Minka: A single-family detached home

The Minka or the Japanese farmhouse was one of the earliest forms of the single-family detached home.

Before this time in human evolution, it was common for peasants (not so much the aristocracy) to share their living spaces.

Instead of individual beds, large groups of people would sleep together on one "mattress"; flooring that was not earth was unheard of; and people cooked, ate, slept and procreated all within the same space.

But then, during an era of unprecedented peace and prosperity in Japan (1600-1868), people began to differentiate themselves from their neighbours.

Now, one house would provide shelter for only one family.

Servants who had previously slept around their master's hearth came to be landowners in their own right and built separate houses of their own. 

Retired heads of households moved out to make way for the younger generations--handing over use of the lone bedroom to young couples so they might procreate with a degree of privacy. 

Walls made of reed and stone marked off a plot of land as private and distinct from a public space.

(It's noteworthy that peasants were not allowed to construct walls for the longest time.)

Spaces inside the home were differentiated by varying floor levels and materials. Work areas had floors of earth, living and sleeping areas had higher floors of wood and straw mats (tatami). 

Later on, variations in ceiling height also served to demarcate spaces.

Domestic livestock were banished from the home — animal habitation had to be separate from human habitation.

Finally, for the first time, household altars took pride of place in many peasant homes. Where once peasants would have simply worshipped the ancestors of the households of which they were dependents, now they were celebrating their own unique ancestral lineage.

Sources:

"Minka: The Quintessential Japanese Home."