“The laws of thermodynamics smell of their human origin.”

I think what Percy Bridgman meant when said this was that the laws of thermodynamics can not be solved. The laws of thermodynamics are laws that are simply set by nature that can not be proven wrong similar as to how we can not prove or disprove our human origin. 

The laws of thermodynamics as well as many other laws of physics are all set in stone, hence why they are called laws. After studying thermodynamics in Harvard for many years, Bridgman concluded that there were simply 2 laws that will have to accepted by society and is impossible to prove against. Those 2 laws were: the conservation of energy and the natural dissipation of energy. Later there would be a third law added but was not concluded by Bridgman, which that maximum efficiency can not be reached. Bridgman was not trying to take a stab at religion’s human origin belief. He was asserting that the human origin is impossible to prove because nobody has record of the beginning of humanity. And was comparing these laws to prove how adamant these rules applied and how they can not be proven against. So these rules as set as they apply in nature, are just mysterious and unbelievable as our human origin.