Not all due to infant mortality. Communicable diseases in general commonly resulted in death regardless of age. Remember that germ theory was only introduced in the last decade of the 19th century. Before germ theory urban sanitation was generally horrible and ideas of how diseases were caused and spread were simply wrong. Also, there was a poor health care infrastructure and no social security net. Homelessness was high, if you lost your job it could have meant starvation, and if you got any degenerative disease in your 40s and 50s you were likely to die as well. Now that we have handled communicable diseases (by and large), we are turning our attention to getting better at stopping degenerative diseases. This will eventually be solved with the maturity of stem cell therapies.Is this average from the 20th century of 45 because of infant mortality?