Evolutionary Model of Depression as an Adaptation for Blocked Social Mobility

Objectives@#In regard to the social competition hypothesis, depression is viewed as an involuntary defeat strategy. A previous study has demonstrated that adaptation in microenvironments can result in a wide range of behavioural patterns including defense activation disorders. Using a simulation model with evolutionary ecological agents, we explore how the fitness of various defence activation traits has changed over time in different environments with high and low social mobility. @*Methods@#The Evolutionary Ecological Model of Defence Activation Disorder, which is based on the Marginal Value Theorem, was used to examine changes in relative fitness for individuals with defensive activation disorders after adjusting for social mobility. @*Results@#Our study examined the effects of social mobility on fitness by varying the d-values, a measure of depression in the model.With a decline in social mobility, the level of fitness of individuals with high levels of defense activation decreased. We gained insight into the evolutionary influence of varying levels of social mobility on individuals’ degrees of depression. In the context of a highly stratified society, the results support a mismatch hypothesis which states that high levels of defence are detrimental. @*Conclusions@#Despite the fact that niche specialization in habitats composed of multiple microenvironments can result in diverse levels of defensive activation being evolutionary strategies for stability, decreased social mobility may lead to a decrease in fitness of individuals with highly activated defence modules. There may be a reason behind the epidemic of depression in modern society.

Principles of Archaeogenetics and the Current Trends of Ancient Genome Studies / 체질인류학회지

Archaeogenetics is an academic discipline that aims to establish scientific facts of human history by integrating ancient DNA analyses with archaeological and anthropological evidence. After ancient DNA research was initiated about 30 years ago, it has been innovated so rapidly that the range of analysis has been extended toward the whole genome sequence of ancient genomes in recent 10 years. By this development, researchers have been able to study in detail the origins and migration patterns of hominin species and ancient human populations by approaches of evolutionary genetics. This study has reviewed main principles of the archaeogenetic analysis and the current trends of ancient genome studies with recent achievements. While sampling techniques and statistical analyses have been improved, typical research methods have been established by the findings on hominins and ancient western Eurasia populations. Recently, archaeogenecists have been applying the methods to studying those in other geographical areas. Nonetheless, there is still the lack of ancient genome research about populations in Eastern Asia including the Korean peninsula. This review ultimately aims to predict possibilities and promise of future ancient genome studies of ancient Korean populations.

Paleopathological Studies of Infectious Disease: Examination of the Osteoarchaeological Research / 체질인류학회지

Reconstructing the impact of infectious disease on past populations is one of the main fields in paleopathological studies. The initial phase of paleopathology was descriptive, focusing on the identification and presence of disease in the past. However, currently paleopathological studies are moving toward probing questions about the larger picture of origin and transmission of disease agents. In this study, paleopathological studies of major infectious disease (i.e., tubuerculosis, treponemal disease and leprosy) were reviewed through osteoarcheological work published in American Journal of Physical Anthropology, International Journal of Osteoarchaeology, Journal of Archaeological Science and International Journal of Paleopathology from 1981 to 2017. A basic objective of this research was to examine many types of research in paleopathology and to characterize research trend in this field. As paleopathological studies becomes more abundant, the approaches to infectious disease have been increasingly specialized and interdisciplinary from 1980. Also, methodology used in paleopathology continues to evolve through the holistic approaches of molecular analysis, radiology and histopathology. Ultimately, this study reinforces the importance for retention of large-scale skeletal collections for paleopathological study in population perspective. In the near future, Korean paleopathology can contribute in the reconstructions of the history of disease and its effect on past human populations.

A Study of Bilateral Asymmetry Pattern in the Eye Orbit and Nose of the Joseon Dynasty Skeletal Group Using Geometric Morphometrics / 체질인류학회지

In this study, the pattern of bilateral asymmetry in the eye orbit and nose of the Joseon Dynasty skeletal group was analyzed using geometric morphometrics. For this, 38 adult males and 38 adult females from the Joseon Dynasty skeletal group belonging to the 15(th) to early 20(th) centuries were examined. For geometric morphometric analysis, Procrustes superimposition was performed on 10 landmarks in both eye orbits and 7 nasal landmarks. The data were analyzed by multivariate analysis of variance with partial least square scores. In results, the lateral landmarks had more impact on the bilateral asymmetry in the eye orbit and nose than the center landmarks. The eye orbit and nose on the right side of the face seemed bigger than those of the left side, while the direction of asymmetry in the eye orbit and nose was different. The correlation between asymmetry patterns in the eye orbit and nose were statistically significant (p<0.01). The results of this study will be useful for examining causes of bilateral asymmetry in the eye orbits and noses of the Korean population.

