Pavel N. Prudkov (1999) Human Evolution Expanded Brains to Increase Motivational Ability,. Psycoloquy: 10(012) Brain Expertise (3)

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PSYCOLOQUY (ISSN 1055-0143) is sponsored by the American Psychological Association (APA).
Psycoloquy 10(012): Human Evolution Expanded Brains to Increase Motivational Ability,

Commentary on Skoyles on Brain-Expertise

Pavel N. Prudkov
Ecomon LTD
Snezhnaya 14-2-18
129323 Moscow, Russia


Skoyles (1999) points out the paradoxical relationship between brain size and intelligence, suggesting that evolution expanded human brains to increase a hypothetical capacity to develop expertise. We note a few weaknesses and inconsistencies in the concept of expertise capacity and suggest that this concept is very vague and needs further elaboration. Evolution expanded human brains to provide the ability to construct and maintain social motivations, a distinctively human property that underlies the development of human civilization and culture. This ability can explain the facts noted in Skoyles's target article and has new implications for the relationship between brain size, intelligence and motivation.


Homo erectus, IQ, brain size, cortex, differences, evolution, expertise, frontal individual intelligence, language, social motivation
1. Skoyles (1999) considers the relationship between brain size and intelligence and proposes that the increase in brain weight from Homo erectus to modern Homo sapiens sapiens was associated with the capacity to develop expertise. The facts considered in the paper are indeed very interesting; however, there are some obvious weaknesses and inconsistencies in the hypothesis proposed to explain them.

2. The need for a hypothetical cognitive capacity to develop expertise is not obvious. Skoyles infers this capacity from the difference in performance between novices and experts. He implicitly suggests that the practice in a particular domain activates this cognitive capacity, which provides the substrate for the specialized processing and performance of experts. It is easy, however, to find a simpler explanation for the performance difference: it is on the basis of such long-term factors as motives and personal traits that practice activates and induces the requisite changes in brain structures. Indeed, Skoyles considers data from expertise in violin playing as an example of the influence of expertise on the cerebral cortex. This influence is unlikely to be that violin playing is an innate property of violinists.

3. Brain organization for expertise capacity is unclear. Skoyles writes: "Intelligence may be related to IQ tests, but the intelligence which was central to the evolution of our brains could be associated with something IQ tests do not measure: expertise capacity." (par. 39). This probably means that either different kinds of intelligence are partly separate in the brain, or, for those that share a single brain system, a special factor can influence the expertise capacity without changing IQ scores. Skoyles provides no information on this problem. Moreover, the brain size increase during the transition from Homo erectus cannot have been associated only with expertise capacity because there were also changes in the brain systems responsible for language, bipedal locomotion and self-control. Concentrating on intelligence that "is central to the behaviour of our species," Skoyles does not even consider this possibility.

4. There is an inconsistency in the role of expertise capacity in the cognitive processes of modern people. Skoyles writes: "the capacity to develop expertise is not necessary for normal life in a modern industrial society" (par 36). This implies that a considerable part of the brain that is very important in complex probabilistic situations is now inactive and useful only in a few exotic domains such as races, chess, and music. This sounds strange and even dangerous for the future of human civilization. However, our civilization still has a chance, for Skoyles refers to the following criterion for expertise: "before people can show expertise in any domain they must have performed several hours of practice a day for a minimum of 10-years" (par. 34). Millions of people meet this criterion, and Skoyles is probably among them. Such an inconsistency in the role of expertise capacity is a reflection of the fact that the target article contains no unequivocal definition of expertise and expertise capacity. Instead, Skoyles illustrates with examples from various domains (violin playing, chess, racing, etc.). However, inconsistent conclusions can be drawn from these examples. Given the vagueness of the concept of expertise capacity, it is difficult to understand its role in evolution.

5. The hypothesis of expertise capacity cannot explain the facts considered in Skoyles's paper because the hypothesis itself needs a serious clarification. However, there is a useful aspect to Skoyles's ideas. To find it we return to the criterion for expertise. To acquire expertise in a particular domain an individual must take years or even decades and overcome the many problems inevitable in this process. Only with a strong domain-specific motivation is such perseverance possible. On the other hand, as pointed out above, long-term motives arising from practical activity can give rise to the cognitive traits which distinguish experts from novices.

6. It is of accordingly interest what sort of motivation underlies acquiring expertise. A main property of these motivations is that they are social, they originate from interactions with other people. An individual cannot became an expert (e.g., a great chess player) in a domain that is completely absent from his social environment. Another important feature is that these motivations are long-term, sometimes life-long; the brain can sustain them as long as necessary.

7. No nonhuman animal seems to have a motivational system with similar characteristics (Hinde 1970). Of course, animals have long-term motivations (sex, hunger, thirst, etc.) but these are all innate. An animal can form learned motivations, but only when one of the basic drives is activated (e.g., a hungry chimpanzee can use branches as tools but does not store them for another day; Fabri 1976).

8. The ability to construct and maintain long-term motivations with no innate basis may be the greatest achievement of evolution; this, rather than the faculty of language determines human civilisation and culture. Indeed, if the motivation system of organisms is restricted by innate constraints, the behaviour of organisms also lies within those constraints, irrespective of the flexibility of their language or other cognitive structures. Hence the ability to construct and maintain long-term social motivations is necessary not only to acquire expertise but also to construct new domains: for example, without this ability any development in making tools would be impossible.

