Charles Robert Darwin (1809-1882) was unexpectedly asked for the position of naturalist on board of the ship the H.M.S. Beagle. Darwin would support the captain with geological, mineralogical and biological observations, but would also accompany the captain for the next five years in his room. Upon his return, Darwin was known as a talented and respected geologist and collector of biological samples. He had made a number of important observations, which were the beginning of his development of the theory of evolution through natural selection: a revolutionary biological theory with immeasurable implications for psychology.

What did Darwin's life look like?

Darwin came from a rich and respected family. His father was a doctor, his mother was from a famous family that produced Chinese tableware, and his grandfather, Erasmus Darwin (1731- 1802), was one of the most famous intellectual figures of his time. From early on in his live, Darwin possessed two important qualities. First of all, he was very curious and had a love for nature. He was also a warm and sympathetic man, which made him loved with almost everyone he met.

Darwin was sent to a medical school where he learned taxidermy. He didn’t think medications was interesting enough and he had bad memories of this school period. His father therefore placed him at the University of Cambridge, where Darwin was prepped to become an Anglican pastor. Here he became a member of a club called the Gourmet Club. This club was known for their hunt for birds and beasts, which were previously unknown to the taste buds of man. However, this came to an early end when they tried to eat a brown one owl.

Darwin liked geometry, but nevertheless had 'an argument' with binomial theory. Instead, he liked nature, and especially collecting beetles provided him with a lot of fun. He called this his "proof of my zeal." Darwin's enthusiasm for natural history and his friendly personality drew the attention from Cambridge's more scientifically oriented faculty. These people were mainly John Stevens Henslow (1796-1861) and Adam Sedgwick (1785-1873), professors in botany and geology. Darwin went on one of their excursions to the countryside and spent a lot of time with Henslow. After graduating in 1831, he went to the north of Wales for a summer for a geological tour with Sedgwick.

Darwin's journey on the Beagle began in December 1831. Darwin devised a sample bag, which he dragged behind the ship and in which he caught thousands of sea creatures he subsequently examined and classified. He read about geology, geography and biology. He kept a detailed diary in which he described his observations and thoughts. The crew called him 'the philosopher'. After two years, they had only investigated the east coast of South America, after which the Beagle went on for two more years along the west coast before they embarked on their long journey towards the Galapagos Islands, Tahiti, New Zealand, Australia and the Cape of Good Hope. The journey lasted a total of 5 years.

What were Darwin's geological discoveries?

During the first months at sea, Darwin read the 'Principles of Geology', written by Charles Lyell. This book promoted a theory called uniformitarianism: the most important characteristics of the earth are the result of gradual processes, which took place over an immeasurable one amount of time. And in the present it happens just as much as in the past. Lyell disputed the, then predominant, alternative theory of catastrophism, which stated that geological features arise as a result of a few relatively sudden and enormous natural disasters or catastrophes on the earth’s surface. Part of the attraction of catastrophism was the compatibility of it with a literal interpretation of the Bible. For instance, the great flood represents the main geological natural disaster, such as a tsunami. Catastrophism also corresponded well with the, then generally accepted, estimate of the age of the earth as only about 6,000 years, such as calculated by the Irish archbishop James Ussher (1581-1656). He did this by adding up the ages of the patriarchs from the Old Testament after Adam and Eve, as given in the Bible. Uniformitarianism required an immensely longer period of time for gradual processes that mountains have formed and cause other cumulative effects.

Before the departure of Darwin, Henslow and Sedgwick encouraged him to read Lyell's book the reading and thinking about it, but not believing in it. Still, Darwin became increasingly involved the impression. For example, he found fossils of sea animals high in the Andes region and an earthquake Chile caused parts of the coast to suddenly be a few feet higher than the sea level than before. Comparative events were more common over an immeasurable period in the time, as described by uniformitarianism. Darwin wrote these findings and sent them his work to Lyell and other geologists. This gave him the reputation in England as an influential geological observer and led to a scientific opinion in favour of it uniformitarianism. Darwin also assumed that the earth was already very old, what a necessary condition for his later evolution theory.

What were Darwin's biological discoveries?

