The weight of humanity

Not everyone is on board with the idea of the ‘anthropocene’ – the name for the new geological age we find ourselves in, where humans are the dominant force. Among the common objections is that the anthropocene is more an expression of hubris than impact: we are kidding ourselves if we think that we puny humans could ever change something as enormous and beyond us as planet earth.

There are a number of answers to that, including the fact that the name comes from geologists naming observable phenomena. But one of the more powerful signs of human dominance comes through calculating the world’s zoomass – the weight of the world’s land animals. If we add up all the wild animals, and all the humans and our domesticated animals, which is larger?

A few years ago Vaclav Smil used population figures for humans, wildlife and domesticated animals, and worked out the totals. It’s not a pretty picture. Wildlife numbers have been declining, with the total weight of wild mammals halving between 1900 and 2000. At the same time, the human population has been growing in both numbers and living standards, adding more and more farmed animals to feed us. There are now over one and a half billion cows providing us with meat and dairy, three chickens for every person, and hundreds of millions of sheep and horses and pigs.

Counting forwards, the total weight of humans and all our animals overtook the total weight of wild animals at some point in the 19th century. But 1900 it was a third higher. By 2000 rising humanity and declining wildlife had pushed the ratio to 10 to 1. Today we take up an estimated 97%. Just 3% of that total weight is wild animals.

To clarify, we’re talking about vertebrate life on land here. Insects would vastly outweigh us, and bacteria dwarves that number again. We’re not counting ocean life (but if you’re wondering, there aren’t nearly enough whales to challenge us, though the plankton that they eat would give us a good run for our money). Still, we are counting elephants and hippos, rats and mice, birds and amphibians, all coming to 3% of the total. We just have that many cows.

On that basis, is humanity dominating planet earth? Of course it is. We are choosing what animals thrive and multiply, we need a growing slice of the earth’s surface and its plantlife to feed them, and the emissions from those animals – cows in particular – is helping to change the chemistry of the atmosphere. The anthropocene it is.


  1. So if we value biodiversity, we have GOT to humainly reduce human numbers. Bring on universal education for girls!

  2. Yes, although there’s no way to reduce human numbers except in the long term. The more urgent priority is to reduce the number of livestock, especially cows. 1.4 billion cows is an extraordinary number, and their climate impact is disproportionate. Unlike humanity, we can start reducing their numbers today by eating less meat and dairy.

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