Language Diffrences

I find the idea of language acquisition to be very interesting. Particularly the fact that there are universal melodies that exists surprises me. What does that mean about our evolution and the nature of language? I had always believed that language had developed in isolation across the globe and that therefore languages could be vastly different, i.e. the tonal languages of the far east versus the romance languages. It most likely leads back to a time in which all humans did not speak. I wonder what other studies reveal universal truths about the nature of humans across culture. There is the famous fact that humans are naturally scared of the dark and snakes, but that is much more logical and biological then the way in which a mother speaks to her infant. I also find language captivating in that the language that we learn defines ways in which we think and perceive of the world. Some languages don't have tenses or phrases that apply to English. For example, I was once living in Argentina working on a cattle ranch and was invited to meet people in town on the weekend. When we decided what time to meet, they kept saying tardecita, and I could not understand or get them to say a specific time, thinking I was misunderstanding, I asked the owner of the ranch, who spoke English, what the word tardecita meant. He laughed and explained that it meant anytime between noon and four. This of course, to me, as someone from the United States, was a totally foreign concept. Learning the word, changed the way I perceived of time and revealed to me another cultures relationship to time. In this way language acquisition and the nature of language is fascinating.