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The history of life's formation and the origin of its stereochemistry are nearly as multifaceted as the life itself. In this review, we focus on analyzing the step‐by‐step path leading to what we can define as "life" in parallel to what we know about the emergence of enantiomeric imbalance and subsequent transition to full homochirality. We start at the level of assembly of the building blocks of life from inorganic molecules and build up to the polymerization and formation of nucleic acids and peptides. We report and analyze different theories at various stages of this development and try to elucidate the most plausible theory. [ABSTRACT FROM AUTHOR]

The world in which we live is homochiral. The ribose units that form the backbone of DNA and RNA are all D‐configured and the encoded amino acids that comprise the proteins of all living species feature an all‐L‐configuration at the α‐carbon atoms. The homochirality of α‐amino acids is essential for folding of the peptides into well‐defined and functional 3D structures and the homochirality of D‐ribose is crucial for helix formation and base‐pairing. The question of why nature uses only encoded L‐α‐amino acids is not understood. Herein, we show that an RNA‐peptide world, in which peptides grow on RNAs constructed from D‐ribose, leads to the self‐selection of homo‐L‐peptides, which provides a possible explanation for the homo‐D‐ribose and homo‐L‐amino acid combination seen in nature. [ABSTRACT FROM AUTHOR]

Die Welt, in der wir leben, ist homochiral. Die Riboseeinheiten, die das Rückgrat von DNA und RNA bilden, sind alle D‐konfiguriert, und die kodierten Aminosäuren, aus denen die Proteine aller lebenden Arten bestehen, weisen an den α‐Kohlenstoffatomen eine L‐Konfiguration auf. Die Homochiralität der α‐Aminosäuren ist unerlässlich für die Faltung der Peptide in wohldefinierte und funktionelle 3D‐Strukturen und die Homochiralität der D‐Ribose ist entscheidend für die Ausbildung einer Helix und die Basenpaarung. Die Frage, warum die Natur nur kodierte L‐α‐Aminosäuren verwendet, ist nicht geklärt. Wir zeigen hier, dass eine RNA‐Peptid‐Welt, in der Peptide an aus D‐Ribose aufgebauten RNAs wachsen, zur Selbstselektion von homo‐L‐Peptiden führt, was eine mögliche Erklärung für die in der Natur beobachtete Kombination von homo‐D‐Ribose und homo‐L‐Aminosäuren liefert. [ABSTRACT FROM AUTHOR]

A higher rate of nestling development reduces their exposure time to predators, which is advantageous but simultaneously it involves an increased parental investment in incubation, brooding and feeding, which may be difficult to obtain by a single parent. An interesting question is whether, and to what degree, a single parent in a typical bi-parental species is able to compensate the lack of its mate's contribution in species with fast developing nestlings. Our study species is the Blackcap Sylvia atricapilla, a small passerine that experiences high levels of nest predation and rapid development of nestlings. We test the hypotheses that (i) single parents are not able to fully compensate for the lack of mate in itffc rearing a brood and (ii) parents pay cost for breeding alone by increasing the time that the offspring is exposed to predators in the nest. We also inquire in potential trade-off be- tween brooding and feeding and its consequences for nestling growth in nests reared by single parents. Our results show that single parents were able to compensate for the lack of the mate in terms of feeding rate, but this was at the cost of time spent brooding. Nestlings in uni-parental nests grew more slowly and lagged about two days behind their bi-parental counterparts, which may extend nestling exposure time to a predator by about 20%. In an environment with high nest predation risk, this is expected to strongly affect offspring survival. Slower growth of single-parent nestlings might have resulted from deficiency in brooding of poikilothermic offspring observed in our study, which reveals the important role of both mates in shortening the nestling period. It also demonstrates that although single parents are capable of full mate compensation in one activity, it is by the cost of other parental investments, finally leading to impairment in offspring development. [ABSTRACT FROM AUTHOR]

In my paper entitled Seeking a return to Poland. The case of "Gomulka Aliyah" immigrants in Israel (1956-1960) I describe the emigration of Polish citizens of Jewish origin to Israel in the second half of the 1950s. From October 1956, when Wladyslaw Gomulka came into power in Poland, it became possible for Polish Jews to relocate in to Israel. Leaving Poland was not obligatory for Jews in that period, but a rise in anti-Semitism and disappointment with the communist regime in Poland led a number of Polish citizens of Jewish origin to make the decision to emigrate. In the period of 1956 to 1960 approximately 50,000 Jews went to Israel. However, after few months of living in the New Homeland, some of the new immigrants from Poland were seeking to return. Difficult living conditions, an unfamiliar language, and unemployment led Polish Jews to request repatriation. That was in most of the cases impossible, as most of them had given up on Polish citizenship while immigrating to Israel. [ABSTRACT FROM AUTHOR]