The human race only takes up a small fraction of all the life on Earth, but our impact on our planet’s biodiversity has been catastrophic, reveals a new study. Since the dawn of civilization, half of all the life forms that populate the Earth have been eradicated, New Scientist reports.
The paper, published yesterday in the Proceedings of the National Academy of Sciences, reveals that, although insignificant in comparison with the mass of other species, humans have contributed to the disappearance of 83 percent of wild mammals and half of the plant biomass on our planet.
Study lead author Ron Milo, a biologist at the Weizmann Institute of Science in Israel, says that these findings are “pretty staggering.”
“It is definitely striking, our disproportionate place on Earth.”
According to Science Magazine, the authors initially set out to discover what protein is most abundant on Earth. The researchers spent three years analyzing the scientific literature on Earth’s biomass, or the weight of all the creatures living on the planet, and ended up uncovering a few unsettling truths about our place in the great scheme of things.
The team measured the carbon footprint of all life on our planet and discovered that the world’s biomass weighs about 550 gigatons of carbon (GT C). More than 80 percent of all this life is comprised of plants, which outweigh people by about 7,500 to 1 and make up 450 GT C of the Earth’s biomass. Around 13 percent (or 70 GT C) of all life on Earth is represented by bacteria, while everything else takes up just 5 percent of planet’s biomass.
For instance, fungi (yeast, mold, and mushroom) make up 2 percent of all living things, weighing in at 12 GT C. Meanwhile, all the animals on the planet — half on which are arthropods, including insects, spiders, and crustaceans — weigh just 2 GT C. At the same time, all the 7.6 billion people in the world represent just 0.01 percent all life on Earth and weigh a mere 0.06 GT C — the same as krill and termites.
“The fact that the biomass of fungi exceeds that of all animals sort of puts us in our place,” James Hanken, a Harvard evolutionary biology professor, who wasn’t involved in the study, said in a statement.
Despite the tiny proportion we occupy in Earth’s biomass, our influence on the other creatures that share our planet has been disastrous, notes ABC News.
Aside from cutting in half the entire plant biomass in the past 10,000 years, our species is responsible for the loss of 80 percent of marine animals and has decimated 15 percent of all fish species and 83 percent of the Earth’s wild mammals, the researchers found out.
In addition, humans have bred livestock and poultry to a degree that now exceeds the world’s wild fauna. Of all the mammals living on Earth, humans and their livestock represent 96 percent (36 percent and 60 percent, respectively), meaning that just 4 percent of the planet’s mammals are wild animals, shows an infographic published by The Guardian.
Our domesticated cattle and pigs outweigh all wild mammals by 14 to 1, while the chickens and other poultry we breed for meat and eggs now make up 70 percent of all the birds in the world.
Excessive whaling has reduced the population of marine animals to just one fifth in the last three centuries, whereas only one sixth of the wild mammals that roamed the Earth before we took to farming has managed to survive man’s industrial revolution.
The research unveils that, despite accounting for just one ten-thousandth of life on Earth, humans have had an enormous influence on the natural world, Milo points out.
“I would hope this gives people a perspective on the very dominant role that humanity now plays on Earth.”
As the biologist explains, our dietary choices and constant expansion on the planet have reshaped the habitat of wild animals and birds.
E.O. Wilson, a reputed Harvard biologist, who didn’t participate in the study, also chimed in on the impact that our civilization has had on the rest of the species that dwell on our planet.
“Even though short in numbers, we have managed to throw a lot of sand in the air and mess up a lot of things,” said Wilson.