Import a track-log into Google Earth and study the relationships evident between the path taken and major features of the terrain and vegetation visible in the software.

Compare points in a track-log to ascertain patterns such as:

• Maximum slope of elevation gains and losses
• Percent of travel at a given slope
• If a goal is known, deviation from a straight course

Compare points in a track-log with known points to ascertain patterns such as:

• Slope perpendicular to travel

For travel between two points A and B, where A has greater elevation than B and the slope does not change signs, a human will follow the same path water would take, or the reverse. That is, a human will follow the path of least resistance, generally holding to ravines.

Selection of a goal is based on visibility, which is not good in ravines. Humans will come up out of their 'easy' paths in order to see terrain and pick a new goal.

• Contradicting the water flow theory

A human will walk along a hillside, keeping a virtually constant elevation.

• Contradicting the water flow theory

When climbing or descending a particularly steep hill, a human will follow switchbacks, rather than climb straight up.