Glottalic theory
The glottalic theory is that Proto-Indo-European had ejective stops instead of voiced stops and so it had p’ t’ k’, not b d g, as the traditional version of the Proto-Indo-European sound system.
The glottalic theory was made in the United States by Paul Hopper and in the Soviet Union by Thomas V. Gamkrelidze and Vyacheslav V. Ivanov. The earliest theory was made by the Danish linguist Holger Pedersen that did not have glottalized sounds.
Earlier linguists, such as André Martinet and Morris Swadesh, saw the potential of replacing glottalic sounds for the supposed plain voiced stops of Proto-Indo-European. The idea stayed hypothetical until more evidence for it was published in 1973 by Hopper in the journal Glossa and by Gamkrelidze and Ivanov in the journal Phonetica.
Sources
change- Paul J. Hopper, "Glottalized and murmured occlusives in Indo-European." Glossa 7:2:1973, 141-166.
- Thomas V. Gamkrelidze and Vjacheslav V. Ivanov, Indo-European and the Indo-Europeans, translated by Johanna Nichols, 2 volumes. Berlin and New York: Mouton de Gruyter, 1995.
- Robert S.P. Beekes, Comparative Indo-European Linguistics. John Benjamins, 1995.
- Anthony Fox, Linguistic Reconstruction. Oxford, 1995.