Regression estimates of the gross reproduction rate using moments of the female age distribution.
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The effect of a decline in mortality on the gross reproduction rate.
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Adolescent↗
Growth rate, population entropy, and perturbation theory.
This paper is concerned with the connection between two classes of population variables: measures of population growth rate--the Malthusian parameter, the net reproduction rate, the gross reproduction rate, and the mean life expectancy; and measures of demographic heterogeneity--population entropy. It is shown that the entropy functions predict the response of the growth rate parameters to perturbations in the age-specific fecundity and mortality schedule. These results are invoked to introduce the notion of environmental intensity. The intensity function, expressed in terms of the entropy parameters, is applied to give a comparative study of the effect of environmental factors on the dynamics of Swedish and French populations.
Age Factors↗
[Effect of temperature and food concentration on the population dynamics of three Brachionus calyciflorus strains].
Effects of temperature (20 degrees C, 25 degrees C, 30 degrees C) and food concentration (1.5, 3.0, 6.0, 9.0 x 10(6) cells x ml(-1)) on the population dynamics of Brachionus calyciflorus of Qingdao, Wuhu and Guangzhou strains were studied by means of individual culture. The result showed that the temperature was an important factor affecting generation time and intrinsic rate of population increase. With rising of temperature, the intrinsic rate of population increase increased, but generation time decreased. There were significant effects of food concentration on life expectancy and average lifespan. The effect of strain on net reproductive rate, generation time, life expectancy and average lifespan was also significant. Net reproductive rate, generation time, life expectancy, and average lifespan of Guangzhou strain was all the maximum, and that of Wuhu strain minimum among the three strains. The rotifers fed on the algae at the concentration of 3.0 x 10(6) cells x ml(-1) had the longest life expectancy and average lifespan, but those at 9.0 x 10(6) cells x ml(-1) had the shortest. Net reproductive rate, generation time, gross reproductive rate, life expectancy, and average lifespan of the three strains decreased linearly with the rise of temperature, except for the net reproductive rate of Guangzhou strain, while the intrinsic rate of population increase of all the three strains and gross reproductive rate of Guangzhou strain increased linearly with the rise of temperature. The relationships between all the life history parameters of Qingdao and Guangzhou strains and food concentration were all curvilinear, however, those between generation time, average lifespan, and life expectancy of Wuhu strain and food concentration could all be described by linear regression.
Animals↗
Temporal differences in the regional twinning rates in Sweden after 1750.
When twinning rates are studied, maternal age and parity should be considered. Data on parity are seldom available. We studied information about the mean parity, using the gross reproduction rate, the total fertility rate and the crude birth rate. These are strongly correlated with the mean parity. The crude birth rate is more readily available than the gross reproduction rate or the total fertility rate. Earlier studies have shown that it is difficult to model variations in the twinning rate with data for the macrolevel. In this study these findings are explained by theoretical analyses and illustrated by empirical data. Sweden, having the oldest continuous population statistics and high twinning rates, offers excellent possibilities for analyses of the twinning rate. We considered data for the counties of Gotland, Alvsborg and Stockholm and the city of Stockholm from 1749 to 1960 and for Sweden until 1996. For Alvsborg, the twinning rate was low for the whole period, showing no statistically significant decreasing trend. It is mainly about 11-14 per thousand, which is only 50-60% of the twinning rate in Gotland in the 18th century. In Gotland, in the county of Stockholm, in the city of Stockholm and in Sweden as a whole, the decreasing trends in the twinning rate were statistically significant. The decreasing twinning rates converge towards the low twinning rate of Alvsborg. After standardization of the twinning rate, the differences remained and the low rate in Alvsborg could not be explained by maternal age.
Birth Rate↗
Culture, religion, and fertility: a global view.
