More about Galapagos...the one island that had a (known) human population with scientific research underway had a facility which was raising the famous Galapagos tortoises, from eggs. Each infant had been "dated" on its undershell, when it hatched, using a marker.
Years later when we moved to a town north of here we visited a zoo. In that zoo was a teenage tortoise from, yes, the island. And, yes, its date remained on its undershell and yes, it was there when I was.