Does biology have general laws that apply to all levels of biological organisation, across all evolutionary time? In their book “Biology’s first law: the tendency for diversity and complexity to increase in evolutionary systems” (2010), Daniel McShea and Robert Brandon propose that the most fundamental law of biology is that all levels of biological organisation have an underlying tendency to become more complex and diverse over time. A range of processes, most notably selection, can prevent the expression of this tendency, (...) but they predict that, on average, we should see that lineages tend toward greater diversity and complexity, driven by fundamentally neutral processes. Their hypothesis can be summarised as “diversity is easy, stasis is hard”. Here, I consider evidence for this “zero force evolutionary law”. It provides a fair description of evolutionary change at the genomic level, but the predictions of the proposed law are not met for broad scale patterns in the evolution of the animal kingdom. (shrink)

Art and science is an area of research that has strengthened recently, mainly due to the impact of interdisciplinary work. At the same time, approaches between the humanities and the sciences have succeeded in re-signifying traditional views towards critical positions such as postcolonialism, especially in the colonially so-called “Global South”. In this paper, we want to review the case of the work of the Mexican artist Octavio Ocampo through works that present the case of biological and cultural evolution. From this, (...) we want to reflect on the public perception of science in Mexico, the tensions between social and natural sciences, and the urgent need to strengthen the postcolonial discourse in scientific practice. (shrink)

A series of recent studies on extant coelacanths has emphasised the slow rate of molecular and morphological evolution in these species. These studies were based on the assumption that a coelacanth is a ‘living fossil’ that has shown little morphological change since the Devonian, and they proposed a causal link between low molecular evolutionary rate and morphological stasis. Here, we have examined the available molecular and morphological data and show that: (i) low intra-specific molecular diversity does not imply low mutation (...) rate, (ii) studies not showing low substitution rates in coelacanth are often neglected, (iii) the morphological stability of coelacanths is not supported by paleontological evidence. We recall that intra-species levels of molecular diversity, inter-species genome divergence rates and morphological divergence rates are under different constraints and they are not necessarily correlated. Finally, we emphasise that concepts such as ‘living fossil’, ‘basal lineage’, or ‘primitive extant species’ do not make sense from a tree-thinking perspective.Editor's suggested further reading in BioEssays Tree thinking for all biology: the problem with reading phylogenies as ladders of progress Abstract. (shrink)

Stem cells did not become a proper research object until the 1960 s. Yet the term and the basic mind-set—namely the conception of single undifferentiated cells, be they embryonic or adult, as the basic units responsible for a directed process of development, differentiation and increasing specialisation—were already in place at the end of the nineteenth century and then transmitted on a non-linear path in the form of tropes and diagrams. Ernst Haeckel and August Weismann played a special role in this (...) story. The first coined the term Stammzelle (stem cell), the second was the author of the first cellular stem-tree diagram. Even today, I shall argue, the understanding of stem cells, especially the popular perception, is to a large extent a Haeckelian–Weismannian one. After having demonstrated this, by analysing the terminology, in this essay I will focus on the use of cytogenetic tree diagrams between 1892 and 1925 and on the tacit understanding of stem cells that they transmit. (shrink)

Phylogenetic trees are a crucial backbone for a wide breadth of biological research spanning systematics, organismal biology, ecology, and medicine. In 2015, the Open Tree of Life project published a first draft of a comprehensive tree of life, summarizing digitally available taxonomic and phylogenetic knowledge. This paper reviews, investigates, and addresses the following questions as a follow-up to that paper, from the perspective of researchers involved in building this summary of the tree of life: Is there a tree of life (...) and should we reconstruct it? Is available data sufficient to reconstruct the tree of life? Do we have access to phylogenetic inferences in usable form? Can we combine different phylogenetic estimates across the tree of life? And finally, what is the future of understanding the tree of life? A schematic of the process of building a unified tree of life. Inputs are published phylogenetic estimates and a unified taxonomy. These inputs are combined into a summary supertree containing ≈2 million taxa. The relationships among any subset of taxa may easily be accessed and used in downstream analyses. (shrink)