Rapid morphological change in living humans: implications for modern human origins

Human body size and body proportions are interpreted as markers of ethnicity, 'race,' adaptation to temperature, nutritional history and socioeconomic status. Some studies emphasize only one of these indicators and other studies consider combinations of indicators. To better understand the biocultural nature of human size and proportions a new study of the growth of Maya-American youngsters was undertaken in 1999 and 2000. One purpose of this research is to assess changes in body proportion between Maya growing up in the US and Maya growing up in Guatemala. Height and sitting height of 6-12-year-old boys and girls (n=360) were measured and the sitting height ratio [sitting height/height]x100, a measure of proportion, was calculated. These data are compared with a sample of Maya of the same ages living in Guatemala and measured in 1998 (n=1297). Maya-American children are currently 10.24 cm taller, on average, and have a significantly lower sitting height ratio, (i.e. relatively longer legs, averaging 7.02 cm longer) than the Guatemala Maya. Maya-American children have body proportions more like those of white children in the US than like Maya children in Guatemala. Improvements in the environment for growth, in terms of nutrition and health, seem to explain both the trends in greater stature and relatively longer legs for the Maya-Americans. These findings are applied to the problem of modern human origins as assessed from fossil skeletons. It has been proposed that heat adapted, relatively long-legged Homo sapiens from Africa replaced the cold adapted, relatively short-legged Homo neandertalensis of the Levant and Europe [J Hum Evol 32 (1997a) 423]. Skeletal samples of Maya adults from rural Guatemala have body proportions similar to adult Neandertals and to skeletal samples from Europe with evidence of nutritional and disease stress. Just as nutrition and health status explains the differences in the body proportions of living Maya children, these factors, along with adaptation to climate, may also explain much of the differences between the Neandertal and African hominid samples.     

Delineating genetic relationships among the Maya

By 250 AD, the Classic Maya had become the most advanced civilization within the New World, possessing the only well-developed hieroglyphic writing system of the time and an advanced knowledge of mathematics, astronomy and architecture. Though only ruins of the empire remain, 7.5 million Mayan descendants still occupy areas of Mexico, Guatemala, Belize, El Salvador, and Honduras. Although they inhabit distant and distinct territories, speak more than 28 languages, and have been historically divided by warfare and a city-state-like political system, and they share characteristics such as rituals, artistic, architectural motifs that distinguish them as unequivocally Maya. This study was undertaken to determine whether these similarities among Mayan communities mirror genetic affinities or are merely a reflection of their common culture. Four Mayan populations were investigated (i.e., the K'iche and Kakchikel from Guatemala and the Campeche and Yucatan from Mexico) and compared with previously published populations across 15 autosomal STR loci. As a whole, the Maya emerge as a distinct group within Mesoamerica, indicating that they are more similar to each other than to other Mesoamerican groups. The data suggest that although geographic and political boundaries existed among Mayan communities, genetic exchanges between the different Mayan groups have occurred, supporting theories of extensive trading throughout the empire.     

Porotic Hyperostosis and Paleoepidemiology: A Forensic Perspective on Anemia among the Ancient Maya

Porotic lesions caused by childhood anemia are commonly found on ancient Maya crania and have been cited as evidence for extremely poor nutrition during the Classic Period. We reconsider this characterization in the light of recent data on childhood anemia in rural Guatemala and the prevalence of porotic hyperostosis in crania of forensic skeletal remains of rural highland Maya from Plan de Sanchez, Baja Verapaz, which date to 1982. The abundance of porotic hyperostosis in adults from Plan de Sanchez fits well with the number of modern rural children suffering from anemia, but the lesions are very rare compared to archaeological series. Although some minor change in diet and infection may contribute to differences in porotic hyperostosis, it is likely that higher mortality leads to fewer anemic lesions in modern adult crania. We hypothesize that more anemic children survived to adulthood in the past than do today, [iron-deficiency anemia, porotic hyperostosis, Maya, nutrition, forensic anthropology, osteological paradox]     

Economic and anthropological assessments of the health of children in Maya immigrant families in the US.

