The Darwinian revolution suggested four major ideas: 1) gradual changes take place in a species; 2) man evolved from some lower form of animals; 3) those organisms that adapted to a particular environment will survive; 4) the environment selects for survival which species or which factors in a species (e.g. intelligence, will, exercise, strength) are favorable. The first generalization leads to the second; and the third leads to the fourth. The last two points represent the ma;or interpretations of survival. Change the environment to meet the needs of the individual or recognize that inheritance or special advantage permit some individuals to excel or survive in a particular environment.


But what accounts for the modification of or the variation within species or between related species? Lamarck had assigned a more active role to the behaving organism. In the process of adapting to the environment, the animal would necessarily exercise, resulting in enlarged muscles or change structures. These changed structures were acquired characteristics and were passed on to subsequent generations. Use or disuse of parts resulted in the elaboration or elimination of structures. Lamarck's first law (1809) stated that: "In every animal ... a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ ... while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears (Bartlett, 1968, p. 475)."

By this he meant that certain structural changes in one's ancestors could be passed along. If one generation of people exercised a finger and the muscles grew larger as a result, this anatomical change could be passed on to subsequent generations. Giraffes were believed to have long necks because they had to stretch to get the bananas out of the trees. And each generation stretched a little more and passed that difference down to subsequent generations. Conversely, if certain structures were not used (like tails of humans) then they might not be passed on in later generations. The acquired characteristics were really the products of activity which somehow changed the genetic code and was passed along. McDougall and other psychologists attempted to prove this theory by training rats in such a way that exercise produced a change of musculature; observations were then made to see whether this change cropped up in later generations. It did not. This procedure is not to be confused with selective breeding, where bright rats have been bred together to produce a strain of bright offsprings. Acquired characteristics assume that changes produced in one generation are passed on to subsequent generations inherited; selective breeding is the mating of individuals with the same characteristics and observing if it occurs in the offspring.**

Lamarck held that there were progressive changes in the development of a species. There were, more generally, progressive changes in the universe. This point of view, known as finalism, assumed that the universe was moving in the direction of something "better." What was really "better" is never quite clear, but most finalists have taken the position that the universe has been moving in the direction of humans or those things which humans value (Simpson, 1951, p. 108). Man develops by some unexplained impulse within him which produces gradual improvement. It is this impulse which accounts for systematic changes in the structure of the species. Such an optimistic belief in the eventual betterment of both mankind and the universe is found in the positions of the French Lamarckians, German nature-psychologie, and the Americans McDougall and Edward Cope. Erasmus Darwin, grandfather of Charles Darwin and of Francis Galton, also believed in purposeful struggle.

Inherent purposefulness in the universe rather than blind striving after survival is a central doctrine in most religions. Therefore, Darwin and modern evolutionists clashed with church leaders. Sometimes the discord between scientist and theologian was only semantic, as expressed in the following poem by W. H. Carruth, "Each in His Own Tongue:"

A fire-mist and a planet --
A crystal and a cell --
A jellyfish and a saurian,
And caves where the cave-men dwell;
Then a sense of law and beauty;
And a face turned from the clod --
Some call it Evolution,
And others call it God.

Darwin had observed wide differences among plant and animal species. These differences within any species cried for explication. There were two explanations for the variation -- causes from without or strivings from within. A second issue, whether variation tends toward a progressive development, was generally supported by the advocates of internal strivings. Erasmus Darwin, Lamarck, and McDougall all represented this group. They believed in progressive development -- man as but a part of an evolving universe.

The number of prominent vitalistic scientists gradually declined during the latter part of the nineteenth century. The last great vitalist, the physiologist Johannes Mueller and the evolutionist Herbert Spencer, could no longer hold out against their younger counterparts, Helmholtz and Darwin. Psychologists in the Helmholtz School of medicine turned to the models of physics and chemistry and relied only upon physical and chemical forces to explain biological phenomena. Transformation equations were being generated; energy changes from one kind to another was an empirical fact. Mechanical energy could be transformed into electrical energy and then into chemical energy. The interrelation among forms of energy is a major physiological explanation. The concept of force was challenged by the conservation of energy doctrine. Life force was unnecessary to explain animal functions.

Charles Darwin (1809-1882)Photo of Darwin

Darwin made contributions to this issue, through a program of careful observation, description, and analytical thinking. Darwin argued for continuous development of the species. He not only provided evidence for the gradual change in the species, but he went one step further and developed a theory to account for change. The theory went something like this: some characteristics of species survive because they are adaptive in a particular environment; others fade out because they are not adaptive. Why can't all variations survive? Because there is limited food supply, according to Malthusian theory. So you really have two possibilities: either 1) the amount of food equals or exceeds the number of animals (or the amount needed) so there is no problem, and everyone survives; or, 2) the amount of food is less than the number of animals (or amount of demand), and so some animals survive and others die. Since animals are basically selfish they will compete for the available food.

