By Don Pinnock – Daily Maverick
The number of wild creatures is dwindling as the ones we have domesticated grow … and grow.
A new study by scientists at Israel’s Weizmann Institute of Science, published in Nature, has taken on an extraordinary challenge: to weigh all the mammals on Earth — not individually, of course, but in terms of biomass, the total mass of living matter.
By tracing this back to the year 1850, the researchers have shown just how profoundly humanity has reshaped the animal world.
Their results are both fascinating and sobering. In 1850, the total biomass of wild mammals — everything from whales to elephants to mice — was estimated to be roughly equal to that of humans and our domesticated animals combined. Since then, while humans’ weight on the planet has multiplied many times over, the collective mass of wild mammals has more than halved. Today, humans and our livestock outweigh all wild mammals by about 10 to one.
A new way of seeing life
When we talk about the loss of wildlife, it’s usually in terms of species extinctions. However, extinction statistics can hide the scale of ecological change. Losing a single rare species equates to losing millions of individuals from a common species. Biomass offers a more holistic picture: not just who’s alive, but how much life exists.
The researchers, led by Lior Greenspoon, Elad Noor and Ron Milo, used a vast range of historical data, models and population records to construct a timeline of mammal biomass from 1850 to the present — the first global attempt to do so at this level of detail.
What they found was a story of human expansion, industrialisation and unintended consequences for the rest of the animal kingdom.
Expanding footprint
In 1850, the human population was about 1.2 billion. Today, it’s more than eight billion. During that time, the researchers said, the average human body also became heavier — by roughly 30% — due to improved nutrition and changing lifestyles.
Combining these two trends, they estimated that the total biomass of humanity grew from around 50 million tonnes in 1850 to 420 million tonnes today — an eightfold increase.
And we haven’t grown alone. Our domesticated mammals — mainly cattle, pigs, buffalo, sheep and goats — have exploded in number. Cattle alone make up about two-thirds of all livestock biomass, and their combined weight has quadrupled since 1850.
When the authors added up all domesticated mammals, including pets and human-associated rodents like rats and mice, they found that their total mass rose fivefold. Altogether, humans and our domesticated mammals now account for around 1.1 billion tonnes of biomass — nearly three times the estimated total for all mammals in 1850.
For marine mammals — whales, seals and dolphins — the picture is particularly dramatic. Using models based on centuries of whaling records and population data, the team estimated that the biomass of wild marine mammals fell by about 70% since 1850.
The mid-1800s marked the dawn of industrial whaling, driven by inventions such as the exploding harpoon. The largest whales — blue, humpback, fin and sperm whales — once made up 80% of marine mammal biomass. By the mid-20th century, relentless hunting had driven many populations to the brink. The decline only began to slow after 1986, when the International Whaling Commission banned commercial whaling. Some populations have partially recovered, but many remain far smaller than before.
Expanding footprint
In 1850, the human population was about 1.2 billion. Today, it’s more than eight billion. During that time, the researchers said, the average human body also became heavier — by roughly 30% — due to improved nutrition and changing lifestyles.
Combining these two trends, they estimated that the total biomass of humanity grew from around 50 million tonnes in 1850 to 420 million tonnes today — an eightfold increase.
And we haven’t grown alone. Our domesticated mammals — mainly cattle, pigs, buffalo, sheep and goats — have exploded in number. Cattle alone make up about two-thirds of all livestock biomass, and their combined weight has quadrupled since 1850.
When the authors added up all domesticated mammals, including pets and human-associated rodents like rats and mice, they found that their total mass rose fivefold. Altogether, humans and our domesticated mammals now account for around 1.1 billion tonnes of biomass — nearly three times the estimated total for all mammals in 1850.
For marine mammals — whales, seals and dolphins — the picture is particularly dramatic. Using models based on centuries of whaling records and population data, the team estimated that the biomass of wild marine mammals fell by about 70% since 1850.
The mid-1800s marked the dawn of industrial whaling, driven by inventions such as the exploding harpoon. The largest whales — blue, humpback, fin and sperm whales — once made up 80% of marine mammal biomass. By the mid-20th century, relentless hunting had driven many populations to the brink. The decline only began to slow after 1986, when the International Whaling Commission banned commercial whaling. Some populations have partially recovered, but many remain far smaller than before.