Darwin found, among other things, the megatherium. This fossil had the skeleton of a modern sloth, but the size of a modern elephant. A strange creature of rhinoceros format, but then without horns, he called a toxodon. This and other strange fossils also fascinated the English naturalists. Fossils were important for the uniformitarianism-catastrophism discussion, and the question became how and when the fossils had ended up in the stone. Darwin also collected thousands of living plant and animal species, most of which still unknown among scientists.

While reflecting on his biological findings, he adopted two general lines of thought. Firstly, he regularly asked himself what the possible functions of the found animal properties could be. The changing colour of an octopus to the colour of the background was clear to him. Where other observers saw the behaviour of a certain animal as 'slow' and called it 'stupid', Darwin searched for the use. The sensitivity for the functional adaptation of all biological phenomena later helped him to come to his theory of evolution. His second major thought line started almost accidentally when Darwin began to notice geographical distribution of species. He saw that animals on both sides of the Andes were often totally different each other, despite that the climate and other conditions were generally the same. The giant turtles, for example, showed small but characteristic differences in the forms of their shield, what told an experienced observer informed on which island they were born. Several populations of the common brown finch differed only in the size and shape of their beaks. These standard observations later proved to be of great importance to Darwin when he thought about the possible origin of different animal species.

Darwin wanted to return home in October 1835, especially because he was curious after his family had told him that he was already well known in scientific circles. The samples he sent had remained well preserved, and Henslow had made extracts from passages of his letters and these were published by the Cambridge Philosophical Society: Darwin's first scientific publication.

How did the theory of evolution come to be?

His book 'Journal of Researches in Geology and Natural History of the Various Countries Seen during the Voyages of the H.M.S. Beagle, under the Command of Captain FitzRoy, R.N. ', from 1832 to 1836, became an immediate bestseller and established Darwin as a forerunner in his field, and a popular naturalist and traveling writer. In 1837, Darwin began writing down his line of thought. In one of his notebooks he specifically addressed one of the most difficult and controversial questions in biology (sometimes called 'the mystery of the Mysteries'). This question was about how the millions of different animal species who inhabit the earth originally had come to be. 

The answer to this question that at that time was accepted was that all types were created at one and the same moment, as one complete and unchangeable entity. Holders of this traditional view argued that the theory is confirmed by the first chapter of Genesis, which states that on the fifth day, God had created "every moving, living being" on earth. The more scientific term for this was the 'argument of design'. This term originally comes from the philosopher / theologian William Paley (1743-1805). According to Paley, the amazingly complicated organs of different animal species are so perfectly constructed and adapted to their function that they must be designed by some kind of powerful and expert designer, or rather 'the hand of God'.

Darwin knew that a similar theory of gradual evolution had already been promoted by his grandfather Erasmus Darwin. In addition, in 1809, the zoologist Jean Baptiste Lamarck (1744- 1829), had suggested that species evolved and changed as a result of inherited physical changes, which arose from voluntary training or just no longer using certain organs. For example, the giraffe used to have a shorter neck, which meant that he often had to stretch to get to the leaves. Slowly but surely the muscles stretched further with each generation, which eventually led to the modern giraffe we know now, according to Lamarck.

But despite Lamarck and Erasmus Darwin’s thoughts on the idea of ​​evolution, the theory was by no means accepted among the scientific attention. Erasmus had proposed no way in which this evolution could take even happen and the Lamarck theory did not explain how non-voluntary characteristics (such as camouflage) would occur. In addition, the evolution was also contradictory with the literal description in Genesis of the creation of all species, which was strongly advocated by the Anglican church. So, when Charles Darwin returned from his journey, the idea of ​​evolution was still seen as not respectable and had not yet taken any kind of shape that it could be seriously considered as an alternative to the existing design.

In the months after his return, Darwin concluded that the idea of ​​evolution, or "Transmutation", of species had to be taken seriously. The staggering number of different species in nature,  though often only subtly different from each other, seemed to point more on a long existing and still ongoing process over many generations of species, rather than on a single, separate creation of all species. In addition, he personally had observed extinct fossil species that resembled modern species in everything except in size. In addition, there were the Galapagos finches whose distinctly different beak structures suggested that gradual changes and developments across generations were indeed possible. Darwin knew that breeders had managed to create different varieties or breeds of pets, by careful selection of preferential characteristics over many generations. Sheepdogs are an example of such a carefully bred breed.