Immigration from developing countries to the US generally increases access to health care and clean water, but it also introduces some unhealthy lifestyle patterns, such as diets dense in energy and little regular physical activity. We present a transdisciplinary model of child health and examine the impact of immigration on the physical growth and health of Maya children in Guatemala and the US. Maya-American children are much taller and have longer legs, on average, than their counterparts in Guatemala. This suggests that immigration to the US improves their health. However, the Maya-American children also are much heavier than both Guatemalan Maya and White American children, and have high rates of overweight and obesity. Quantile regression analysis indicates that Maya are shorter except in the upper tail of the stature distribution, and have higher Body Mass Index (BMI) in the tails, but not in the middle of the BMI distribution. Leisure time spent in front of a television or computer monitor tends to raise BMI in the middle and lower tail of the distribution, but not in the upper tail.     

Plasticity,political economy,and physical growth status of Guatemala Maya children living in the United States

Migration of Maya refugees to the United States since the late 1970s affords the opportunity to study the consequences of life in a new environment on the growth of Maya children. The children of this study live in Indiantown, Florida, and Los Angeles, California. Maya children between 4 and 14 years old (n = 240) were measured for height, weight, fatness, and muscularity. Overall, compared with reference data for the United States, the Maya children are, on average, healthy and well nourished. They are taller and heavier and carry more fat and muscle mass than Maya children living in a village in Guatemala. However, they are shorter, on average, than children of black, Mexican-American, and white ethnicity living in Indiantown. Children of Maya immigrants born in the United States tend to be taller than immigrant children born in Guatemala or Mexico. Families that invest economic and social resources in their children tend to have taller children. More economically successful families have taller children. Migration theory and political economy theory from the social sciences are combined with plasticity theory and life history theory (parental investment) from biology to interpret these data. Am J Phys Anthropol 102:17–32, 1997. © 1997 Wiley-Liss, Inc.     

Ritual responses to drought: An examination of ritual expressions in Classic Maya written sources

Planting and rain-beckoning rituals are an extremely common way in which past and present human communities have confronted the risk of drought across a range of environments worldwide. In tropical environments, such ceremonies are particularly salient despite widespread assumptions that water supplies are unproblematic in such regions. We demonstrate for the first time that two common but previously under-appreciated Maya rituals are likely planting and rain-beckoning rituals preferentially performed at certain times of the year in close step with the rainy season and the Maya agricultural cycle. We also argue for considerable historical continuity between these Classic Maya ceremonies and later Maya community rituals still performed in times of uncertain weather conditions up to the present day across Guatemala, Belize, and eastern Mexico. During the Terminal Classic period (AD 800-900), the changing role played by ancient Maya drought-related rituals fits into a wider rhetorical shift observed in Maya texts away from the more characteristic focus on royal births, enthronements, marriages, and wars towards greater emphasis on the correct perpetuation of key ceremonies, and we argue that such changes are consistent with palaeoclimatic evidence for a period of diminished precipitation and recurrent drought.     

Assessing the impact of ancient Maya animal use

Tropical forest animals are at high risk worldwide as a result of over-exploitation and forest clearing. Zooarchaeological studies of animal use by the ancient Maya of the southern lowland regions of Guatemala, Honduras, Belize, and Mexico provide long-term historical information on animal populations under conditions of human population growth and climatic change that is valuable to both archaeology and conservation biology. In this paper, zooarchaeological data from 35 chronologically defined faunal sub-samples recovered from 25 ancient Maya archaeological sites are used to assess the effects of ancient hunting on animal populations of the Maya region between the Preclassic and Colonial periods (2000 BC–AD 1697). The variations in species abundance are used as a proxy for describing changes in ancient Maya hunting practices and hunted animal populations, interpreted on the basis of hunting efficiency models from foraging ecology. A significant reduction in the proportion of large mammals, particularly Odocoileus virginianus, in zooarchaeological assemblages between the Late Classic (AD 600–850) and Terminal Classic/Postclassic periods (AD 850–1519) suggest that over-hunting during the Late Classic may have led to a reduction in availability of these animals to the ancient Maya hunters in the later periods. This finding is discussed in relation to important social and environmental variations to evaluate the impact of hunting and other factors such as forest clearance and climate on ancient animal populations in the Maya region.     

