Library of Excerpts

Heterochony: Part 1

This page contains a collection of excerpts from sources used to support Shift Theory, an alternative theory of human evolution. Click here for an introduction to this new and unique theory of evolution.

"The existence of mammary ridges on the embryo concording with ancient synapsids suggests that those ancient animals also had nutrient-supplying ridges on their bodies for which there is no paleontological evidence. On the human embryo, the mammary ridges gradually coalesce and finally resolve into discrete nipples on day 58. This event concords almost exactly with the lowermost Triassic, where the fossils of Cynognathus are found. Discrete mammary glands and a fused secondary palate in the enbryo coincide with a fused secondary palate in the fossil record." (Swan, Lawrence W. (1990) The concordance of ontogeny with phylogeny. Bioscience 40: 380)

[quote from Gowaty, 1992, p. 231-240] "Juvenilization decreases the threat some men may feel when confronted with women; many men are comfortable around women whom they can clearly dominate and are profoundly uncomfortable around women whom they cannot so clearly dominant. The hypothesis that femininity signals ability to be dominated through juvenilization is an alternative to, but not necessarily mutually exclusive of, other evolutionary hypotheses that posit that femininity signals, sometimes deceptively, reproductive value and fertility." (Jones, Doug (1995) Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 727)

“Testosterone-dependent secondary sexual characteristics in males may signal immunological competence and are sexually selected for in several species. In humans, oestrogen-dependent characteristics of the female body correlate with health and reproductive fitness and are found attractive. Enhancing the sexual dimorphism of human faces should raise attractiveness by enhancing sex-hormone-related cues to youth and fertility in females, and to dominance and immunocompetence in males. Here we report the results of asking subjects to choose the most attractive faces from continua that enhanced or diminished differences between the average shape of female and male faces. As predicted, subjects preferred feminized to average shapes of a female face. This preference applied across UK and Japanese populations but was stronger for within-population judgements, which indicates that attractiveness cues are learned. Subjects preferred feminized to average or masculinized shapes of a male face. Enhancing masculine facial characteristics increased both perceived dominance and negative attributions (for example, coldness or dishonesty) relevant to relationships and paternal investment. These results indicate a selection pressure that limits sexual dimorphism and encourages neoteny in humans.” (Perrett DI, Lee KJ, Penton-Voak I, Rowland D, Yoshikawa S, Burt DM, Henzi SP, Castles DL, Akamatsu S (1998) Effects of sexual dimorphism on facial attractiveness. Nature 94 (6696): 884-7)

"Recently, Garstang has elaborated this view very skilfully, and has shown that there has been an evolution along the line of fertilized eggs (or zygotes), in consequence of which animals have modified their ontogenies and so changed the shape of the final stage of development, viz. the adult. But a series of adult forms modified in this way is phylogeny, and os phylogeny is the result of ontogeny instead of being its cause. Garstang has thus arrived at the same point of view as Hurst, who wrote: 'I do deny that the phylogeny can so control the ontogeny as to make the latter a record of the former.' An identical point of view has since been expressed by Ekman, Franz, Fuchs, Nauck, Schindewolf, and Shumway. Similarly, Berg allows that ontogeny anticipates phylogeny." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 8)

"Child has solved this problem by showing experimentally that the first thing which has to be settled in a developing egg is the polarity, i.e. which part of the egg will give rise to the front and which to the hind end of the future animal. As soon as the polarity is established, local diversities arise and result in the qualitative differentiation of the different parts. Now in many cases the determination of this polarity seems to be the result of the action of factors which are external to the fertilized egg. In other cases it is possible that the polarity of the egg is derived from that of the oogonium which gave rise to it, but this merely pushes the question of the origin of polarity back in time. However this may be, it is clear that all the way through development the internal factors produce nothing of themselves, but they enable the animal to react in definite ways to the external factors and by this means give rise to structure after structure in the process of development. Heredity does not account for the individual, but merely for the potentialities some of which are realized in the individual. In other words, the internal and transmitted factors are by themselves unable to 'produce' an animal at all. The first rigorous analysis of the relation of internal and external factors in development is due to Lankester, who showed that they can only be regarded as co-operating in the production of all the characteris of the organism. The same point of view has been developed by Goodrich, who stresses the distinction which has to be drawn between the process of transmission of the internal factors from parent to offspring, and the process of production in the offspring of characters similar to those which were possessed by the parent. 'An organism is moulded as the result of the interaction between the conditions or stimuli which make up its environment and the factors of inheritance. No single part is completely acquired, or due to inheritance alone. Characters are due to responses, and have to be made anew at every generation.' Similar views have been expressed by Conklin. These conclusions, which are based on definite experimental evidence, have a far-reaching importance. In the first place they show that the question -- Are acquired characters inherited? -- has no meaning, for all he characters of an organism are both inherited and acquired; they would not be developed at all unless the organism possessed the requisite internal and inherited factors and unless the external factors were sufficiently 'normal' to evoke the 'normal' developmental responses. A change in either the internal of the external factors will result in a departure from normal development. What the questioners really mean is -- Can an effect originally produced as a response to an environmental stimulus come subsequently to be produced regularly without that stimulus? In other words, can external factors become internal? When, therefore, Hyatt defined an acquired character as 'a modification which makes its appearance in the adult or later stages of development and is obviously dependent for its origin upon other than hereditary causes', he is really describing the effect of an external factor, but that does not justify him in excluding the articipation of internal factors in producing that effect." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 12-13

"To put the matter as succinctly as possible, no case has yet been satisfactorily proved in which, as a result of external factors, the development of an animal has undergone a modification and in which these external factors have become internal and transmitted, so that the same modification has come to be invariably produced in all the subsequent ontogenies of descendant animals without the necessity for the external factors which orginally evoked the modification. Until such a case has been proved, it cannot be believed that the effects of external factors and of use and disuse on body or mind are transmitted or play any part in ontogeny in subsequent generations. Somatic induction, or the transmission of the effects of use and disuse, constitute the kernel of the Lamarckian point of view; and it is curious that while we still lack evidence, viz. direct induction, though of course he was prophetic and correct in rejecting the view that direct induction can produce an adaptive inherited response to the environmental stimulus. It would be very convenient if it were possible to accept an explanation of the origin of internal factors and of their adaptive nature on the lines of Lamarck's hypothesis of the effects of use and disuse, but in the present state of knowledge it is not possible. It is necessary to adopt a humbler position and admit that the causes of origin and change in the genetical factors of organisms are unknown. Once they have arisen or changed (mutated), selection plays an all-important part in moulding their effects." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 15-6)