In the fall of 1838, Darwin suddenly devised a plausible mechanism for the gradual evolving of countless stable species in a natural state, after reading the book "For amusement" by Thomas Malthus. Malthus believed that most people are destined to live in poverty, because their possibilities to enlarge the population are much better than their possibilities to increase food production. Malthus therefore stated that ultimately the population size will exceed food production, which will lead to a general state of scarcity and poverty. This theory took hold of Darwin's imagination. Every species will,   left over generations, produce an innumerable amount of individuals. Only a part of them, however, will survive the hardships of their environment and will be capable to breed and continue the species. Those who survive will generally be those individuals who are best adapted to the dangers that occur in the environment. If their adaptive characteristics are hereditary, their offspring will also have these characteristics and survive and procreate in greater numbers than their less advantaged comrades. Darwin had thus finally found a plausible mechanism for the theory of evolution species.

Think of the beaks of the finches. One can assume that one group ended up on an island rich in nuts and seeds, but with a lack of insects hidden in crevices. The finches that are here the greatest chance of survival, had a relatively strong and thick beaks, that were good for the opening and eating of the seeds. This caused that more finches with such a beak survived to breed, which caused a second generation with an average slightly thicker beak than the first generation. After many generations in which this process continued, a stable population of birds with broad and strong beaks evolved. The second group of finches, who had ended up on an island with an environment poor in seeds and nuts, but richer in insects, underwent an opposite process. Darwin therefore suggested that different environments inevitably and constantly impose a natural selection on their inhabitants, making the survival and reproduction of their species disproportionately favoured to certain individuals. The "nature", or the environment, will constantly select the individuals that survive the best and allow those to reproduce. These selective effects of nature are ruthless and can go for countless generations (very different from the animal breeder), leading to the creation of a stable, species as a whole, instead of a short-lived breed or variety.

Darwin thus did not only see ‘nature' (that is, the presence or absence of food, competitors, predators and the other ever-changing requirements of the environment) as a restriction to the unlimited growth of a population. He also saw nature as the power that selects which individuals, with which hereditary characteristics, have the greatest chance of survival and reproduction. Looking at the enormously long time (where the new geological uniformity theory suggests a period of at least millions of years instead of thousands years), changes and variations in the natural environment were localized,  countless changes in selection must have been produced. This would lead to the gradual evolution of countless different species. So the natural selection provides the 'motor', or the mechanism, that is theoretically needed to support an evolutionary process.

Darwin knew that his theory would not be accepted so quickly, partly because it was a theory that brought disturbing assumptions about the role of man in nature. The Bible sees man in a separate category from the animals, but Darwin saw anatomical similarities with many animals and placed man in the ecological system. In 1842 and 1844, he wrote summaries of the theory, but did not publish them. He told only a handful of reliable friends, including the geologist Lyell and botanist Joseph Hooker (1817-1911), about his belief in evolution. Not until 1856, eighteen years after his first inspiration, Darwin found that he had enough evidence for his theory to publish it. He started working on a work titled 'Natural Selection', which he expected to contain about 3,000 pages.

However, in 1858 Darwin was brutally disturbed by a letter and a manuscript from the naturalist Alfred Russel Wallace. While Wallace was recovering from malaria, he had thought of a new evolution theory, and wrote about it to Darwin. Shocked, Darwin read the letter Wallace sent him about a theory that was originally his. He did not know how to respond to this and forwarded the manuscript to Lyell and Hooker, who had insisted on it before that he had to publish his theory before anyone else did. His friends arranged one honourable compromise. Excerpts from the unpublished summary of Darwin from 1844 and the Wallace's new paper would both be read, in the absence of both authors, on the next meeting of the Linnean Society. This is a reputable organization dedicated to researching and classifying plants and animals. Because of this the development of the evolution theory of natural selection was officially shared in July 1858 by Darwin and Wallace. Ironically, however, little attention was paid to it and even in the official report stated that nothing important had been discovered that year.