Patterns of growth and malnutrition among preschoolers in Belize

An anthropometric survey of 750 preschoolers was conducted during 1979 in Belize to assess nutritional status in two districts, one coastal and the other inland. Mothers were interviewed concerning reproductive history, child's health and dietary history, and associated factors. Analysis included the recognition of low arm circumference, weight-for-age, stature-for-age, and weight-for-stature. Survey results indicate that about 25% of the children, birth to 5 years old, show evidence of stunting, while 2.5% show evidence of wasting. Comparisons of rates of malnutrition by ethnic group reveal that the Maya and Garifuna (Black Carib) children are significantly more commonly malnourished than others. Applying a discriminant function to groups of children designated as “poor” and “better-than-average” growth classes reveals several factors which may be contributory to the etiology of preschool malnutrition in Belize. The frequency of diarrhea and age at introduction to solid foods, are significantly related to growth retardation among preschoolers. Analysis of 24-hour-diet recalls corroborates the patterning of malnutrition among ethnic groups.     

Sacred Giants: Depiction of Bombacoideae on Maya Ceramics in Mexico,Guatemala, and Belize

Sacred Giants: Depiction of the Malvaceae Subfamily Bombacoideae on Maya Ceramics in Mexico, Guatemala, and Belize This study categorized and identified plants depicted on Maya ceramics from the Classic Period (250 a.d.–900 a.d.). We chose art objects with a predominance of iconographic images of Malvaceae subfamily Bombacoideae, which are easily identified morphologically and have culinary, medicinal, ceremonial, economic, and cosmological significance to the Maya. Among ten species of Bombacoideae native to the Southern Lowlands region of Central America (Belize, parts of Guatemala, and Mexico), the Maya utilized at least six, which also have Maya names. We observed four or five bombacoid species depicted on Maya ceramics; most images were identifiable to genus. Burial urns and incensarios (incense burners) commonly had images of trunk spines of Ceiba pentandra, the Maya “World Tree.” Flowers of Pseudobombax ellipticum, a plant used to make ceremonial beverages, were most similar to floral images portrayed on vessels, bowls, and plates, although the morphologically similar flowers of Pachira aquatica may also be depicted. Plants representing Quararibea funebris or Q. guatemalteca, which were used during preparation of cacao beverages, were discernable on drinking vessels.     

Language and cultural contacts among Yukatekan Mayans

The Yukatekan branch of the Maya language family, spread across the Yucatán Peninsula of Mexico, northern Guatemala, and Belize, began to diversify approximately 1,000 years ago. Today it has four branches: Mopan Maya, Itzaj Maya, Lakantun Maya and Yukatek Maya proper, which have widely varying language statuses. Lakantun and Itzaj Maya are seriously threatened, while Mopan appears to have a stable or growing population of approximately 10,000 speakers and Yukatek has a very large number of speakers, perhaps 750,000. However, even many Yukateks believe that their language is threatened and that shift to Spanish is underway. During the past millennia there has been a series of contacts involving migration, trade, warfare, and flight among the different branches, as well as with other Mayan languages and with the Spanish. This paper examines a variety of different kinds of contact, and how the different language varieties were involved and affected. One goal of the paper is to better understand how the dynamics of inter-cultural contacts affects language practices resulting in very different language statuses and ideologies.     