"That the general idea is true that the genes produce their different effects by working at definite speeds, can further be shown by raising or lowering the temperature of the environment, which accelerates or retards the rate of action. This is why a primrose which at a temperature of 20 degrees C. has red flowers, will have white flowers if it is grown at 30 degrees C. It also supplies the reason why the fur of the extremities (ear, paws, and the tip of the tail) of Siamese cats is dark, for the temperature of these places is lower than in the body generally." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 19-20)

"Apes when new born have very much lighter skins than adults; additional pigment becomes deposited during later development, and the same is true of the Negro. In this respect the white races are neotenous, for they retain the embryonic conditions of other forms. One of the most interesting cases of this kind is that of the hair, for Bolk has shown that a progressive series in reduction can be made out in the monkeys, apes, and man: 1. the monkey is born with a complete covering of hair; 1. the gibbon is born with the head and back covered with hair, and the other regions are covered later; 3. the gorilla is born with the head covered with hair, and the other regions are partially covered later; 4. man is born withhead covered with hair, and the other regions are scarcely covered at all later. It is noted that the lanugo, which forms a very fine covering to the unborn infant before being lost, is also present in unborn apes. Further, the lanugo is retarded in man, for he has not completely shed it by the time of birth. This series shows that the neoteny of man as regards hair is associated with a progressive retardation in the rate of its development. This retardation in the rate of development of the body, it will be remembered, is all that is required to produce the other human features mentioned above. It therefore becomes interesting to inquire whether the rate of human somatic development is really slow as compared with that of other mammals. That this actually is the case is proved by a table which was given in Chapter III (p. 22). Bolk has been able to give additional proof of this by a study of the development of teeth. In the apes the milk-teeth are cut directly after birth, the 1st molar is cut soon after the 2nd premolar, and the replacement of the milk-teeth then takes place, accompanied by the cutting of the 2nd and 3rd molars. In man, the cutting of the milk-teeth is only finished two years after birth, and this is followed by a pause until at five or six the 1st molar is cut. After this, the milk-teeth are replaced, and not until this is done does the 2nd molar appear. The 3rd molar may be cut after the 2nd, but its development is often so retarded that it is not cut at all. Indeed, retardation characterizes the development of the human dentiton as a whole. (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 58-9)

"The result of the last few chapters has been to show that each of the theoretically possible effects of heterochrony in producing phylogeny has actually accurred in the evolution of different animals." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 88)

"It is to be expected, therefore, that is those cases where paedomorphosis has occurred, resulting in the production of markedly new types such as the chordates, much of this evolution will have been clanestine, and there will be a gap in the record of fossil ancestors of the new type. In other words, the theory of paedomorphosis not only explains the gaps in the fossil record, but also supplies the reason why such gaps must be expected." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 100)

"A word of caution is necessary here. Repetition of characters interests us as a reflection of events which were manifested in the ontogenies of the ancestors and are continued in those of the descendants. But there are cases of repetition which clearly call for a special explanation. for instance, Needham has drawn attention to the fact that nitrogen excreted by adult invertebrates, fishes and birds takes the form of ammonia, urea, and uric acid respectively. The chick embryo starts by excreting ammonia, then urea, and lastly uric acid, thus apparently providing a case of recapitulatory repetition of adult ancestral characters. But even apart from the fact that the chemistry of urea-production in the chick embryo (involving the arginine-arginase system) is not the same as that of adult fishes (which takes place by means of the ornithine cycle), this case is instructive in bringing out the principle of parallelism of processes showing increasing degrees of complexity, exemplified by the series ammonia-urea-uric acid. Many other such sequences are cited by Needham, and there is apparently a natural order in which things can be done: a necessitation which affects all ontogenies alike. Repetition of such sequences is evidence, therefore, not of any influence of phylogeny on ontogeny, but of the limitations of physico-chemical possibilities in the transition from the simple to the more complex." (de Beer, G. R. (1951) Embryos and Ancestors. Clarendon Press: Oxford. p. 102)

“Young women appear to be attractive to young men owing to the combination of paedomorphic and secondary sexual signal characteristics which they present to them initially at a distance. Hairlessness, voice tone, complexion and girlish behavior all have a childlike character that in ethnological terms appear to lower the probability of a male aggressive response of to appease if one is present. These same characteristics are likely to reduce male fear and anxiety on closer approach and to permit sexual expression. The male begins to display in various “show-off” performances including physical prowess (such as, dancing), exhibitions of virtuosity in the social graces, in demonstrations of charm and sensitive virility. These displays attract the female’s attention and provide the basis upon which she may choose to respond to or reject the male’s approach: or more usually, simply fail to observe them. ... From the purely ethological viewpoint this sequence has much in common wiht courtship in birds and often mammals....” (Sexual selection in the primates (1972) John H. Crook in Sexual selection and the descent of man 1871-1971 Campbell, Bernard (ed.) pp. 274)

"...cell size is inversely related to metabolic rate" (Riska, B. & Atchley, W.R. (1985) Genetics of growth predict patterns of brain-size evolution. Science 229: pp. 669)

"Because body size can evolve in these different ways, by change in different components of growth, the parallel change induced in brain size may differ. This will depend upon the timing, during growth, of pleiotropic gene effects. For example, if pleiotropic gene effects influencing these two traits occur mostly in the early portions of body growth, body-size evolution occurring by change in later growth will induce little parallel change in brain size. Evolution occurring by change in early growth, however, will induce greater change in brain size for a given amount of body-size evolution." (Riska, B. & Atchley, W.R. (1985) Genetics of growth predict patterns of brain-size evolution. Science 229: pp. 669)

