A critique of the chronometric evidence for hominid fossils: I. Africa and the Near East 500-50 ka

The chronometric dating evidence for all hominid fossils from Africa and the Near East that have previously been dated to 500-50 ka is critically assessed using the concept of chronometric hygiene, and these dates are revised using Bayesian statistical analyses where possible. Sixteen relevant hominid sites lacking chronometric evidence are briefly discussed. Chronometric evidence from 37 sites is assessed in detail. The dates for many hominid fossils are poorly constrained, with a number dated by comparisons of faunal assemblages-a method that does not have good chronological resolution for much of the last million years. For sites with stratigraphic sequences of dates, it is generally possible to refine the dating, but in some cases, the revised chronology is less precise than previous chronologies. Fossils over 200 ka in age tend to be poorly dated, but for the last 200 kyr, dating is better due to the availability of electron-spin-resonance and thermoluminescence dating. Consideration of the chronologies favored by the proponents of the out-of-Africa and multiregional hypotheses of human evolution shows their selectivity. The chronological assessment of the fossils here is compatible with either hypothesis. If evolutionary schemes that do not rely on the morphology of the hominid fossils to decide the sequence of fossils are to be built, then further dating is required, alongside full publication of existing dates.     

Scaled down method for the reproducible recovery to high purity of human serum albumin from low volume blood samples

A basic need for a protein-based dosimeter is a purified protein. In this communication we present an isolation protocol and an HPLC-based assay which allows one to determine the purity of the isolated albumin. A total of 168 human blood samples were collected from workers of a benzene processing plant and from nearby countryside at Kohtla-Järve, Estonia. Albumin was isolated from plasma by sequential precipitation and the purity was determined by HPLC. The amount of albumin present in plasma varied between the individuals, being 147 ± 26 mg/5 ml (n=168), which is about 59% of plasma albumin. However, the isolated albumin was highly pure (100.9 ± 8.2%, n=5). All albumin samples analyzed demonstrate two peaks in HPLC analysis. The two peaks detected were collected and subjected to MS analysis, which demonstrates a difference of 120 mass units between the two albumin products isolated. We have developed an assay, which is easy to carry out and is not too labor intense. The HPLC analysis can be applied to confirm the purity of the isolated albumin as well as to confirm the quantity of the albumin in samples.     

Age-specific variation in the secular trend for stature: A comparison of samples from industrialized and nonindustrialized regions

Age-specific secular trend patterns for children in industrialized world regions have a regular pattern, beginning low at age 6 and increasing to a maximum at age 10 to 14, then declining. While magnitude differs, the patterns are ordinarily parallel, especially in the female samples. However, age-specific secular trend values for children from developing regions, or from areas of industrialized countries not benefitting substantially from development, are irregular in pattern and magnitude. Consequently, it is difficult to predict age at maximal secular change. We suggest that fluctuating environmental circumstances in these developing countries influence growth and, hence, the pattern of secular trend. As more stable environmental conditions relating to growth are present in the industrialized countries, this leads to more stable patterns of growth and age-specific patterns of secular change.     

Memory in retroviral quasispecies: experimental evidence and theoretical model for human immunodeficiency virus

Viral quasispecies may possess a molecular memory of their past evolutionary history, imprinted on minority components of the mutant spectrum. Here we report experimental evidence and a theoretical model for memory in retroviral quasispecies in vivo. Apart from replicative memory associated with quasispecies dynamics, retroviruses may harbour a "cellular" or "anatomical" memory derived from their integrative cycle and the presence of viral reservoirs in body compartments. Three independent sets of data exemplify the two kinds of memory in human immunodeficiency virus type 1 (HIV-1). The data provide evidence of re-emergence of sequences that were hidden in cellular or anatomical compartments for extended periods of infection, and recovery of a quasispecies from pre-existing genomes. We develop a three-component model that incorporates the essential features of the quasispecies dynamics of retroviruses exposed to selective pressures. Significantly, a numerical study based on this model is in agreement with the experimental data, further supporting the existence of both replicative and reservoir memory in retroviral quasispecies.     

