So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

BIOCHEMISTRY IN ANAESTHESIA Modern Trends In Anaesthesia. II. Aspects of Hydrogen lon Regulation and Biochemistry in Anaesthesia. Edited by Prankis T. Evans, M.B., B.S., F.R.C.S., F.F.A. R.C.S., and T. Cecil Gray, M.D., FF.A. R.C.S., Hon.F.F.A. R.A.C.S. (Pp. 219+vii; illustrated. 60s.) London: Butterworths. 1962. In this stimulating book a group of experts have written on hydrogen-ion regulation and biochemistry in anaesthesia. This vast subject has been divided rather artificially and only certain aspects of biochemistry have been covered, and the divisions are more related to clinical practice than basic physiology and biochemistry. TIhe sections have been written by specialists in each field; the material they contain is beyond criticism, and there is valuable practical advice. Some chapters are well written, though others are not so easy to read. All are packed with information, and, what is equally valuable, they provide a source of further information for the inquiring mind, for the references and bibliographies are excellent. It is a pleasure to have complicated electrophysics presented in a readable way (\" Measurement of pH and Pco l\"); \"The Cholinesterases\" is an embracing account of difficult physiological and biochemical problems. Throughout the book there is a wealth of valuable material, indeed so much so that at times too much appears to have been attempted within the space available, as in \" Effects of Hypercapnia.\" These are minor criticisms of a good book, or perhaps it would be wiser to call it a collection of papers on chosen subjects, for there is understandably a lack of cohesion among the various chapters, and even some slight overlapping, which renders the whole less valuable than its several parts. No one can read these papers without interest and profit (and occasionally amusement) and they should fulfil the editor's hope that they will stimulate further interest in basic science. The book is well presented; the printing and paper are good, but the price will not encourage widespread use of the book among the younger members of our specialty. G. E. H. ENDEPBY.

Blood Groups in Man.

Final body height is achieved as the result of a combination of genetic and environmental factors. The aim of this article is to review past studies on body height that have followed different scientific traditions. In modern Western societies, about 20% of variation in body height is due to environmental variation. In poorer environments, this proportion is probably larger, with lower heritability of body height as well as larger socioeconomic body height differences. The role of childhood environment is seen in the increase in body height during the 20th century simultaneously with the increase in the standard of living. The most important non-genetic factors affecting growth and adult body height are nutrition and diseases. Short stature is associated with poorer education and lower social position in adulthood. This is mainly due to family background, but other environmental factors in childhood also contribute to this association. Body height is a good indicator of childhood living conditions, not only in developing countries but also in modern Western societies. Future studies combining different scientific traditions in auxology are needed to create a more holistic view of body height.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0021932003002633

Determinants of variation in adult body height.

This is a very large compilation of growth data with an extremely wide coverage of population groups, many of which will be completely unknown to all but the professional ethnographer. There is, however, a disappointingly narrow coverage of variables (length, weight, body widths, circumferences and proportions, skinfold thicknesses, and maturity). Many of the findings are relevant to an important question: should one set of growth reference data be used throughout the world, thus allowing ready comparability between groups, or should there be separate sets for each major racial group or even a multitude of local sets? The studies summarized in this volume indicate many population groups have similar potentials for growth in major body dimensions. For example, the narrower range of means among European than among African groups that range from "tribal" to well-off indicates the range of variation in growth would be reduced greatly if the environmental circumstances allowed

Worldwide Variation in Human Growth

Chunyan He and colleagues report genome-wide association studies for both age at menarche and age at natural menopause from the Nurses Health Study and the Women's Genome Health Study

Genome-wide association studies identify loci associated with age at menarche and age at natural menopause

Genetic variance analysis of 15 dental occlusal and arch variables is based on cross-cultural comparison of twin variances (U.S. Whites and Northwest Indian Punjabis). Both samples exhibit high genetic versus environmental partition of variance. However, monozygotes and dizygotes have unequal variance, which invalidates conventional genetic variance ratios. The pattern of environmental biases on the zygosities is quite different in the two groups. Revised estimates that acknowledge zygosity heterogeneity (hence unequal environmental influences) are generally much lower for occlusal traits, whereas arch size measurements are unaffected.

Comparative genetic variance and heritability of dental occlusal variables in U.S. and Northwest Indian twins.

