Joan C. Stevenson

Technical note: Prediction of sex based on five skull traits using decision analysis (CHAID)

Osteologists commonly assess the sex of skeletal remains found in forensic and archaeological contexts based on ordinal scores of subjectively assessed sexually dimorphic traits. Using known-sex samples, logistic regression (LR) discriminant functions have been recently developed, which allow sex probabilities to be determined. A limitation of LR is that it emphasizes main effects and not interactions. Chi-square automatic interaction detection (CHAID) is an alternative classification strategy that emphasizes the information in variable interactions and uses decision trees to maximize the probability of correct sex determinations. We used CHAID to analyze the predictive value of the 31 possible combinations of five sexually dimorphic skull traits that Walker used previously to develop logistic regression sex determination equations. The samples consisted of 304 individuals of known sex of English, African American, and European American origin. Based on practical considerations, selection criteria for the best sex predictive trait combinations (SPTCs) were set at accuracies for both sexes of 75% or greater and sex biases lower than 5%. Although several of the trees meeting these criteria were produced for the English and European American samples, none met them for the African American sample. In the series of out-of-sample tests we performed, the trees from the English and combined sample of all groups predicted best.

Parental investment, self-control, and sex differences in the expression of adhd

Women do most of the parenting. To provide a stable and healthier setting for children they must sublimate their own interests and feelings, which puts greater pressures on women to communicate needs clearly or to be deceptive when the occasion demands. The likely advantage in communication skills and self-control may ameliorate the impact of disorders like ADHD where the most serious deficit is in self-inhibition. This would account for the strikingly uneven male to female sex ratio of 2:1 (in epidemiological samples) to 10:1 (in clinical settings), the higher threshold for females, and the sex difference in the pattern of associated mental disorders.

Birth intervals and early childhood mortality in a migrating Mennonite community

Short birth intervals are associated with increased mortality in challenging settings, and the objective here was to explore the significance of birth spacing relative to the neonatal, postneonatal, and early childhood mortality for rural Mennonites from one congregation in two settings: Russia, 1825–1874, and Kansas, 1875–1924, in light of two causal mechanisms: maternal depletion and sibling competition. Vital events of families reconstructed from church records comprised a total of 930 and 1,484 births in Russia and Kansas, respectively, by 381 mothers. Bivariate analyses indicate that mortality is higher in Russia relative to Kansas for births with the shortest previous intervals for all three age categories, and for neonates born before the shortest subsequent intervals. Cox regression analyses indicated that only a few factors played a statistically significant role. Mortality risk was increased in Russia by having mothers >35 years and shorter subsequent intervals for the neonates, shorter subsequent intervals for the postneonates, and having mothers >35 years, and shorter previous and subsequent intervals for early childhood. In Kansas, mortality risk was increased by shorter subsequent intervals and being a member of a multiple birth for neonates, shorter previous and subsequent intervals and being a member of a multiple birth for postneonates, and being a member of a multiple birth, when the preceding child dies, and a shorter subsequent interval for early childhood. The increased risk in Russia associated with being born to an older mother and the increased risk in the total sample for the older age categories with the shortest previous intervals provide moderate support for the maternal depletion hypothesis. That longer subsequent intervals increase survivorship in all settings for all age categories provides limited support for the sibling competition hypothesis. Am. J. Hum. Biol. 12:50–63, 2000.

Teaching Human Evolution

A \ s science educators, we have two goals in writing this paper. The first is to show the importance of teaching human evolution to all students. The second is to provide up-to-date resources for classroom teachers to use in teaching the subject. Secondary biology textbooks suffer from the inherent limitations of mass produced books making it difficult for them to stay current with rapidly changing scientific fields such as paleoanthropology. One of our motives for writing this paper is to compensate for this inherent limitation of textbooks.

Immunoglobulin Allotypes in Southwest Asia: Populations at the Crossroads

Southwest Asia has a long history of contact with Central Asian and with Sub‐Saharan African populations. Is the genetic structure of these populations reflective of these historical facts? To study this, data was generated on the immunoglobulin heavy chain (GM) and light chain (KM) allotypes from seven Arab and three non‐Arab populations in SW Asia to examine the relationship of these populations to SE European, NW Indian, Sub‐Saharan African, and Central Asian populations. Like mtDNA and Y chromosome markers, the GM haplotypes are largely continent specific making them an excellent tool for the detection of gene flow whereas the KM markers are less informative. Six of the nine GM haplotypes detected in SW Asians are Indo‐European, Sub‐Saharan African, or East Asian specific. The allotype results indicate variable but significantly higher Sub‐Saharan African gene flow in Arab populations (average 26.9%; 15.0–61.6%) vs. the non‐Arab populations (average 7.3%; 9.0–13.4%), but higher levels of Central Asian gene flow in the non‐Arab populations (average 28.8%; 10.5–48.8%) vs. the Arab populations (average 9.0%; 0.0–26.4%). Principal components analysis and hierarchical cluster analysis based on the immunoglobulin allotypes are consistent with the historical population contacts of this part of the world and reflect the power of the GM haplotypes in dissecting population relationships. However, the KM*1 frequencies were only correlated with the degree of African gene flow (Pearson r = 0.69, P = 0.026) in SW Asian populations. Am. J. Hum. Biol., 2008.

