I was in my teens when I first became aware of places in Poland called Gdynia and Gdańsk. I remember wondering how they could be pronounced without omitting the initial g. The nearest thing in English seemed to be the ɡəd- sequence in Lady Godiva ɡəˈdaɪvə and Godolphin (nowadays we have another example in Gaddafi), but I knew that wasn’t right. Yet as an initial cluster gd- seemed impossible to pronounce.
Then I realized that English does have the articulatory sequence gd, but in final position. We get it in the past tense of verbs ending in g, thus for example bagged bægd, hugged hʌgd. We get it medially, too, in Ogden ˈɒɡdən. All I needed to do was to transfer this gd to syllable-initial position.
That still seemed very difficult to do. The reason (I know now) is that in English we normally pronounce these plosive sequences as overlapping articulatory gestures. You can’t hear the release of the g in hugged, or for that matter in Ogden, because it is ‘masked’ by the concurrent hold phase of the d. What you hear is a velar approach, a long hold, and an alveolar release (if you’re lucky). And we don’t ever have this sort of thing at the beginning of a syllable.
It wasn’t until I first visited Poland, when I was twenty, that I discovered that in Polish the initial plosives in Gdańsk ɡdaj̃sk and Gdynia ˈɡdɨɲa are not like the English gd in hugged. Rather, when my Polish friends demonstrated the pronunciation to me, they released the velar plosive BEFORE completing the approach for the dental. This inevitably gave rise to a tiny transitional vocoid between the two hold phases, but it was not long enough to count as a separate schwa segment (compare the definite schwa in English Godiva).
If you can play .ogg sound files, Wikipedia has one of Gdynia here.
Despite my A level in Greek, somehow I’d failed to realize that classical Greek has an exactly parallel, but voiceless, cluster in words such as κτείς kteís ‘comb’ and κτίσις ktísis ‘foundation’. (What we did to pronounce those words in the Classical Sixth I can no longer remember.)
The stem of κτείς is κτεν- kten-, and from this is derived the modern zoological Latin name Ctenophora, the phylum of marine animals also known as ‘comb jellies’. In English we abandon any attempt at the initial plosive cluster, and pronounce them simply as tɪˈnɒfərə.
Modern Greek has dissimilated the plosive sequence, making the first element fricative. The modern word for ‘comb’ is χτένι ˈxteni.
So there are two attested escape routes: deletion or dissimilation.
But the Poles succumb to neither of these tempting articulatory simplifications, and persist with a sequence of plosives. Unmasked.