Human impact: Homo sapiens caused more species to become extinct pre-Agricultural Revolution with a global population of several million than they’ve made extinct since the Columbian Exchange.
I’m big into environmentalism and sustainability, particularly on the agricultural side. The “feed the world” question, soil loss, carbon cycles, all fascinate me. Overpopulation is less of an issue than the way modern society is designed. Whether we can redesign society without a hard collapse because of resource depletion is a hard question, and history does not offer favorable examples. There are a number of alternative agricultural and urban planning models that could drastically reduce our planetary impact with small impact to quality of life, but they require huge paradigm shifts to enact.
I have three kids, we had our first at only 21 and until the last couple years made a median income, and we’re still not close to six figures. It’s a single income currently, but I worked part time for many years until recently. I ran a few scenarios and if we had the same number of kids, even having them very young, but had our frugal spending levels and had waited to buy our house until after the crash (when we would have had a more responsibly sized down payment) we would already be close to FI, maybe 3 years away or so.
As it stands we were relatively irresponsible in our 20s and didn’t find MMM until 29, but even so we should be FI by 45-50, possibly 5 years longer if we decide to buy acreage and move out of the city.