It’s counter-intuitive that initial stages of agricultural development led to a backwards for individual well being but it did often make quality of life worse for the typical individual.
FWIW Wikipedia on the Neolithic Revolution:
Despite the significant technological advance, the Neolithic revolution did not lead immediately to a rapid growth of population. Its benefits appear to have been offset by various adverse effects, mostly diseases and warfare.[57]
The introduction of agriculture has not necessarily led to unequivocal progress. The nutritional standards of the growing Neolithic populations were inferior to that of hunter-gatherers. Several ethnological and archaeological studies conclude that the transition to cereal-based diets caused a reduction in life expectancy and stature, an increase in infant mortality and infectious diseases, the development of chronic, inflammatory or degenerative diseases (such as obesity, type 2 diabetes and cardiovascular diseases) and multiple nutritional deficiencies, including vitamin deficiencies, iron deficiency anemia and mineral disorders affecting bones (such as osteoporosis and rickets) and teeth.[58][59][60] Average height went down from 5’10" (178 cm) for men and 5’6" (168 cm) for women to 5’5" (165 cm) and 5’1" (155 cm), respectively, and it took until the twentieth century for average human height to come back to the pre-Neolithic Revolution levels.[61]
So, “urbanization” (in quotes because early cities would have a few thousand people although by early-to-mid bronze age up to 80,000 in larger Sumerian cities) and agriculture made food supplies more reliable but not necessarily more nutritious.
From same article regarding disease:
Throughout the development of sedentary societies, disease spread more rapidly than it had during the time in which hunter-gatherer societies existed. Inadequate sanitary practices and the domestication of animals may explain the rise in deaths and sickness following the Neolithic Revolution, as diseases jumped from the animal to the human population. Some examples of infectious diseases spread from animals to humans are influenza, smallpox, and measles.[65] In concordance with a process of natural selection, the humans who first domesticated the big mammals quickly built up immunities to the diseases as within each generation the individuals with better immunities had better chances of survival. In their approximately 10,000 years of shared proximity with animals, such as cows, Eurasians and Africans became more resistant to those diseases compared with the indigenous populations encountered outside Eurasia and Africa.[66] For instance, the population of most Caribbean and several Pacific Islands have been completely wiped out by diseases. 90% or more of many populations of the Americas were wiped out by European and African diseases before recorded contact with European explorers or colonists. Some cultures like the Inca Empire did have a large domestic mammal, the llama, but llama milk was not drunk, nor did llamas live in a closed space with humans, so the risk of contagion was limited. According to bioarchaeological research, the effects of agriculture on physical and dental health in Southeast Asian rice farming societies from 4000 to 1500 B.P. was not detrimental to the same extent as in other world regions.[67]
In addition to disease, mummies from Egypt show that bronze age people were filled with parasites. Heck, one of the Biblical passages about the Hebrews leaving Egypt has God promising them that I will put on you none of the terrible diseases of Egypt which you have known.
A thought experiment can help explain this: hunter-gatherers tended to be smaller groups of people with less contact with others. Disease has less opportunity to spread.
Now, picture a late stone age or early bronze age city. People are crowded together, more than they ever have before. If one gets a communicable disease soon everyone will have it. It’s an ancient petri dish where diseases can more easily mutate into other forms: in addition to dealing with all the same diseases as their nomadic ancestors from a half dozen generations before they soon will have brand new illnesses against which there is no immunity.
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Apologies for going the lazy Wikipedia route but this ain’t no college essay.