 Good morning, John. I want to tell you about one of the coolest things I've ever found out in my life. It really threw me for a loop and I want to throw you for the same loop. So join me on the journey. When studying life on our planet, it is sometimes useful to think about, like, how much the living matter of the planet weighs. On its own. I'm- this is enough of this coat. On its own, the idea of living matter is pretty freaking weird, right? Living matter. But that's what we are. And that matter has mass. Like, I have about 90,000 grams of living matter. Or do I? Like, not really. Most of its water, like, life couldn't exist without it, but it isn't really part of the living system. It's kind of just like an ocean that I'm carrying around in a sack with me everywhere I go, so that I can do the chemistry that is life. What the scientific establishment has decided to do is just count the carbon, which makes sense. I think that's a good way to do it. Of course, it's not perfectly precise, but it's precise enough. We call this biomass. For example, if you look at the biomass of all mammals, around a third of it is human beings. If that seems weird to you, it's gonna be way weirder than that. That's like the least weird thing in the video. Another third is cows! Just cows! Now, you might be thinking that leaves the final third for wild mammals. I'm sorry, no. Uh, further 30% is the rest of the agricultural animals. And 4%. 4% of mammal biomass is wild mammals, all of the whales and elephants and skunks and armadillos and trues. Now, is that the weirdest thing in the video? No, it's not. I used to think, when I heard this stat, that this meant that there used to be 100% wild mammals and now like 96% of them have been replaced by agricultural animals and humans. That's not what happened. Around 100,000 years ago, humans had a very tentative foothold on the planet. Pretty insignificant species in terms of biomass. And at that point, wild mammal biomass was at its peak, but it'd been roughly the same for a very long time. It wasn't increasing, it wasn't decreasing, it was quite stable. Between 100,000 years ago and 10,000 years ago, human biomass changed some, but was still pretty insignificant at 10,000 years. But wild mammal biomass dropped by like 25%. A very big, very fast drop. We call this the quaternary megafauna extinction. It was an extinction event of almost entirely very large mammals. Lots of debate about this. Definitely a contributor to it was humans. It's very tightly coincided with the arrival of humans in North and South America and then separately in Australia. But what happens next is the very weird part. Between 10,000 years ago and 100 years ago, agriculture happens, like in a big way. Wild mammal biomass falls by a further third, but the total mammal biomass increases beyond what it ever was. Purely because of humans and livestock. And now, in the year 2022, humans by themselves represent three times more biomass than all mammals combined before humans. We are heavy. In the last 100,000 years, there has been an 85% decrease in the wild mammal biomass and an 800% increase in the total mammal biomass. Throughout this video, I've been trying to not have any particular judgment about whether the world should be the way that it is, just that it's fascinating that it is the way that it is. But entering into our conclusion here, it's bad. Like, it's bad to have an 85% decrease in wild mammal biomass. But it's also very complex. Like, the earth is absolutely 100% at its historical maximum of complicated brains. I don't know if y'all caught this, but a few days ago, some baby was born that was the 8 billionth person on the planet. I hope they at least got a certificate. So I don't really know what to say about this, except that obviously we need to be doing all of this quite thoughtfully, because this is a very big and fast change. And I think that you can make the case that we are actually doing it more thoughtfully now than we were 100 years ago. It's also really great to be able to get coffee and socks delivered to your door once a month, and to know that there are people working hard to try and do that as thoughtfully as possible. Coffee plantations can, for example, lead to a lot of deforestation, but it can also be done in partnership with a forest. The small farmers who work with the awesome coffee club work hard to decrease deforestation and to practice regenerative agriculture. The sock club's closing Monday. There will not be another Vlogbrothers video between now and then, so if you want to sign up, you got to do it now. The coffee club will remain open perpetually. John, I'll see you on Tuesday.