamarck's theory of evolution is generally wrong is that acquired characteristics don't affect the DNA of sperm and eggs. A giraffe's gametes, for example, aren't affected by whether it stretches its neck; they simply reflect the genes the giraffe inherited from its parents. But as Quanta reported , some aspects of evolution are Lamarckian.

For example, a Swedish study published in 2002 in the European Journal of Human Genetics found that the grandchildren of men who starved as children during a famine passed on better cardiovascular health to their grandchildren. Researchers hypothesize that although experiences such as food deprivation don't change the DNA sequences in the gametes, they may result in external modifications to DNA that turn genes "on" or "off."

Such changes, called epigenetic changes, do not modify the actual DNA sequence itself. For instance, a chemical modification called methylation can affect which genes are turned on or off. Such epigenetic changes can be passed down to offspring. In this way, a person's experiences could affect the DNA he or she passes down, analogous to the way Lamarck thought a giraffe craning its neck would affect the neck length of its offspring.

What is the evidence for evolution?

The Theory of Evolution is one of the best-substantiated theories in the history of science. It is supported by evidence from a wide variety of scientific disciplines, including genetics, which shows that different species have similarities in their DNA.

There is also evidence supporting the Theory of Evolution in paleontology and geology. This is through the fossil record, which shows how that species that existed in the past are different from those present today, according to Bruce S. Lieberman and Roger L. Kaesler in "Prehistoric Life: Evolution and the Fossil Record " (Wiley, 2010).

There is also evidence for Darwin's theory found in developmental biology. It has been discovered that species that seem very different as adults pass through similar stages of embryological development, suggesting a shared evolutionary past, according to the open-access textbook "Concepts of Biology ."

Evidence for whale evolution from paleontology

Ambulocetus natans swimming underwater. (Image credit: Nobumichi Tamura/Stocktrek Images via Getty Images)

The critical piece of evidence was discovered in 1994, when paleontologists found the fossilized remains of Ambulocetus natans, which means "swimming-walking whale," according to a 2009 review published in the journal Evolution: Education and Outreach . Its forelimbs had fingers and small hooves, but its hind feet were enormous relative to its size. The animal was clearly adapted for swimming, but it was also capable of moving clumsily on land, much like a seal.

When it swam, the ancient creature moved like an otter, pushing back with its hind feet and undulating its spine and tail.

Modern whales propel themselves through the water with powerful beats of their horizontal tail flukes, but A. natans still had a whip-like tail and had to use its legs to provide most of the propulsive force needed to move through water.

In recent years, more and more of these transitional species, or "missing links," have been discovered, lending further support to Darwin's theory. For example, in 2007, a geologist discovered the fossil of an extinct aquatic mammal, called Indohyus , that was about the size of a cat and had hooves and a long tail.

Scientists think the animal belonged to a group related to cetaceans such as Ambulocetus natans. This creature is considered a "missing link" between artiodactyls — a group of hoofed mammals (even-toed ungulates) that includes hippos, pigs, and cows — and whales, according to the National Science Foundation .

Researchers knew that whales were related to artiodactyls, but until the discovery of this fossil, there were no known artiodactyls that shared physical characteristics with whales. After all, hippos, thought to be cetaceans' closest living relatives, are very different from whales. Indohyus, on the other hand, was an artiodactyl, indicated by the structure of its hooves and ankles, and it also had some similarities to whales, in the structure of its ears, for example.

Evidence for whale evolution from genetics & developmental biology

The last shore-dwelling ancestor of modern whales was Sinonyx, top left, a hyena-like animal. Over 60 million years, several transitional forms evolved: from top to bottom, Indohyus, Ambulocetus, Rodhocetus, Basilosaurus, Dorudon, and finally, the modern humpback whale.

(Image credit: NOAA)

Genetic evidence also supports the idea that whales evolved from land mammals and provides information about the exact branching of the evolutionary tree. For instance, in 1999, researchers reported in the journal Proceedings of the National Academy of Sciences that according to genetic analysis of "jumping gene" sequences, which copy and paste themselves into genomes, hippos were whales' closest living relatives. Before 1985, researchers thought pigs were more closely related to whales, but this 1999 study overturned that idea, as the Associated Press reported.

In 2019, researchers reported in the journal Science Advances about which genes within the whale genome were inactivated during the process of the creature's evolution from land mammals, as Science Friday reported. The researchers could tell that certain genes, including one involved in making saliva, had been inactivated because there are remnants of them, which the researchers call genomic fossils, in whale genomes. This indicates that whales evolved from a salivating creature.

