Insights into the palaeobiology of an early Homo infant: multidisciplinary investigation of the GAR IVE hemi-mandible, Melka Kunture, Ethiopia

Childhood is an ontogenetic stage unique to the modern human life history pattern. It enables the still dependent infants to achieve an extended rapid brain growth, slow somatic maturation, while benefitting from provisioning, transitional feeding, and protection from other group members. This tipping point in the evolution of human ontogeny likely emerged from early Homo. The GAR IVE hemi-mandible (1.8 Ma, Melka Kunture, Ethiopia) represents one of the rarely preserved early Homo infants (~ 3 years at death), recovered in a richly documented Oldowan archaeological context. Yet, based on the sole external inspection of its teeth, GAR IVE was diagnosed with a rare genetic disease–amelogenesis imperfecta (AI)–altering enamel. Since it may have impacted the child’s survival, this diagnosis deserves deeper examination. Here, we reassess and refute this diagnosis and all associated interpretations, using an unprecedented multidisciplinary approach combining an in-depth analysis of GAR IVE (synchrotron imaging) and associated fauna. Some of the traits previously considered as diagnostic of AI can be better explained by normal growth or taphonomy, which calls for caution when diagnosing pathologies on fossils. We compare GAR IVE’s dental development to other fossil hominins, and discuss the implications for the emergence of childhood in early Homo.

The Effects of Maternal Prenatal Stress on Fetal and Child Development

This chapter describes the effects of maternal prenatal stress on fetal and child development. There is considerable evidence from both animal and human studies that if the mother is stressed during pregnancy this increases the likelihood of her offspring having a range of altered behavioral and other neurodevelopmental outcomes, together on occasion with increased stress reactions. It is possible to suggest adaptive reasons for many of these effects. The behavioral outcomes, such as increased anxiety in females, will make them more vigilant and able to detect danger. More aggression in males may make them better at dealing with this danger.An increased risk of other outcomes such as preterm delivery, earlier menarche, and reduced telomere length, reflect an accelerated life history pattern from birth to death. These too may be of evolutionary advantage in conditions of external threat.

The evolution of human life course

Homo sapiens’ life history pattern possesses both fast and slow components, in a combination that is unique among the extant great apes. One of the issues debated in current evolutionary research is the role played by phenotypic plasticity as a non-genetic means of adaptation to evolutionary challenges. While life history parameters are shaped at a species level by genetic adaptations via natural selection, they remain very sensitive to changes in the environment. Relying on updated evidence and on key explanatory tools of the Extended Evolutionary Synthesis (phenotypic plasticity, niche construction, and inclusive inheritance), it is likely that environmentally induced plasticity led the way in human life history evolution, promoting subsequent genetic accommodation. To the extent that culturally transmitted behaviors altered the selective pressures that acted on life history traits across generations during human evolution, a culturally driven plasticity dynamic shaping human life history traits can be identified. Two case studies in particular are discussed: the human adaptations to the domestication of fire and the self-domestication hypothesis.

Argulus from the Pascagoula River, MS, USA, with an Emphasis on Those of the Threatened Gulf Sturgeon, Acipenser oxyrinchus desotoi

Species of Argulus (Branchiura Thorell, 1864) are common ectoparasites of freshwater, estuarine, and marine fishes. Argulid identification and taxonomy is often confusing because many species are reported to parasitize multiple host species, have similar morphological characters, and come from various salinity regimes. Gulf sturgeon is an anadromous fish natal to drainages in the north-central Gulf of Mexico, and as with many endangered species, has a poorly documented parasite community. During Gulf sturgeon tagging and monitoring studies (2016–2019) in the Pascagoula River, MS, USA, species of Argulus were collected from Gulf sturgeon as well as other incidentally captured fishes. Argulus flavescens Wilson, 1916 was found on Gulf sturgeon and flathead catfish, Argulus americanus Wilson, 1902 on bowfin, and Argulus bicolor Bere, 1936 on Atlantic stingray. We provide morphological details and measurements for these species as well as the first confirmed 28S rDNA molecular data. Argulus flavescens was more abundant and prevalent on larger Gulf sturgeon and on sturgeon captured in freshwater rather than estuarine habitats. Our results indicate that A. flacescens may not tolerate estuarine salinities and that the anadromous life-history pattern of Gulf sturgeon could help rid them of A. flavescens when they emigrate from their riverine habitats.