SummaryThe relationship of early and late menarche with adult body dimensions has been studied on a sample of 147 young adult women drawn from an urban Punjabi population of Chandigarh and Ludhiana. The results indicate that girls with early menarche (age 10 to 11) have significantly smaller skeletal dimensions (both longitudinal and transverse) and more subcutaneous fat than those with average or late menarche. The girls with late menarche have on average more height for weight than early maturers. Results indicate that there is a biological determinant of the observed association between menarcheal age and fatness and adult body size.

Age at menarche in relation to adult body size and physique.

To examine the relative role of genetic and environmental factors on pelvic morphology, data on 60 pairs of female twins (30 monozygotic (MZ) and 30 dizygotic (DZ)) were analyzed. Fourteen pelvic measurements were normally distributed, and two were not. Association of twin type with the mean value of a trait was found in only 1 out of 8 traits. Heterogeneity of variance between zygosities was observed in 4 pelvic traits (50%), invalidating within-pair estimates of genetic variance for these traits. Evidence of stronger environmental covariance for MZ than DZ twins was observed for only one trait (sitting height iliocristale). A significant genetic component of variation was observed for age at menarche and in the pelvic area. In instances where inequality of variances between zygosities was demonstrated, total among-pair and within-pair mean squares were larger for dizygotic than for monozygotic twins. This is interpreted as evidence of greater environmental influence between zygosities. Environmental modification was not of the same magnitude in various pelvic traits. Bitrochanteric breadth had the highest magnitude of cultural heritability, indicating that cultural factors played an important role in determining hip breadth.

Genetic basis of human female pelvic morphology: a twin study.

Data on susceptibility to motion sickness were collected on a sample of 535 individuals divided into eight groups. The prevalence of motion sickness among Tibetans and Northeast Indians (28%) was slightly higher than Northwest Indians (26%). Generally speaking, females (27.3%) were more susceptible than males (16.8%). Among different groups, the highest incidence of susceptibility to motion sickness (SMS) was recorded in schizophrenic patients (30%), while the lowest in rowers (zero percent). Ears and eyes are the most potent receptors of provocative motion that causes sickness. Individuals with greater spatial and motor control, reflected in sports like rowing, athletics and professions like armed and paramilitary forces, were less susceptible to motion sickness. The SMS was significantly higher in individuals who suffered from spatial disorientation (35.05%), migraine (26.31%), gastrointestinal disorders (26.82%) and those who were more sensitive to unpleasant odours (24.64%) and preferred sweet flavours (24.48%) than their counterparts. These correlates have been utilized to explain the genesis of sickness using threshold model. Genetic and environmental pathways are strongly advocated. Past episodes of motion sickness acted as a strong psychological attribute in determining further episodes. The roadway buses and trucks proved more effective passive transportation types that caused sickness. The voluntary stabilization of the head and neck movements and gaze control proved very effective natural measures adopted by 38% subjects to avoid or limit motion sickness. About 50% of susceptible individuals became less susceptible or fully acclimatized to motion sickness due to habituation. The mean age at acclimatization was 21.98 +/- 5.93 years.

/pdf/prevalence-and-correlates-of-susceptibility-to-motion-2pi2ohg62b.pdf

Prevalence and correlates of susceptibility to motion sickness.

Data on 40 anthropometric measurements from 144 nuclear families in Chandigarh, India, are presented. Most families contain a pair of monozygotic or dizygotic twins, one or more singleton siblings, and their parents. Familial correlations for age-sex standardized, normalized measurements are estimated by maximum likelihood for marital, parent-child, sibling, and twin pairs. Heterogeneity tests for sex-specific subtype correlations male-male, male-female, female-female) indicate that the sex of the relative plays no significant role in the magnitude of the familial correlations except for maternal effects and differences among male and female twin pairs for a few of the variables. Marital correlations are high for body measurements, but not for head or face variables. Twin correlations seem to indicate a higher level of heritability than correlations from other family members.

Krishan Sharma

Papers

Comparative genetic variance and heritability of dental occlusal variables in U.S. and Northwest Indian twins.

Age at menarche in relation to adult body size and physique.

Genetic basis of human female pelvic morphology: a twin study.

Prevalence and correlates of susceptibility to motion sickness.

A family study of anthropometric traits in a Punjabi community: I. Introduction and familial correlations