There's also evidence of cetacean evolution from developmental biology. Developmental biology illustrates the fact that animals that are very different as adults share similarities as embryos because they are evolutionarily related. For example, as embryos, cetaceans started to develop hind limbs, which disappear later in development, while the forelimbs remain and develop into flippers, according to the journal Evolution: Education and Outreach . This suggests that cetaceans evolved from a four-legged ancestor.

Is the theory of evolution controversial?

Despite the wealth of evidence from the fossil record, genetics and other fields of science, some people still question the theory of evolution's validity. Some politicians and religious leaders denounce the theory, invoking a higher being as a designer to explain the complex world of living things, especially humans.

School boards debate whether the theory of evolution should be taught alongside other ideas, such as intelligent design or creationism.

Mainstream scientists see no controversy. "A lot of people have deep religious beliefs and also accept evolution," Pobiner said, adding, "there can be real reconciliation."

Evolution is well supported by many examples of changes in various species leading to the diversity of life seen today. "Natural selection, or to put it another way — variation, heredity, and differential fitness — is the core theory of modern biology," John Lambshead explains. "It is to biology what, say quantum mechanics and special relativity are to physics or the atomic model is to chemistry."

Additional reporting by contributors Alina Bradford, Ashley P. Taylor and Callum McKelvie

Additional resources

The National Oceanic and Atmospheric Administration has a presentation on whale evolution.
To read the theory in its original form, see Darwin's book, "On the Origin of Species ."
Check out this article for an overview of natural selection.
To understand the difference between a theory and fact, see this National Academy of Sciences website .

Famous evolutionary theories | Blog 4brain

Where did the first living organisms come from, and thanks to what mechanisms did they develop? These questions have always troubled the minds of people. If you ask a student how a person appeared, then he will most likely tell about the origin of man from a monkey, guided by the theory of Charles Darwin.

But it is worth noting that Darwin's theory of evolution is not the only one. In the article we will talk about other views on the origin and development of living organisms.

Creationism

This evolutionary theory assumes that life arose as an act of creation of the Higher forces. The main postulates of creationism:

All biological diversity was created by the Creator, and remains unchanged to this day.
There is a certain "Ideal", which is the prototype of every living organism. Under the influence of the environment, the "Ideal" was modified and embodied in every living being. A clear realization of the "Ideal" itself was impossible.

A prominent representative of creationism is the Swedish natural scientist and professor of medicine Carl Linnaeus. He worked at the university and was in charge of a garden where plants were grown for educational experiments. Seeds were sent to Linnaeus from all over the world, so the flora of the botanical garden was extensive. It was this diversity that prompted Linnaeus to create a classification of all living beings.

The scientist identified three main kingdoms: animals, plants and minerals. The principles of classification were as follows:

According to Linnaeus, animals live, grow and feel. For example, if you hit a tiger with a stick, then the reaction of the animal will follow.
Plants live, grow, but do not feel. If you hit a poplar with a stick, it will not react.
Minerals do not live and do not feel, they only grow.

A little later, Linnaeus excluded minerals from the classification of living beings, since their belonging to inanimate nature was obvious. The scientist divided the two remaining classes into smaller groups according to the principle of hierarchy. Thus, the following taxonomic groups were distinguished: kingdom, class, order, genus and species.

Linnaeus proposed to introduce a single form for the species name (binary nomenclature). Since the time of Linnaeus, the names of all types of living organisms consist of two Latin words: the first is the name of the genus, the second is the specific epithet. The third component of the name is the name of the researcher who described this species for the first time.

For example, the common wolf is designated as Canis lupus Linnaeus, where Canis is the genus (dog), lupus is the specific epithet (wolf), and Linnaeus is the name of the scientist (Linnaeus). Or Homo sapiens Linnaeus (the Homo sapiens, named so by Linnaeus).

Transformationism

Transformationism is a system of beliefs that explains the appearance of some types of living organisms from others as a result of changes that occur due to natural causes. The main feature of the concept of transformism is that it does not consider the issue of the primary origin of life, but only studies the change of species.

Georges-Louis Leclerc, Comte de Buffon, a French biologist and popularizer of scientific knowledge, occupies a special place among famous transformists. He adhered to the following ideas in the concept of transformism:

There are a number of highly organized living organisms, the transformation of which leads to the emergence of new species.
The world is material, all living things arise according to the laws of nature.
The main drivers of change that lead to the emergence of new species are climate and food.