Research Methodologies of Evolutionary Psychiatry / 신경정신의학

Evolutionary psychiatry is a branch of medical science concerning mental disorders, and also a multidisciplinary research field with close relation to psychology, anthropology, evolutionary biology, neuroscience, and ethology. Although evolutionary psychiatry is a promising area for further psychiatric studies, it is still in its infancy. Thus, there are no certain research methods using evolutionary approaches toward mental diseases. It is still at the level of adopting and applying the research methods of the aforementioned adjacent fields. We aim to investigate a variety of research methods proposed to date and then compare them, which will provide a glimpse of the future of evolutionary psychiatry in the upcoming era.

The Study of Cranial Shape Variation in a Population from Joseon Dynasty using Geometric Morphometrics / 체질인류학회지

Traditional morphometrics uses ratios between measured values such as the cranial index and the upper facial index. However, with these ratios alone, it is impossible to represent the shape of the entire cranium in a three-dimensional space because ratio does not express coordinate data. This methodological limitation of traditional morphometrics makes it difficult to evaluate relations between cranial parts. However, it is important to assess relations between cranial parts because cranial parts change their shapes in an integrated way. Therefore, this study adopted geometric morphometrics to overcome the limitations of traditional morphometrics and provide a more enhanced visual analysis of the cranial shape. Using geometric morphometrics, this study focused on variations of cranial shapes in a population from Joseon Dynasty to obtain their specific characteristics. This study investigated variations of cranial shapes in 57 individuals from Seoul Gyeonggi province who lived in the 15th to the early 20th centuries. The coordinates of the crania were collected by MicroScribe G2X (Immersion Corporation, USA) and statistically analyzed using principal component analysis. The results showed that the variations in cranial shapes of females were reflected mostly in width, length of cranium, position of bregma, shape of posterior part of cranium, and length of facial bone. The cranial shapes of the males varied mostly in length, width, height of cranium, size of mastoid process, and length of facial bones. The cranial length became shorter when the cranial width became broader in both sexes. However, cranial height and facial length showed different variations between the two sexes. In addition, the variation in females only showed evidence of static allometry. The results of this research provide basic information about cranial shapes in a population from Joseon Dynasty and will be useful in future studies such as analysis on between-group differences. By identifying within-group variations first, researchers focusing on between-group differences will likely avoid erroneous conclusions.

Biomechanical Properties of Femoral Diaphyseal Cross-sectional Shape from the Eunpyeong Population / 체질인류학회지

Long bone diaphyseal cross-sectional shape as a primary measure of biomechanical loading has attracted much attention in physical anthropology. Especially, lower limb bones have been widely used to reconstruct the mobility pattern of the past population. In this research, the cross-sectional size of the femoral shaft was investigated for the human skeletal remains excavated from the Eunpyeong site, dating the period spanning from the mid-15th to the early 20th centuries. The purpose of this research is to examine and report the biomechanical characteristics of the past populations living during Joseon Dynasty period. The results showed that Eunpyeong population was grouped into the 'platymeric category (i.e., platymeric index below 84.9). Females were more platymeric (i.e., more laterally flattened) than males and the sexual dimorphism was statistically significant. In addition, the samples of Eunpyeong site showed a relatively lower pilasteric index (i.e., more round) compared to the populations reported in other studies. The results of this research provide an insight to shed light on the ecological environments, subsistence strategies, and life styles of the past populations. Yet, for more detailed interpretation, it appears necessary to take into account other types of indicators for biomechanical stresses and accumulate more archaeological evidences.

Rethinking the Possibilities and Limitations of a Study on the Skeletal Markers Reconstructing the General Level of Physical Activity / 체질인류학회지

The reconstruction of activity and of work patterns has been approached by examinations of activity-related skeletal markers. Among several different methods, in particular, a number of anthropologists have widely applied the patterns of enthesopathies and degenerative joint disease in studies of past activity. The purpose of this study is to better understand and use these indicators in reconstructing the levels of physical activities of past populations. This review will provide information on the most recent anthropological research on the behavioral interpretation on degenerative joint disease and enthesopathies, to better use these indicators in understanding past populations. There are obvious limitations in using these markers, and it is necessary to consider them. Firstly, it is uncertain as to whether there are certain activities that are performed repetitively throughout their lives of those who lived in past civilizations. A second limitation involves the etiology of skeletal markers related to mechanical stress. There are multiple-factors, including genetic predisposition, sex, the aging process, and diet that may affect the way people practice a specific activity. Accordingly, this makes it difficult to evaluate the underlying etiological factors and their roles in activity-related skeletal changes. In conclusion, to circumvent these limitations, the use of multiple skeletal markers together in studies of the activities of past populations may enable to more reliable interpretations. However, to ensure more reliable interpretations, the validity of such combinations of makers should be challenged. Therefore, more work on the validity of activity-related markers is needed to clarify the activities that are responsible for the development in life of the features observable in skeletal populations. This type of research can contribute to the discussion of the use of activity-related skeletal markers in studies of behavioral interpretations with more certainty regarding which morphological characteristics are responses to physical activity and mechanical loading as the pathogenesis of such characteristics.

