Demarcation among objects and things is somewhat arbitrary, because our mind tends to exclude the continuity among hidden or unknown structures of the world. We are used to draw lines of separation among things that we judge different, arbitrarily excluding or including issues in our description, to achieve positive demarcations that allow a pragmatic treatment of the world based on regularity and uniformity (Popkin and Maia Neto, 2007; Autrecourt, 1340). In touch with set theory, observers tend to spatially and temporally split the set of the entire world in different, arbitrary, fictious subsets that could not really stand for different objects or events. The same scientific concept of “observable” lies on the choice of variables in peculiar experimental settings: scientists, putting aside most of the variables, focus their efforts on a few features. For example, elementary particles are fully defined just in terms of three experimental observables, i.e., charge, spin and mass, letting aside, for practical purposes, less “useful” features. There’s a plenty of boundaries in math, physics and biology. In these disciplines, the concept of boundary is grounded on the presence of internal and external surfaces. This concept seems straightforward in math, and in particular in topology, where we are in front of planes split into an “interior” region bounded by curves and an “exterior” one, containing all of the nearby and far away exterior points.
Concerning the biophysical realm, many accounts of our real world, both philosophical and biological, are used to think at living being as individual, self-preserving, unique subjects equipped with borders, such as cellular membranes, envelopments, Markov blankets, and so on. The canonical illustration of biological organisms depicts “something” equipped with some peculiar activity, confined into itself, which struggles against (and cooperates with) the external world, in order to keep its entropy as low as possible and devoted to self-preservation (Ramstead et al., 2019). However, despite such stereotypical descriptions, the things get much more complicated when we approach the real word and its physical/biological content. The demarcation among objects, things and living beings could be somewhat arbitrary. The same limitation holds for the very concept of evolution, which is based on species. Our concept of species is very arbitrary, because it throws (not experimentally demonstrated) borders among living beings. Thinking, e.g., to different populations of Homo, despite we are used to consider Sapiens, Neandertals, Denisovians, Floresians as different species, genetic studies undoubtedly point towards their ancient ibridation, which occurred more than once in different prehistorical contexts (Slon et al., 2018). Concerning our DNA, the delimitation of a species from another is sometimes difficult, due, e.g., to the presence in animal genome of viral and bacterial sequences. To make an example, the horizontal transmission and lateral transduction of genetic material described here by Chen et al. (2018) is able to overtake the so-called canonical “species-specific” barriers, making sometimes difficult to clearly encompass individual living beings in a given species.

1) Autrecourt, Nicholas of. About 1340. The Universal Treatise. Marquette University Press, Milwaukee, Wisconsin, 1971.
2) Chen J, Quiles-Puchalt N, Chiang YN, Bacigalupe R, Fillol-Salom A, et al. 2018. Genome hypermobility by lateral transduction. Science, Vol. 362, Issue 6411, pp. 207-212. DOI: 10.1126/science.aat5867.
3) Popkin RH, Maia Neto JR (Editors). 2007. Skepticism: An Anthology. Prometheus Books. ISBN 1591024749 (ISBN13: 9781591024743).
4) Ramstead MJD, Constant A, Badcock PB, Friston KJ. 2019. Variational ecology and the physics of sentient systems. Physics of Life Reviews. In press.
5) Slon V, Mafessoni F, Vernot B, de Filippo C, Grote S, et al. 2018. The genome of the offspring of a Neanderthal mother and a Denisovan father. Nature, 561, 113–116.

Arturo Tozzi (corresponding Author),
Center for Nonlinear Science, University of North Texas
1155 Union Circle, #311427 Denton, TX 76203-5017 USA