According to Buffon, the antlers on the deer's head were formed due to the fact that he ate the leaves and branches of shrubs, and the tail of the beaver in the process of evolution was covered with scales because the diet of the rodent was scaly fish.

From the point of view of modern science, Buffon's ideas seem absurd. However, his main achievement was the assumption of the possibility of changing species.

The French biologist was the first to suggest the origin of man from apes.

The first evolutionary theory

The author of the first theory about the evolution of the organic world was the French scientist Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck. His first botanical work was about the flora of France and had the same name. "Flora of France" brought real fame to Lamarck, and after the royal botanical garden was transformed into the Paris National Museum of Natural History, Lamarck was offered to head the chair of worms there.

However, Lamarck found the name of the department unpleasant, and he decided to rename it the Department of Invertebrate Zoology, thus giving the name to the whole group of animals, which is still used today. The biodiversity of worms turned out to be so great that it inspired Lamarck to create the first evolutionary theory.

The main conclusions made by the scientist:

The simplest organisms appeared due to spontaneous generation. Inorganic substances served as the material for this.
All highly organized creatures originated from one primitive organism, such as the shoe ciliate.
The driving factor in the emergence of new species was the desire of all living beings for perfection. Lamarck formulated the law of gradation, which said: regardless of the environment, every organism strives to increase the level of organization.
Purpose is an innate property of all living things. Under its influence, the organs necessary to adapt to living conditions are formed. The scientist called this conditionality the law of exercise-non-exercise of the organs. For example, the okapi animal, eating branches of more and more tall trees, was forced to stretch its neck, which led, according to Lamarck, to the appearance of the giraffe.
Growth of animal organs is controlled by fluids of unknown nature. The movement of fluids through the body is carried out by an effort of will. For example, birds living in a swamp sought to rise above the swamp and directed the fluids to their feet. The accumulation of fluids led to the lengthening of the bird's legs and the appearance of herons.
Characters acquired by animals in the course of their interaction with the environment are inherited by their offspring. Moreover, Lamarck spoke about the inheritance of only acquired traits, that is, those that improve the performance of any functions.
Species do not exist in wildlife, there are only individual individuals. The division of animals into categories is done by man solely for convenience.

Lamarck believed that man evolved according to the same laws as other living organisms. The ancestors of man were "four-armed" monkeys who descended from the trees and were forced to adapt to the conditions of existence on earth. The body acquired a vertical position, the shape of the skull and jaw changed. The man became two-handed. Initially, communication between individuals was carried out through facial expressions and gestures, later speech, psyche and mental activity appeared.

Charles Darwin's theory of evolution

The prerequisite for the creation of the theory of evolution was the five-year round-the-world voyage of the English naturalist Charles Darwin on the Beagle ship. Since Darwin graduated from the theological faculty of the University of Cambridge, before the trip his ideas about the creation of the world were based on a literal understanding of the text of the Bible. However, the round-the-world voyage on the Beagle completely turned the worldview of the scientist.

The following observations helped Darwin think about the formation of living organisms by natural causes:

Similarity of flora and fauna in geographically close areas.
Dependence of the shape and size of animal organs on the food they eat. Darwin noticed that several varieties of finches live in the Galapagos Islands, which differ from each other in their massiveness and long beak, because they eat different foods.
In every geographic area, there is a certain amount of biological diversity that develops there over time. Paleontology helped Darwin to make this conclusion. In South America, a scientist discovered the remains of fossil sloths that were similar to their modern counterparts. However, the remains of sloths have never been found in England. This is because America, not England, was the habitat of this species.
The savages of the Tierra del Fuego archipelago are capable of surviving in harsh conditions without having bodily adaptations, such as huge fangs, fur or claws.

Returning from his travels, Charles Darwin began work on the book The Origin of Species by Means of Natural Selection, or the Preservation of Favorable Breeds in the Struggle for Life. The main postulates of Darwin's evolutionary theory, described in the book:

Each species of plants and animals is changeable. Variability is observed both in the wild and among domesticated representatives of flora and fauna.
There is hereditary variability in fitness, that is, in how well an animal or plant performs the functions for which various organs exist.
In nature, there is a geometric progression of reproduction. This means that for each pair of organisms, many more offspring are born than are able to feed in the habitat. Given the limited resources, Darwin concluded that there was a struggle for existence.
If there is hereditary variability in fitness and the factor of the struggle for existence, then the conclusion suggests itself that there is natural selection in nature. That is, the best individuals survive, which pass on the predominant characteristics to their descendants, which leads to the formation of new breeds.
Speciation is divergent. This means that the original view is divided into two or more new ones.