Darwin wanted to support his theory with a lot of evidence. Now his 'secret theory', however, was unveiled, he wanted to quickly publicize the theory publicly. This did not necessarily have to be with his thousands of pages of 'Natural Selection', but a long enough work to illustrate the strength of the theory. That is why he spent a year writing 'On the Origin of Species by Means or Natural Selection, or the Preservation of Favoured Races in the Struggle for Life '. This book, with 490 pages, was published in 1859 and became the most influential book of the century. Although the book is mainly about plants and animals, a debate arose as to whether or not people stood separate from this development and were a special creation from God, or actually were "descendants of the apes."

The kind Darwin himself refrained from the polemics (a 'written war'), but found a particularly strong supporter in Thomas Henry Huxley. Huxley was an expert in it the anatomy of primates and wrote Darwin with conviction right after he had read 'Origin of Species'. He was called the "Darwin’s Bulldog" after he, among other things, defended the natural selection in a debate in 1860 against Samual Wilberforce, the bishop of Oxford.

A year later, two new scientific discoveries were made. First, fossils of the extinct archeopteryx were found, the oldest bird ever to have existed. This being had 'fingers' on it his wings and vertebrae and a tail like a reptile. Darwin had previously speculated that the birds had evolved from the reptiles, so with this discovery his theory was supported. Then, in1861, an African discoverer restored the skulls and stuffed the bodies of gorillas. The gorilla turned out to be anatomically very similar to humans. These discoveries 'proved' nothing for the evolution and related species but that it did provide clues that supported the credibility of the theory really helped. Further evidence followed quickly, and within a few years, the arguments of the Origin were generally accepted by an overwhelming majority of expert researchers.

What did Darwin write about psychology?

In 'Origin of Species' Darwin added a short and prophetic paragraph in which he suggested that the human mental qualities can ultimately be seen as the result of evolution. In the next decade, he left the elaboration of this idea to others, including his cousin Francis Galton (1822-1911), which is discussed more in the next chapter. Darwin did not pay much attention to psychology, but in 1870 he published 'The Descent of Man', in 1871 'Selection in Relation to Sex', in 1872 'The Expression of the Emotions in Man and Animals' and in 1877 'A Biographical Sketch of an Infant'.

In the end, Darwin described in 'The Descent of Man' that people are the descendants of animal ancestors. He opened this argument with the structural similarities between people and the higher class of animals, for example similarities in bones, muscles, blood vessels, intestines, nerves and "the most important of all organs", the brain. All these features place homo sapiens very likely in the domain of physically evolving species. Hereafter, Darwin wanted show that there is no fundamental difference between humans and higher mammals in mental abilities such as courage and kindness. For example, he stated that dogs show much of the same range of emotions as people, such as jealousy, pride, shame and even a form of humour. Animals show memory, attention and curiosity and because dogs can also dream, visible in their running and wagging while they sleep, also can be stated that they have the ability of imagination. In addition, Darwin stated that animals show the basic principles of reason, the only characteristic of the soul that Descartes had exclusively attributed to mankind. They benefit from learning from experience, communicate with each other through sound and gestures and appreciate 'beauty', clearly sporting preferences for different body markings and embellishments. After having considered many of these examples, Darwin concluded categorically: "The difference in spirit between humans and higher mammals, however large it is, there is clearly one of gradations and not of kind ".

The Victorian century in Great Britain is known for the extreme differences in attitudes and beliefs about race and the causes of ethnic differences. One of the extremes was the polygenists, who argued that the non-European, "wild" people clearly are a different kind of beings. The monogenists, on the other hand, believed in the shared origin and kinship of all human groups, although they also observed widely varying theories for to explain the racial or ethnic differences among themselves. Some, for example, attributed these differences mainly to the environment and to cultural variables, while others believed the African groups descended from the Biblical Ham, the son of Noah. They state that their offspring are cursed by God and condemned to slavery by the offspring of Noah's other sons.