Population structure of the Classic period Maya

This study examines the population structure of Classic period (A.D. 250-900) Maya populations through analysis of odontometric variation of 827 skeletons from 12 archaeological sites in Mexico, Guatemala, Belize, and Honduras. The hypothesis that isolation by distance characterized Classic period Maya population structure is tested using Relethford and Blangero's (Hum Biol 62 (1990) 5-25) approach to R matrix analysis for quantitative traits. These results provide important biological data for understanding ancient Maya population history, particularly the effects of the competing Tikal and Calakmul hegemonies on patterns of lowland Maya site interaction. An overall F(ST) of 0.018 is found for the Maya area, indicating little among-group variation for the Classic Maya sites tested. Principal coordinates plots derived from the R matrix analysis show little regional patterning in the data, though the geographic outliers of Kaminaljuyu and a pooled Pacific Coast sample did not cluster with the lowland Maya sites. Mantel tests comparing the biological distance matrix to a geographic distance matrix found no association between genetic and geographic distance. In the Relethford-Blangero analysis, most sites possess negative or near-zero residuals, indicating minimal extraregional gene flow. The exceptions were Barton Ramie, Kaminaljuyu, and Seibal. A scaled R matrix analysis clarifies that genetic drift is a consideration for understanding Classic Maya population structure. All results indicate that isolation by distance does not describe Classic period Maya population structure.     

Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region

We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (⁸⁷Sr/⁸⁶Sr) and oxygen (δ¹⁸O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region.     

Genetic Evidence for Multiple Sources of the Non-Native Fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in Southern Florida

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions.     

Growth status of disadvantaged urban Guatemalan children of a resettled community

This paper reports the physical growth and body composition from the first year of longitudinal study of 519 Guatemalan children, and their families, from a disadvantaged urban community consisting largely of refugees of the 1976 earthquake. Four cohorts are described, composed of children of 1,3,5, and 7 years at examination. The children are smaller, weigh less, and have reduced fat stores compared either to NCHS reference data or to upper SES Guatemalan children. Stature (or length) and head circumference deviate more from reference data than do triceps or upper arm muscle circumference. Greater deviations are found in the linear dimensions of males than of females. These children are the smallest yet described from Guatemala City, though they are slightly larger than available rural samples. This suggests a continuum of environmental effects acting upon the growth of children of differing socioeconomic levels.     

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

Early-life conditions shape childhood growth and are affected by urbanization and the nutritional transition. To investigate how early-life conditions (across the “first” and “second” 1000 days) are associated with rural and urban children's nutritional status, we analyzed anthropometric data from Maya children in Yucatan, Mexico. We collected weight, height and triceps skinfold measures, then computed body mass and fat mass indices (BMI/FMI), in a cross-sectional sample of 6-year-olds (urban n = 72, rural n = 66). Demographic, socioeconomic and early-life variables (birthweight/mode, rural/urban residence, household crowding) were collected by maternal interview. We statistically analyzed rural-urban differences in demographic, socioeconomic, early-life, and anthropometric variables, then created linear mixed models to evaluate associations between early-life variables and child anthropometric outcomes. Two-way interactions were tested between early-life variables and child sex, and between early-life variables and rural-urban residence. Results showed that rural children were shorter-statured, with lower overweight/obesity and cesarean delivery rates, compared to urban children. Household crowding was a negative predictor of anthropometric outcomes; the strongest effect was in boys and in urban children. Birthweight positively predicted anthropometric outcomes, especially weight/BMI. Birth mode was positively (not statistically) associated with any anthropometric outcome. Cesarean delivery was more common in boys than in girls, and predicted increased height in urban boys. In conclusion, urbanization and household crowding were the most powerful predictors of Maya 6-year-old anthropometry. The negative effects of crowding may disproportionately affect Maya boys versus girls and urban versus rural children. Early-life conditions shape Maya children's nutritional status both in the “first” and “second” 1000 days.     

