Human represents 0.01% of life on Earth: study

For the first time, researchers have managed to put in figures the mass that represents life on Earth. Their results show not humanity respersents only a small percent of the total biomass.

By comparing humanity to the whole of life on Earth, our species literally does not carry weight. Despite our 7.6 billion people, we account for only 0.01% of life on the planet. Yet, despite our apparent insignificance, our influence on the rest of earthly life is undeniable.

Climate change, deforestation and overfishing are all commonly cited examples. It is still difficult to realize the magnitude of our impact before quantifying it. A study published in PNAS gives us a first glimpse of the distribution of life on Earth during the Anthropocene.

Estimate life

To arrive at these figures, the researchers estimated all of the terrestrial biomass. There are several ways to measure it, but they have opted for the mass of carbon, which is the element on which all terrestrial life is based and which has the advantage of avoiding the variability of the water content.

To arrive at their estimates, they have compiled hundreds of studies on the presence of large and small scale living beings. This type of census is done by observation using satellites or by analyzing DNA present in rivers or in the soil; it allows to estimate the present species as well as their number.

Their first result is astronomical: the total biomass composed of living beings on Earth would be about 550 gigatonnes of carbon (one gigatonne represents 1 billion tons). Of this number, 86% is found on land, 13% is buried underground and only 1% is found in the oceans.

The undisputed champions are the plants that represent, by weight, 82% of all life on our planet. They are followed by bacteria, which represent 13% of life.

The remaining 5% therefore includes all other life forms, from insects to mammals. This is how the researchers were able to say that 0.01% of terrestrial life is human, which is three times less than the mass of all viruses or all worms.

In this same way, the mass of humanity is also 12 times smaller than that of fish, 17 times smaller than insects or 200 times smaller than that of mushrooms.

Life rearranged for our needs

Even if these figures are stunning, they reveal how much humanity has changed life on Earth to serve its consumer needs.

Only with mammals, the mass of humanity suddenly goes to 36%. The group that ranks first is … our livestock! About 60% of mammals on Earth are farm animals, such as beef, pork and other farm animals. This means that the remaining 4% represents all wild mammals on the planet.

The situation is not much better for birds, 70% of which are for our consumption. Wild birds make up the remaining 30%. These two data show how our consumption habits have changed the course of life on Earth.

The researchers have also been able to estimate that the mass of life has greatly diminished since the arrival of humanity. Up to 83% of terrestrial mammals may have died out since the beginning of our civilization. The same is true for 80% of marine mammals, 50% of plants and 15% of fish.

According to these researchers, the magnitude of the task does not allow them to give precise figures. It is, however, the first comprehensive assessment of the importance of life on Earth, which also serves as a basis for assessing the environmental impact of our activities.

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