(Photo: sunny67/pexels)
The world’s mammal biomass has undergone a dramatic shift over the past 175 years, with wild mammals declining sharply while humans and domesticated animals now dominate nearly the entire mass of mammalian life on Earth. The findings come from a new Nature Communications (November 2025) study that underscores the scale of human-driven ecological change.
According to the research, global wild mammal biomass in 1850 was estimated at around 200 million tons (Mt) — roughly equivalent to the combined biomass of humans and domesticated mammals at that time. Today, that balance has shifted overwhelmingly. Human and livestock biomass has surged to approximately 1,100 Mt, while wild mammals have plummeted.
Marine Mammals
The study reports that wild marine mammals experienced the steepest decline, falling by nearly 70% since 1850. This collapse is linked largely to historical commercial whaling, though modern pressures such as climate change, ecosystem disruption, and food-web degradation continue to weaken marine populations.
For terrestrial wild mammals, the decline exceeds 50%. Within species groups where estimates are possible, biomass has decreased from about 50 Mt in the mid-19th century to just 20 Mt today. The authors note that the true loss is likely far greater due to limited historical data and conservative modeling assumptions.
“Human and livestock biomass now vastly outweighs wild mammals, reflecting the enormous scale of human impact on Earth’s ecosystems,” the researchers, Lior Greenspoon wrote. “Biomass decline is not only the loss of individuals — it is the erosion of ecological functions that maintain environmental stability.”
The study highlights that biomass provides a crucial metric beyond species extinction or population counts. Many mammal species still persist, but with drastically reduced biomass, their ability to perform ecological roles — from seed dispersal to regulating prey populations and shaping habitats — is severely diminished.
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Effect of People Growth
Rapid human population growth, expanding industrial agriculture, land-use change, and hunting pressure are identified as the primary contributors to this global shift. Researchers warn that this imbalance has far-reaching implications for biodiversity, climate resilience, and global food systems.
In its conclusion, the study calls for urgent strategies to restore wild mammal biomass. These include habitat restoration, stronger marine protections, curbing illegal and unsustainable hunting, and transforming food production systems that currently depend heavily on livestock and land conversion.
With the gap between human-dominated and wild biomass widening each year, scientists caution that the planet is approaching a critical threshold. “If the current trajectory continues,” the authors warn, “we risk losing fundamental components of Earth’s life-support systems.” (Sulung Prasetyo)