Body composition and nutritional status of urban Guatemalan children of high and low socioeconomic class

The effects of socioeconomic differences on the nutritional status of two groups of urban living children are considered via an anthropometric assessment of body composition. The sample consists of 981 Guatemala City children, 7.00 to 13.99 years old, of high and low socioeconomic status (SES). High SES children have larger median values for triceps skinfold, subscapular skinfold, arm circumference, and estimated mid-arm muscle and fat areas than low SES children. Compared with children of a US reference sample, the high SES children generally have larger values for all variables and the low SES children have smaller values. However, the differences between the low SES children and the children of the other two samples are greater for arm fat area than for arm muscle area. The analysis suggests that low SES Guatemalan children suffer to a greater extent from chronic energy, rather than protein, undernutrition. A similar pattern of energy malnutrition has been observed for rural Guatemalan children. These combined data suggest that estimates of fat reserves of the arm provide a useful indication of nutritional status for Third-World children. Results from rural Costa Rican and Honduran studies have been taken to mean that muscle reserves are better than fat reserves as indicators of nutritional status in developing countries. But, those studies did not estimate cross-sectional muscle and fat areas and only considered the extremes of the population distribution for muscle and fat.     

Variation in juvenile dependence

Notable in cross-cultural comparisons is the variable span of time between when children become economically self-sufficient and when they initiate their own reproductive careers. That variation is of interest because it shapes the age range of children reliant on others for support and the age range of children available to help out, which in turn affects the competing demands on parents to support multiple dependents of different ages. The age at positive net production is used as a proxy to estimate the close of juvenile economic dependence among a group of Maya subsistence agriculturalists. Maya children produce more than they consume by their early to mid teens but remain in their natal households for a number of years before leaving home and beginning families of their own. The Maya results contrast markedly with those from several groups of hunter-gatherers and horticulturalists for whom we have similar data. Even in the Maya case, where children are self-sufficient at a relatively young age, parents are unable to support their children without help from others. The production surplus of older children appears to help underwrite the cost of large Maya families and subsidize their parents’ continued reproduction.     

Plant use by the q’eqchi’ maya of belize in ethnopsychiatry and neurological pathology

Plant Use by the Q’eqchi’ Maya of Belize in Ethnopsychiatry and Neurological Pathology. Economic Botany 59(4):326–336, 2005. Neurological and mental health disorders are extremely debilitating, and sufferers in developing countries often rely on traditional practitioners for these medical needs. Few studies have focused on botanical remedies used in this context, although these offer interesting treatment alternatives. The present study investigated plant use for the treatment of neurological and mental health disorders by Q'eqchi' Maya healers of southern Belize. We found that these healers generally recognize and treat epilepsy/seizures, headache, madness, fright (susto), depression, numbness, insomnia, and stress with herbal remedies. Quantitative analyses showed that there is selection for the use of certain species and botanical families, namely for species of the Pteridophyta division and for plants from the Piperaceae family. This study denotes the importance and selectivity of plant use by Q'eqchi' healers of southern Belize for the treatment of neurological and mental conditions and points to a possible underrepresentation of these disorders in the ethnobotanical literature.     

Seasonal pattern in the rate of growth in height of children living in Guatemala.

Monthly increments of height for a sample of 164 Guatemala City school children are analyzed for the presence of a seasonal pattern in rates of growth. It is found that pre and post adolescent children follow a seasonal pattern of growth but adolescent children do not. It is suggested that the results are due to an effect of seasonal changes in ultraviolet light availability and the synthesis of vitamin D3 as mediated by the level of maturation of each child.     

Biocultural Factors in School Achievement for Mopan Children in Belize

Mayan children in Belize face a number of challenges to school success. Their families are the poorest of the poor, and the Mopan children in this study exhibit poor growth and poor school achievement. But a direct relationship between growth and school achievement was evident only for current nutritional status, not for nutritional history. A combination of quantitative and qualitative data revealed that school achievement for these Mopan children may relate more to family attributes and attitudes than to health and nutritional status. The strongest predictors of school achievement were father's literacy and grade level in school.