Compared with the rest of the mass of all life on Earth, mankind has nothing at all. But despite such “insignificance,” the trace left by humanity on this planet is truly destructive for everything else. One of the main goals of biology as a science is to understand the mechanisms of functioning of the biosphere in general, in all its complex interrelations, internal and external. For this, it is important to have reasonable quantitative estimates of the mass of living organisms – both in general and in individual taxa. But as the authors of the article, published in the journal Proceedings of the National Academy of Sciences, note, there is no modern data on this.
Within the framework of the most comprehensive study aimed at quantifying the mass of all living organisms present on our planet, American and Israeli scientists have established that humanity accounts for only 0.01 percent of the total biomass. But despite our physical insignificance in comparison with all the variety of life that surrounds us, history clearly shows who actually dominates the planet.
“I hope our work will provide a clear understanding of the dominant role that a person plays for all life on Earth,” says Ron Milo, a biologist at the Weizmann Institute in Israel.
“It is certainly amazing and completely disproportionate to our place on the planet.”
Ron Milo and his colleagues took about three years to search and analyze the extensive literature (the list of references in a short article reaches fifty points). In order to exclude the effect of different water contents in different organisms, they evaluated the estimate by the amount of carbon that is associated with one or another realm of the living. According to this indicator, the total mass of the entire biosphere of the Earth was about 550 Gt (gigaton, billion tons).
Despite its colossal numbers, viruses constitute only a tiny fraction of this mass – 0.2 Gt. Undoubtedly the same leaders were plants with their mass of 450 Gt (80 percent of the total biomass), with most of the weight belongs to land plants: land biocenoses in general account for 470 Gt of bound carbon. Second place goes to bacteria. They account for about 70 Gt (15 percent). Next come mushrooms – 12 Gt, Archaeus – 7 Gt and protozoa – 4 Gt.
Surprisingly, animals gain a total of only 2 Gt of carbon mass, with half of it coming from insects. The share of mankind – 0.06 Gt – is comparable with the mass of the entire termite group, but almost 10 times more than the total mass of all wild mammals on the planet, which is about 0.007 Gt.
But the mass of creatures owed their numerous to man, far exceeds the mass of mankind: thus, domestic animals – cattle, pigs and others – “outweigh” all wild mammals; the mass of domestic – more than 20 times. The same story with birds. We also significantly influence the mass of plants: for the last 10 thousand years, people have halved it.
All these figures, of course, are interesting, but the task of scientists was not to estimate the mass of living beings, but to find the main source of proteins on Earth. Until they found him; There were difficulties with the evaluation of the mass and composition of soil microorganisms. Ron Milo and his colleagues expect to answer their question before the end of this year.