This study tries to assess the effects of culture and religion on fertility after accounting for a country's socioeconomic standing. Analysis of covariance models are estimated for 128 countries with time-series covering the period 1950-1975. The dependent variable is the gross reproduction rate; independent variables are the infant mortality rate, an aggregate indicator of female educational standing, and gross domestic product per person as well as categorical variables for religion and cultural region. It turns out that the European countries have generally lower fertility than could be expected from their socioeconomic standing. In the Arab countries, culture and religion tend to have strong positive effects on fertility. Across cultures, Catholicism has a fertility-increasing effect but it--like the effect of all religions except Islam--is diminishing over time. In contrast, the effect of culture (as measured by a regional variable) on the level of national fertility has been increasing at the expense of socioeconomic effects.
Birth Rate↗
Life tables of Venturia canescens (Hymenoptera: Ichneumonidae) parasitizing the Mediterranean flour moth (Lepidoptera: Pyralidae).
Effects of temperature, adult feeding, and host instar on life table parameters of Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) parasitizing larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were studied in the laboratory. Experimental adults lived under various regimes of temperature (15, 20, 25, and 30 degrees C), food supply (with or without access to honey), and host instar (second, third, fourth, and fifth). Temperature increase resulted in higher values of the intrinsic rate of natural increase (r(m)), the net reproductive rate (R(o)), the finite capacity of increase (lambda), and the gross reproductive rate (GRR), whereas it was followed by decrease of the mean generation time (G) and the doubling time (DT) values. Feeding on honey caused remarkable increase of r(m), R(o), and GRR, whereas r(m) and lambda reached their maximum when full-grown hosts (fifth instar) were parasitized. This is the first time life table parameters of V. canescens have been studied. The findings of the current study are discussed on the basis of improving V. canescens performance as a biological agent against moth pests of stored products.
Animals↗
[Some remarks about the spatial differentiation of fertility in Poland].
"Some problems are discussed in connection with the estimation and interpretation of regression equations. Stability in time is suggested as one of the criteria of goodness of fit.... Several regression equations are estimated giving the gross reproduction rate as a linear function of the proportion of economically active females outside agriculture (SUMMARY IN ENG, RUS)
Birth Rate↗
Malnutrition and high childhood mortality among the Onge tribe of the Andaman and Nicobar Islands.
OBJECTIVES: A study was conducted among the Onge tribe of the Andaman and Nicobar Islands with the objectives of identifying demographic factors responsible for the decline in their population and assessing their nutritional status, which is an important determinant of child survival. STUDY DESIGN AND SUBJECTS: The study included estimation of indices of fertility and child mortality, and assessment of nutritional status. All individuals of the Onge community settled on Little Andaman Island were included. RESULTS: The mean total marital fertility rate was estimated to be 5.15 live births per woman and the general fertility rate was 200 live births per 1000 married-woman-years. Although the gross reproduction rate was estimated to be 2.2 female children per married woman, the net reproduction rate was only 0.9 surviving female child per married woman. The mean infant mortality rate during the past 30 years was 192.7 per 1000 live births, and the child survival rate was found to be only 53.2%. A mild to moderate degree of malnutrition was found in 85% of children of pre-school age and severe malnutrition in 10%. The Onges had low intakes of iron, vitamin A and vitamin C. All the screened Onges were found to be infested with one or more intestinal parasites. CONCLUSIONS: High childhood mortality appears to be the predominant demographic factor responsible for the decline in the Onge population. The high prevalence of undernutrition and micronutrient deficiency disorders could be important factors contributing to the high childhood mortality.
Adolescent↗
Life tables and development of Bemisia argentifolii (Homoptera: Aleyrodidae) at different temperatures.
The life history of Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) on tomato (Lycopersicum spp.) was studied based on the age-stage, two-sex life table at 15, 20, 25, 28, 30, and 35 degrees C. The intrinsic rate of increase (r) at these temperatures is -0.0176, 0.0667, 0.1469, 0.1611, 0.1745, and 0.0989 d(-1), respectively. The relationship among the gross reproductive rate (GRR), the net reproductive rate (R0), and the preadult survivorship (l(a)) is consistent with GRR > l(a) x GRR > R0 for all results at different temperatures. The mean generation time is 81.9, 48.6, 28.4, 25.3, 22.1, and 18.2 d, respectively. The developmental rate of the egg stage at different temperatures fit a linear equation with a thermal summation 89.2 degree-days and a developmental threshold of 11.4 degrees C. The developmental rates of the nymphal stage fit the model of Stinner et al. and the parameters of C, Rmax, k1 and k2 were 0.085, 0.0833, 5.298, and -0.263, respectively.
