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Livestock losses caused by wild carnivores foster negative attitudes and promote retaliatory killings, threatening the future of carnivore populations. Measures to bring about coexistence between humans and carnivores are of great importance to carnivore conservation. The study questionnaire survey involved 180 respondents from Eastern Serengeti tribes (Maasai and Sonjo), all of which owned livestock. Reported livestock depredation in 2016 by the Maasai tribe (pastoralists) was higher than that by the Sonjo tribe (agropastoralists) because the Maasai own many livestock and live closer to the Serengeti National Park boundary. Most livestock depredation occurred during the day when livestock were out feeding and during the dry season. Spotted hyenas (Crocuta crocuta) were the most commonly reported carnivore responsible for livestock depredation. Livestock depredation caused by lions (Panthera leo) and cheetahs (Acinonyx jubatus) was only reported by the Maasai tribe. Leopards (Panthera pardus), jackals (Canis spp.), and African wild dogs (Lycaon pictus) were responsible for more livestock depredation of the Maasai livestock. A similar study was performed six years earlier, in 2010. Therefore, this study brings insight to the temporal changes of livestock depredation patterns and changes of carnivorous species causing livestock depredation in the Eastern Serengeti ecosystem. The Maasai and Sonjo are the main tribes living in the Eastern Serengeti ecosystem. The Maasai preferably use knives and/or spears, whereas the Sonjo use bows and poisoned arrows to protect their livestock against depredation by wild carnivores, and both tribes prefer the use of multiple techniques to increase the efficiency of livestock protection. Key words: Boma, herding, Maasai, preferences, Sonjo, tribe, weapons.

Sexual selection theory suggests that males benefit more than females from multiple mates and that sexual selection is weak in monogamous mating systems. However, little research on sexual selection has been conducted simultaneously in men and women, and we lack a detailed understanding of the socioecological factors that can influence it. Here, we examined the effects of wealth and sex on 2 distinct episodes of human sexual selection (marry once and remarry) in historical Norwegian populations with imposed monogamy, where remarriage was only possible after widowhood. We quantified sexual selection using the Bateman gradient. We also examined the underlying proximate factors that might influence the odds of remarriage and reproduction after widowhood. We found that the intensity of sexual selection corresponds well with Bateman gradients measured in other monogamous populations and was stronger for those who married once than for those who remarried. The selection gradients on "marry once" were affected by neither sex nor wealth. However, when we measured the gradients on "remarry," sexual selection was stronger on wealthy men and women compared with those who were poor. Remarriage age was the most important underlying factor explaining how widows increased reproductive success. For widowers, it was to remarry a younger woman than themselves. In conclusion, we show that sexual selection can operate on both sexes in a monogamous population and suggest that under certain circumstances (when very wealthy), women can benefit as much as men can by remarriage.

Stable pair bonds are widespread in humans and reproductive success varies greatly among pairs. Determinants of fitness may be based on testosterone-dependent sexually dimorphic traits. Prenatal condition is a critical period of physical development, and fetal testosterone has a profound effect on adult behavior and reproduction. Maternal parity (the number of previous births) might be a proxy for fetal testosterone because the prenatal level of male sex hormone, testosterone, is previously shown to decrease across parities. Offspring reproductive potential may, therefore, be positively associated with low parity in sons and high in daughters, by different masculinization by testosterone. In this study, we explored the effects of maternal parity on offspring’s subsequent (individual and pair-specific) life histories including number of grandchildren (controlling for age at marriage, number of siblings, social status, and year of birth) in a Norwegian preindustrial society. We found that parity was a positive predictor of daughters’ and negative (but not significantly; P = 0.058) predictor of sons’ subsequent fitness. Furthermore, within the mated pairs, the difference between the parity of their 2 mothers was a strong predictor of each couple’s fitness. Sons born to mothers of low parity married to daughters from mothers with high parity had much higher number of grandchildren than, for example, sons of mothers with high parity married to daughters of mothers with low parity. The result highlights the importance of early prenatal condition on human life histories, particularly pair-bond duration and fitness, and that parity may have an impact on offspring pair-specific fitness in the studied population.

Stable pair bonds are widespread in humans and reproductive success varies greatly among pairs. Determinants of fitness may be based on testosterone-dependent sexually dimorphic traits. Prenatal condition is a critical period of physical development, and fetal testosterone has a profound effect on adult behavior and reproduction. Maternal parity (the number of previous births) might be a proxy for fetal testosterone because the prenatal level of male sex hormone, testosterone, is previously shown to decrease across parities. Offspring reproductive potential may, therefore, be positively associated with low parity in sons and high in daughters, by different masculinization by testosterone. In this study, we explored the effects of maternal parity on offspring’s subsequent (individual and pair-specific) life histories including number of grandchildren (controlling for age at marriage, number of siblings, social status, and year of birth) in a Norwegian preindustrial society. We found that parity was a positive predictor of daughters’ and negative (but not significantly; P = 0.058) predictor of sons’ subsequent fitness. Furthermore, within the mated pairs, the difference between the parity of their 2 mothers was a strong predictor of each couple’s fitness. Sons born to mothers of low parity married to daughters from mothers with high parity had much higher number of grandchildren than, for example, sons of mothers with high parity married to daughters of mothers with low parity. The result highlights the importance of early prenatal condition on human life histories, particularly pair-bond duration and fitness, and that parity may have an impact on offspring pair-specific fitness in the studied population. Key wor ds: early condition, grandchildren, pair bond, parity, reproductive success, testosterone. [Behav Ecol]