Re-evaluating the health of coral reef communities: baselines and evidence for human impacts across the central Pacific

Numerous studies have documented declines in the abundance of reef-building corals over the last several decades and in some but not all cases, phase shifts to dominance by macroalgae have occurred. These assessments, however, often ignore the remainder of the benthos and thus provide limited information on the present-day structure and function of coral reef communities. Here, using an unprecedentedly large dataset collected within the last 10 years across 56 islands spanning five archipelagos in the central Pacific, we examine how benthic reef communities differ in the presence and absence of human populations. Using islands as replicates, we examine whether benthic community structure is associated with human habitation within and among archipelagos and across latitude. While there was no evidence for coral to macroalgal phase shifts across our dataset we did find that the majority of reefs on inhabited islands were dominated by fleshy non-reef-building organisms (turf algae, fleshy macroalgae and non-calcifying invertebrates). By contrast, benthic communities from uninhabited islands were more variable but in general supported more calcifiers and active reef builders (stony corals and crustose coralline algae). Our results suggest that cumulative human impacts across the central Pacific may be causing a reduction in the abundance of reef builders resulting in island scale phase shifts to dominance by fleshy organisms.     

Oscillating prostacyclin and thromboxane generation by human vessels: biological and mathematical evidence for negative feedback control

The presented study investigates the time-dependent release of PGI₂ and TXA₂ by isolated human umbilical veins in vitro using the radio-immunoassay for measurement. After changing the nutritional fluid—Krebs-Henseleit solution at pH 7.4, 37°C, 95% O₂/5% CO₂—the release graph oscillates. These oscillations with time were verified by variance analysis and are very similar for both substances. This indicates one or several negative feedback mechanisms acting on the common path of synthesis from the membrane-bound phospholipids to PGH₂, which are effective in the regulation of eicosanoid biosynthesis in vitro. A mathematical function describing the observed PGI2 and TXA₂ synthesis is communicated.     

Environmental change, extinction and human activity: evidence from caves in NW Madagascar

In the last 2000 years, changes on the island of Madagascar have resulted in the modification of key environments and the extinction of nearly all large native animals. Humans have long been suspected as the primary cause of this ecological catastrophe, but the exact mechanisms of the island's rapid transformation and the role of natural factors such as climate change remain uncertain. Caves in northwestern Madagascar are helping researchers to disentangle these factors, by providing many types of datable information concerning the past in close physical proximity. U -series dated pollen spectra from the caverns of Anjohibe provide a 40,000-year record of vegetation in the vicinity. Bone deposits from caves in the region provide new site records for extinct taxa, including Babakotia radofilai Godfrey et al . 1990, Plesiorycteropus madagascariensis Filhol 1895, and Mullerornis sp. Several extant taxa that were present in the region in the late Holocene are now locally extinct. Archaeological evidence from the caves suggests little or no human activity in the vicinity or interaction with the fauna at these sites until recent centuries.     

Recent environmental change in North African wetland lakes: diatom and other stratigraphic evidence from nine sites in the CASSARINA Project

All nine wetland lakes in the CASSARINA North African suite of sample sites have been disturbed strongly by human activity during the 20th century. Dated lake sediment core were used to provide evidence of the extent of recent environmental change at each site. Sedimentary diatoms at seven sites were useful for inferring salinity change trends during the last century. At two sites preservation problems severely degraded the sedimentary diatom record. Sediment core integrity was otherwise established.Lithostratigraphic measurements indicated some site specific changes in soil erosion and sediment composition but, for the Egyptian Delta lakes, no physical signal synchronous with Aswan High Dam construction was found. Sedimentary diatom assemblages were generally site characteristic and halophilous taxa were common. At two sites planktonic diatoms indicated some recent eutrophication but generally the assemblages were more indicative of salinity changes. Diatom-inferred salinity trends for the seven sites typically indicated that reductions in water salinity occurred sometime during the early or mid 20th century.Rather than climate, hydrological modification of water resources is implicated as the primary driver of salinity changes during most of the 20th century. In the western North African region these modifications were mainly local land drainage and water diversion programmes to alleviate winter flooding and/or promote summer water availability. In the Delta region, the Nile has been intensively exploited since antiquity and intensively so from the late 19th century to release more fresh water for agriculture. Here, diatom records indicate that freshening began well before the Aswan High Dam but salinity fluctuations have tended to diminish during the latter part of the 20th century. A small reversal in the water freshening trend in the 1980/90s was possibly a response to land subsidence/sea-level change or to reduced freshwater supply.Freshwater supply to the sites is generally diminishing as former freshwater surpluses switch to deficit. One site (Merja Bokka, Morocco) became completely dry in 1998 as agriculture encroached and Megene Chitane, the only acid lake in Tunisia, is currently affected by excessive inflow abstraction. At the beginning of the 21st century, eight of the nine CASSARINA sites persist as viable but modified aquatic ecosystems. They nevertheless continue to support valuable aquatic biodiversity, especially in the Delta sites and in Chitane. The modern diatom communities are clearly tolerant of considerable environmental change but the remaining sites are increasingly threatened by major hydrological disturbance. Base-line floristic data for the late 20th century are given but continuous biomonitoring combined with effective management is needed urgently to help conserve North Africa's diminishing natural wetland lake resources.     