Age Factors↗
Urban and rural differences in mortality and causes of death in historical Poland.
The purpose of this paper is to document and interpret urban-rural differences in mortality in the past. To this end, we used data on mortality in Wielkopolska, Poland, in the 19th century and at the beginning of the 20th century. The data on mortality in rural areas (N = 1,173,910 deceased), small towns (N = 573,903 deceased), and Poznań, the capital of the Wielkopolska region (N = 86,352 deceased), were gathered from original Prussian statistical yearbooks (Preussische Statistik). Causes of death were also analyzed (rural areas, N = 449,576 deceased; small towns, N = 238,365 deceased; Poznań, N = 61,512 deceased). Mortality measures such as crude death rate (CDR), infant death rate (IDR), and neonatal and postneonatal death rates were calculated. Life tables were constructed for both stationary and stable population models and measures of the opportunity for natural selection calculated (Crow's index I(m), potential gross reproduction rate R(pot), and biological state index I(bs)). Relative frequencies of leading causes of death were computed. Stratification depending on the place of residence was evident in all mortality measures as well as in the values of the life tables and the measures of the opportunity for natural selection, but it was reverse of what is observed today in developed countries. In Poznań (a large industrial city), the mortality situation was the least favorable. It was caused by large population density, lack of water supply and sewage systems (up to 1896), and bad working conditions. The values of CDR ranged between 26.89-31.46, and IDR between 190.6-280.5. Newborn life expectancy (for a stable population model) was 31.6 years, I(m) = 0.79, R(pot) = 0.85, and I(bs) = 0.47. The most common causes of death were tuberculosis, other diseases of the respiratory and circulatory systems, dysentery and diarrhea, and cancer. These diseases were less common in rural areas, so they had the most favorable values of mortality measures (CDR between 22.87-27.32, IDR between 181.8-219.4, life expectancy of newborn e(0) = 42.12, I(m) = 0.55, R(pot) = 0.93, I(bs) = 0.60). Infectious diseases (other than tuberculosis), frailty at birth, and frailty in old age were the most frequent causes of death in rural areas. Small towns (population <20,000) had a mortality intermediate between city and rural areas.
Cause of Death↗
[A specification of the gross (or net) reproduction rate by birth order].
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Birth Order↗
A reconstruction of the population of north Italy from 1650 to 1881 using annual inverse projection with comparisons to England, France, and Sweden.
"North Italy annual population and vital rates are reconstructed from 1650 to 1881 using series of vital event indices from many rural parishes and cities. Inverse projection is applied to the reconstructed series of vital events and population to generate annual age distribution, gross reproduction rate, net reproduction rate, life expectancy at birth, and infant mortality rate. The results are compared with official sources and detailed demographic rates produced by annual inverse projection using data from England, France, and Sweden. Over the long term, North Italy is generally characterized by stagnant and relatively high mortality. Fertility and nuptiality are relatively high at the beginning and at the end of the period." (SUMMARY IN FRE)
Demography↗
[Population reproduction rates for all of Japan, 1980].
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Age Factors↗
Demographic trends and biological status of historic populations from Central Poland: the Ostrów Lednicki microregion.
