How about the other half of the question? A "microfoundation" is a set of local-level pathways and mechanisms through which a social process is caused or mediated. It is a particular set of individual circumstances that create the patterns of behavior that aggregate to the observed social outcome. For example, the microfoundation for an observed failure to carry off a successful tiger hunt is the set of circumstances of recruitment through which eligible participants are enabled to "free-ride" on the participation of others.
So -- do social practices have "microfoundations"?
First, consider the social reality of a practice like wine-making. Pre-modern artisanal wine makers possess an ensemble of techniques through which they grow grapes and transform them into wine. These ensembles are complex and developed; different wine "traditions" handle the tasks of cultivation and fermentation differently, and the results are different as well (fine and ordinary burgundies, the sweet gewurztraminers of Alsace versus Germany). The novice artisan doesn't reinvent the art of winemaking; instead, he/she learns the techniques and traditions of the elders. But at the same time, the artisan wine maker may also introduce innovations into his/her practice -- a wrinkle in the cultivation techniques, a different timing in the fermentation process, the introduction of a novel ingredient into the mix.
So the practice of Alsatian winemaking in the seventeenth century has a complex social reality. There are elements of knowledge and practice common among many wine growers in the region; there are differentiating changes over space and time; and the whole tradition has a history that extends backward in time and space. We might imagine that the geo-history of the winemaking traditions of Alsace would track the continuity, change, and transformation of the complex of practices across time and space -- perhaps in the form of a set of dynamic maps illustrating the diffusion of the tradition, and the diffusion of variants and modifications, over space and time.
Now we are ready to come back to the question of microfoundations. There are at least two aspects of this story that require microfoundations, corresponding to persistence and change: the social mechanisms of reproduction of the practice from generation to generation (persistence) and the social mechanisms of transmission of innovation across space and time (change). (There is an interesting analogy here with the reproduction of a genotype over time, with faithful reproduction and mutations.) If we committed the intellectual sin of reification and imagined that there is one unique and extended social practice that is "Alsatian winemaking wherever it occurs," we would have missed a crucial part of the story just told; there is no essential social practice of winemaking (or greeting a neighbor or decorating the house for Passover). Rather, there are bundles of bits of knowledge, assumptions, judgments, and behaviors that are embodied in the thoughts and actions of individuals at a certain time; and there are social mechanisms through which these bundles of knowledge are transmitted across generations and across space and time.
Seen from this point of view, the study of the persistence, change, and brachiation of a social practice or traditional technology is a genuinely fascinating window into patterns of human activity over time. If it were possible to trace the travel of an innovation in the fermentation process from its origin in a given village, along the circuits of the periodic markets, across a jump to a more distant place (by long-distance ship, for example) we would have a "marker" of the routes of social interaction and travel that were characteristic of seventeenth-century rural Alsace. The logic of this investigation would be similar to that pursued by historical linguistics, observing the gradual transformation of the syntax, phonology, or vocabulary of a language over several centuries and an extended region.
And the topic of microfoundations is an important theoretical question in this story. It invites us to ask several foundational questions:
"What are the social processes within which the complex social practice is embodied in human behavior and knowledge at a certain time?"
"What are the social processes through which this body of knowledge is transmitted relatively intact from one generation to the next?"
"What are the social mechanisms of transmission through which these clusters of human knowledge and their variations are conveyed across space and across social groups (from village to village)?"