So what does all that have to do with Julie? Self awareness is the very reason humans adorn their bodies with ornaments ranging from diamond earrings to tattoos. Self awareness leads to self expression. Once you know who you are, you want others to be impressed.
So perhaps -- and this is just speculation because no one knows for sure -- Julie stuck that blade of grass in her ear for the first time because she wanted the big guy across the compound to notice that she was different from all the other ladies. The ears, after all, are considered one of the body's erogenous zones.
That opens another possibility. Perhaps the use of jewelry began long before humans appeared on the planet, even before our ancestors began hanging a tooth, or a piece of animal hide, on their bodies, about 75,000 years ago, based on some of the oldest artifacts ever found.
The first to do it could have been followed by many, the old "monkey see, monkey do" ritual. We don't know yet.
The sad part of this story is Julie died awhile back. But amazingly, her tradition lives on. Two of her buddies, Kathy and Val, continued to be seen even after Julie's death with a blade of grass hanging from one ear.