A STUDY OF THE POPULATION NEAR AIOME, NEW GUINEA

The Melanesian Dwarf Tribe of Aiome, New Guinea

The Aiome dwarf tribe in the mountains near the Ramu river and its southern tributaries was studied. Observations, measurements and photographs were made of 15 men and five women who came in a party to the Aiome airstrip. The measurements are embodied in Table 1 (p. 280). They include eye and skin colour; head length and breadth; ear length and breadth and the presence of a lobe; stature; development of brow ridges and relative depression of the nasal root. Other observations are in the text. The mean male stature was 147.9 cm which is roughly the same as that of the Congo Pygmies. The shortest woman was only 125.5 cm. high. The C.I. of the men was 78.51 and the ears are smaller than in most races.

The head-dress, decorations and “dances” are illustrated in Figs. 1-18.

The skin colour of Papuans is a shade lighter than in the Australian aborigines. In a study of skin colour of Papuans, Macintosh (1960) finds that the natives recognize and have names for three shades of colour. These appear to be due to (1) the homozygous (2) the heterozygous condition, and (3) the absence, of a minor gene for skin colour.

The fact that the blood group genes A, B, M, S, R1 and R2 of the Aiome dwarfs are closely similar to those of the tails in the Mount Hagen area justifies the conclusion that a single gene dwarf mutation is involved. The Aiome and Wissel Lake dwarfs (400 miles apart) differ greatly in the frequency of the A, M, S and R2 (cDE) genes, but agree in the B and R1 (CDe) frequencies. The blood groups of the Congo Pygmies similarly agree with those of the Bantu, from whose ancestors they may have been derived.

The early literature regarding dwarf races is reviewed and the question of a Negrito race in southeast Asia is discussed. It is concluded that the term Negrito should probably be confined to the dwarf race in the Philippines. They perhaps reached the Philippines from Borneo when the sea-level was down during the last ice age.

On the basis particularly of skull form, the Andamanese were probably derived from the tall population of adjacent Malaya or Burma. The significance of their steatopygy and peppercorn hair is not clear, as these characters are found in the South African Bushmen.

The Semang of Malaya are mixed and of doubtful origin. The dwarf nature and relationships of the Kadar in South India remains uncertain. The incised designs on their wooden combs suggests a possible very ancient cultural connection with the Malayan dwarfs and the Philippine Negritos. A Negrito-like remnant in Queensland may represent in part the source from which the Tasmanian aborigines developed. The Veddas are outside the Negrito grouping. They are probably Australoids of reduced dimensions who migrated to Ceylon during the last ice age.

The various dwarf groups in New Guinea are of local (and probably relatively recent) origin, having no connection with Negritos, who appear to be of much earlier origin, probably before the last ice age. Various localities with populations of different mean stature are listed in Table 3, and others are mentioned in the text.

A statistical treatment of Bijlmer's measurements of stature, nasal and cephalic index, with the aid of Dr. Fraser Roberts, shows that many of the groups in Dutch New Guinea are significantly different. A fuller statistical investigation dealing with both stature and blood groups, is required to elucidate this situation. A tentative hypothesis is put forward, involving the fractionation of the original dwarf gene in the process of back-crossing between tails and dwarfs.

In New Guinea the coastal people are the tallest, those in the higher mountain areas are conspicous dwarfs, populations in intermediate areas being shorter in different degrees than the coastal tribes. That crossing takes place is shown by the occurrence of occasional men who are much taller than the rest of their group or tribe. Further studies of Papuan statures should also throw light on the origin of multiple genes for stature.