Darwin was a strong supporter of the monogenist position. According to Darwin, there existed also no doubt that the environmental and educational variables were very important the production of individual differences between people and that mainly slavery had had a terrible effect on its victims. During his journey aboard the Beagle Darwin was appalled by the relations between masters and slaves on Brazilian plantations. He concluded that the character of the slaves was generally superior to that of their white ones masters, who he called the 'polished barbarians' as they oppressed and belittled their slaves. Darwin saw skin colour as a natural adaptation to different exposures to direct sunlight.

The full title of Darwin's book was "The Descent of Man, and Selection in Relation to Sex." The last part of this title contains the controversial topic: the issue of differences between men and women. In his book, he called this sexual selection: the gradual selection and evolution of characteristics that are particularly beneficial for reproductive success. To pass on genetic material, one must not only physically survive but also form couples in order to reproduce. Men and women are a preference for a certain kind of life partner, creating a pressure for a certain type of beauty to evolve. Darwin believed that sexual selection also influenced human evolution, resulting in a number characteristic mental and physical differences between the sexes. Darwin's faith in the different emotional dispositions of men and women reflect his acceptance of the Victorian idea of complementarity of the sexes. This was the belief that men and women evolved and had different, but complementary, psychological characteristics. Women had a greater chance to be sensitive and caring, and men were competitive and ambitious. Despite his impartiality in attributing positive mental qualities to women, Darwin was unambiguous when it came to intellectual qualities. He assumed a general male intellectual superiority. Darwin argued that men have changed more through evolution than women and as a result show more mutual variation. According to this variation hypothesis for example, the range of men of different lengths are greater than in women, when you measure the length of populations of adult men and women. Darwin wrote that the cause of this greater variation among men was unknown. He did not fit this idea explicitly on the intellectual differences between men and women. Others, however, did, claiming that in a large population of men there are more cases of extremely high intelligence, compared with a comparable group of women.

What did Darwin write about the expression of emotions?

In 'The Expression of the Emotions in Man and Animals', Darwin wrote that human emotional expressions are possibly hereditary and evolved properties, which can best be described as the direct or indirect consequences or reactions that have an adaptive or survival value. Some emotional expressions seemed obvious, like someone making big eyes when they are surprised can help with the more complete and clear vision of the surprising object. The adaptive the value of other expressions is less clearly distinguishable, as these expressions probably arose because they are the direct opposite of an evolutionary useful response. Darwin concluded that the three general principles (direct usability of expression, opposites, and direct activation of the nervous system) can apply to all emotional expressions in animals and people.

An important goal of the book was to show that while some human reactions do not have a clear survival function anymore, they did in the past. Blushing, for example, was the result of multiple collaborative but perfectly understandable animal reactions, which possibly has to do with more striking body parts that come under conscious attention. This is an example of how this book assumed that people possess many residual properties of animals. Darwin also described that all known human groups have similar emotional expressions.

Five years after 'The Expression of the Emotions' Darwin remembered a detailed log that he had kept track of his firstborn child. Thirty - seven years later, he looked at his notes on the many reflexes of his son and published a rewritten piece of ten pages. Nowadays this work is still seen as a milestone in the history of child psychology. This paper also dealt with the role that instinctive reflexes, habits, emotions play in adapting to a child’s surroundings. Darwin saw the development of his son as the gradual strengthening, an increase of complexity, and a fusion of the originally simple and isolated actions. Take language for example: only after hearing and understanding words for a certain period of time would his son be able to form and invent new meaningful words. He suggested that the development of an individual is roughly along the same lines as the evolution of the species what this individual belongs to. While learning language, his son accelerated through the same phases where pre-human ancestors presumably went through. That is why Darwin suggest that each individual, in one way or another, still finds the remains within them of the principles of their long evolutionary past. This was also another element of his general argument for evolution.

What was Darwin's influence on psychology and the society?

Darwin became a rich man, and in his comfortable study, he wrote a number of important books, especially about plants. Each book helped to strengthen his theory of evolution. However, he became seriously ill, and no one knew what the diagnosis was, so he did not go out anymore. He eventually died of heart disease.

