Choose one other Indo-European culture and compare and contrast it to the culture discussed in question 3 above with respect to each culture’s Indo-European nature.
In many ways, the story of the Celts and Romans demonstrates how interactions with other peoples, and the subsequent diffusion of beliefs and cultural practices, are more important to the evolution of a culture than is a common heritage.
Some 4,000 years ago, a group of migrants arrived in central Europe. They, perhaps, spoke a language that historical linguists would call Proto-Italo-Celtic. A few centuries later some of these migrants continued migrating, moving south into what we now call the Italian peninsula, leaving their cousins behind to become the Celts. By the time they returned as conquerors the Italics, led by Rome, had become very estranged cousins indeed.
Looking at the differences between the La Tène Celts and the Roman Republic it seems clear that the Celts, entrenched in their deep forests, were the more conservative, retaining many traits of earlier Indo-European society while the Romans, by moving south, had become part of the great crucible of knowledge sharing that was the Mediterranean with its adjacent trade routes out through the Middle East, India, and onward to China.
For instance, the Celts retained their chieftain-ruled tribal nature which they shared with the Germanic peoples among others, while the Romans, inspired by the Greeks, deposed of their monarchs and adopted a democratic system of government which served as a central governance body as the state grew. The Celts also seem to have retained a simple tripartite societal structure while Roman society became far more complex with different classes based more on wealth than on function.
As far as religious life went, our knowledge of La Tène Celtic beliefs is sketchy indeed with most archaeological evidence only dating back to after the Roman conquest. With the Latins, however, it is clear that they quickly re-aligned themselves towards the east, subsuming many of their own divinities into Greek mythology and adopting eastern, non-Indo-European cults via the Greeks such as that of Bacchus and, later, Isis, to name just two.
The Latins and Celts shared a much closer common heritage than did the Latins and the Greeks. However in the end, the closer contact between the latter two over the last few centuries before the common era meant that when the Romans came conquering, they were by far more like the Greeks in religion, government, and social structure than they were to the Celts.