Darwin's premises appeared to be; 1) if the animals are all similar, then the survival and expiration will be random. Survivors in subsequent generations will then be either: a) similar, or b) reflecting random differences. 2) On the other hand, animals are different, both between and within species. The differences Darwin observed, remained consistent, varying slightly over succeeding centuries. What accounts for this continuity? One could postulate stronger physique, destined by God, "chosen" persons, or selective factor. Darwin believed that the key lay in some selective factor, a variable in a particular species that systematically contributed to the survival of one kind of structure and the gradual extinction of another. This hypothesis he chose to test. On the basis of his findings, he concluded that there was a correlation between the kinds of structures he observed and particular characteristics of the flora and fauna of the environment. For example, he found dark-skinned persons, but never light-skinned persons, in hot climates. Conversely, he found light-skinned persons, but never dark-skinned persons, in cold climates. Physical structure of the body or morphological or phenotypic characteristics seemed to be correlated with environmental characteristics. The theory was that morphology and environment were attracted to each other, that they were good for each other in some way. In other words, because the structure was adaptive it was selected out to survive. Nature, then, did the selecting; thus, natural selection.

A third part of the theory accounted for changes in the selected structures over time. Is there a continuous selecting of finer and still more finer refinements from the complex structure? Not quite. There are random kinds of changes, called mutations, which occur in the process of the transmission of the genetic material. The real problem was to account for change that was relatively permanent. The problem was to find some explanation for variation, not for the exceptions to a pattern. The differences themselves might form a pattern. One major change, occurring in over-populated England, was the differences in increase of humans relative to the increase of food. Thomas Malthus (1776-1834), English economist, noted that population increases geometrically and food increase arithmetically; he concluded that poverty was unavoidable unless checked by war, famine, or disease.

Charles Darwin, returning in 1838 from his voyage to South America, read Malthus' essay on population. He agreed that mankind was on a collision course with a resulting struggle for survival. If a struggle for existence is inevitable, then those forms of life that are best equipped will survive and others will become extinct. Those species or members of a species who were most fit for any particular environment would survive; the least fit would become extinct. The survival of the fittest was not a Nietzschean concept. It is not the superman that destroys his adversary or eliminates the depraved. As Singer (1959) suggests, the weak or timid may survive, for ". . . he that fights and runs away lives to fight another day (p. 510)." This may require the fleet of foot rather than those with physical prowess. It is nature, then, that selects. Darwin therefore called his theory "natural selection."

Two concepts, survival of the fittest and natural selection, formed modern evolutionary thinking and became known as Darwinism. These tenets account for the preservation of certain species and, conversely, the extinction of others. Darwin's work led the psychology of individual differences into two directions -- one as a descriptive science, the other, an explanatory science. In the first case, differences within groups as well as similarities between groups were topics for study. If variation was continuous, rather than discontinuous, and if one species emerged from another, then the principles governing animal behavior should be generalizable across species strains. Out of this approach the fields of comparative psychology and human developmental psychology both emerged. Since ontogeny was believed to recapitulate phylogeny, the two fields of animal psychology and developmental psychology mushroomed in succeeding years.

Evolutionary theory was forever under attack, more because of the religious implications than because of any other reason. But the incomprehensibility of the theory was also a major stumbling block. Many intelligent men could simply not accept the bold assertion of a rational man emerging from a dumb chimp. Acceptance of this proposition was compounded when some eager critics introduced straw men by comparing the highest form of animal life with a brute. How could a Shakespeare be thus explained? The difference between civilized man and primitive man is much greater than the difference between the latter and that of a chimp. Viewed in these terms, the evolution of man is not so improbable (Fiske, 1873).

To read the original works of Darwin, visit the web site below which contains works as well by Wallace, William James, and others.


Comparative Psychology.

Animal psychology, frequently called comparative psychology, emerged from Darwin's attempt, using the observational method, to identify the common behaviors between animals and humans. His book, Expressions of the Emotions in Man and Animals, was published in 1872. John Romanes, elaborating on the observational method, devised the anecdotal method and published in 1882, Animal Intelligence, the first comparative psychology book, showing the continuity between animals and humans. Several decades later, many believed that animals did have minds. "... few persons of any degree of culture will now be found prepared to deny that the inferior animals have minds. The questions now to be settled are: what kind of minds (Mills, 1887, p. 652)?" If animals had minds, then studying them would aid our understanding of humans. But studying the animal mind often led to anthropomorphizing, ascribing human characteristics to animals. It was Lloyd Morgan (1852-1936), in what became known as "Morgan's canon," who cautioned against such an error by stating that we should not attempt to interpret actions as the result of a higher psychological process if one of a lower process on the psychological scale would suffice. Morgan thus applied the law of parsimony (i.e., the simplest explanation is the best) to animal behavior.

