In that interview, Dr. Nathalie Cabrol said that she thought exploration was an original and fundamental drive in all life forms. Well the article she guest posted on the Blog Life At The SETI Institute explains a lot more detail of her philosophy on who the original explorers were. Here is a snippet:
"Each species goes as far and as fast as its evolutionary path can take it. This path is dictated by that species’ exposure to the environment and to other species. We (as in life in general) are all trying to constantly expand our horizon, for there is gain in doing so. At the most primary level the gain is physical survival through a greater range of environments, which provide additional resources to supply a greater number of individuals of the same group. The curiosity and awe that we humans associate with exploration is a late comer. Understanding when this driving force developed is by itself a fascinating subject. I do not believe the first bacteria were curious about their environment; they simply tried to adapt to it."
Not only was her article a fascinating read, the commentary and counterpoint was really good too.