The US patent act clause 102 says that nothing can be patented if it is prior public knowledge. If the public has been aware of the material and its benefits, then it is not possible to patent. Clause 102 then goes on to define ‘public knowledge’ as only that of Americans’ and no one else. Not the billions of Indians, Native Americans or Africans, their knowledge. Their natural resources are not represented or protected by this act.
Read more here.