Emerging from this whole discussion of evolutionary theory were certain implications. It became apparent that in Lamarck's theory it is the exercise that produce changes; in Darwin's theory it is the environment which produces changes, or which selects for survival. This seemed to lead to the following assumptions:

1. Structural change requires adaptation.
2. Adaptation is good (because it accounts for, or leads to, survival).
3. Change is good (assumed simply because adaptation, change and good are related).

From 1859 to 1959 a gradual shift of emphasis occurred in the notions of adaptation and change. Often there was only the mere substitution of terms. Adaptation is good. Ways were sought of adapting to conditions. There were various kinds of adaptation. Mental health was adaptive, and so mental hygiene courses were taught. The well-educated person was adaptive, and so educational adjustment was taught. But then, all of a sudden, the emphasis switched from admiration for adaptation to admiration for change. Change which had been a means of adaptation, now became the end in itself. Change itself became valued. Somehow the reasoning went -- if the means are good, then the ends must be good. So change in itself is good. This is a reversal of the reasoning that the ends justify the means. In this case, the means justify the ends. George Gaylord Simpson, the noted historian of science, put it very well when he said:

It is a childish idea -- but one deeply ingrained in our thinking, especially on political and social subjects -- that change is progress. Progression merely in the sense of succession occurs in all things, but one must be hopelessly romantic or unrealistically optimistic to think that its trend is necessarily for the good (Simpson, 1951, p. 108).

Another way in which change was valued was in changing the environment rather than the individual. Why not turn things around and have the environment adjust to the individual? This would make adjustment easier. The botanists had discovered that certain environments were best for certain plants and that by modifying the environments the result would be healthy, blossoming plants. The ecological movement, which actually began early in this century, recognized the need for adequate space, at least, in the struggle for survival (Drude, 1906).

In the twentieth century, then, man begins to take control of his environment. Adaptation means control, either consciously or unconsciously, of either oneself or his surroundings. In Adlerian psychology, one compensates for a felt weakness either by substitution or by over-exaggeration. One controls his environment. Mental health specialists advocated, with Dewey, that perhaps the environment needed changing, rather than the individual. But, the individual himself could be an agent for change. It was the democratic form of government which emerged as an expression of felt needs; a community actually worked out its own self-government. It was not just enough to change oneself to accommodate to the environment; one may need to change the environment to accommodate to the felt needs of the individual. Schools, agriculture, space, weather, resources, all were subject to considerable change according to the group's desires. Any factor blocking change was anathema to democracy, adjustment, and individual development. The "establishment" was seen as a barrier to change. Change became an end in itself; the more evident the change the more highly valued the result.

One difficulty, however, was that changing both the environment and person required the simultaneous change of both one's relationship to his environment and the person's own self concept. Persons then lost, as Erickson phrased it, their sense of identity; but the loss resulted from reasons different than those he proposed. He contended that changes in society diminish one's identity; there was a functional relationship between the two. But he needed to take it one step further; it was the individual who was changing society. And the individual was doing so to perpetuate his own prized values. So you can't preserve personal values and identity by changing the environment; the change diminshes the identity being preserved. It was only gradually that persons began to discover that a changing environment required stable patterns against which one could construct an image of himself. During the 1970's young people began moving towards traditional patterns of dress, crafts, communal living, primitive agriculture, and fundamentalistic and primitive religions, all reminiscent of the nineteenth century.

The second influence by Darwinian ideas upon psychology was the question of inheritance. If either Lamarck or Darwin was correct in stating that new characteristics got transmitted to subsequent generations, then the mechanism of transmission needed to be understood. Mendel had discovered the basic genetic principles operating for plants and animals. Such studies were easy to conduct because of easy reproducibility and because of the absence of experimental restrictions. An understanding of human inheritance, however, could only be inferred from descriptive studies.