"Head circumference measurements from birth to 7 years, obtained from lognitudinal data on children born between 1970 and 1977, are set against those from studies made in the United Kingdom earlier this century. A positive secular trend is shown. The children's heads were significantly larger than those born in the same locality 25 years earlier. Growth charts should be updated, as necessary, with each succeding generation." (Ounsted M, Moar VA, & Scott A (1985) Head circumference charts updated. Archives of Disease in Childhood 60: 936)

[citations removed] "Nevertheless, detailed examination of growth data on 15 birth cohorts form 1961 to 1975 showed a continuing positive trend for height among primary school children in England and Scotland, although at a slower rate than Cameron's estimates for any period between 1905 and 1954. With small exceptions (which could have occured by chance) the heights and weights of boys and girls in our study did not differ at any age from those of boys and girls born in the same city a generation earlier. The median values were also very similar to those in the standard charts, but head circumference measurements were larger, indicating that the secular trend upwards in head size, which was evident during the first half of this century, continued into the 1970's. .... Our data also suggest that girls may achieve their maximum head circumference historically earlier than boys. " (Ounsted M, Moar VA, & Scott A (1985) Head circumference charts updated. Archives of Disease in Childhood 60: 937)

"Perhaps the facial proportions that Jones interprets in terms of age cues also indexed some other aspect(s) of female mate value. One possibility is hormonal status, which Jones considers unlikely. Yet high androgen levels in women are positively correlated with reproductive system dysfunctions, and observable indices of high androgen levels, such as acne, hirsutism, and a high waist-to-hip ratio--seem to be systematically percieved as unattractive. To my eye, the faces in Jone's figure I apear to differ more in "masculinity" than in age." (Symons, D (1995) response to...Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 741-43)

"1. Women whose facial proportions make them look younger than their actual age (as measured by regression equations predicting age as a function of facial proportions) are perceived as more attractive by male raters from five populations (but see n. 4). 2. A sample of U.S. female models has significantly more neotenous facial proportions than a sample of U.S. female undergraduates and a strikingly low predicted age, about 7 years, according to regression equations predicting age as a function of facial proportions. 3. Cardioidol strain, a mathematical transformation shown by earlier research to provide a good model for changes in facial proportions during the course of maturation and to affect the percieved ages of faces, also has an effect on female facial attractiveness according to U.S. raters. The effect is nonlinear, suggesting that neoteny is a component of attractiveness only up to a certain point. 4. Results for male attractiveness in the above studies are weak and / or inconsistent." (Jones, Doug (1995) Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 734)

"The evolution of modern Homo sapiens over the past 100,000 years has been marked by a trend toward increasingly craniofacial neoteny, including reduced prognathism, increased brachycephaly, and general gracilization in a number of populations. (Weidenreich 1945, Newman 1962, Brace and Mahler 1971, Frayer 1981). Biological anthropologists have generally invoked natural selection for ecological adaptation of nonadaptive forces such as pleiotropy or biased mutation to explain these trends. The analysis in this paper suggests that sexual selection may also be involved." (Jones, Doug (1995) Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 735)

"Since, in comparison with genetic transmission, social transmission typically results in a more rapid diffusion of a preference through a population, culturally generated sexual selection may be unusually fast, and the alleles underlying favored traits may be selected to high frequency in just a handful of generations. This analysis suggests that (1) there should be local, society-specific correlations between favored traits and mating preferences; (2) sexual selection may account for cross-cultural variation in traits underlying attractiveness; and (3) recent selection may have modified any predilections favored throughout the Pleistocene." (Laland KN (1995) reply to.... Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): 728-9)

"Let us summarize the argument up to this point. Human beings are anomalous among sexually selected species in the importance attached to female (relative to male) appearance in mate choice. Human beings are anomalous in another respect as well: female fertility commonly declines to zero long before the end of the life span. As a result of menopause there is considerably more age-related variance in fecundity among adult females than among adult males in our species. The second anomaly may explain the first: the importance attached to female attractiveness in our species may reflect the operation of adaptations for assessing age-related changes in fecundity, a component of female mate value." (Jones, Doug (1995) Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 727)

"In other words, given that attractiveness varies with age, individuals may be more or less attractive than others of the same age in part because they have facial proportions associated with younger or older ages. Because the retention of traits from early stages of the life cycle into later stages, relative to ancestors or to other members of the population, is known as neoteny ("holding on to youth"), the proposition above may be rephrased: given that attractiveness varies with age, neoteny may be a component of facial attractiveness. This proposition may hold with particular force for female facial attractiveness: a by-product of the human male's attraction to markers of youthful fecundity may be an attraction to adult females presenting markers of youth to an exagerated or "supernormal" degree." (Jones, Doug (1995) Sexual selection, physical attractiveness, and facial neoteny: cross-cultural evidence and implications. Current Anthropology 36 (5): pp. 728)

"However, this discrepancy became understandable when it was realized that the newborn infant concords very well with 20 million years ago in the Miocene epoch, when our ancestors were apes of some sort. Newborn infants can often grasp and suspend themselves and even swing enough to suggest brachiation. Their hallux or big toe is often highly movable and the rest of their feet (showing a slope of their curled toes that is virtually tranverse) are apelike. In an evolutionary sense, a newborn concords well with some ancestral Miocene ape. However, after nine months of a year, when the curve is found at the time of birth, a child approaches the evolutionary present. It starts to stand erect and practices with its lumbar curve before it walks upright. Its hallux assumes a forward position, and its starts to acquire the normal slope of human toes. The chin acquires a better-defined protuberance that expresses Homo sapiens as a species, and the jabberings of an infant transform into human speech." (Swan, Lawrence W. (1990) The concordance of ontogeny with phylogeny. Bioscience 40: 383)

"Some extreme varants are associated with the deviations of psychological function that we describe as psychosis. These states are seen as boundaries of the distribution of personality variation, including the capacity for language and emotional expression. In particular, those with the earliest manifestations (i.e. schizophrenia, Asperger's syndrome and autism) have the greatest impairments of communication and social ability, and also demonstrate a failure to develop anatomical asymmetry. In summary, key features of the theory are that the psychoses are disorders of specifically human evolution, arising from variation in the genes controlling hemispheric asymmetry that has led, by the mechanism of sexual selection, through progressive delay in maturation (neoteny) to increased brain size and intelligence. The most readily testable prediction is that the gene for asymmetry (and by implication contributing to predispostion to psychosis) should be X-Y homologous." (Crow TJ (1995) A Darwinian approach to the origins of psychosis. Br J Psychiatry 167(1):24)

