A piece from Science on how humans are 'hardwired' for geometry will probably be popping up all over the place ... it includes this bit:

For thousands of years, people have wondered if the basics of geometry came naturally to all humans or if they were something you had to learn through instruction or cultural experiences. According to Plato’s writings, Socrates attempted to determine how well an uneducated slave in a Greek household understood geometry, and eventually concluded that the slave’s soul “must have always possessed this knowledge.”

While a slave in a Greek household would have been introduced to aspects of geometry through the Greek language and culture, the Mundurukú villagers who participated in the new study did not have this head start. Nevertheless, the 14 Mundurukú children, as young as 6 years old, and the 30 adults who were quizzed by anthropologist Pierre Pica from Paris VIII University did well on the basic geometry test.

... not sure what test Plato used, but I doubt anyone will seriously consider the test they did do (examples in the whole article) 'geometry' in anything except a very loose sense.