Let us give an example of how Charles Darwin explained the work of natural selection using the example of a giraffe. Initially, giraffes differed in the length of the neck. Individuals that had longer necks expended less energy plucking high-growing leaves. Giraffes with short necks were forced to look for low-growing trees, expending a lot of energy and lacking food.

Thus, the offspring of long-necked giraffes gained an advantage in the struggle for survival and gradually replaced giraffes with shorter necks.

Man, according to Darwin, descended from a lowly organized ancestor. The scientist proved that man is not an act of creation of the Higher forces, but appeared due to natural selection, supplemented in the process of anthropogenesis by the result of exercise-non-exercise of organs.

Synthetic theory of evolution

The modern or synthetic theory of evolution (STE) is a symbiosis of Darwinism and genetics. Basic postulates of STE:

The population is the unit of evolution.
An elementary evolutionary event is a persistent change in gene structures in a population.
The emergence of new adaptations in living organisms to living conditions occurs as a result of a combination of small mutations.
Mutations and other factors of evolution (eg population waves, genetic drift) are non-directional, random. Only natural selection is directional.
Evolution is divergent, gradual and long.
Macroevolution (the evolution of genera, families, orders, classes, types of living organisms) occurs according to the laws of microevolution (evolution of species).
Evolution can follow the path of biological progress or biological regression.
The main laws of evolution are irreversibility, progressive complication of forms and adaptability to the environment.
Evolution has no purpose. It's just a process.

STE was born at the beginning of the 20th century and is currently the most relevant. The following scientists made a significant contribution to the formation of the modern theory of evolution: the geneticist and entomologist Feodosy Grigorievich Dobzhansky, the statistician and evolutionist Sewell Wright, the biologist Sergey Sergeevich Chetverikov, the geneticist Ronald Fisher, and the biochemist John Haldane.

All living things are in motion. This fact is undeniable. Change in time is evolution. The Universe will continue its metamorphoses further, and with it our knowledge of the essence of this amazing process will evolve.

We hope you found this article helpful. Friends, be inquisitive, and may your interest in life not wane. Good luck!

Key words:1LLL

Theory of evolution. From Darwin to the synthetic theory of evolution.

But I think that...

Evolution is just a theory and nothing has been proven! Scientists have long disproved Darwin! How humiliating it is to believe that we are descended from monkeys! If you agree with these statements, then congratulations. The last 200 years of scientific development have clearly passed you by. It's forgivable if you've spent two centuries frozen in the ice of the Arctic. But for a modern person to believe in the failure of the evolutionary theory is a terrible bad manners.

What do we know about scientific theories?

Let's start with the most general statement.

"Evolutionary theory is just a theory," your neighbor on the reserved seat tells you, hinting that no one has tested it in practice. But this is only in everyday conversation "theory" - something divorced from reality. And in science it is exactly the opposite. Observable facts come first. Then - their logical and mathematical generalizations, on the basis of which regularities are derived. And then, from a system of laws, a scientific theory grows. So when a field of knowledge is called a theory, it means that it has been tested in practice a huge number of times. Assumptions in science are called hypotheses.

How does it work?

If you put a monkey at a typewriter, and he will press random keys, "War and Peace" will not be printed. So there is no need for fairy tales about random changes that led to the emergence of complex organisms! A fair statement, but the role of chance in evolution is limited. In order to understand this, let's try to briefly describe how evolution works.

There are three main forces in the evolutionary process: heredity, variation and selection.

Life is based on DNA (or RNA), which encodes information about the structure of the organism. During reproduction, DNA replication occurs and the entire set of traits is passed on to the next generation. As a result, the daughter organisms are similar to the parent, as well as to each other. Where do the differences come from?

When doubling a DNA molecule, errors are possible. They can occur spontaneously or under the influence of external factors, and they can be considered completely random. Such changes in DNA are called mutations. The result of a mutation is the appearance of a new trait. Some mutations render an organism unviable, but most mutations are harmless and, under certain conditions, even beneficial. The same variability arises - with external similarities, many differences arise between organisms. And these differences make it possible to respond differently to changes in the environment.