Individual health and the visibility of village economic inequality: Longitudinal evidence from native Amazonians in Bolivia

Mounting evidence suggests that income inequality is associated with worse individual health. But does the visibility of inequality matter? Using data from a horticultural-foraging society of native Amazonians in Bolivia (Tsimane’), we examined whether village inequality in resources and behaviors with greater cultural visibility is more likely to bear a negative association with health than village inequality in less conspicuous resources. We draw on a nine-year annual panel (2002–2010) from 13 Tsimane’ villages for our main analysis, and an additional survey to gauge the cultural visibility of resources. We measured inequality using the Gini coefficient. We tested the robustness of our results using a shorter two-year annual panel (2008–2009) in another 40 Tsimane’ villages and an additional measure of inequality (coefficient of variation, CV). Behaviors with low cultural visibility (e.g., household farm area planted with staples) were less likely to be associated with individual health, compared to more conspicuous behaviors (e.g., expenditures in durable goods, consumption of domesticated animals). We find some evidence that property rights and access to resources matter, with inequality of privately-owned resources showing a larger effect on health. More inequality was associated with improved perceived health – maybe due to improved health prospects from increasing wealth – and worse anthropometric indicators. For example, a unit increase in the Gini coefficient of expenditures in durable goods was associated with 0.24 fewer episodes of stress and a six percentage-point lower probability of reporting illness. A one-point increase in the CV of village inequality in meat consumption was associated with a 4 and 3 percentage-point lower probability of reporting illness and being in bed due to illness, and a 0.05 SD decrease in age-sex standardized arm-muscle area. In small-scale, rural societies at the periphery of market economies, nominal economic inequality in resources bore an association with individual health, but did not necessarily harm perceived health. Economic inequalities in small-scale societies apparently matter, but a thick cultural tapestry of reciprocity norms and kinship ties makes their effects less predictable than in industrial societies.     

Physical attractiveness and reproductive success in humans: evidence from the late 20th century United States

Physical attractiveness has been associated with mating behavior, but its role in reproductive success of contemporary humans has received surprisingly little attention. In the Wisconsin Longitudinal Study (1244 women, 997 men born between 1937 and 1940), we examined whether attractiveness assessed from photographs taken at age 18 years predicted the number of biological children at age 53–56 years. In women, attractiveness predicted higher reproductive success in a nonlinear fashion, so that attractive (second highest quartile) women had 16% and very attractive (highest quartile) women 6% more children than their less attractive counterparts. In men, there was a threshold effect so that men in the lowest attractiveness quartile had 13% fewer children than others who did not differ from each other in the average number of children. These associations were partly but not completely accounted for by attractive participants' increased marriage probability. A linear regression analysis indicated relatively weak directional selection gradient for attractiveness (β=0.06 in women, β=0.07 in men). These findings indicate that physical attractiveness may be associated with reproductive success in humans living in industrialized settings.     

Progenitor cells isolated from the human heart: a potential cell source for regenerative therapy

Background. In recent years, resident cardiac progenitor cells have been identified in, and isolated from the rodent heart. These cells show the potential to form cardiomyocytes, smooth muscle cells, and endothelial cells in vitro and in vivo and could potentially be used as a source for cardiac repair. However, previously described cardiac progenitor cell populations show immature development and need co-culture with neonatal rat cardiomyocytes in order to differentiate in vitro. Here we describe the localisation, isolation, characterisation, and differentiation of cardiomyocyte progenitor cells (CMPCs) isolated from the human heart. Methods. hCMPCs were identified in human hearts based on Sca-1 expression. These cells were isolated, and FACS, RT-PCR and immunocytochemistry were used to determine their baseline characteristics. Cardiomyogenic differentiation was induced by stimulation with 5-azacytidine. Results. hCMPCs were localised within the atria, atrioventricular region, and epicardial layer of the foetal and adult human heart. In vitro, hCMPCs could be induced to differentiate into cardiomyocytes and formed spontaneously beating aggregates, without the need for co-culture with neonatal cardiomyocytes. Conclusion. The human heart harbours a pool of resident cardiomyocyte progenitor cells, which can be expanded and differentiated in vitro. These cells may provide a suitable source for cardiac regeneration cell therapy. (Neth Heart J 2008;16: 163-9.)     