Shortly after Darwin's death, social Darwinism was founded. However, despite having Darwin's name for the movement, credit was just as much due to the productive philosopher Herbert Spencer (1820- 1903). They also held a number of ideas that Darwin did not support. Spencer was already a supporter of Lamarck's theory of evolution, even before Darwin’s Origin written, and wrote 'Principles of Psychology' in 1855. In the ambitious "synthetic philosophy" program, Spencer made an effort to classify of the various disciplines of biology, psychology, sociology and anthropology under one principle evolutionary view. He stated that individual organisms, species, political systems and entire societies are the same in the concept that they all have a tendency to evolve from relatively simple and homogeneous entities into more complex and heterogeneous entities. He believed that such evolution produced a very popular "progress", assuming that by the unrestrained competition among individuals, only the strongest survived. The strongest could then maintain the species. Progress of all animal species should be maximized by societies and governments that allowed free competition. Darwin was somewhat reluctant towards Spencer and his synthetic philosophy.

Within the developing discipline of psychology, Darwin had a more permanent and positive influence. Just before his death he gave his younger friend George J. Romanes (1848-1894) full access to his notes on animal behaviour. Romanes added these notes to his own research and published two ground breaking books: 'Animal Intelligence' (1882) and 'Mental Evolution in Animals' (1883). Romanes described his work as comparative psychology, a name that was chosen as an analogy of the established discipline of comparative anatomy. Romanes argued that the research on the similarities and differences between multiple animal / psychological functions might shed light on their human counterparts, on the same way that the research on physical structures did. Within the human psychology, Darwin's theory demanded that the mind and behaviour, in general, no longer could be viewed as a static, "given" fact. Both could only be described and analysed.

Christine Ladd-Franklin introduced work within the field of visual sensation (from chapter 5) with a Darwinian perspective by stating that the different "components" of colour perception occurs at various points in evolutionary development: first black and white, then blue-yellow and finally red-green. After Darwin, the human psychology became more focused on variability and differences between people, instead of their generality and similarities.

What are recent developments?

The American Paul Ekman states that there are actually universal emotion expressions, namely the facial expressions that show fear, anger, envy, sadness and pleasure. Nowadays, the central question is whether evolution goes gradually, as Darwin believed, or suddenly and in dramatic "leaps". The explanation of unselfish (altruistic) behaviour led to a different debate between evolutionary theorists. When individuals risk their own lives for another, logically this can be seen as a selective disadvantage compared to completely egocentric individuals. That is why the question arises why altruism, a seemingly "non-adaptive" characteristic, does not disappear due to natural selection. A possible explanation is that what that evolves is the group as a whole and not the individual. Another explanation is that the genes of someone who shows altruistic behaviour and the person to whom this is shown, strong have similar genes, so these genes are not 'exterminated'. This last idea comes among others from E.O. Wilson's 'Socio-biology: The New Synthesis' in 1975 and from the bestseller of Richard Dawkins 'The Selfish Gene' in 1976. This basic approach, which tries to explain social behavioural characteristics as a result of individual but interacting genes that replicate itself through successive generations, is described as socio-biology.

The field known as evolutionary psychology was developed. The practitioners of this psychology go beyond that of socio-biology, they freely use all aspects of the modern evolutionary theory to think up empirically researchable hypotheses about human behaviour. In drawing up these hypotheses, they take the idea that the environment in which we life now differs greatly from the environment our ancestors lived in. This idea infers that some human behavioural and psychological characteristics may have been necessary in the past, even though they are no longer useful now. In 1992, the book 'The Adapted Mind: Evolutionary Psychology and the Generation of Culture’ was written, and in 1997 came the book "How the Mind Works'. The evolutionary perspective remains an essential and vivid aspect of the modern psychological investigations and in the development of theories.

ExamTips

• The most common misconception people have about Darwin is that he went on the Beagle because he wanted proof of his theory of evolution. However, the opposite is true. He joined the Beagle because of his academic skills and only  formed his theory later during the trip.
• The big difference between Darwin and Lamarck is that Lamarck believed that there was a point, a perfection as endpoint of evolution. He believed evolution was working to an eventual goal and that humans were that perfect goal. Darwin, however, knew that evolution was radom and that eventually, even humands would evolve further.