Paradise Lost?

In this chapter, Lieberman explains the evolutionary consequences of farming.  After the end of the Ice Age, when the climate was more temperate, farming emerged in many different places around the world.  At first, early farmers supplemented their diet with hunting, but they eventually learned to domesticate animals for food.  Quickly, farming became the dominant strategy, with only a few groups of hunter-gatherers left.  Lieberman explains that the likely cause of this was the ability of farmers to grow more food, and therefore support more children.  In fact, for farmers, children are an asset, because they can help work.  However, although farming generated more food, it was less nutritious and less varied which results in nutrient deficiencies and mismatch diseases.  Additionally, if crops fail, farmers are at risk for severe famines, something that never occurred with hunter-gatherers.  Lieberman explains that farming required much more work than hunting and gathering, and required more power and less endurance.  However, Lieberman explains that one of the consequences of farming is the increased population size, and therefore increased infectious disease.  Farming also allows for permanent settlements and increased population density, which also increases infectious disease.  Farming also requires trading, which exposes people to new infections.  Lieberman explains that hunter-gatherer societies likely suffered from parasites, vector borne diseases, and zoonotic diseases, but did not suffer from large scale human to human transmitted epidemics.  Additionally, farmers suffered from poor sanitation, which only increased their risk of disease and allowed rodents and fleas to spread illness.  In fact, rats and mice quickly evolved to take advantage of farmers.  Living with animals also increased farmers’ risk of zoonotic diseases, and irrigation from crops created ideal environments for mosquitoes.  Lieberman estimates that over 100 mismatch diseases were caused by the Agricultural Revolution, and although technology is advanced, we are still vulnerable to new epidemics.  Lieberman says that because of technology, society rarely worries about epidemics currently, but he warns that “perhaps this complacency is misguided”, as the population is larger and denser than it even has been.  In these current times, I feel as though this particular statement is very relevant.  Even though farming exposed the human population to infectious disease, humans have evolved resistance to many diseases, including malaria, and have evolved mutations to help humans adapt to domestication.  Additionally, cultural improvements, such as farming tools have improved the lives of farmers.  Clearly, early farmers suffered from mismatch diseases, and have developed ways to mitigate the symptoms of these problems.