I have just finished reading a collection of Raymond Chandler's novellas, all of them set in the Los Angeles County of the 1930s. Aside from the excellent writing and the great character Phillip Marlowe, the thing that really struck me about the stories is the descriptions of the material surroundings of the characters. For example, in most of the offices that Marlowe visits the furnishings include a spittoon.
What fascinates me about this is the fact that spittoons, once a common item in public places, almost entirely vanished by the end of WWII. During the early 20th century, people shifted from chewing tobacco to smoking. Part of the reason for the shift was the post-WWI influenza epidemic leading to a greater consideration about the transmission of fluids from the respiratory system. Fears of tuberculosis also played a role. Other reasons for the change were clear, but less physically tangible: the ready availability of chewing gum led to it replacing tobacco as the "chew" of choice, and cigarettes (considered more sanitary) began to fulfill people's tobacco habits.
The end result is the same: the spittoon, once a common item within households and public places, vanished by the middle of last century. When I read about an item like this, I always find myself wondering how archaeologists, lacking written records, would deal with such a change in material culture.
There are many different theoretical schools in anthropology, but we can break them very roughly into two types of traditions: those who seek explanation for changes in adaptations to the environment, and those who seek explanations in the social and symbolic experiences of the people who made use of the material culture. The spittoon is interesting in that it clearly can be accurately described by both sides, and both sides would fail to provide the full explanation.
The removal of spittoons was preceded, and pushed by, the influenza epidemic, and the presence of tuberculosis in most cities also played a role. Someone looking at the increased mortality rates and the routine presence of tuberculosis scars on the bones of the dead combined with residue analysis on the spittoons themselves might work out that there was a public health crisis in play, and that the removal of the spittoons might be worked out from that.
Other archaeologists might work out that, as the frequency of spittoons decreased, the materials associated with producing cigarettes and chewing gum increased. They might, from this, argue that chewing tobacco came to be seen as old-fashioned and low class, and that cigarettes and chewing gum became ascendant as an attitude of greater upward-mobility spread through the culture.
My own experience interacting with my colleagues leads me to think that most of my colleagues would argue for one of these two explanations, and might pay lip service to the other but generally brush it off. Of course, the truth is that both are true and both fed each other. The public health concerns may have spurred the removal of the spittoons, but it also created a set of social pressures that resulted in chewing tobacco and the use of spittoons being seen as low-class and disgusting, which further led to these items being seen as unsanitary, and so on in circles. A social/symbolic explanation and a material/biological explanation are both necessary to fully explain why a common piece of material culture became rare to the point of near-extinction (it's now almost solely a piece of specialist equipment for wine tasters - ironically making the spittoon a high-class item).
Anyway, it's something to consider the next time that you hear an archaeologist describe a change in the archaeological record as being solely or primarily due to one type of change (environmental, biological, social, etc.). Sometimes it's accurate to assign cause to one factor, but often it isn't.