Calling up at least seven people to the Torah (or more if there's a barmitzvah, aufruf, etc) is a custom that goes back to the Talmud. However, the traditions of where exactly we make those breaks are much more recent. Maimonides, in his Laws of Prayer, gives some general guidelines; each aliyah should be a minimum of three verses, and the subject matter of each sub-section should begin and end with something upbeat and positive. In the 13th century, Rabbi Menachem Ha'Meiri wrote: "The exact division is not known; rather each reader does as he pleases provided he begins and ends with the good."
The earliest printed divisions we have is from a book, Tikkun Yissachar, published in the 16th century. The author cites manuscript sources that he found from the Gaonic Period (fifth to 10th centuries), recording ancient traditions of where the breaks should be. An 18th-century work explains that fixing the breaks avoids the bickering that would otherwise break out in the community about where the reader should stop. Perhaps that's why nearly every printed Chumash includes the standard breaks.