Heterogeneity in the protein cores of mucins isolated from human middle ear effusions: evidence for expression of different mucin gene products

High molecular weight mucins were isolated and purified from human middle ear effusions of children with Otitis Media with Effusion (OME) classified into three groups, (1) thick and (2) thin from anatomically normal children and (3) effusions from cleft palate patients. Amino acid analyses of the purified mucins from the three pools were similar but not identical with characteristic contents of serine threonine and proline (32%, 28%, and 38% for pools (1) (2) and (3) respectively). Proteinase resistant glycopeptide fragments corresponding to the tandem repeat domains of cloned mucin genes showed marked differences both between the three mucin pools and with the composition of the tandem repeat sequences of the cloned mucin genes expressed in the airways. Studies on the antigenic identity of middle ear mucins found an epitope likely to be present on MUC5AC, but only accounting for a maximum of 15% by weight and no reactivity was found with antibodies to MUC2 or MUC1. A polyclonal antibody raised to thick effusion mucins reacted strongly with human salivary mucin suggesting the presence of MUC5B epitopes. These studies suggest that more than one mucin gene product is secreted by the human middle ear mucosa and that there may be further mucin genes expressed by the middle ear that have yet to be cloned.     

Marxism and human sociobiology: A comparative study from the perspective of modern socialist economic reforms

Modern socialist economic reforms which center on the establishment of a commodity based economic system, demand a reconsideration of human nature. Marxism and human sociobiology give different answers to questions about human nature, but neither is complete in itself. It seems timely, therefore, to suggest that a combination of biological understanding with a Marxist-based social understanding would produce a more adequate notion of human nature, thereby helping us to resolve a number of problems posed by reforms currently taking place in socialist countries. We might also hope to face new challenges posed in the future.     

Late Quaternary Palaeoichnological Sites from the Southern Atlantic Coast of Buenos Aires Province,Argentina: Mammal,Bird and Hominid Evidence

Palaeontological and palaeoichnological studies were made along the southeastern coast of Buenos Aires province, Argentina. Continental Late Pleistocene and continental, transitional and marine Holocene stratigraphic units were identified. The former are represented by fossil mammal bones and ichnites dated from 16,000 to 12,000 y. B.P. Continental Early Holocene beds dated circa 8,100 years B.P. contain fish, rodent and bird remains. Middle Holocene sediments 6,930 to 6,570 years B.P. are recorded by deposits bioturbated by estuarine crabs. During the Late Holocene, between 5,000 and 4,800 B.P., a marine transgression is recorded by a very rich mollusc fauna. The palaeoenvironmental variety recorded along a few tens of kilometers of the coast is a distinctive feature of this part of the Argentine coastal region. At Monte Hermoso beach, in the eastern part of the studied zone, archaeological materials were dated 7,300 years B.P., and human footprints dated 7,125 years B.P. were also recorded. In January 2005 some isolated human footprints were found at Pehuen-Co palaeoichnological site, which are older than those found at Monte Hermoso beach and of the same age as the oldest human archaeological findings in Patagonia, that is about 12,000 yeas B.P.     

beta-Endorphin: evidence for the existence of opioid and non-opioid binding components for the tritiated human hormone in NG108-15 cells

Human beta-endorphin (beta h-EP) binding on neuroblastoma X glioma hybrid NG108-15 cells using tritiated human beta endorphin (3H-beta h-EP) as a primary ligand was found to have a component which was not displacable with [D-Ser2 )-Leu-enkephalin-Thr6 (DSLET). The beta h-EP binding on these cells after saturation of the delta opiate sites with 200 nM DSLET was further characterized with synthetic beta h-EP analogs. The nonopioid binding site appears to recognize beta h-EP-(6-31), beta h-EP-(21-31) and beta h-EP-(28-31). Under these conditions, these COOH-terminal segments fully displace the tritiated beta h-EP. However, beta h-EP-(1-27) does not further displace 3H-beta h-EP in the presence of DSLET. The fact that a combination of DSLET and beta h-EP-(6-31) results in a full displacement of 3H-beta h-EP provides direct evidence for the existence of two binding sites for beta h-EP in NG108-15 cells, one recognizing the NH2-terminal enkephalin sequence and the other the non-opioid COOH-terminal segment.     

