What's the reason?
It more than likely started in the port cities of Italy after the Roman Empire. I say after, because before that Latin was a widely spread language. After the fall of the Roman Empire, imported languages started taking over, as conquerors and immigrants came from many different parts of the ancient world: The Carolingians (mixing early German and French into northern Italy), The Visigoths (mixing German, Spanish and French), the Normans (descending from Vikings from Northern France, they took over Southern Italy), Saracens (Muslims that invaded southern Italy and settled in Sicily), the German tribes (in pre-Christian times and in the middle ages), French (taking over northern Italy in the 1400s) and Austrians.
Latin itself morphed into what we now call the Italian language. But even "modern" Italy didn't become a cohesive nation until the 1860s, and still today Italians are very region-centric, with many varied dialects still spoken throughout the country. One example I witnessed is on the train from Bari to Rome. The announcements were in three languages: English, Italian and Southern Dialect. And believe me, Dialetto sounds very different than "proper" Italian--my Dad spoke it. He was from Molfetta. My Mom couldn't understand him. She spoke another Dialetto from Naples.
At the end of this post is a video of a charming Italian gent illustrating the many subtleties of hand gestures. You could learn to have an entire conversation without words!
When I was a kid, my parents told me not to eat with my hands... but speaking with my hands was absolutely permitted.