Sir Francis Galton (1822-1911)

Francis Galton (who apparently had no middle name), was a cousin of Charles Darwin. Like his famous cousin, Galton had a scientific bent involving careful observation and the production of descriptive studies. He gathered data to support the notion of inherited human characteristics by looking for similarities and patterns among various family trees. Galton led the way in applying the principles of variation to human characteristics. His interest in inherited genius was evident in his ethological studies on the "mental peculiarities of different races," published in MacMillan's Magazine in 1865. Galton was struck by the observation that eminent persons had a large percentage of eminent relatives; and he proceeded to systematically study the geneology of prominent personages in England. This was the first use of empirical data to demonstrate the inheritance of mental traits. The inheritance of physical forms had been demonstrated earlier and was not questioned. The inheritance of mental traits had been proposed earlier, but it was an unpopular idea and there was no supporting evidence available. Further, in his "The Inheritance of Intelligence," Galton shows that intelligence varies according to the normal probability curve.

Galton did not limit his researches to biographical information. During the International Exhibition in 1884, and then at the Kensington Museum between 1885 and 1890, Galton systematically measured 9,337 persons (including 35 pairs of identical twins, 783 brothers, and 150 families) (Reisman, 1966).

Galton's work on inherited genius became well known because it was admired by some and criticized by others. It supported the nationalistic and ethnocentric beliefs of some and it threatened the belief in unlimited possibilities of others. Americans discarded the genetic implications of Galton's doctrine but immediately absorbed the statistical techniques which he and his student Karl Pearson developed. It was finally through the work of Cattell, a student of both Wundt and Galton, that objective means for measuring mental ability was transferred to the research laboratories in America. We will turn shortly to the development of this field in psychology.

Galton was known for a wide range of methods and research problems. His approach was that of a raw empiricist. Probably more than any other psychologist, he was noted for devising novel and clever means for recording observations and for quantifying psychological variables. For example, he once constructed a simple recording device by strapping a pin to his finger with which he pricked little holes in respective quadrants on a card carried in his pocket. He could, thereby, record political judgments by age or party affiliation. The resulting punched paper was a scattergram. At a later date, he attempted to summarize the data from his scattergrams by a single index, a correlation coefficient, by the help of his student, Karl Pearson.

Other equipment designed by Galton included a simple whistle placed inside his walking cane, which could produce a shrill sound when a rubber bulb placed at the end of the cane was squeezed. In this fashion, Galton measured the auditory threshold level for various animals as he walked along the streets of London or through the Zoological Gardens at South Kensington. Another device was the composite photograph made of persons with similar character patterns. He took a number of photographs of different persons and lined them up in such a fashion that the planes passing through the nose and eyes were superimposed. Then, as if one were flipping the pages of a phone book, each picture was exposed for a fraction of a second on a photographic plate, thereby producing a composite picture representing the "ideal" type for that personality (Galton, 1883). In this way, Galton reversed the process of analysis, reduced the variability among persons, and came up with a synthesis of individual differences. Not so terribly scientific, perhaps, but it does represent a special kind of British ingeniousness.

The study of individual differences did not just happen to evolve into a program of eugenics in the United States as well as in England. Galton examined the data on the differences among individuals and he concluded that differences followed along family lines. He concluded that heredity rather than environment accounted for family similarities. How could the "good" traits in a culture be preserved? He was led to the conclusion that the "good" should be encouraged to breed more children than should the "bad." This was eugenics.***

Several of the American psychologists were interested in eugenics. G. Stanley Hall favored a eugenics movement. But it was a slow process, and subsequently he recommended education. "Much as our hearts warm to the program of eugenics and needful and beneficent as it is for permanent stabilization, it is so slow that we must now give prime attention, according to the principle of 'safety first,' to training (Hall, 1923, p. 515)."

Although Cattell was actively engaged in the eugenics movement, he perceived the dangers of taking the applications too far. His biographer writes: "Although himself President of the Eugenics Research Association, Gattell cautions that hereditarian knowledge not be permitted to obstruct the extension of opportunity including education; acknowledging the authoritarian qualities of such men as Galton, Pearson, and Thorndike, Cattell nevertheless thinks their hereditarian positions extreme and untenable (Joncich, 1968, p. 322)."


Circle those answers which are correct (one or more) or fill in the blank spaces.

1. When was Charles Darwin's "The Origin of Species" published (within a quarter of a century)?
a. 1801
b. 1827
c. 1859
d. 1893

2. "The modification of animal form through effort on the animal's part, further to adapt to its environment, and the inheritance, by its progeny of those acquired modifications" was stressed by ______________________.
a. Goethe
b. Charles Darwin
c. Erasmus Darwin
d. Lamarck

3. A comparative psychologist primarily does which of the following?
a. compares various theories of psychology.
b. studies differences in cultures
c. observes and analyzes abnormal types
d. studies animals.

