Before hominins intentionally chipped stone to make tools, they likely used sharp rocks already shaped by natural forces.

"Technological innovations were crucial for human evolution," says Karakostis ... Although both tasks required cognitive effort, the use of cutting tools involved significantly more extensive ...

Evolution Power Tools, DeWALT and others offer metal-cutting chop saws that make precise miter cuts that are unavailable with abrasive-disk saws. They’re double the cost of a conventional chop ...