Good morning Hank it’s Tuesday You recently made a video about  the overall biomass of humans, and how humans and their livestock  together comprise over 90% of the total biomass of mammals,  and this got me to wondering how our biomass compares  to non-mammals, and it turns out that  at least in terms of weight, uh, we are sort of a rounding error.

Okay, so biomass is one way we use  to understand the prevalence of different life forms on Earth;  like there are obviously way more bacteria on earth than there are humans,  but we are larger and also, not to brag, a little bit more complex. And so biomass can be a helpful way of thinking about;  like of all the carbon in all the living things on Earth, how much of it is,  say human, and how much of it is, say, microbial.

Humans amount to about 2.5% of total animal biomass. Wild mammals,  everything from squirrels to mice to elephants–comprise 0.3%. Our livestock–cows, pigs, etc– make up about 4%  another 4% is aquatic invertebrates like coral and jellyfish.

Fish make up 29% of animal biomass– their total weight is more than 10 times  that of humans–  and arthropods are around 42% of animal biomass. So, at least by biomass,  most animal life is either fish or arthropods. But in a biomass sense,  animals are a tiny, tiny part of the story.

Lke, animals make up much less than 1% of earth’s biomass. Like we are down here. We weigh less than viruses.  A lot less. 12% of Earth’s biomass  is bacteria– all the bacteria combined  weigh about 200 times more than humans do.

And we are also dramatically  outweighed by fungi and protists and especially by plants which  comprise over 80% of Earth’s total biomass. From a biomass perspective, this is a plant planet  with a scattering of other lifeforms. And I think this is important to understand,  because one thing about humans is that we’re a little self-aggrandizing.

Like, we tend to place ourselves right at the center of the story of Earth. And I guess in some ways, that’s justified–  we are different from other forms. Not least because of writing  and video and other communication technologies.  We can efficiently share knowledge across space and time.

And we do currently have outsize power; our behavior is causing extinctions  and reshaping the climate, and our habitats. Like, I live in Indiana, which people tend to think of as  an endless conglomeration of corn fields,  but 400 years ago, this was all hardwood forest. Indiana is not a corn land it is a forest land that we terraformed for corn.

So yeah, we are very powerful  and we are causing big changes to our biosphere. But we also shouldn’t exaggerate our power. Like, we are just a form of life.

The world is very big and we are a very small part of it–  not just in terms of biomass but also like, in terms of time. This ginkgo tree looks very much like the ginkgo trees from the Jurassic Age,  over 150 million years ago. We, meanwhile, have been around for about  300,000 years–or .2 percent of the ginkgo’s history.

Earth, and indeed life on Earth, will be okay without us,  the Earth has recovered from far greater shocks than humans.  The thing is, I want us to stay around. Like, I realize that this is a somewhat countercultural opinion at the moment,  but I’m broadly in favor of humans. Like I think viruses are interesting  and everything, but I just think we’re more interesting.

I tend to think we should conceive of the situation less egotistically,  and more realistically. Not that we are in danger of destroying life on earth,  but that we are in danger if we don’t make better choices of making earth  less habitable for us and other complex lifeforms. Because ultimately, to me what’s most valuable  and important about earth,  is not that its a planet, but that it is a habitat,  which currently hosts a huge array of life and contains altogether around  550 gigatons of carbon of  which we are about 0.01%.

Hank, I’ll see you on Friday.