The History of L N and R

Once again, we have to go WAY back. To Common Gaelic to be exact, which has a lovely balanced system of sonorants - L N and R that is:

To begin with, the *r means that there was an initial slender r but we have no idea what that was phonetically. It's a mystery.

The above system is nice and balanced in the way that you had two "strong" variants of each sound which would occur at the beginning of words and two "weak" ones which you would get in the middle or at the end of words or as the result of lenition!

So you'd get:

Taking a big leap in time most modern Scottish Gaelic dialects have evolved the following system:

Which creates a small problem - since the system is now 3 sounds short and somewhat unbalanced, how do you deal with lenition? Well ... two ways.

1. By making one sound "double up" for two
2. By "not" leniting

What does this mean practically? To begin with, the l in long and balach sound exactly the same now and when you lenite l in mo long for example, there is no sound change. Initial [Lʲ] still lenites as it did in Common Gaelic, so leabaidh becomes mo leabaidh [mə lebɪ].

Both initial n sounds on the other hand now lenite to weak [n]:

1. nead [Nʲed] ⇨ mo nead [mə ned]
2. nàbaidh [Naːbɪ] ⇨ mo nàbaidh [mə naːbɪ]

Initial slender r has merged with initial broad r i.e. there is only one initial r sound left, strong [R] which lenites to [r]:

1. rionnag [RuNag] ⇨ mo rionnag [mə ruNag]
2. ràmh [Raːv] ⇨> mo ràmh [mə raːv]

Sooo ... what does this have to do with initial consonant clusters? Lots. The second consonant is considered non-initial, which means that in Common Gaelic it would have had the "weak" pronunciation. But since we have lost two of the "weak" sounds, we have to make do somehow, so the initial broad l has to fill the gap that the departure of non-initial broad l has left so [bɫ] becomes [bL] and so on. In essence, the old system is perpetuated wherever possible except where that isn't possible any more due to a loss of some of the sounds. Which is why the system today is a bit messy.

Incidentally, not all dialects have evolved the same system and Ulster Irish retains the most complete set of sonorants amongst the Gaelic languages and dialects:

Ulster Irish

Connacht Irish

Munster Irish

And looking at Scotland:

Harris Gaelic

Rosshire

East Sutherland

and most others have. Fun, ain't it?