Legally you'd run into §101 problems for patenting a natural occurrence. And you'd run into prior art problems because people have been walking before your pate

Legally you'd run into §101 problems for patenting a natural occurrence. And you'd run into prior art problems because people have been walking before your patent. Could you slip one through the patent office? Probably not anymore. But a big weakness in the patent examination process is that the USPTO mostly relies on other patents and academic articles. So sometimes you can get some commonly known and well understood products and processes patented because the USPTO doesn't find any written evidence of prior art.