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

Hinton and Carlson (Am J Phys Anthrop 50: 325, 1979) have demonstrated a temporal trend of decreasing temporomandibular joint size in Nubian skeletons. Spanning a time range from 3400 B.C. to 1100 A.D., these populations show no evidence of genetic evolution, yet the size of the mandibular fossa of the cranium decreased by 5%. Hinton and Carlson attribute this decrease to gradual reduction of chewing stress, resulting from a change toward softer agriculturally-based dietary substances. We have similarly analyzed mandibular fossa size in a sample of slave skeletons excavated from a burial ground at Newton sugar plantation on Barbados. The burial population spans the period from about 1660 to 1820. Historical records indicate that it represents a broad mixture of various populations imported from the west African coast and possibly a small number from southeast Africa; records also suggest that, by the mid 1700's, the majority was born in Barbados and that, by the late 1700's and early 1800's, between 10 and 15% showed some European

Temporomandibular Joint Size Decrease in American Blacks: Evidence from Barbados

Village-dwelling Punjabi youths show significantly better dental occlusion and less chronic respiratory allergy than their city-dwelling counterparts. Field diagnosis finds posterior crossbite the only occlusal condition correlated with mouth breathing in the samples studied.

Mouth breathing, occlusion, and modernization in a north Indian population. An epidemiologic study.

Since the time of Darwin and Huxley, it has been a common opinion that extant hominoids (apes and man) are unified by a manner of locomotion and posture, and associated derived functional morphology, indicating a closely related and distinct group. Haeckel (1868), Keith (1923) and Gregory (1928) early documented the body proportion synapomorphies supporting the monophyly of hominoids. Schultz (e.g., 1950; 1963) provided large amounts of confirmatory data. Simons (1972), Simons and Pilbeam (1965), Simons and Fleagle (1973), Pilbeam (1969), Conroy and Fleagle (1972) and Zwell and Conroy (1973) have spread the idea that long-term parallelism is the cause of hominoid similarities. More recently, the hypothesis of hominoid parallel evolution has been proposed more rigorously in terms of allometry-the differential growth of body segments. Thus, hominoid morphology and proportions are seen as having developed from parallel increase in body size and necessarily associated allometry, suggesting that more than one kind of locomotor pattern could have given rise to their distinctive shape. Three specific hypotheses have been proposed in this regard. Biegert and Maurer (1972) show that arm length, and less markedly leg length, is positively allometric among cercopithecoid (Old World) monkeys and that some hominoids lie on the regression line extrapolated from the monkey sample indicating "generalized proportions" in a larger size range. Their regressions are of skeletal segment length ratios versus a vertebral measure of trunk

Primate skeletal allometry and hominoid evolution

Skull shapes and the map: Craniometric analyses in the dispersion of modern homo (Papers of the Peabody Museum of Archaeology and Ethnology, Volume 79). By W. W. Howells. 189 pp. Cambridge: Harvard University Press. 1989, $35.00 (cloth), $14.95 (paper)

Occlusion—how the teeth fit togetherwithin and between the arches—has important consequencesfunctionally and especially esthetically. Occlusalvariation is considerable in modern westernized societies,but the occurrence and extent of the variationappear to be lower in the past and lower in non-westernizedgroups. This methodological paper describesseveral commonly-used variables that, collectively,characterize occlusal variation. Methods are describedfrom the literature that measure the location and extentof tooth relations in all three planes of space. Our goalis that, by describing methods in a single source, it willpique the interest of dental researchers to collect thesedata, so that the space-time distributions of occlusalvariations can be known in more detail.

/pdf/quantification-of-dental-occlusal-variation-a-review-of-4fz3g6a9m6.pdf

Robert S. Corruccini

Papers

Temporomandibular Joint Size Decrease in American Blacks: Evidence from Barbados

Mouth breathing, occlusion, and modernization in a north Indian population. An epidemiologic study.

Primate skeletal allometry and hominoid evolution

Skull shapes and the map: Craniometric analyses in the dispersion of modern homo (Papers of the Peabody Museum of Archaeology and Ethnology, Volume 79). By W. W. Howells. 189 pp. Cambridge: Harvard University Press. 1989, $35.00 (cloth), $14.95 (paper)

Quantification of Dental Occlusal Variation: A Review of Methods