Final answer:
The same genetic code refers to the universal genetic code shared across nearly all species, indicating a common ancestor who inhabited Africa roughly 200,000 years ago, and this universality is used to trace evolutionary relationships.
Step-by-step explanation:
The concept of a 'same genetic code' refers to the near universal system of nucleotide triplets, or codons, which code for the same amino acids across almost all forms of life on Earth, from bacteria to humans. This universal genetic code suggests that all life shares a common ancestor, which has been traced back through mitochondrial DNA (mtDNA) studies to have lived in Africa around 200,000 years ago. This ancestor passed on its genetic code to its descendants, which evolved into the diverse forms of life we see today. The genetic code's resistance to change, a phenomenon known as the 'frozen accident', played a crucial role in maintaining this relationship across different species, underscoring the theory of a common origin of life. The universality and conservation of the genetic code allows us to compare DNA sequences among species to establish evolutionary relationships and trace our lineage back to this common ancestor.