Reproductive Measures, Fitness, and Migrating Mennonites: An Evolutionary Analysis

Given the same reproductive span, more children with shorter interbirth intervals and less parental attention per child should not do as well. There should be intermediate optima in family sizes, but only two studies have demonstrated optima. The goal here is to determine whether the relationship between fitness and fertility is linear and whether this relationship masks underlying variation in reproductive behaviors in a Mennonite congregation that lived in two disease settings, Prussia/Russia vs. Kansas. The relationships between children born and fitness were determined by calculating linear and quadratic regressions for total, Prussia/Russia vs. Kansas, and families with deaths vs. families with no deaths for total, Prussia/Russia, and Kansas. Variation was examined in terms of measures of reproductive success and reproductive span. Comparisons were made by t tests with Bonferroni correction. Regressions demonstrate equally well that the more children women bear, the higher the reproductive success, whether in the harsher disease ecology of rural Prussia/Russia or in less challenging rural Kansas and whether the women experience deaths or not. Prussian/Russian mothers bore significantly more children (6.5 ± 0.3) than Kansan mothers (5.6 ± 0.2) over longer reproductive spans but did not significantly increase the number of surviving children (4.9 ± 0.2 vs. 4.7 ± 0.2, respectively). Families experiencing deaths vs. no deaths exhibit significantly longer reproductive spans, reflecting a significantly earlier start at childbearing and a later finish, and produce significantly more children (5.4 ± 0.2 vs. 4.2 ± 0.2). Cox regressions were run, and the most significant covariates to negatively affect survivorship to 15 years were death in the family and length of the previous interbirth intervals. There was variation in families, but perhaps most had adequate nutrition, which may explain the lack of optima in fitness.

Changes in fertility relative to starting stopping and spacing behaviors in a migrating Mennonite community 1775-1889.

Fertility change over time in a migrating Mennonite church congregation is reconstructed through genealogies developed from church registries of vital events during 1725-1924. The congregation was located in Prussia from 1725-1821, in Russia from 1822-1874, and in Kansas, U.S.A., from 1875-1924. Age-specific marital fertility rates were relatively low and usually peaked for women aged 25-29. Total fertility rates ranged from 1.19 to 5.29. These relatively low figures for a natural fertility population may partly reflect underreporting of births and deaths of infants, but it also reflects the heterogeneity in fertility evident for this population. Some women had many children while others were having either few or none. This pattern changed twice. Fertility was lowest during residence late in Prussia and early in Russia, peaked during residence late in Russia, and has decreased slightly for women born in the United States.

Existential and object authenticity in Southwestern pottery: Intertwined and complementary

A much discussed concept, authenticity is still very important to collectors and museums in 2013 with respect to Native American art, but few have examined the dynamic between artist and buyer in relation to how concepts of authenticity affect the exchange. Useful here is a constructivist approach that examines authenticity with respect to local perceptions, values and setting. Existential authenticity is revealed through statements by the potters of Santa Clara and San Ildefonso Pueblos, New Mexico, and object authenticity is derived from attributes of the pot and potter partly from online advertisements for 571 pots. The proxies for existential values predict 39 per cent of the cash value of the pot. Ongoing discussions among all the stakeholders preceding juried competitions conserve potters’ values and support artist agency. These values, as expressed in the pottery, are likely part of buyers’ attraction to the pottery.

Biocultural Approaches to the Emotions (review)

preliminary policy decisions and plans. This book was interesting in that it provided me with a better understanding of the environmental endocrine hypothesis, something I was only vaguely aware of up till now. More importantly, the book provided me with many details regarding the scientific and social dimensions of public policy, a topic I knew even less about. Given my ignorance, I tend to view the book more as a thorough introduction to the general nature of policy analysis, using the environmental endocrine hypothesis as an example. As such, this would make a valuable text in upper-division courses on public health or related fields.

The symbolic species: The co-evolution of language and the brain

This article is a review of two contrastive views on the co-evolution of language and the brain – The Language Instinct by Steven Pinker (1994) and The Symbolic Species by Terrence Deacon (1997). As language is a trait unique to mankind it can not be equated with nonlinguistic communication – human or nonhuman. This points to a special human brain architecture. Pinker’s claim is that certain areas on the left side of the brain constitute a language organ and that language acquisition is instinctual. To Deacon, however, those areas are non-language-specific computational centers. Moreover, they are parts in a larger symbolic computational chain controlled by regions in the frontal parts of the brain. To Deacon, a symbolic learning algorithm drives language acquisition. The increase in size of the human brain in relation to the body may be due to a “cognitive arms race”. Both Pinker and Deacon agree on the evolutionary advantage of the ability to establish and maintain social alliances and contracts and to outsmart social cheaters but they disagree on what this cheating involves. Pinker defines cheaters as social parasites, while Deacon defines them adulterers.