Scientists estimated the mass of all life. It’s mind boggling.
And if we zoom in on all animal life, we again see how insignificant humans are compared to everyone else in the kingdom. Arthropods (insects) outweigh us by a factor of 17. Even the mollusks (think clams) weigh more.
What’s missing from this chart is just as important
Yet despite our small biomass among animals, we’ve had an overwhelmingly huge impact on the planet. The chart above represents a massive amount of life. But it doesn’t show what’s gone missing since the human population took off.
The authors of the PNAS article estimate that the mass of wild land mammals is seven times lower than it was before humans arrived (keep in mind it’s difficult to estimate the exact history of the number of animals on Earth). Similarly, marine mammals, including whales, are a fifth of the weight they used to be because we’ve hunted so many to near extinction.
And though plants are still the dominant form of life on Earth, the scientists suspect there used to be approximately twice as many of them — before humanity started clearing forests to make way for agriculture and our civilization.
The census in the PNAS paper isn’t perfect. Though remote sensing, satellites, and huge efforts to study the distribution of life in the ocean make it easier than ever to come up with estimates, the authors admit there’s still a lot of uncertainty. But we do need a baseline understanding of the distribution of life on Earth. Millions of acres of forests are still lost every year. Animals are going extinct 1,000 to 10,000 faster than you’d expect if no humans lived on Earth. Sixty percent of primate species, our closest relatives on the tree of life, are threatened with extinction.
We have to know how much more we stand to lose.