A new statistical method for estimating divergence dates of species from DNA sequence data by a molecular clock approach is developed. This method takes into account effectively the information contained in a set of DNA sequence data. The molecular clock of mitochondrial DNA (mtDNA) was calibrated by setting the date of divergence between primates and ungulates at the Cretaceous-Tertiary boundary (65 million years ago), when the extinction of dinosaurs occurred. A generalized least-squares method was applied in fitting a model to mtDNA sequence data, and the clock gave dates of 92.3 +/- 11.7, 13.3 +/- 1.5, 10.9 +/- 1.2, 3.7 +/- 0.6, and 2.7 +/- 0.6 million years ago (where the second of each pair of numbers is the standard deviation) for the separation of mouse, gibbon, orangutan, gorilla, and chimpanzee, respectively, from the line leading to humans. Although there is some uncertainty in the clock, this dating may pose a problem for the widely believed hypothesis that the pipedal creature Australopithecus afarensis, which lived some 3.7 million years ago at Laetoli in Tanzania and at Hadar in Ethiopia, was ancestral to man and evolved after the human-ape splitting. Another likelier possibility is that mtDNA was transferred through hybridization between a proto-human and a proto-chimpanzee after the former had developed bipedalism.

Dating of the human-ape splitting by a molecular clock of mitochondrial DNA.

ilbstract. Autocorrelation is a very general statistical property of ecological variables observed across geographic space; its most common forms are patches and gradients. Spatial autocorrelation. which comes either from the physical forcing of environmental variables or from community processes, presents a problem for statistical testing because autocorrelated data violate the assumption of independence of most standard statistical procedures. The paper discusses first how autocorrelation in ecological variables can be described and measured. with emphasis on mapping techniques. Then. proper statistical testing in the presence of autocorrelation is briefly discussed. Finally. ways are presented of explicitly introducing spatial structures into ecological models. Two approaches are proposed: in the raw-data approach, the spatial structure takes the form of a polynomial of the x and .v geographic coordinates of the sampling stations; in the matrix approach. the spatial structure is introduced in the form of a geographic distance matrix among locations. These two approaches are compared in the concluding section. A table provides a list of computer programs available for spatial analysis.

https://www.jstor.org/stable/pdfplus/1939924.pdf

Spatial Autocorrelation: Trouble or New Paradigm?

Border Gateway Protocol (BGP) is the protocol backing the core routing decisions on the Internet. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems (AS). Point of concern in BGP is its lack of effective security measures which makes Internet vulnerable to different forms of attacks. Many solutions have been proposed till date to combat BGP security issues but not a single one is deployable in practical scenario. Any security proposal with optimal solution should offer adequate security functions, performance overhead and deployment cost. This paper critically analyzes the deployment issues of best three proposals considering trade-off between security functions and performance overhead.

Comparative analysis of

Darwin (1859, pp. 11-14, 143-150) stressed the evolutionary importance of covariation between characters in populations and its "most imperfectly understood" connection with correlated responses to artificial and natural selection. After the turn of the century the discoveries of pervasive pleiotropy and linkage of Mendelian factors revealed the underlying genetic mechanisms. Existing theory on the dynamics of correlated characters has been developed in the limited framework of practical plant and animal breeding. Methods of multivariate analysis, functional analysis and optimality criteria popular among evolutionists, do not account for dynamical constraints imposed by the pattern of genetic variation within populations. Consideration of phenotypic variation often does not suggest any clear mechanism connecting growth patterns or adult variation to interspecific evolution. When there is individual variation in development, no necessary correspondence exists between ontogenetic and adult variation in a population (Cock, 1966, pp. 148-15 1). It is also common for the pattern of adult variation within a species to differ from that at higher taxonomic levels (Simpson, 1953, pp. 25-29). An example which will be investigated here is the brain weight:body weight relationship. At various taxonomic levels, brain and body weights tend to follow the allometric equation

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1979.tb04694.x

Quantitative genetic analysis of multivariate evolution, applied to brain:body size allometry.

The principles of classification and a classification of mammals. Bulletin of the AMNH ; v. 85

Molar cusp-size variability in relation to odontogenesis in hominoid primates.

Genetic variance analysis of 56 tooth size traits was based on a sample of 58 pairs of twins (23 MZ and 35 DZ) from Chandigarh, India. Results of a t-test for equality of means showed no association of zygosity with any of the traits. Heterogeneity of total variance was found in 18 traits, which invalidates conventional genetic variance estimates and reveals considerable hidden environmental determinance. In contrast to other studies, Indian MZ twins had higher variance than did DZ twins, in most instances. There was also evidence of stronger environmental covariance for MZ and DZ twins. The study revealed substantial, complex environmental determination for some dental dimensions, especially of incisors and second molars.

Genetic Variance in Dental Dimensions of Punjabi Twins

I N an innovative article of I978 Herbert S. Klein and Stanley L. Engerman, addressing the problem of fertility differentials between slave populations of the United States and the British Caribbean, emphasized that the significant difference between the two areas in rates of natural increase is largely explainable by the higher fertility of American slaves. They contended that differences in the child-spacing period could partially account for differences in fertility rates: in the West Indies, birth interval ranged between three and four years, while in the United States it was close to three years. While acknowledging that spacing could result from several factors, Klein and Engerman focused on the lactation period and found that the breast-feeding interval for North American slave women "was generally about one year, while for the West Indies it was typically at least two years."1 Students of Caribbean slave life have long accustomed themselves to working with limited information. Although sources for investigating the institution of slavery and its political and economic dimensions are abundant, the more mundane aspects of slave sociocultural and domestic life were much less apt to be recorded by contemporary white observers. Whatever the implications for understanding slave fertility patterns, the topics of lactation and weaning very well illustrate the limited data base that scholars often have been obliged to employ in treating the domestic behavioral patterns of Caribbean slaves.

/pdf/weaning-among-west-indian-slaves-historical-and-41k6k4y1xa.pdf

Weaning among West Indian slaves: historical and bioanthropological evidence from Barbados.

Genetic variance and heritability were estimated for 16 dental occlusal variables, based on a sample of 23 MZ and 35 DZ twin pairs from Chandigarh, India. Results of the t -test for equality of means showed association of zygosity with only one of the 16 variables (posterior teeth displacement), thus showing bias in the trait's genetic variance analysis. Heterogeneity of variance among zygosities was demonstrated for seven traits suggesting considerable amount of hidden environmental influence. There was evidence of stronger environmental covariance for monozygotic than for dizygotic twins. In contrast to other such studies, Indian MZ twins indicated higher variance than the DZ twins for a number of traits. These observations demonstrate some complex environmental determinism for occlusal traits, while significant genetic variance obtains for arch and palate measurements.

Genetic basis of dental occlusal variations in northwest Indian twins.

Specimens dating back to the VIII Century B.C. indicate Etruscans may have been the first people to employ orthodontic bands to improve tooth alignment. A survey of dental occlusion in Etruscan cranial remains, however, shows very good typical occlusion and almost no crowding. Thus, these people do not represent the earliest development of epidemiologically high prevalence of malocclusion, a feature instead reserved for the later industrial world.

Robert S. Corruccini

Papers

Molar cusp-size variability in relation to odontogenesis in hominoid primates.

Genetic Variance in Dental Dimensions of Punjabi Twins

Weaning among West Indian slaves: historical and bioanthropological evidence from Barbados.

Genetic basis of dental occlusal variations in northwest Indian twins.

"Orthodontistry" and dental occlusion in Etruscans.