The concept of a healthy population structure is typically left out of the ongoing over/under population debates. There are some exceptions, e.g. discussion of

The concept of a healthy population structure is typically left out of the ongoing over/under population debates. There are some exceptions, e.g. discussion of the gender imbalance that came about in many regions of China as a result of the now-defunct one-child policy, or the stresses facing societies with a high ratio of elderly to young people (Japan, US boomers, etc). Fundamentally, we want to avoid population boom-bust cycles as those tend towards destructive outcomes (famine, war, disease, migration), and instead have a stable steady-state population structure that's pyramidal and gender-balanced, and neither increasing nor decreasing. Whether this is possible without increased authoritarianism is an open question. Similarly, we want to ensure that all regions of the planet have access to the basic necessities of life, water and food and shelter, as otherwise the refugee and immigration crises will expand. This is where the climatic instability brought on by fossil fuel combustion will have varying impacts, with some regions being hit much harder than others. The solution is investment in resilient infrastructure (instead of wars). Personally I like the idea of preserving a half-wild Earth, as a planet packed from one end to the other with nothing but human beings and their crops sounds a lot like a dystopian hellscape.