"A 'failure of neoteny' might therefore correspond to an extreme of development of cerebral asymmetry, for example, a failure to establish dominance in one or other hemisphere. Consistent with this prediction is evidence from morphological studies (Crow et al, 1989; Crow, 1990a,b; Faikai et al, 1992) that patients with schizophrenia have an arrest of development of asymmetry." (Crow TJ (1995) A Darwinian approach to the origins of psychosis. Br J Psychiatry 167(1):22-23)

"It is satisfying to consider embryos and adults as merely different parts of the slope of a curve subject to natural selection. If biologists cannot agree to Haeckel's concept, "ontogeny recapitulates phylogeny," there may be room for a less ringing slogan, "ontogeny concords with phylogeny."" (Swan, Lawrence W. (1990) The concordance of ontogeny with phylogeny. Bioscience 40: 384)

"First, there are differences in the level of sexual activity of adolescent females. Goodall (1968) discovered that adolescent female common chimpanzees, whose sexual swelling is not attractive to males, do not copulate very often. By contrast, adolescent female pygmy chimpanzees are in the age class that copulates most frequently. Second, there are great differences in the length of sexual inactivity before and after parturition. Among common chimpanzees, a female does not resume her estrous cycle for 30 months (primiparous female) to 48 months (multiparous female) postpartum (Goodall, 1983), and during this period, she does not copulate. In contrast, pygmy chimpanzees usually resume estrus and copulate much earlier. Third, there are differences in the duration of maximum swelling in normal estrous cycle (coinciding with the menstrual cycle). In wild common chimpanzees, the duration is 9.6 days (25% of a cycle of 37.2 days) (Tutin, 1979). In pygmy chimpanzees, the period of maximal swelling usually lasts for more than 20 days (more than 43% of a cycle of 46 days), or twice as long as for common chimpanzees. The long estrous period of a female pygmy chimpanzee relative to a common chimpanzee, no matter what her physiological stage, certainly results in a higher copulatory frequency. The menstual cycle of an adolescent female common chimpanzee, 42.6 days on average, is longer than that of an adult (Young and Yerkes, 1943). Furthermore, the cycle of sexual swellings is very irregular, and the period of maximal swelling is longer than that of an adult. the adolescent female pygmy chimpanzee is almost always in an estous condition, and should not be used for comparisons. The adult female pygmy chimpanzee, however, has a sexual physiology similar to that of an adolescent female common chimpanzee. First, the lenth of the menstrual cycle of an adult female chimpanzee, 46 days (Handler, Malenky, and Badrian, 1984), is closer to that of an adolescent female common chimpanzee than to that of an adult female common chimpanzee. Second, the pattern of sexual swelling of the adult female pygmy chimpanzee is irregular and long, resembling that of an adolescent female common chimpanzee. Perhaps the female pygmy chimpanzee is neotenous in its sexual physiology." (Kano, T. (1992) The Last Ape: Pygmy Chimpanzee Behavior and Ecology; Stanford Univ. Press, Standord p. 160)

[abstract] "BACKGROUND. The onset of psychotic illness in the reproductive phase of life with a decrease in fecundity (and approximately constant incidence across populations) requires an evolutionary explanation. What is the survival value of the predisposing gene or genes? METHOD. Evolutionary theories, including the author's, are reviewed and critically compared. RESULTS. Some theories (e.g. Huxley et al, 1964) postulate an advantage outside the nervous system: such theories fail to explain either the characteristic age distribution or constant incidence. More plausible are theories that relate the advantage to diversity of personality structure or social ability, or even to general intelligence, i.e. to the areas of function in which the phenomena of psychosis arise. CONCLUSIONS. It is argued that psychosis arises as the boundary of a distribution of variation in cerebral structure generated in the course of hominid evolution. Language played a central role, with the critical changes taking place on the basis of a mutation that allowed the two cerebral hemispheres to develop with a degree of independence. Sexual selection (differing criteria in females and males in choosing a mate) acting on this genetic innovation has generated a dimension of competence in social interaction in relation to which there has been a progressive increase in cerebral size by delayed maturation (neoteny). A sexual dimorphism in cerebral asymmetry and the sex difference in age of onset of psychosis can be parsimoniously explained if a gene regulating the relative growth of the two hemispheres is X-Y homologous." (Crow TJ (1995) A Darwinian approach to the origins of psychosis. Br J Psychiatry 167(1):12-25)


"The theme of developmental delay which unifies multiple experimental observations in human and rodent diabetic embryopathy is also prominent in other teratogenic conditions. Altered fetal growth and ossification has been demonstrated in the response of rodents or humans to many different terotegens such as ethonal (Lee and Leichter, 1983), phenylalanine (Brass it al., 1982), and zinc deficiency (Hurley and Swenerton, 1966)." (Wilson, G. N. (1988) Heterochrony and human malformation. American Journal of Medicine, Genet 29: pp. 318)

"Delayed maturation of liver function, somatomedin-like activity, osseous development and the occurence of malformations such as midfacial hypoplasia, single cardiac ventricle or holoprosencephaly suggest heterochrony as a prominent theme in the genesis of Down syndrome." (Wilson, G. N. (1988) Heterochrony andhuman malformation. American Journal of Medicine, Genet 29: pp. 315)

