A Brief History of the Guitar
There is evidence that a four string, guitar-like instrument was played by the Hittites (who occupied a region now known as Asia Minor and Syria) around 1400 BC. It had characteristically soft, curved sides--one of the primary features of anything identifiable as a guitar or predecessor. The Greeks also produced a similar instrument which was later modified by the Romans, though both versions appear to have lacked the curved sides. What is interesting here is that it seems this Roman cithara appeared in Hispania (now known as Spain) centuries before the Moorish invasion.
It had long been assumed that it was only after this invasion and the introduction of the Arabic ud in the South that a guitar-like instrument first appeared in Spain. But with the Roman cithara arriving centuries prior, we might say that although the ud influenced the development of the guitar it is not the true ancestor. According to this theory, the Spanish guitar derived from the tanbur of the Hittites, kithara with a "k" of the Greeks and then the cithara with a "c" of the Romans.
However, following the arrival of the Moors, the Roman cithara and the Arabic ud must have mixed and exerted mutual influences on one another for many centuries. Although there is no specific documentation, it is likely that makers of uds and citharas would have seen each other's work, if only through presentation by traveling troubadours. By 1200 AD, the four string guitar had evolved into two types: the guitarra morisca (Moorish guitar) which had a rounded back, wide fingerboard and several soundholes, and the guitarra latina (Latin guitar) which resembled the modern guitar with one soundhole and a narrower neck.
In the late 1400's, the vihuela was born by adding doubled strings and increasing its size. It was a large plucked instrument with a long neck (vibrating string length: 72 to 79 cm) with ten or eleven frets and six courses. It was the vihuela which became the preferred instrument of the Spanish and Portuguese courts and remained so until the late 1600's when orchestral and keyboard instruments became more prominent.
Although the guitar existed concurrently during this period, the vihuela and lute had overshadowed it until the end of the 17th century when the lute had acquired too many strings, was too hard to play and tune, and the vihuela was slowly replaced by the four and five course guitars (which had seven and nine strings respectively: one single high string, and three or four remaining courses--or pairs--of strings). It was perhaps the addition of the fifth course in the late 16th century that gave the guitar more flexibility and range and thus improved the potential of the repertoire that led to its ascent.
By the end of the 18th century and the beginning of the 19th, some guitars already used six single strings and employed fan struts under the soundboard. These struts were added for structural support to allow thinning of the top for greater resonance and for better distribution of sound across the board. Other contemporaneous developments included the use of a reinforced, raised neck using ebony or rosewood for the fingerboard, and the appearance of machine tuners in place of the wooden pegs. (It is noteworthy that the raised fingerboard had a great impact on the technique of the instrument since the strings were then too far from the soundboard to rest one's finger on the face for support.) These guitars would be unmistakably recognized by us as early classical guitars.
Beginning with the early 19th century, in the works of Agustin Caro, Manuel Gonzalez, Antonio de Lorca, Manuel Guiterrez from Spain and other European makers including Rene Lacote, and Johann Staufer, we find the direct predecessors of the modern classical guitar. By 1850, the guitar was prepared for its most important breakthrough since its inception, the work of Antonio Torres Jurado. With the encouragement of Julian Arcas and his own brilliant intuitions, Torres refined the strutting of the guitar to include as many as seven struts spread out like a fan under the soundboard. He increased the body size and the width of the neck considerably. These improvements allowed for greater volume and bass response as well as the development of a left hand technique for richer repertoire. The guitar was now prepared for the demands of the solo performer and the concert stage.
Although there have been continued developments since the middle 1800's, our modern guitar retains most of what was developed nearly 150 years ago. No one can say if we have reached the end of the evolution of the guitar, but until now, many of the best guitars from the point of view of volume, projection and sheer beauty of tone were made by the great makers, Torres, Ramirez and Arias from the second half of the last century!