Climatic influences on human body size and proportions: ecological adaptations and secular trends

This study reevaluates the long-standing observation that human morphology varies with climate. Data on body mass, the body mass index [BMI; mass (kg)/stature (m)2], the surface area/body mass ratio, and relative sitting height (RSH; sitting height/stature) were obtained for 223 male samples and 195 female samples derived from studies published since D.F. Roberts' landmark paper "Body weight, race, and climate" in 1953 (Am. J. Phys. Anthropol. 11:533-558). Current analyses indicate that body mass varies inversely with mean annual temperature in males (r=-0.27, P < 0.001) and females (r=-0.28, P < 0.001), as does the BMI (males: r=-0.22, P=0.001; females: r=-0.30, P < 0.001). The surface area/body mass ratio is positively correlated with temperature in both sexes (males: r=0.29, P < 0.001; females: r=0.34, P < 0.001), whereas the relationship between RSH and temperature is negative (males: r=-0.37, P < 0.001; females: r=-0.46, P < 0.001). These results are consistent with previous work showing that humans follow the ecological rules of Bergmann and Allen. However, the slope of the best-fit regressions between measures of body mass (i.e., mass, BMI, and surface area/mass) and temperature are more modest than those presented by Roberts. These differences appear to be attributable to secular trends in mass, particularly among tropical populations. Body mass and the BMI have increased over the last 40 years, whereas the surface area/body mass ratio has decreased. These findings indicate that, although climatic factors continue to be significant correlates of world-wide variation in human body size and morphology, differential changes in nutrition among tropical, developing world populations have moderated their influence.

Evidence for a secular trend in heights and weights of adults in Papua New Guinea

Evidence for a secular change in heights and weights of adults of 13 populations in Papua New Guinea was sought by comparing data collected at two different times, using three types of source. These are: (1) values obtained from the literature; (2) previously unpublished measurements made by author; and (3) data found in the research notes of A.C. Haddon, and which were collected between 1897 and 1914. An increase in heights and weights has taken place in some, but not all, populations examined, whilst a decrease in adult body size has taken place in a smaller number of groups.

Insulin-like growth factors in pygmies. The role of puberty in determining final stature

We measured the serum concentrations of insulin-like growth factors (IGF) I and II and testosterone in pygmy children, adolescents, and adults, as well as in controls, to determine more precisely the role of these factors in controlling growth. We had previously shown that growth hormone levels were normal in pygmies. Prepubertal pygmy children and controls did not differ in linear growth or in serum concentrations of IGF I and II. In pygmy adolescent boys, the mean (+/- SEM) serum concentration of IGF I was only one third that in control adolescents, who were similar to the pygmies in age and Tanner stage of development (154 +/- 22 vs. 435 +/- 37 ng per milliliter; P less than 0.01). A similar difference in IGF I concentration was observed in girls (278 +/- 18 vs. 570 +/- 25 ng per milliliter; P less than 0.01). IGF II and testosterone levels were normal in all groups. There was a significant difference in growth between controls and pygmies only during puberty. There was a marked acceleration of growth in the controls during adolescence, but such an acceleration was absent or blunted in the pygmies. These findings suggest that the short stature of adult pygmies is due primarily to a failure of growth to accelerate during puberty. We postulate that IGF I is the principal factor responsible for normal pubertal growth and that testosterone does not accelerate growth appreciably in the absence of an increase in the level of IGF I.

Growth of the Asai child of the Madang district of New Guinea

A total of 249 children and 805 adults living in the Asai valley of the New Guinea highlands was examined and measured for height, weight, sitting height and skinfold thickness. Mean ages for groups of children were calculated from regression equations of height on age for different dental stages.

The growth of the Asai child in all measured parameters is slower than that reported from any other world situation. The relationship between the growth of the Asai child and adult size confirms the finding, previously reported for New Guinean populations, that adult stature in a traditional society is proportionally related to, and possibly determined by, the growth rate of children in that society.

Adult stature, which is at the lower end of the range for New Guinean populations, falls slightly with age, due to a decrease in trunk length. Weights and skinfold thickness, in common with other New Guinean populations, show a progressive fall with age.

The role of malnutrition in the slow growth pattern is discussed and evidence is presented from New Guinean and other studies to support the hypothesis that natural selection for slow growth and shorter adult height occurs in conditions of nutritional deprivation.