The most interesting insight that I've had in the past several days is that I can trace my ancestry back to a particular individual who lived about 1,600 BC in Northern Italy. As I understand it, he is the individual who "started" the U152 subclade. In particular, the gene mutation is the one he passed down to the rest of the U152 line. It is then possible to talk about and research where this U152 line lived and when.
The U152 subclade is a sub-sub-sub-clade of the R1b haplotype, of which I'm a member. A deeper U152 subclade is the L20 of which I am also a member. A comparably deep but different U152 subclade is the L2 of which Jim Maule is a member and I am not. The split occurred sometime after 1,600 BC. Scholars are researching where members of the L20 and L2 subclades lived and moved then. Some ended up in Scandanavia. Others in Belgium and Southern France.
The second most interesting insight that I have had is that some members of these subclades almost certainly became Celts. (The Celts came later than our guy, so I guess we have to call him a Proto-Celt.)
There is far more research on this than I ever imagined. A lot is available on the Family Tree DNA website in the U152 Project. I'm not sure is this is available to the public, but try here.
There are many groups studying this niche, including this one focusing on the U152-L2 branch. I suspect I'll find one for "my" branch of U152-L20. (Both are preceded by "R1b".)
But by far the most comprehensive is a paper in pdf format by David K. Faux. To say it is "comprehensive" is an understatement. In terms of our time frame, 1,600 BC, skip to page 35.
The Bituriges of Belgium were later, but researches are hard at work to connect later U152 people with them. That would in effect mean connecting L2's and L20's with them. The l2's have a slightly closer connection at the present time.
It's very likely that the U152 group is associated with the "Beaker Culture" group of that time. The grouping here is by pottery rather than DNA.
Much data! But the takeaway is person who defined the U152 subclade 3,600 years ago.