Final answer:
The theory that the genetic code's current structure is a 'frozen accident' is challenged by evidence of specific evolutionary processes and genetic code variations that indicate a more complex origin and evolution of the genetic code.
Step-by-step explanation:
The falsification of the frozen accident theory comes from positive evidence of specific evolutionary processes that show how the genetic code has evolved, rather than it being a product of chance.
The frozen accident theory, proposed by Francis Crick, posits that the genetic code's current form is largely a result of historical accident and that any change to this code would be highly disadvantageous since it determines the amino acid sequences of many evolved proteins. However, discoveries of genetic code variations in nature and advances in genetic engineering that allow incorporation of noncanonical amino acids into proteins provide evidence against the theory's universality.
Additionally, evolutionary studies into the translation machinery—such as ribosomes and tRNA molecules—and experiments in protein synthesis indicate a more complex evolutionary history of the genetic code, involving processes like stereochemistry, natural selection, and code expansion that are not adequately explained by mere chance as suggested by the frozen accident hypothesis.