Michel Loreau writes:

The diversity of life is awe-inspiring. However, while biologists tend to focus on the multitude of species and how they live, what unites them may at times be more interesting than what sets them apart. In the era of “big data” and its deluge of information, this diversity can now begin to be perceived as a whole, discerning universal properties common to all creatures large and small.

It was already known that there exist simple mathematical laws that correlate an organism’s body mass to some of its most fundamental characteristics, such as its metabolism, growth, mortality and abundance. Within the broad taxonomic groups of living things, these characteristics are linked to body mass by a power law whose exponent often nears ¾. An organism’s metabolic rate therefore increases in proportion to its body mass raised to the ¾ power, which means that metabolism does not grow as rapidly as mass. These are the laws of scale, which have fascinated evolutionary biologists and ecologists for decades. However, the links between the four fundamental features of organisms (metabolic rate, growth rate, mortality rate and abundance) had never been studied systematically and in conjunction across all living beings.

With my colleagues at the Autonomous University of Barcelona (Spain), Princeton University (US) and Charles University (Czech Republic), we have for the first time assembled data from several thousand studies on thousands of species spanning all forms of life (animals, fungi, plants, bacteria). Our findings, published in the journal PNAS, confirm that, despite the immense diversity of life, quite a few of its most important traits comply with universal laws that link the species to their body mass, from the blue whale down to the tiniest protists. These simple relations are surprisingly strong, and reveal unexpected correlations that had not been fully appreciated before. [Continue reading…]