Some behavioural aspects on the Hemidactylus species of Bangladesh

Hemidactylus is a taxonomically complex genus and little is known about its feeding and breeding behavior in Bangladesh. Most of the species of this genus have a preference to live within human habitations, and play an important role in ecosystem, controlling insect pest population. Their breeding strategy is almost similar with each other and associated with their body structure. Review of literature found that there is a relationship between life history pattern and their reproductive biology. They lay two eggs per clutch usually and the highest egg number (12) has been recorded for H. frenatus. Strong significant positive correlation (r = 0.91) was found for preclaocal-femoral pores and egg number. Besides, significant negative correlation was found for average female body size and egg number (r = 0.96). Previous work and observation records showed that feeding habit is almost similar among all species of Hemidactylus and dipteran insects were the mostly consumed food item. J. Biodivers. Conserv. Bioresour. Manag. 2019, 5(1): 77-84

New DNA coalescent models and old population genetics software†

The analyses of often large amounts of field and laboratory data depend on computer programs to generate descriptive statistics and to test hypotheses. The algorithms in these programs are often complex and can be understood only with advanced training in mathematics and programming, topics that are beyond the capabilities of most fisheries biologists and empirical population geneticists. The backward looking Kingman coalescent model, based on the classic forward-looking Wright–Fisher model of genetic change, is used in many genetics software programs to generate null distributions against which to test hypotheses. An article in this issue by Niwa et al. shows that the assumption of bifurcations at nodes in the Kingman coalescent model is inappropriate for highly fecund Japanese sardines, which have type III life histories. Species with this life history pattern are better modelled with multiple mergers at the nodes of a coalescent gene genealogy. However, only a few software programs allow analysis with multiple-merger coalescent models. This parameter misspecification produces demographic reconstructions that reach too far into the past and greatly overestimates genetically effective population sizes (the number of individuals actually contributing to the next generation). The results of Niwa et al. underline the need to understand the assumptions and model parameters in the software programs used to analyse DNA sequences.

Brain ontogeny and life history in Pleistocene hominins

A high level of encephalization is critical to the human adaptive niche and emerged among hominins over the course of the past 2 Myr. Evolving larger brains required important adaptive adjustments, in particular regarding energy allocation and life history. These adaptations included a relatively small brain at birth and a protracted growth of highly dependent offspring within a complex social environment. In turn, the extended period of growth and delayed maturation of the brain structures of humans contribute to their cognitive complexity. The current palaeoanthropological evidence shows that, regarding life history and brain ontogeny, the Pleistocene hominin taxa display different patterns and that one cannot simply contrast an ‘ape-model’ to a ‘human-model’. Large-brained hominins such as Upper Pleistocene Neandertals have evolved along their own evolutionary pathway and can be distinguished from modern humans in terms of growth pattern and brain development. The life-history pattern and brain ontogeny of extant humans emerged only recently in the course of human evolution.

Anadromy and residency in steelhead and rainbow trout (Oncorhynchus mykiss): a review of the processes and patterns

Oncorhynchus mykiss form partially migratory populations with anadromous fish that undergo marine migrations and residents that complete their life cycle in fresh water. Many populations’ anadromous components are threatened or endangered, prompting interest in understanding ecological and evolutionary processes underlying anadromy and residency. In this paper, we synthesize information to better understand genetic and environmental influences on O. mykiss life histories, identify critical knowledge gaps, and suggest next steps. Anadromy and residency appear to reflect interactions among genetics, individual condition, and environmental influences. First, an increasing body of literature suggests that anadromous and resident individuals differ in the expression of genes related to growth, smoltification, and metabolism. Second, the literature supports the conditional strategy theory, where individuals adopt a life history pattern based on their conditional status relative to genetic thresholds along with ultimate effects of size and age at maturation and iteroparity. However, except for a generally positive association between residency and high lipid content plus a large attainable size in fresh water, the effects of body size and growth are inconsistent. Thus, individuals can exhibit plasticity in variable environments. Finally, patterns in anadromy and residency among and within populations suggested a wide range of possible environmental influences at different life stages, from freshwater temperature to marine survival. Although we document a number of interesting correlations, direct tests of mechanisms are scarce and little data exist on the extent of residency and anadromy. Consequently, we identified as many data gaps as conclusions, leaving ample room for future research.

New data on the biology and habitat preferences of the oligochaete species Ripistes parasita (Annelida: Clitellata: Naididae): a case study in a temporary woodland pond

Studies carried out in woodland ponds located in an industrial area of southern Poland revealed the occurrence of a large population of Ripistes parasita (Schmidt, 1847) in one of them. This is a naidid species that is not usually abundant in oligochaete communities. Its ecology and biology is poorly known and thus the aim of this study was to characterise the environmental conditions influencing the occurrence of R. parasita and to assess its population dynamics and life history pattern. R. parasita occurred in a pond with soft water and a low level of mineralisation, a pH ranging from 6.1 to 7.0, and a high content of nitrogen and phosphorus. During our investigation, considerable seasonal changes in the occurrence and population density were detected. Specimens of this species inhabited alder leaf deposits in winter and early spring while in summer and autumn they occupied in large number floating Nuphar lutea leaves. A stepwise regression analysis showed a relationship between the temperature and dissolved oxygen content in the water and the density of R. parasita. The R. parasita reproduced asexually by paratomy (between May and November). The mean doubling time (days) for the population was 22.4. Only a few individuals (less than 1% of the population) matured in September and October.