Vegetation dynamics in central Africa since 18,000 yr BP: pollen records from the interlacustrine highlands of Burundi, Rwanda and western Uganda

A standardized analysis of palaeoecological data, in the form of six pollen sequences and forty- four radiocarbon ages, has permitted a region-wide reconstruction of Late Quaternary vegetation dynamics for the interlacustrine highlands of central Africa.
A landscape widely dominated by ericaceous scrub and grasslands, but also supporting sparse patches of open-canopied montane forest, possibly in those areas with a topography most favourable to the growth of trees, is indicated for the last glacial maximum of 18,000 yr bp . Major expansions in the extent of upper altitudinal forms of montane forest occurred from around 12,500 yr bp , while lower moist montane forest—the expected climax for much of the region today—did not become prominent until 11,000 yr bp to 10,000 yr bp . From the palaeoecological evidence at least, it appears that the major east Central forest refuge, proposed by some workers on the basis of current species' distribution patterns, did not extend to the eastern flanks of the Albertine Rift.
A late glacial–early Holocene transition is only fully chronicled in two of the sites. However, it appears that the expansion of lower montane forest had a time-transgressive pattern across the region, and was not simply from low to high altitude. The composition of forests during the early Holocene appears to have been different to that in the later stages of the present interglacial, as taxa presently associated with wetter and/or more open forest types were much more common. Pollen data also indicate that higher altitude parts of the interlacustrine highlands were more attractive to the earliest (possibly Bantu-speaking) farmers and metal-workers. There is evidence of wide-spread forest clearance around the beginning of the present millennium, possibly as a result of substantial changes in socio-economic conditions, and patterns of settlement, associated with the onset of the Late Iron Age.     

Analysis of the human replication protein A:Rad52 complex: evidence for crosstalk between RPA32, RPA70, Rad52 and DNA

The eukaryotic single-stranded DNA-binding protein, replication protein A (RPA), is essential for DNA replication, and plays important roles in DNA repair and DNA recombination. Rad52 and RPA, along with other members of the Rad52 epistasis group of genes, repair double-stranded DNA breaks (DSBs). Two repair pathways involve RPA and Rad52, homologous recombination and single-strand annealing. Two binding sites for Rad52 have been identified on RPA. They include the previously identified C-terminal domain (CTD) of RPA32 (residues 224-271) and the newly identified domain containing residues 169-326 of RPA70. A region on Rad52, which includes residues 218-303, binds RPA70 as well as RPA32. The N-terminal region of RPA32 does not appear to play a role in the formation of the RPA:Rad52 complex. It appears that the RPA32CTD can substitute for RPA70 in binding Rad52. Sequence homology between RPA32 and RPA70 was used to identify a putative Rad52-binding site on RPA70 that is located near DNA-binding domains A and B. Rad52 binding to RPA increases ssDNA affinity significantly. Mutations in DBD-D on RPA32 show that this domain is primarily responsible for the ssDNA binding enhancement. RPA binding to Rad52 inhibits the higher-order self-association of Rad52 rings. Implications for these results for the "hand-off" mechanism between protein-protein partners, including Rad51, in homologous recombination and single-strand annealing are discussed.     

Efficacy and safety of dietary supplements containing CLA for the treatment of obesity: evidence from animal and human studies

Dietary supplements containing conjugated linoleic acid (CLA) are widely promoted as weight loss agents available over the counter and via the Internet. In this review, we evaluate the efficacy and safety of CLA supplementation based on peer-reviewed published results from randomized, placebo-controlled, human intervention trials lasting more than 4 weeks. We also review findings from experimental studies in animals and studies performed in vitro. CLA appears to produce loss of fat mass and increase of lean tissue mass in rodents, but the results from 13 randomized, controlled, short-term (<6 months) trials in humans find little evidence to support that CLA reduces body weight or promotes repartitioning of body fat and fat-free mass in man. However, there is increasing evidence from mice and human studies that the CLA isomer trans-10, cis-12 may produce liver hypertrophy and insulin resistance via a redistribution of fat deposition that resembles lipodystrophy. CLA also decreases the fat content of both human and bovine milk. In conclusion, although CLA appears to attenuate increases in body weight and body fat in several animal models, CLA isomers sold as dietary supplements are not effective as weight loss agents in humans and may actually have adverse effects on human health.