"The need to hunt large animals may have been a main stimulus in the development not only of many physical features but also of social life and language. There is little evidence to go on but it is easy to imagine that the populations that survived contained genes ensuring co-operation among individuals, as well as efficient tool-making and tool-using. Hunting may well have been difficult for females and young and this would have led to the formation of stable social groups, with specialization of functions and sharing the results of the chase. This could be achieved by development of tendencies to co-operate, of which there are considerable signs already in monkeys and apes, though not usually for the purpose of getting food. Co-operation to drive, trap, and kill large prey such as antelopes or even elephants requires a reduction of competitive and aggressive behavior between individuals. In a sense this could be said to involve in man the continuation throughout life of the characteristic features found among juveniles of monkey and other animal communities. There are indeed several signs that the evolution of man had involved a process of 'juvenilization' or even 'foetalization'. Such a change, technically called neoteny (or paedomorphosis), has in fact occured often in the course of the evolution of diverse animals (De Beer 1958). It is not difficult to understand how a delay in the rate of development of the reproductive system relative to the rest of the body could be produced by even a small genetic change; for instance , one affecting the pituitary gland. The result might be a striking alteration int he age structure of the population and hence in the psychology of its members." (Young, J.Z. (1971) An Introduction to the Study of Man: Clarendon Press, Oxford p. 478-9)

"Rates of evolutionary change in different early hominid groups during the same length of secular time, exhibited principally as differences in the rate of neotenous mutations --- among other factors --- are quite sufficient, it is suggested, to explain such apparent anachronisms as neanthropic types of man in the Middle or even Early Pleistocene and a palanthropic type of man in the Upper Pleistocene --- always, providing, of course, that we are also finally able to understand the adaptive value of these neotenous changes." (Montagu, Ashley (1955) Time, morphology, and neoteny in the evolution of man. American Anthropologist 57: pp. 27)

"The hypothesis advanced in this paper suggests that commencing with a single hominid ancestral population, which has subsequently separated into several geographically isolated populations, that in addition to such factors as mutation, natural selection, isolation, drift, and the like, neotenous mutations have played an important role in adding to the quanta of morphological difference among such populations. Neotenous mutations occuring at a more rapid rate in some early populations than in others would, at least in part, be responsible for the development of morphologically modernlike types of man at a period contemporary with the flourishing of such types of Pithecanthropus, Heidelerg, and Solo man. The hypothesis suggests that in the latter types neotenous mutations occured comparatively infrequently." (Montagu, Ashley (1955) Time, morphology, and neoteny in the evolution of man. American Anthropologist 57: pp. 27)

"Another part of the story, speculative but crucial, concerns the highly impressionable state of human infants, the males of whom seem to have developed a sexual liking for "maternal" females --- females that reminded them of their nursing mothers. Sexual imprinting, in which the young memorize features of their parents, and then seek out those features in mates when they mature, is prevalent in animals." (Margulis, L & Sagan, D. (1991) Mystery Dance, On the Evolution of Human Sexuality: Summit Books, New York pp. 96)

"If early, impressionable human infants imprinted on their nursing mothers, males would have grown up with a confusing lust for women who were not ovulating, but lactating. Genetically disadvantageous to males, this confusion would have been a genetic advantage to females who, sexually attractive almost all season round, stood a better chance of keeping fathers to help with children." (Margulis, L & Sagan, D. (1991) Mystery Dance, On the Evolution of Human Sexuality: Summit Books, New York pp. 97)

"Sexually immature, prepubescent boys enjoy a range of sexual response similar to that of adult women. Kinsey and his coworkers reported, "The most remarkable aspect of the preadolescent population is its capacity to achieve repeated orgasm in limited periods of time. This capacity definitely exceeds in the ability of teen-age boys who, in turn, are much more capable than older males." The response of young boys, including mulitiple climax without losing an erection, "is," according to biologist Donald Symons, "perhaps similar to orgasmic women." Neither prepubescent orgasmic boys nor women ejaculate sperm, and thus the "ability of females to experience multiple orgasms may be an incidental effect of their inability to ejaculate."" (Margulis, L & Sagan, D. (1991) Mystery Dance, On the Evolution of Human Sexuality: Summit Books, New York pp. 86)

See Cope for additional info.

<104(100-101)> "In one of his most famous articles, Konrad Lorenz argues that humans use the characteristic differences in form between babies and adults as important behavioral cues. He believes that features of juvenility trigger "innate releasing mechanisms" for affection and nurturing in adult humans. When we see a living creature with babyish features, we feel an automatic surge of disarming tenderness. " See rest of page for Gould's tie to neotonous features.

<104(103)> Chart taken form Lorenz

<104(106)> "Our embryonic skulls scarcely differ from those of chimpanzees. And we follow the same path of changing form through growth: relative decrease of the cranial vault since brains grow so much more slowly than bodies after birth, and continuous relative increase of the jaw. But while chimps accentuate these changes, producing an adult strikingly different in form from a baby, we proceed much more slowly down the same path and never get nearly so far. Thus, as adults, we retain juvenile features. To be sure, we change enough to produce a notable difference between baby and adult, but our alteration is far smaller than that experienced by chimps and other primates." "A marked slowdown of developmental rates has triggered our neotony. Primates are slow developers among mammals, but we have accentuated the trend to a degree matched by no any other mammal. We have very long periods of gestation, markedly extended childhoods, and the longest life span of any mammal. The morphological features of eternal youth have served us well. Our enlarged brain is, at least in part, a result of extending rapid prenatal growth rates to other areas. (In all mammals, the brain grows rapidly in utero but often very little after birth. We have extended this fetal phase into postnatal life.)"

<104(132-3)> "By the time we became upright as A. afarensis, the game was largely over, the major alteration of architecture accomplished, the trigger of future change already set. The later enlargement of our brain was anatomically easy. We read our larger brain out of the program of our own growth, by prolonging rapid rates of fetal growth to later times and preserving, as adults, the characteristic proportions of a juvenile primate skull. And we evolved this brain in concert with a host of other neotenic features, all part of a general pattern."

<105(64-5)> Lists Bolk's neotonous features: 1) bulbous cranium 2) juvenile face 3) Position of foramen magnum 4) late closure of skull sutures 5) ventral pointing of vaginal canal 6) strong, unrotated, nonopposable big toe plus others.

<111(576-7)> Description by Darwin of neotonous elements of human females.

