Before the 1600s, scientists didn't formally divide organisms into two groups. The concept of classifying living things into distinct groups was still developing.

Here's a breakdown:

* Ancient Greeks and Romans: They did observe and categorize the natural world, but their classifications were based on practical usefulness rather than scientific principles. For example, plants were categorized based on whether they were edible or medicinal.

* Medieval Period: The focus shifted to religious interpretations of the natural world. The idea of a Great Chain of Being, placing humans at the top of a hierarchical ladder of life, became influential.

* The Renaissance and the 1600s: This period saw a renewed interest in observation and empirical evidence. This set the stage for the development of more scientific approaches to classification, which eventually led to the establishment of taxonomy in the 1700s.

So, to answer your question, there wasn't a specific "two groups" division before the 1600s. The development of scientific classification took place gradually and was heavily influenced by the philosophical and religious ideas of the time.