As far as the traditional music of Europe generally is concerned, however, the picture is rather patchy, with mostly rather small islands of polyphonic vocalizing surrounded by a sea of monophonic and unison singing, dominated by solo genres such as the epic, lyric song, ballad, religious chants and intonations, etc. (I am, of course, omitting the European "classical" and "popular" traditions, what Jordania aptly calls "professional polyphony," with which I'll be dealing presently.) Alan Lomax called these mostly isolated pockets of untutored group harmonisation "Old European" style, as opposed to the "Modern European" style of the solo songs and ballads.
To better understand why Lomax would characterize this style as "Old European," we need to back up a bit to consider the meaning and history of (traditional) vocal polyphony worldwide. For this purpose, I'd like to quote some authoritative, and convincing, comments from Jordania's book:
A study of local polyphonic traditions suggests that the prevailing tendency of the historical dynamics is the disappearance of the vocal polyphonic traditions. Actually,this is not a prevailing, but the only tendency. Historically documented cases of the disappearance of polyphonic traditions come from Europe, Asia, America, and Oceania. On the contrary, the documented cases of the appearance of vocal polyphonic traditions (as the natural evolution of polyphonic singing from monophony) are conspicuously absent. This means that the universally accepted idea of the natural evolutionary transformation of monophonic singing into polyphonic singing is a fiction, totally unsupported by the evidence. . . 
According to my model, the earlier we go in human and hominid prehistory, the more polyphony will be found, and ultimately, the origins of polyphony must be somewhere in the very process of the evolution of our human ancestors in Africa, before their dispersal throughout different continents of our planet . . . .
I remember very well that every time ethnomusicologists start discussing the distribution of polyphonic traditions throughout Europe and try to discuss the possible reasons for the emergence of choral singing, one of the most popular ideas among ethnomusicologists is the crucial importance of the “mountain factor”. “Look”, someone would say, “most of the European mountain ranges are populated by the carriers of the polyphonic tradition. There is something in this. Somehow mountains help to create polyphony”. . . But there is another very important peculiarity of the distribution of polyphonic traditions in Europe as well: besides the mountain regions, there are also very important non-mountain regions with traditions of vocal polyphony. . .
Most importantly, there is one very important common feature that unites most of the European polyphonic traditions. Mountains, large forests, islands- these are all geophically isolated regions. . . This fact suggests that mountains do not help to create polyphony . . . but as geographically isolated regions, they help polyphony and other elements of the culture to survive [212-213].
For Jordania, the most likely explanation for the European situation is the migration of Indo-European speaking peoples into the continent during the Neolithic, a development that forced the older populations, with their more archaic polyphonic traditions, into marginal areas, such as certain mountain, forest and island refuges.