4. Anthropomorphize means to:
a. Speculate on the descent of man
b. study the changes in the human species
c. extend to an animal human attributes
d. endow animals with associative memory

5. John Romanes was a(n):
a. experimentalist
b. behaviorist
c. advocator of the "anecdotal method"
d. adversary of the theory of evolution

6. Who undertook to offset the anthropomorphic tendency in the interpretation of the animal mind by an appeal to the 'law of parsimony'?
a. J. Henri Fabri
b. C. Lloyd Morgan
c. Jacques Loeb
d. George John Romanes

7. The Pearson Product Moment Correlation Coefficient is named after a student of:
a. Darwin
b. Lamarck
c. Galton
d. Cattell

8. In his article on "The Inheritance of Intelligence," Galton attempts to demonstrate that intelligence:
a. is a product of experience
b. can be divided into classes of approximately
equal numbers of persons
c. varies according to the normal probability

9. Galton is considered the founder of:
a. general psychology
b. individual psychology
c. Gestalt psychology
d. behaviorism


8 or more correct, go to Module 2
Less than 8 -- complete exercises on next page.



1. Darwin believed that there was some kind of correlation between an organism's:
a. structure and environment
b. emotions and intelligence
c. structure and intelligence
d. intelligence and adaptation

2. You can tell from its title that the book,Expression of the Emotions in Man and Animals, was written by:
a. Wundt
b. Pearson
c. Kohler
d. Darwin

3. The theory of acquired characteristics was advanced primarily by

4. The most prominent English psychologist, the one who attempted to describe the variation of traits among humans was

5. In contrast to Wundt, the work of Galton was:
a. descriptive
b. empiricistic
c. imaginative
d. experimental
e. naturalistic
f. nomothetic

6. The observation and comparison of mentalphenomena at different levels of the animal hierarchy is called:
a. observation psychology
b. comparative psychology
c. objective psychology
d. developmental psychology

7. The objective of Romanes' studies was to demonstrate that:
a. animals are not automata
b. animals have intelligence
c. there is a mental continuity between animals and man
d. the laws of association apply equally to animals' minds

8. How would you characterize Romanes' approach or technique?
a. experimental
b. observational
c. introspective
d. anecdotal

9. Which of the following men was responsible for the "law of parsimony?"
a. Romanes
b. Loeb
c. Lloyd Morgan
d. Lubbock

10. Sir Francis Galton was:
a. dogmatic
b. empirical
c. institutionalized
d. systematic

11 . Galton's scientific contributions covered such fields as:
a. inheritance
b. anthropological and psychological problems
c. eugenics
d. all of the above.


3. Lamarck
1. A
7. C
5. A,B,C,E,F
9. C
11. D
2. D
10. B*
4. Galton
8. B,D
6. B

*NOTE: In item 10, "d. systematic" is not correct because of the special meaning of "systems." True, Galton was very orderly and systematic in his collection of data. But he was not systematic in the sense that he organized findings into an integrated theory. "Systems of psychology" means "theories of psychology," or at least the putting of all relevant findings into an organized whole. Thus, a "systematist" deals with abstractions and is theoretical. Galton, on the contrary, was a practical and skillful observer.



1. The theory of natural selection begins by making what assumption about the statistical characteristics of the species?
a. large mean
b. small range
c. large standard deviation
d. skewed distribution

2. Which of the following men was the first to believe in the inheritance of acquired characteristics?
a. Goethe
b. Erasmus Darwin
c. Charles Darwin
d. Lamarck

3. One's sense of identity is threatened in twentieth century America because of the great emphasis placed on:
a. stability
b. mutations
c. change
d. inherited characteristics

4. What is the title of the first book on comparative psychology?
a. Animal Intelligence
b. The Origin of Species
c. Animal Behavior
d. none of these

5. Who suggested the continuity between animal and human behavior?
a. J. Mueller
b. Bain
c. Romanes
d. Hering

6. The book, Expressions of Emotions in Man and Animals, was written by a:
a. German
b. Englishman
c. Frenchman
d. American

7. "In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale . ." this law is known as:
a. theory of tropism
b. Lloyd Morgan's canon
c. Metamorphosis of parts
d. Malthus' theory of limitation

8. Correlation means:
a. causation
b. association
c. both a and b
d. neither a nor b

9. Sir Francis Galton was not:
a. developmental
b. experimentalistic
c. flexible
d. practical

10 The careers of Galton and Wundt demonstrate:
a. the marked similarity among men in psychology
b. the general difference between English and German science
c. an intolerant attitude resulting from over specialization
d. the argument against national types

11. Galton attempted to apply which evolutionary principle to this study of humans?
a. natural selection
b. catastrophism
c. acquired characteristics
d. variation


9 or more correct, go to Module 3
Less than 9 -- complete exercises on next

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