These shoes were made on a last.

Last: First of all, you can find the last of the shoe by looking under the insole.

While scientists say the shoe was stuffed with grass, acting like a shoe tree to hold its shape, it had been worn.

This is just what it sounds like, a board in the bottom of the shoe. Board lasts offer more support but are not real flexible.

Many major running-shoe companies are starting to offer gender-specific lasts (the forms shoes are built on) instead of the unisex lasts they currently use, resulting in better-fitting shoes.