What do a bacterium, an elephant and Carmen de Mairena have in common? It sounds like a joke, but scientists have been searching for a century for the constant that governs all forms of life, and that defines how organisms grow or how their metabolic rates vary. Just as Stephen Hawking was looking for a theory of everything to understand the laws of the universe, different scientists have provided alternatives for this ecological theory of everything, which is true in all cases, from the simplest and smallest organism, to the largest and most complex .
Finding this constant is a particularly difficult task, given that the variety of species on the planet is vast. And what do we do when we have to handle a huge amount of data? That’s. In the 21st century, turning to artificial intelligence: a study by the Institut de Ciència i Tecnologia Ambientals of the Autonomous University of Barcelona (ICTA-UAB) has used big data to conclude what this ecological constant could be: growth.
The conclusions of the new study put in check what was, until now, the most accepted hypothesis for the problem of the ecological constant. It was developed by Max Kleiber in the 1930s, and is known as the Metabolic Theory of Ecology.
To develop it, the scientist measured the metabolic functioning of a multitude of species and concluded that there was a simple and invariable relationship between all of them: the amount of energy needed to make the body work is proportional to the body mass raised to power 3/4.
But this hypothesis has a weak point, as detailed in this Nobbot article: assuming (as it is) that all living organisms are three-dimensional, according to mathematics, this metabolic rate should be able to scale to the 2/3 power of body mass.
The new study published by the ICTA-UAB takes a new approach to this theory. Growth and mortality are also consistently related to body size. According to them, it is the growth rate of the species that determines life, and the only constant among the different types of living organisms.
As the researchers note in the paper, published by the journal PNAS : “The metabolic scale theory has had a profound influence on ecology, but the central links between the characteristics of the species have not been formally tested throughout the domain at the time. that the theory claims to apply ”.
To reach this conclusion, the scientists collected data from all eukaryotes for the major laws of body mass scale: metabolism, abundance, growth, and mortality.
In contrast to metabolism, growth follows a constant ∼3 / 4 scaling within many groups and in all eukaryotes. “Our findings are incompatible with a metabolic basis for the growth scale and instead point to growth dynamics as the foundation of the biological scale,” the researchers note. “We propose that instead of limiting growth, metabolism adjusts to growth needs.”
This means that the growth rate has profound implications for living things, and that there should be a kind of growth rate that articulates the laws that govern all living organisms.
But it is not enough to define a simple mathematical relationship. The implications of the growth rate in living beings will have to be further studied, and how it can act as a factor, for example, in the development of diseases. Growth could be the key in understanding life as a whole.
More information:
Linking scaling laws across eukaryotes.
