total weight of wild mammals less than 10% of humanity

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The total weight of Earth’s wild land mammals, from elephants to bison and deer to tigers, is now less than 10% of the combined tonnage of men, women and children living on the planet.

A study by scientists at Israel’s Weizmann Institute of Science, published this month, concludes that wild land mammals alive today have a total mass of 22 million tons. By comparison, humanity now weighs a total of around 390 million tons.

At the same time, the species we have domesticated, such as sheep and cattle, plus other parasites such as urban rodents, add another 630 million tons to the total mass of creatures that now compete with wild mammals for Earth’s resources. Land. . The biomass of pigs alone is almost twice that of all wild land mammals.

The figures clearly demonstrate that humanity’s transformation of the planet’s wildernesses and natural habitats into a vast global plantation is already underway, with devastating consequences for its wild creatures. As the study authors emphasize, the idea that Earth is a planet that still has vast plains and jungles teeming with wild animals is now seriously out of line with reality. The natural world and its wild animals are fading as the human population of nearly eight billion continues to grow.

Fin whales feeding in the Gulf of California. The study found that the species has the highest biomass of any ocean creature. Photograph: Nature Picture Library/Alamy

“When you watch wildlife documentaries on TV, for example the wildebeest migration, it’s easy to conclude that wild mammals are doing quite well,” lead author Ron Milo told the magazine. Observer.

“But that intuition is wrong. These creatures are not doing well at all. Its total mass is around 22 million tons, which is less than 10% of humanity’s combined weight and amounts to only around 6 pounds of wild land mammals per person. And when you add in all of our cattle, sheep and other livestock, that adds up to another 630 million tons. That’s 30 times the total for wild animals. It’s amazing. This is a wake-up call for humanity.”

The study, The Global Biomass of Wild Mammals, also reveals that those that do best, such as white-tailed deer in the US and wild boar, find it easiest to adapt to the presence of humans. Both species can be found near settlements and are occasionally kept as pets. “Even in nature, humanity’s fingerprints are obvious,” added Milo, whose team’s study is published in the American journal. Proceedings of the National Academy of Sciences.

As part of the paper, researchers Lior Greenspoon and Eyal Krieger collected biomass data for about half of all known mammals and used machine learning computational models on other zoological samples to estimate the other half.

The grim numbers for land mammals were matched by those found in the oceans. The total mass of marine mammals was estimated to be around 40 million tons. Fin whales have the largest total biomass with sperm whales and humpback whales ranking second and third, respectively.

The domesticated to wild mass ratios emphasize the active role humans play in shaping mammal abundance on Earth.


Common pet species were also found to be major contributors to humanity’s planetary impact. Domestic dogs have a total mass of about 20 million tons, close to the combined biomass of all wild land mammals, while cats have a total biomass of about 2 million tons, almost double that of the African savannah elephant. “These domesticated to wild mass ratios emphasize the active role that humans play in shaping mammal abundance on Earth,” the researchers state in their paper.

Biomass studies are not the only way to quantify the animal world. The number of species is also revealing. As an example, it has been found that there are 1,200 species of bats representing one-fifth of all terrestrial mammal species and two-thirds of all individual wild mammals by number of heads. However, they make up only 10% of the biomass of wild terrestrial mammals.

“Biomass is complementary to species richness and other diversity metrics, and can serve as an indicator of the abundance and ecological footprint of wild mammals on a global scale,” the researchers say.

Estimates made two years ago by the team suggested that there were around 50 million tons of wild mammals on Earth. The new figure, calculated using a host of techniques including AI, indicates that the crisis facing the planet’s wildlife appears to be far worse than first thought. How quickly the depletion of wild mammals is taking place now needs to be urgently assessed, they say, and is the focus of the next phase of the study that will assess the amount of biomass loss that has occurred over the past 100 years.

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