If inherited traits allow you to feel comfortable in certain environmental conditions, the chance to survive and give healthy offspring increases, otherwise it decreases. After a certain number of generations, we will see that there are much more individuals with one set of traits in the population than with another set. This is natural selection. It can be aimed at stabilization, when individuals with extreme values of the trait are culled. For example, too big and too small. And it can be driving, when individuals with deviations of signs receive an advantage. Let's say that in each generation, individuals with sizes larger than average have an advantage. After some time, we will get a population of giants.

The occurrence of mutations and changes in environmental conditions can be called random. But natural selection is not just random.

Where are the facts, Billy?

All right, you say. But my friend claims that the evolutionists have no facts. Where are they, examples of the transformation of one species into another? Why don't we see how a fish turns into a bird? Where are the fossils of transitional species?

Evolution is a continuous process, but its speed is limited by the speed of generational change. Hundreds of generations must change for the changes to become noticeable. Therefore, we can observe the evolution of large organisms only by comparing modern representatives with fossil remains. But the evolution of bacteria is happening before our eyes, and a person influences it in the most direct way, through the creation of new drugs. Yes, and there are examples of small ecosystems in which evolution can literally be seen with your own eyes for very short periods of time.

Because evolution is constant, there are no transitional species as such. Each species is transitional from the previous to the next. But if we take large groups of related organisms, such as fish and amphibians, there are species that combine the features of both groups. Many such transitional forms have been found, and this makes it possible to reconstruct the history of life on Earth with great accuracy.

In order to understand who is related to whom, scientists build special schemes - cladograms. For their construction, data of comparative anatomy are used. And recently, such constructions have acquired colossal accuracy thanks to genetics. These schemes are a real family tree that unites all living things into a single system. Thanks to them, one can, for example, understand how long the common ancestor of any two organisms lived. For example, the common ancestor of humans and chimpanzees lived about 7 million years ago and looked more like a human than a chimpanzee.

As for the facts, science does not accumulate evidence. Science creates models that explain facts. Scientific theories are just such models. Today, the theory of evolution explains the vast majority of phenomena and facts from such fields of science as: paleontology, comparative anatomy and physiology, embryology, genetics, population biology, etc. If all these areas of knowledge are presented as a three-dimensional puzzle, then the central core that holds together everything else, will be the theory of evolution.

However, there are many gaps in evolutionary theory. This applies primarily to the mechanisms of evolution, the rate of occurrence of mutations and the interaction of genes with each other. Well, you say! So Darwinism is nothing more than a mistake! The mistake is to consider the modern theory of evolution as Darwinism.

Has Darwin's theory been abandoned long ago?

Darwinism, or Darwin's theory, is an evolutionary doctrine in the form in which it existed in the second half of the 19th century. It must be said that the very idea of evolution, i.e. changes in species, arose as early as the end of the 18th century. In 1809year J.B. Lamarck published his Philosophy of Zoology, in which he proposed an evolutionary concept called Lamarckism. Charles Darwin was born in the same year.

In 1831, the future evolutionist graduated from Cambridge with a bachelor's degree, having received significant knowledge in the field of theology. However, his main interest was the natural sciences - geology, entomology, botany. From 1831 to 1836, Darwin traveled around the world as a naturalist on the expedition ship Beagle. During the expedition, quite a few important scientific materials were collected. But most importantly, the idea of natural selection arose. It took Darwin another 23 years to substantiate his evolutionary concept. Contrary to popular belief, Darwin's theory is not a bare idea; it is based on the analysis of numerous facts. It was this that ensured the success of the theory, and not at all the worship of authority. Anyone can be convinced of this by reading the book published in 1859.year the book of Ch. Darwin "The Origin of Species".

For its time, Darwinism had a high explanatory and predictive power. Thus, the discovery of Archeopteryx in 1861 confirmed Darwin's idea of the existence of transitional forms. But a number of questions remained unanswered. And first of all - the inheritance of traits. These issues were resolved later, with the development of genetics, embryology and paleontology. From the synthesis of Darwinism and genetics, the modern synthetic theory of evolution (STE) was born.

The crown of creation - or part of nature?

And finally - where is our place on the huge Tree of Life created by evolution? This answer was given 200 years ago by Carl Linnaeus, who placed man in the order of primates along with other monkeys. The further development of science only confirmed and clarified this position. For the theory of evolution, the origin of man is nothing more than a special case, it is studied using the same methods as the origin of whales or ants. And if the results are true for cetaceans, then they are true for us.

The evolutionary history of man today is better studied than that of all other animals. Those disputes and doubts that remain relate to details and do not affect the overall picture. What does it mean? We are indeed descended from monkeys.

Learn more