Human embryos in a dish – modeling early embryonic development with pluripotent stem cells

Stem cell-based embryo models present new opportunities to study early embryonic development. In a recent study, Kagawa et al. identified an approach to create human pluripotent stem cell-based blastoids that resemble the human blastocysts. These blastoids efficiently generated analogs of the EPI, TE, PrE lineages with transcriptomes highly similar to those found in vivo. Furthermore, the formation of these lineages followed the same sequence and pace of blastocyst development, and was also dependent on the same pathways required for lineage specification. Finally, the blastoids were capable of attaching to stimulated endometrial cells to mimic the process of implantation. While more comprehensive analysis is needed to confirm its validity and usefulness, this new blastoid system presents the latest development in the attempt to model early human embryogenesis in vitro.

NEW RADIOCARBON DATES FROM ARCHAEOLOGICAL SITES IN PARTS OF IGBOLAND, SOUTHEASTERN NIGERIA

ABSTRACT This paper presents new results of radiocarbon (14C) ages from archaeological sites in northern Igboland. The study was designed to shed more light on early human occupation and activities in the study area based on sediments from cave and iron-smelting sites. The approach consisted of ethnographic, archaeological, palynological, and slag analyses; these were complemented with 14C dates. The technology adopted as well as the paleoenvironmental conditions that prevailed during the period of human settlement in both sites was revealed. These data, complemented by 14C dates, highlight the human behavioral and subsistence patterns within the region and are comparable to those from similar sites in southeastern Nigeria.

Spatiotemporal changes in early human land use during the Holocene throughout the Yangtze River Basin, China

The contribution of early human activity to the increase in atmospheric CH4 content during the middle to late-Holocene is still debated. The quantitative reconstruction of past changes in land use by early rice agriculture is a key to resolving the issue, because large uncertainties still exist in current prehistoric land use estimates, owing to a lack of direct records. In this study, we used the combination of archaeological data (the area and distribution of archaeological sites) and an improved prehistoric land use model (PLUM) to determine the spatiotemporal changes in land use by rice agriculture throughout the Yangtze River Valley, China, which was the origin and centre of the development of rice cultivation. The results indicate that the area devoted to rice agriculture increased during 10–2 ka BP, and that a significant increase occurred at ~5 ka BP accompanied by a spatial expansion from the northern part of the valley to the entire valley. However, the rice land use area decreased slightly during 4–3 ka BP but then increased after 3 ka BP. We estimate that the CH4 emissions from the rice cultivated area in the Yangtze River Valley increased from ~0.001 (±0.001) to ~1.3 (±0.6) Tg/year during 10–2 ka BP, and the resulting atmospheric CH4 concentrations increased from ~0.004 (±0.002) to ~4.1 (±2.0) ppb, which accounted for 3 (±2)–9 (±5) % of the ‘anomalous atmospheric CH4 increase’ during 5–2 ka BP.

Anatomic variability of the nerves of the triceps surae in early human fetuses

Background. Establishing fetal anatomical variability of intramuscular nerves and their connections plays an important role in the search for and development of new methods for the diagnostic and treatment posterior region of the leg. Objective – to find out the topographic and anatomical features of the innervation of the triceps surae in human fetuses 4-6 months. Methods. The study was performed on 46 human fetuses 81.0-230.0 mm crown-rump length (CRL) length using macromicroscopic preparation, vascular injection, and morphometry. Results. In early human fetuses, the anatomical variability of the distribution of intramuscular nerves in the thickness of the triceps surae was established, which is due to the variability of the structure and topography of the tibial nerve, structural and functional organization of triceps surae, arterial branching and interneural connections in the thickness of the heads of the gastrocnemius and soleus in fetuses of different and the same age groups, and sometimes in the same fetus. Conclusion. The main source of innervation of the triceps surae is the tibial nerve, which can be presented by a single trunk, main and additional trunks, or several independent trunks. The nerves in the thickness of the triceps are unevenly distributed. The highest concentration of muscular branches of the tibial nerve is determined in the medial head of the gastrocnemius and the medial part of the soleus. Information on fetal topography of intramuscular nerves in the thickness of the right and left triceps surae, as well as forms of their anatomical variability, both in fetuses of different and the same age and sometimes in the same fetus, due to structural-functional organization of the components of the triceps surae, the type of branching of arteries and nerves in the thickness of the heads of the gastrocnemius and soleus. Atypical variants of the topography of the tibial nerve and common fibular nerve in early fetuses, as well as interneural connections in the thickness of the components of the triceps surae, are more common on the right lower leg.

Likeness-making and the evolution of cognition

Paleontological evidence suggests that human artefacts with intentional markings might have originated already in the Lower Paleolithic, up to 500.000 years ago and well before the advent of ‘behavioural modernity’. These markings apparently did not serve instrumental, tool-like functions, nor do they appear to be forms of figurative art. Instead, they display abstract geometric patterns that potentially testify to an emerging ability of symbol use. In a variation on Ian Hacking’s speculative account of the possible role of “likeness-making” in the evolution of human cognition and language, this essay explores the central role that the embodied processes of making and the collective practices of using such artefacts might have played in early human cognitive evolution. Two paradigmatic findings of Lower Paleolithic artefacts are discussed as tentative evidence of likenesses acting as material scaffolds in the emergence of symbolic reference-making. They might provide the link between basic abilities of mimesis and imitation and the development of modern language and thought.

Tissue- and ethnicity-independent hypervariable DNA methylation states show evidence of establishment in the early human embryo

We analysed DNA methylation data from 30 datasets comprising 3,474 individuals, 19 tissues and 8 ethnicities at CpGs covered by the Illumina450K array. We identified 4,143 hypervariable CpGs ('hvCpGs') with methylation in the top 5% most variable sites across multiple tissues and ethnicities. hvCpG methylation was influenced but not determined by genetic variation, and was not linked to probe reliability, epigenetic drift, age, sex or cell heterogeneity effects. hvCpG methylation tended to covary across tissues derived from different germ-layers and hvCpGs were enriched for associations with periconceptional environment, proximity to ERV1 and ERVK retrovirus elements and parent-of-origin-specific methylation. They also showed distinctive methylation signatures in monozygotic twins. Together, these properties position hvCpGs as strong candidates for studying how stochastic and/or environmentally influenced DNA methylation states which are established in the early embryo and maintained stably thereafter can influence life-long health and disease.