There are social conditions in other species that can result in extinction of a population group, despite ample resource availability. That's what Calhoun's rat population sink experiments were about.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1644264/pdf/pro...

I don't disagree that the number of human beings on this planet is unsustainable, but I also wonder if there are underlying social pathologies that immigration is only temporarily masking. If we can generalize social behavior (and maybe we can't - but if so, "humans have reason" is not why) in mammals at all, Calhoun's experiments are certainly very alarming.

Japan has 126 million people, while in 1910 it had 50 million. Populations are at similar historic, unprecedented heights throughout most of the world, developed and developing.

We are nowhere near having to worry about extinction due to not enough people.

Please read the PDF I linked. The whole point is that even massive populations can be subject to permanent declines resulting in extinction under the right social conditions.

One might as well say the two thousand rats in the article had nothing to worry about because there were so many of them - but the peak is exactly where the social collapse was irreversible.

Again, I agree that seven billion is not a sustainable number of humans. In terms of resources and environmental damage, seven billion is a catastrophe. What I’m saying is that population declines may be heralding a different kind of disaster.

Is this a totally reasonable thing to say, though, comparing us to rats in this situation? Rats have no concept of extinction or death, humans do. To me, that means a lot.

Not to mention, rat society doesn't change much whether it's ten rats or a hundred. Human culture becomes very different as people aggregate together, so whose to say that the very same social conditions triggered by increasing population will not themselves be changed by decreasing population?

> Not to mention, rat society doesn't change much whether it's ten rats or a hundred.

It turns out rat society is much more complicated than I at least thought, and it definitely changes dramatically once it reaches a critical mass.

> Is this a totally reasonable thing to say, though, comparing us to rats in this situation?

I don't know. It depends on how generalizable social behavior is. I think it's very worrying with the problems we see with socialization in the world today and behaviors that, by analogy, resemble what's going on in Calhoun's experiments. We also have some anecdata from other social animals experiencing different types of collapse, where even though there is the physical capability of reproduction, the social collapse prevents it from occurring.

> Rats have no concept of extinction or death, humans do. To me, that means a lot.

What we abstractly know, for better or for worse, generally has little do with how we act. For example, human populations that experience severe trauma have problems even generations later, despite all their knowledge that their behavior is counterproductive.

I don't think we're too far off from not needing to worry about social behavior in regard to reproduction honestly. We're fairly close to literal test tube babies. Once that point arrives, we just need to have our Soma nearby and society will continue to function properly.

> human populations that experience severe trauma have problems even generations later

I'm very curious how they found a control group for this. Generations, plural, encompasses, among other things, both world wars, and their aftermaths.

The troubles associated with declining citizen working population lies not with pseudo-extinction. There are two big concerns with countries facing this.

One is the fact that there is going to be greater immigrant representation, and immigrants will have/need to have a separate voice. If a society is not well-equipped to handle this, it can face problems from that.

The other is that typically, the ratio of dependents to workers tend to get further skewed, with more dependents being supported by a single worker. This makes for hardship for the population, if not adequately addressed.

How do you propose to sustainably support 7.5 Billion people on this "tiny" planet without engineering?

Perhaps there is a middle ground between "engineering everything" and "without engineering".

He said without engineering everything.

The way your comment is written it is technically a straw man fallacy.