"Subtracting facial length, Broca obtained the following figures for anterior cranium: 78.351 for whites, 72.628 for blacks. In other words, based on the cranium alone, the foramen magnum of blacks lay farther forward (the ratio of front to back, calculated from Broca's data, is .781 for whites, and .720 for blacks). Clearly, by criteria explictly accepted before the study, blacks are superior to whites. Or so it must be, unless the criteria suddenly shift, as they did forthwith." (Gould 1996: 134, The Mismeasure of Man)

"Flexibility is the hallmark of human evolution. If humans evolved, as I believe, by neoteny (see Chapter 4 and Gould, 1977, pp. 352-404), then we are, in a more than metaphorical sense, permanent children. (In neotony, rates of development slow down and juvenile stages of ancestors become the adult features of descendants.) Many central features of our anatomy link us with fetal and juvenile stages of primates: small face, vaulted cranium and large brain in relation to body size, unrotated big toe, foramen magnum under the skull for correct orientation of the head in upright posture, primary distribution of hair on head, armpits, and pubic areas. If one picture is worth a thousand words, consider Fig 7.1. In other mammals, exploration, play, and flexibility of behavior are qualities of juveniles, only rarely of adults. We retain not only the anatomical stamp of childhood, but its mental flexibility as well. The idea that natural selection should have worked for flexibility in human evolution is not an ad hoc notion born in hope, but an implication of neoteny as a fundamental process in our evolution. Humans are learning animals." (Gould 1996: 363, The Mismeasure of Man)

Mivart's description of his belief that birds don't fly by natural selection. (Mivert 1871: 83-86, 144-46. Genesis of Species) [Gould's description of Mivart's beliefs sounded like the acceleration theory of Cope]

"It has been speculated that bonobos evolved through retention of juvenile characteristics into adulthood, a process known as neoteny. For example, the smaller skull of the adult bonobo remined both Schwarz and Coolidge of a juvenile chimpanzee. Bonobos also keep their white tail-tufts, which chimpanzees lose after weaning age. The voices of adult bonobos are as shrill as those of juvenile chimpanzees, and even the frontally oriented vulva is considered a neotenous characteristic, also present in our own species." (De Wall & Lanting 1997: 27, Bonobo)

[quoting Takayoshi Kuroda in interview] "The long dependence of the son may be caused by the slow growth of the bonobo infant, which seems slower than in the chimpanzee. For example, even after one year of age, bonobo infants do not walk or climb much, and are very slow. The mothers keep them near. They start to play with others at about 1.5 years, which is much later than in the chimpanzee. During this period, mothers are very attentive. The two may develop a very intense communication because an infant unable to reach certain objects will call the mother, and the mother then comes over to help." (De Wall & Lanting 1997: 60, Bonobo)

Bonobo life stage chart says Nursing period 0-5, First genital swelling (onset of adolescence) 7, Begins to wander between groups 8, Settles into new group 9-13, Menarche and first full-sized swelling 10, Growth-cessation (adult size reached) 14-16, First offspring 13-15, Cessation of ovulation (menopause) 40, Longevity 50-55. (De Wall & Lanting 1997: 190, Bonobo)

"Now, in the light of various cases observed, where members of the same species or brood are found at adult age to differ in the number of immature characters they possess, we may conclude that man originated in the following way: that is, by a delay of retardation in growth of the body and fore limbs as compared with the head; retardation of the jaws as compared with the brain case, and retardation in the protrusion of the canine teeth. The precise process as regards the hinder thumb remains obscure, but it is probably a very simple matter. The proportions of the young Cebus appella enable it to walk on the hind limbs with great facility, and it does so much more frequently than an adult capucinus with which it is contined. The "retardation" in the growth of the jaws still progresses. Some of our dentists have observed theat the last (3rd) molar teeth (wisdom teeth) are in natives of the United States very liable to imperfect growth or suppression, and to a degree entirely unknown among savage or even many civilized races. The same suppresion has been observed in the outer pair of superior incisors. This is not only owing to a reduction in the size of the arches of the jaws, but to successively prolonged delay in the appearance of the teeth." (Cope 1887: 12, Origin of the Fittest)

"Two characters could hardly be wider apart than the size and development of man's brain and the distribution of hair upon the surface of his body, yet they both lead us to the same conclusion---that some other power than natural selection has been engaged in his production." (Wallace 1895: 197, Natural Selection)

"Throughout the whole of the quadrumana the foot is prehensile, and a very rigid selection must therefore have been needed to bring about that arrangement of the bones and muscles which has converted the thumb into a great toe, so completely, that the power of opposability is totally lost in every race, whatever some travellers may vaguely assert to the contrary. It is difficult to see why the prehensile power should have been taken away." (Wallace 1895: 197, Natural Selection)

"A student of Graham Bell's named Austin Burt went out and looked at the real world to see if the tangled bank fitted the facts. He looked not at whether mammals have sex but at how much recombination goes on among their genes. He measured this quite easily by counting the number of "crossovers" on a chromosome. These are spots where, quite literally, one chromosome swaps genes with another. What Burt found was that among mammals the amount of recombination bears no relation to the number of young, little relation to body size, and close relation to age at maturity. In other words, long lived, late-maturing mammals do more genetic mixing regardless of their size of fecundity than short-lived, early maturing mammals. But Burt's measure, man has thirty crossovers, rabbits ten, and mice three. Tangled-bank theories would predict the opposite." (Ridley 1993: 62, The Red Queen)

"A female deer has little need of a monopolized male. He cannot produce milk or bring grass to the young. So the mating system of a deer is determined by the battle among males, which in turn is determined by how females decide to distribute themselves. Where females live in herds (for example, elk), males can be harem masters. Where females live alone (white-tailed deer), males are territorial and mostly monogamous. Each species has its own pattern, depending on the behavior of the female. In the 1970's zoologists began to investigate these patterns to try to find out what determined a species, mating system. They coined a new term, "socioecology," in the process. Its most successful forays were into antelope and monkey society. Two studies concluded that the mating system of an antelope or a primate could be safely predicted from its ecology. Small forest antelopes are selected feeders and , as a consequence, are solitary and monogamous. Middle-sized, open-woodland ones live in small groups and form harems. Big plains antelopes, such as the eland and African buffalo, live in great herds and are promiscous. At first a very similar system seemed to apply to monkeys and apes. Small nocturnal bush babies and solitary and monogamous; leaf-eating indris live in harems, forest-fringe-dwelling gorillas live in small harems; tree-savanna chimps live in large promiscous groups; grassland baboons live in large harems or multimale troops." (Ridley 1993: 187, The Red Queen)