9. To explain the relationship between brain size and intelligence it is useful to apply an analogy from computer science. There are two parameters which define the productivity of a program running on a computer. One is the basic characteristics of the hardware (e.g., the speed of the processor), the other the efficacy of the algorithm. An effective new algorithm can dramatically increase the productivity of the program (FOOTNOTE 1). It is reasonable to associate the intelligence measured by IQ tests ("natural intelligence") with basic features of the hardware. Like Skoyles, we assume that the basic features of the hardware of Homo erectus were similar to the lower limit of those of modern humans. Since then,however, evolution has preferred not to construct new hardware but to work out flexible, adaptive algorithms thus developing the ability to maintain social motivations. Some questions relating to such self-organizing processes are considered by Prudkov & Rodina (1998).

10. Maintaining a learned motivational process during a long period is a new brain function likely to require a big and complex brain. Evolution selected the individuals with the brains that had the greatest ability to construct and maintain social motivational processes because the advantage of the ability presumably outweighed the handicaps relating to brain size.

11. It is not difficult now to explain some of the puzzling facts in Skoyles's paper: Individuals with small brains can have normal IQ scores because brain size is a consequence of the development of motivation ability rather than IQ. Modest correlations between IQ scores and expertise reflect the fact that motivation rather than intelligence determines expertise.

12. Homo erectus may have been one of the intermediate stages in the development of the ability to maintain social motivations. Unlike nonhuman animals, Homo erectus was able to construct and achieve goals with no innate basis (e.g., to make tools); however, this ability was limited to short periods, such as a few hours. Small brain size may limit long-range motivations. Individuals with small brains may be unable to maintain purposeful processes whose goals can only be achieved in years or decades; their behaviours may be limited to short-term goals, which would handicap their social and professional status. (Such people would perhaps be more suggestible and have a lower level of control over innate drives and emotions.)

13. The literature on retarded people is highly consistent with this hypothesis (Andreanska & Andreansky 1981, Merighi et al. 1990, Zeigarnik 1976). Children (with their relatively small brains) likewise fit this hypothesis. There is considerable correlation (0.76) between IQ at age of 7 and age 18 (Mussen et al. 1984), when individual digit, word, and letter spans reach the average level of adults (Dempster 1981, figures 1-3). In other words, some fundamental properties of "natural intelligence" have already been defined at seven. However, the system of long-term motivation still awaits very substantial development. No data on the motivations of adults with small brain and normal IQ scores are available to this commentator. Such data would be very useful to confirm or refute this idea about the relationship between brain size, intelligence, and motivation.

14. In conclusion, the role of the ability to maintain social motivation seems to be overlooked in contemporary psychology and brain science. Motivational psychologists take it for granted (Heckhausen 1980) but cognitive psychologists neglect it (the paper by Skoyles is an example), although without the ability, reading, writing and other distinctively human cognitive skills would be impossible. Brain scientists associate this ability with properties of the frontal cortex (Luria 1966), however, they provide no information about the organization of long-term social motivations. This ability requires intensive further research.


[1] In the fifties a group of Russian nuclear physicists tried to solve a numerical problem. To this end, they worked out an appropriate algorithm. On the basis of the algorithm a primitive computer at their disposal could only perform the necessary calculations in six months. They had already started calculating when a member of the group showed the problem to Kolmogorov, a famous Russian mathematician. A day later, Kolmogorov provided another algorithm which allowed the problem to be solved in four hours (Samarskyi 1984).


Andreanska, V., Andreansky, M. (1981). Specificity of motivation in handicapped children. Studia Psychologica. Vol 23(4): 289-296.

Dempster, F.N. (1981). Memory span: sources of individual and developmental differences. Psychology Bulletin, 1: 63-100.

Fabri, K.E. (1976). Foundations of animal psychology . MGU (in Russian).

Heckhausen, H. (1980). Motivation und Handeln. Springer-Verlag (Russian translation 1986).

Hinde, R.A. (1970). Animal behaviour. A synthesis of ethology and comparative psychology. Mcgraw-Hill book company.

Luria, A.R. (1966). Higher cortical functions in man. Tavistock Publication, Andover, Hants.

Merighi, J., Edison, M., Zigler, E. F. (1990). The role of motivational factors in the functioning of mentally retarded individuals. In: Issues in the developmental approach to mental retardation, ed. Hodapp, R. M. & Burack, J. A., Cambridge University Press.

Mussen, P.H., Conger, J.J., Kagan, J., Huston, A.C. (1984). Child development and personality. Harper & Row, Publishers.

Prudkov, P.N., Rodina, O.N. (1998). Synthesis of purposeful processes. (manuscript submitted for publication).

Samarskyi, A.A.(1984). Applied mathematics. Nauka (In Russian).

Skoyles, J.R. (1999). Human evolution expanded brains to increase expertise capacity, not IQ. PSYCOLOQUY 10(002). psyc.99.10.002.brain-expertise.1.skoyles

Zeigarnik, B.V. (1976). Abnormal psychology. MGU (in Russian).

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