Modern Times, Modern Bodies

In this chapter, Lieberman covers the changes due to industrialization, and the rapid changes in the past 250 years.  The Industrial Revolution occurred when humans started using fossil fuels to power technology.  In the span of only 12 generations, humans went from doing a wide range of manual work to primarily highly specialized office work.  The Industrial Revolution coincided with an increase in science, which increased knowledge of biology and medicine.  Initially, factory work was just as strenuous as farming.  But as technology increased, and robots took over strenuous tasks, office work began to take over.  Lieberman argues that industrialization profoundly decreased the amount of physical exercise humans get.  Our jobs are no more taxing than sitting down, and the cost of traveling has been reduced by elevators, cars, and planes.  Washing machines and dishwashers have reduced the energy spent on cleaning, and air conditioning and heating has reduced the amount of energy spent on body temperature.  Additionally, industrialization has fundamentally changed our diet.  Large corporations took over small scale farming, and food producers are able to produce cheap, high calorie food.  Most food eaten in the US today is grown industrially, and quantities are high and prices are low.  However, Lieberman explains that industrial food production takes a toll on the environment and the health of the workers.  Although quantity of food increased because of industrialization, the quality decreased, leading to increased obesity in the population.  Lieberman also explains how industrialization increased scientific knowledge, and improved urban conditions with knowledge of sanitation and medicine.  One of the main advances was the discovery of bacteria and viruses, and the invention of vaccines.  Advances in sanitation and plumbing also reduced the burden of disease, and allowed society to combat disease.  All of these changes have resulted in a society with abundant food and less of a requirement of physical activity.  Humans are expected to live longer, but die slower of chronic illnesses.   Lieberman explains that the Industrial Revolution was successful at solving mismatch diseases from the Agricultural Revolution, but created a whole host of new, chronic, mismatch diseases.