"The evidence for neoteny is extensive. Human teeth erupt through the jaw in a set order: the first molar at the age of six, compared with three for a chimp. This pattern is a good indication of all sorts of other things because the teeth must come at just the right moment relative to the growth of the jaw. Holly Smith, an anthropologist at the University of Michigan, found in twenty-one species of primate a close correlation between the age at which the first molar erupted and body weight, length of gestation, age at weaning, birth interval, sexual maturity, life span, and especially brain size. Because she knew the brain size of fossil hominids, she was able to predict that Lucy would have erupted her first molar at three and lived to forty, much like chimpanzees, whereas the average Homo eretus would have erupted his at nearly five and lived to fifty-two." (Ridley 1993: 327, The Red Queen)

"Indeed, the mechanism by which ape-men turned into men was clearly a genetic switch that simply slowed the developmental clock." (Ridley 1993: 328, The Red Queen)

"Turning an ape-man into a man was a simple matter of changing the genes that affect the rate of development of adult characters, so that by the time we stop growing and start breeding, we still look rather lke a baby." (Ridley 1993: 327, The Red Queen)

"I believe that Miller's tale deserves a special twist from the neoteny theory (although he is not convinced). The neoteny theory is well established among anthropologists. And the notion of human monogamous child rearing is well established among sociobiologists. Nobody has yet put the two together. If men began selecting mates that appeared youthful, then any gene that slowed the rate of development of adult characteristics in a woman would make her more attractive at a given age than a rival. Consequently, she would leave more descendants, who would inherit the same gene. Any neoteny gene would give the appearance of youthfulness. Neoteny, in other words, could be a consequence of sexual selection, and since neoteny is credited with increasing our intelligence (by enlarging the brain size at adulthood), it is to sexual selection that we should attribute our great intelligence." (Ridley 1993: 342, The Red Queen)

"Christopher Badcock, a sociologist at the London School of Economics who unusually combines an interest in evolution and an interest in Freud, has propose a similar idea. He suggested that neotonic (or, as he call it, "paedomorphic") traits were favored by female choice rather than male choice. Younger males, he suggests, made more cooperative hunters, and therefore females who wanted meat picked younger-looking men. The principle is the same: Neotenic development is a consequence of a preference for it in one sex." (Ridley 1993: 343, The Red Queen)

"Horses change relatively little in shape during growth, and the heads of Shetland ponies do not differ much from those of the largest workhorses. Pigs, on the other hand, are second only to dogs in diversity of breeds. They are also unmatched among farm animals for marked change of shape during growth. Amounts of intrinsic variation therefore sets limits and supply possibilities to breeders. but even the moset variable of wild species do not become putty in the hands of breeders. Pigs and dogs vary in definite ways during their growth, and only certain shapes are available for selection at definite sizes. Wayne's most persuasive case for internal limits lies in his demonstration that sets of traits in a standard "ontogenetic trajectory: (a sequence of stages from puppy to adult) tend to hang together. Dog breeds are not a hodgepodge of isolated traits, each taken at will from any stage of ontogeny. Traits of juvenility remain associated, and many breeds, particularly among small dogs, continue to look like puppies when adult---an evolutionary process called paedomorphosis (child-shaped) or neoteny (literally, "holding on to youth"). Wayne has shown that---without exception---adults of small breeds resemble the juvenile stages of large dogs more than the adults of other wild canid species (small foxes)---a convincing demonstration that inherited patterns of growth set possibilities of change. Dogs resolutely stick to their own trajectories of growth. "To some extent." Wayne concludes, "many dog breeds represent morphological snapshots between developmental endpoints.... This suggests that small domestic dogs differ from foxes because puppies of small dogs cannot grow out of their distinctive neonate morphology. We know, of course, that breeders can do many wonderful and peculiar things, from making a dachshund into a frankfurter to turning a chihuahua into a hairless rat or a sheepdog into a woolly mimic of its charges. But these peculiarities are imposed upon a basic and unaltered pattern set by constraints of inherited growth. The trajectory of ontogeny provides, as Raymond Capplinger states, a "rough first draft" for all breeds. If ordinary variation in growth provides the main source for breeders, then a wild species' own juvenile stages are the primary storehouse of available change. Under this basic theme of limits, we may understand an old and otherwise puzzling observation about domesticated versus wild species. Over and over again, we note that domestic species develop more juvenile proportions than their wild ancestors. We cannot explain this difference by smaller size (since domestic breeds are often larger than their ancestors) or by conscious selection on the old theme of planned optimality, for what possible common adaptive advantage could have inspired breeders to produce such a similarly shortened face in Middle white pigs, the Niatu oxen of South America, and the pekingese of the Chinese imperial court (see figure). The only sensible coordinating theme behind these similarities is retention by neoteny of juvenile traits common to most vertibrates. If these shared neotenous traits of domesticated species are not products of direct selection by breeders, then what is the common basis of their origin? Most experts argue that these juvenile traits are spinoffs from the true object of selection---tame and playful behavior itself. Organisms may vary as much in rates of development as in form. By breeding only those animals that retain the favored juvenile traits of plaint and flexible behavior past the point of sexual maturity, humans hasten the process of domestication itself. Since traits are locked together in development, not infinitely dissociable as hopes for optimality require, selection for desired juvenile behavior brings features of juvenile morphology along for the ride." (Gould 1993: 391-2, Eight Little Piggies)

"Coppinger notes the great, and usually unappreciated, difference between guarding and herding breeds. Herders control movement of sheep by using predatory behaviors of adult dogs---stalking, chasing, biting, and barking---but inhibiting the final outcome. These breeds feature adult traits of form and behavior; they display no neotenous characteristics. Guard dogs, on the other hand, simply move with and among the flock. They work alone and do not control the flock's motion. They afford protection primarily by their size, for few coyotes will attack a flock accompanied by a one-hundred-pound dog. They behave toward the sheep as puppies do towards other dogs---licking the sheep's face as a puppy might in asking for food, chasing and biting with the playfulness of young dogs, even mounting sheep as young dogs mount each other is sexual play and rehearsal. This neotenous behavior accompanies a persistently juvenile morphology, as these dogs grow short faces, big eyes, and floppy ears. Coppinger has raised guarding and herding dogs together from babyhood. They show little difference in behavior until puberty. Herders then develop the standard traits of adulthood---border collies begin to stalk, while retrievers and pointers live up to their names. But the guarders develop no new patterns and simply retain their youthful traits. Thus, a valuable set of features can be recruited together because they already exist as the normal form and behavior of juvenile dogs. Patterns of growth are rich reservoirs, not sterile strictures." (Gould 1993: 394, Eight Little Piggies)

