The origin of life was a cosmic event happened on primitive Earth. A critical problem to better understand the origins of life in Earth is to glimpse in which chemical scenarios the basic building blocks of biological molecules could be produced. Classic works in pre-biotic chemistry frequently considered early Earth as a homogeneous atmosphere constituted by chemical elements such as methane (CH₄), ammonia (NH₃), water (H₂O), hydrogen (H₂) and hydrogen sulfide (H₂S). Under that scenario, Stanley Miller was capable to produce amino acids and solved the question about the origin of proteins. Conversely, the origin of nucleic acids has tricked scientists for decades as nucleotides are complex though necessary molecules to allow the existence of life. Here we review possible chemical scenarios that allowed not only the formation of nucleotides but also other significant biomolecules. We aim to provide a theoretical solution for the origin of biomolecules at specific sites named “Prebiotic Chemical Refugia”. A prebiotic chemical refugium should therefore be understood as a geographic site in prebiotic Earth on which certain chemical elements were accumulated in higher proportion than expected, facilitating the production of basic biomolecules. Plus, this higher proportion should not be understood as static, but dynamic; once the physicochemical conditions of our planet changed periodically. This different concentration of elements, together with geochemical and astronomical changes along days, synodic months and years provided somewhat periodic changes in temperature, pressure, electromagnetic fields, and conditions of humidity; among other features. Recent and classic works suggesting most likely prebiotic refugia on which the main building blocks of biological molecules might be accumulated are reviewed and discussed.

Hox genes represent an important gene family that is involved in the segmentation pattern and identity of the segments during the formation of the body plan in metazoans. For many years, several studies have sought to establish a correlation between the evolution of these genes and the evolution of large groups of metazoans. Here, we use publicly available sequences of Hox gene clusters to reconstruct the evolutionary history of anterior Hox genes. We show that information harbored by these genes, in part, reflects the evolution and diversification of most animal archetypes, but in many cases, there were conflicts between the evolutionary history of some genes and the history of large groups, these cases may have occurred due to specific and similar selective pressures in relatively distant groups, which may have led to evolutionary convergences. Our findings also reveal that the evolution of Hox genes (and clusters) as a multigene family is consistent to a birth-and-death model constrained by development, where there is a trade-off between a relatively fast gene turnover and their central developmental roles