Wealth and status covary with lifetime reproductive success in preindustrial human populations. Local ecology is likely to modify this association, but details of this presumed relationship are not yet known. We sought to determine whether local ecology modifies the relationship between status and fitness (number of grandchildren). Our approach to the problem was to measure variation in fitness relative to status (landless or with land) and to local ecology (inland versus coastal communities). We also analyzed life history traits that might explain observed variations in fitness. Our results confirm previous findings that both status (landless=9.9 vs. with land=16.5) and ecology (inland=12.3 vs. coast=14.1) affect the number of grandchildren produced by a female in pre-industrial society. We also found that the differences in number of children between the status groups were less pronounced on the coast (landless=12.0 vs. with land=16.1) than inland (landless=7.8 vs. with land=16.8). Our findings are novel because they suggest that the fitness consequences of human status may depend on details of local ecology. We discuss four different mechanisms that could account for these fitness differences: (1) differential reproductive rate of mothers, (2) differential marriage rate of children (3) differential survival rate of children, and (4) different social practices (breastfeeding, inheritance of property and diet).

The aim of this study was to test the hypothesis that parent–offspring conflict over parental investment might have led to the rarity of dizygotic twins in humans. We explored the theoretical prediction that twins maximize their inclusive fitness by the death of a co-twin, while mothers of twins maximize fitness by raising both twins to independence. We used life history data (1700–1900) from two parishes in Central Norway to compare differences in inclusive fitness (measured as number of children reared to the age of 16 years, using Hamilton's rule) between twins and mothers of twins. Our results show that twins maximize their inclusive fitness by the death of a co-twin, while mothers of twins raise more children by rearing both twins to adulthood. However, because twins growing up as singletons may produce higher or at least equal number of offspring than the sum of the two twins growing up together, mothers might gain more grandchildren by allowing twins to grow up as singletons. To conclude, both selfish twins and their mothers might benefit by the death of a co-twin, indicating that there is no parent–offspring conflict responsible for the rareness of twins in these human populations. Finally, we discuss the results in the light of “The Insurance Egg Hypothesis” and “The Natural Selection Hypothesis”.

Life history theory proposes that menopause is either an epiphenomenon or an adaptation. The most recent adaptive hypothesis proposes that menopause in humans has evolved because of conflict between reproducing generations (RCH). Overlapping reproduction between generations may impose fitness costs to older and younger females who co-breed. However, it has yet to be demonstrated by using a measure of evolutionary fitness (i.e. grandchildren). Here, we tested the RCH by using multigenerational life-history data of historical Norwegian women. Our results indicate that both generations seem to experience some fitness benefits with co-breeding (i.e. reproductive overlap and cohabit). This was because both younger and older females who co-bred had more grandchildren than those who did not co-breed. We suggest that younger females may partly had enhanced fitness because they copied behaviour of females of the older generation. Our results do not support the hypothesis that reproductive conflict between generations explains the evolution of menopause in women. Our results, taken together with the growing evidence against several assumptions of the RCH, indicate that 1) the decline in follicle number has no marked increase in women as they reach the age of 38 years; 2) humans do not have an abrupt decline in fertility at mean age of 38 years; 3) menopause is not unique to humans; and 4) there are not high numbers of individuals surviving to older adulthood during our evolutionary past. Finally, we discuss an alternative point of view suggesting that menopause might be understood in the light of both ageing in general as well as our increased lifespan.

Ultraviolet radiation (UVR) can suppress essential molecular and cellular mechanisms during early development in living organisms and variations in solar activity during early development may thus influence their health and reproduction. Although the ultimate consequences of UVR on aquatic organisms in early life are well known, similar studies on terrestrial vertebrates, including humans, have remained limited. Using data on temporal variation in sunspot numbers and individual-based demographic data ( N = 8662 births) from Norway between 1676 and 1878, while controlling for maternal effects, socioeconomic status, cohort and ecology, we show that solar activity (total solar irradiance) at birth decreased the probability of survival to adulthood for both men and women. On average, the lifespans of individuals born in a solar maximum period were 5.2 years shorter than those born in a solar minimum period. In addition, fertility and lifetime reproductive success (LRS) were reduced among low-status women born in years with high solar activity . The proximate explanation for the relationship between solar activity and infant mortality may be an effect of folate degradation during pregnancy caused by UVR. Our results suggest that solar activity at birth may have consequences for human lifetime performance both within and between generations.