[concerning a model of lateralization where stages of human individual development are associated with stages of hominid development] "The 20-step ontogenetic sequence in Table 1 to 4 may be applicable to the phylogenetic emergence of our species. There may not be a one-to-one parallel in developmental stages and ancestral ones because of processes such as neoteny and acceleration (Gould, 1977), which function to alter or affect the former sequence in relation to the latter." (Hammond ed. (Gerald Young author) 1990: 113, Cerebral Control of Speech and Limb Movements)
"Finally, all domestic animals, in both behavior and appearance, retain juvenile traits in adulthood. One of the very first hints in the archaeologicl record of an animal's domestication is the jawbone of a wolf from southwest Asia, dated twelve thousand years ago, in which the fact and muzzel have begun to shorten---an adult with the face of a puppy---crowding the teeth together. It is a process that has been repeated in every domenstic animal." (Budiansky 1992: 17, The Covenant of the Wild)

"The ice sheets moved as much as two hundred feet per year at their swiftest. The entire process was accompanied by other environmental swings, in precipitation, ocean levels, and lake sizes. A series of smaller and faster fluctuations occured within each major glacial period, but even these small cycles were on the order of several degrees over a few hundred years, much greater than anything in historical experience. Raymond Coppinger advances the intriguing argument that such a traumatic fluctuation in habitat would have "penalized" any high degree of specialization within a species. As ranges expanded and contracted, as the forests moved northward behind the returning ice cover and then retreated themselves behind the returning glaciers, a species that was locked into a single, highly specialized mode of existence would be less competitive. It is risky to make hard-and-fast correlations between extinctions and climate, but the entire glacial epoch was marked by the displacement of many animals from their accustomed ranges and by sudden extinctions that may have left many ecological niches unfilled. An enormous variety of new animals appeared---mastodons, mammoths, giant sheep and goats, saber-toothed tigers, huge-horned rhinos---and disapeared." (Budiansky 1992: 74, The Covenant of the Wild)

"How can Darwinian evolution overcome this inherent speed limit on change? There is one source of enormous variation within a species that can be tapped---the change that all mammals and birds undergo in the course of developing from an infant to an adult. The range of variation that one sees within any adult population is miniscule compared with the differences that separate the average adult from the average juvenile. Both physical characteristics---everything from body shape and color to internal organs---and behavior change dramatically during development. And if adulthood is reached before the "normal" process of development is complete, some of the very stikingly youthful characteristics of the species will be locked in, while characterisitically adult behaviors and structures are never developed or activated. Because the entire process of development is under genetic control, relatively small changes in the genes that determine the rate of development can produce enormous changes in the adult form." (Budiansky 1992: 77, The Covenant of the Wild)

"This systematic neoteny, selected as a way to adapt to a changing world, would have laid an even more solid foundation for the interations of humans and other animals. The curiosity, the lack of a highly species-specific sense of recognition, and the retention into adulthood of juvenile care-soliciting behavior (such as begging for food) of neotenates would all have been powerful factors in inducing wolves, sheep, cattle, horses, and many other occupants of Asian and European grasslands of the late glacial era to approach human encampments and to allow humans to approach them. The neoteny that is part of our own evolutionary heritage may have likewise made us more willing to enter into relationships with animals other than the highly specialized one of predator to prey." (Budiansky 1992: 80, The Covenant of the Wild)

"And since neoteny couples traits such as adaptablitity with docility, the selective pressures that manmight apply to animals that encroached upon his place of dwelling---namely tolerating those that are tame, while driving off or killing those that are aggressive---would reinforce this selection of neotenic characteristics." (Budiansky 1992: 89, The Covenant of the Wild)

"But although silver foxes had been bred in captivity since 1892 on fur farms, and although some selective breeding for traits such as fertility and high fur quality had been practiced, the animals were not domesticated in any strict sense. They retained all of the essential characteristics of their wild counterparts. They molted and came into heat ina strict seasonal cycle, as in the wild; their behavior toward humans was no different than that of a wild fox raised in captivity. So Belyaev decided to try an experiment. He would rigorously select animalsapplying but a single criterion: Those animals that shoed consistently tame behavior toward humans would be kept; those that did not would be eliminated from the breeding program. Within five generations changes were already apparent. By 1979, twenty years into the experiment, the results were astonishing. His tame-selected foxes were not just tame; they acted for all the world like domestic dogs. They approached familiar persons and licked their hands and faces. They barked like dogs. They even sought the attention of strangers by whinning and wagging their tails. Their annual molting cycle was disrupted, and the females began to come into heat twice a year, like dogs, and unlike both foxes and wolves. they also developed some physical characteristics of young foxes, such as drooping ears, and some of the variations in traits seen in other domesticated animals, such as piebald coat coloration. Belyaev in an astonishingly short time produced not just one new trait, but a whole package of new characteristics. What he had done, by selecting for nothing more than tameness, was to tap into the same powerful evolutionary tool that nature had employed as a solution to the successive ecological catastrophes of the ice ages: neoteny." (Budiansky 1992: 96-7, The Covenant of the Wild)

"The shifts in patterns of size and shape relative to age among the major body regions in a transformation of P. troglodytes to P. paniscus (Fig 1D) demonstrate that the adult pygmy chimpanzee exhibits paedomorphosis of skull form via neoteny; it is characterized by an overall skull size and shape closely resembling younger subadult stages of P. troglodytes (23). (Shea, B.T. (1983) Paedomorphosis and neotony in the pygmy chimpanzee. Science 222: pp. 522)