Final answer:
The Universal Genetic Code supports the inference that all life on Earth has a common ancestor, highlighted by the fact that almost all organisms use the same genetic code for protein synthesis despite the vast number of possible combinations.
Step-by-step explanation:
The Universal Genetic Code provides additional evidence for the inference that all life on Earth has a common origin. This is highlighted by the astonishing fact that, with a few minor exceptions, nearly all organisms use the same genetic code for protein synthesis, suggesting that this system was established early in the evolutionary process. With approximately 1084 possible combinations of 20 amino acids and 64 triplet codons, the likelihood of different organisms independently evolving the exact same code would be extraordinarily low. Instead, the universal nature of the genetic code supports the idea that all known life forms share a common ancestor.
The conservation of codons across hugely divergent species provides additional evidence for this inference. For example, a strand of mRNA that encodes for globin protein in a horse can be transferred to a tulip, and the tulip will correctly synthesize horse globin. This demonstrates not only the universality of the code but also the robustness of its application across diverse forms of life.
Moreover, the genetic code is described as 'degenerate', which means that most amino acids can be encoded by more than one codon. This degeneracy likely played a role in the code's conservation over time, providing a buffer against mutations that might otherwise have altered protein function dramatically.