An Estimation of Adult Males' Average Stature from the Skeletal Remains of Joseon Period / 체질인류학회지

An average height of adult males of Joseon period was estimated by utilizing excavated skeletal remains of the era. The height estimation formula for Mongoloid males by Trotter and Gleser (1958) was applied to the maximum femur lengths from 85 individuals' skeletal remains identified as grown-up males by the author of this paper. Individual estimations were obtained first, and then the mean of the central numbers of the individual estimations was taken as the group average. The average height of the 85 individuals was estimated 164.49 cm. When the sample was divided by the burial type, a presumed indicator of the socioeconomic status of the buried, those buried in the lime-mortar type burials were generally taller than those buried in the earth-pit type burials. When the Eunpyeong site was examined separately, those excavated from the earth-pit type burials were shorter about 1.5 cm than those excavated from the lime-mortar type burials. Because it is presumed that the earth-pit type burials were mostly used by commoners during the Joseon period, the mean height of the adult males from the earth-pit type burials can be considered as a mean height of adult male commoners of the era. The mean height of those from the earth-pit type burials was 164.09 cm when the total sample was analyzed and 163.19 cm when only those from Eunpyeong were analyzed. When estimated from skeletal remains, the adult Korean male commoners from middle and southern Korea of Joseon period were as tall as or a little taller than those adult Korean males from middle Korea measured by Westerners or Japanese in the late 19th and early 20th centuries.

Patterns of Linear Enamel Hypoplasias among Korean Skeletal Samples from the Joseon Dynasty Period / 체질인류학회지

Dental linear enamel hypoplasia (LEH) is probably one of the most widely used developmental stress indicators among all known skeletal stress indicators. This research examined LEH on the permanent anterior teeth of 160 human skeletal remains from the Joseon Dynasty period. The purpose of this investigation is to understand the characteristics of the developmental stresses experienced by the people of the Joseon period by analyzing the patterns of LEH incidences. The skeletal remains analyzed for this research were excavated during an archaeological investigation at a construction site in Eunpyeong-gu, Seoul, South Korea. Eunpyeong site is estimated to date from the late 15th century to the late 19th century based on the burial type and goods discovered within the graves. Of all the skeletal remains found at this site, 160 individual specimens with at least one of the permanent anterior teeth constituted the sample of the study. Information regarding each individual specimen's sex, age at death, and burial type was collected by the standardized methods. The prevalence and number of LEH by tooth type, and the number of LEH by sex, by burial type, and by age at death were analyzed. Mandibular canines were the most frequently affected teeth, maxillary canines coming next in the occurrence of LEH, and the third turned out to be the maxillary incisors. This result generally agrees with the findings from previous studies. When number of LEH by sex was compared, there was no consistent difference by sex which also agrees with the findings of previous studies. Although specimens from lime-mortar burials tended to have less number of LEH then those from earth-pit burials, a probable indication of the socioeconomic status effect on the formation of LEH, the result was not very pronounced. No obvious association between the number of LEH and age at death was found, either. Finally the results from this study were compared with those reported by other researches on LEH worldwide. Although preliminary in its level of analysis, this study is the first report of the patterns of LEH of a skeletal population of Korea. With more studies of human skeletal remains from the past, it is hoped, physical anthropology can contribute to the understanding of the past life of the Korean people.

A Study of the Relationship between the Nutritional Quality of Life and Stature Sexual Dimorphism

We tested the hypothesis that an improved nutritional environment increases the size of stature sexual dimorphism (SSD) by comparing mean height changes in North and South Korean adults. For the first round of sampling, those North Korean refugees who had reached the age of 20 years before leaving North Korea were selected for the study. Then, two birth-year cohorts born between 1955 and 1959 and between 1980 and 1984 were finally selected for the analysis (383 males and 529 females). North Korean refugee mean height data were compared to the mean height of the comparable South Korean population derived from 2004 Korean size results (373 males and 429 females). The results of the analysis showed that there was no increase in mean height among the refugees, either in males or females, between the two birth-year cohorts. As a result, no change in SSD was observed between the two birth-year cohorts. In contrast, South Koreans showed a remarkable increase in height, with males having a greater increase during the corresponding 25 years. Consequently, South Korean SSD increased significantly with time. These results support the hypothesis that improved nutritional quality increases SSD.