The microregion of Ostrów Lednicki in the province of Wielkopolska was the center of the formation of the Polish State in Early Middle Ages. The analysis of skeletal remains and parish records from the region documented the biological status of inhabitants and its changes over a millennium. The study material comprised 424 human skeletons from an Early Medieval burial ground on Lake Lednica, records of 2,704 deaths from the registers of the Roman Catholic parish of Dziekanowice, made between 1818-1903, data on the deaths of 929,192 inhabitants of rural areas all over the province Wielkopolska obtained from Prussian statistical materials for the years 1865-1900, and comparative data from the literature. Assuming both a stationary population model and a stable population model with nonzero natural increase, parameters of life tables and measures of opportunity for natural selection (Crow's index I(m), potential gross reproductive rate R(pot), and the biological state index I(bs)) were calculated for the Early Middle Ages and for the two periods of the 19th century which were characterized by different laws of land ownership and thus different rural economies. In the first period, peasants were tenants, whereas in the second, they were given freehold of the land they cultivated. Causes of death were also analyzed. A distinct increase in longevity from the early Middle Ages to the end of the 19th and the beginning of the 20th century was found. This was related to a higher level of demographic development in the parish of Dziekanowice during the 19th century, which was achieved earlier than in other areas of Poland. This was confirmed by genetic measures: coefficients of exogamy and coefficients of kinship. The reasons were related to the historical prominence of this region and to its proximity to the first two capitals of the Polish state, Gniezno and Poznań.
Age Factors↗
Mortality changes in a Polish rural community (1350--1972) and estimation of their evolutionary significance.
Changes in the mortality profiles of the population of 13 villages in central Poland have been studied for the medieval and nineteenth-century periods. Three measures, derived from the demographic data, were analyzed within an evolutionary context: (1) Im, the opportunity for selection through differential mortality, (2) Rpot, the potential gross reproductive rate, and (3) Ibs, the index of biological state. Changes in these indicators over time denote sharp differences in the opportunity for natural selection through differential mortality. The greatest changes are associated with technological and organizational transformations of the social system, especially during the first half of the nineteenth century.
Actuarial Analysis↗
Model life table fitting by maximum likelihood estimation: a procedure to reconstruct paleodemographic characteristics from skeletal age distributions.
A procedure is presented that uses the regression coefficients for the Coale and Demeny west model life tables to model selected demographic characteristics from skeletal age-at-death distributions. Model death distributions were constructed and compared to a given skeletal distribution, using methods of maximum likelihood estimation to determine the best fit. Two chi-square tests are employed to evaluate the degree of fit. The resulting model includes estimates of demographic characteristics including gross reproductive rate, crude birth rate and life expectancy. The procedure is applied to three archaeological skeletal samples as test cases: two from eastern North America and one from Mexico. These display a range of correspondence (between the best fitting model and the data) from good to poor. The proposed procedure is a potentially powerful tool for both reconstructing paleodemographic rates and illuminating differences between typical human patterns and those found in archaeological populations.
Actuarial Analysis↗
Paleodemography of the Carlston Annis (Bt-5) Late Archaic skeletal population.
The study presents a demographic assessment of the Carlston Annis (Bt-5) Late Archaic hunting and gathering population recovered from the banks of the Green River in west-central Kentucky. The shell midden habitation and cemetery site originally yielded the remains of 390 individuals. Radiocarbon dates place site occupation between 3,000 and 4,500 y.b.p. The skeletal sample consisted of 354 individuals ranging in age from 7 months in utero to 70 + years. Subadults were aged by seriation of dental and skeletal developmental criteria. Adult ages were determined by the multifactorial summary age method that employed 1) five indicators of adult skeletal age at death, 2) the procedure of age indicator seriation, and 3) differential weighting of age assessments as determined by principal components analysis. Adult sex diagnoses were based on qualitative assessment of pelvic and cranial morphological criteria. The Bt-5 life table analysis yields an E0 of 22.4 years, crude birth of 45, mean family size of 3.3, gross reproductive rate of 2.7, generation length of 26.6 years, and B of .076, indicating a healthy population with a substantial capability to replace succeeding generations. Survivorship profiles and demographic parameters that compare the Carlston Annis (Bt-5) and Indian Knoll (Oh-2) skeletal series are presented. Both populations display type II survivorship curves, with high infant mortality and early onset of elevated mortality rates in adults. Major differences between Bt-5 and Oh-2 demographic parameters concern adult sex ratio and adult age distribution over 30 years. These differences are interpreted to reflect census errors in the Oh-2 demographic reconstruction that were possibly introduced by selective methodological biases and/or taphonomic factors.
Age Determination by Skeleton↗