I read this little story for the first time in a short piece by Daniel Dennett written for John Brockman’s This Explains Everything, and unsurprisingly was totally fascinated. Is it a “just so” story? Is it true? Sea turtles do migrate thousands of miles. And their evolutionary roots have been traced back more than 100 million years.
Daniel Dennett:
I was told some years ago that the reason some species of sea turtles migrate all the way across the So Atlantic to lay their eggs on the east coast of So America after mating on the west coast of Africa is that when the behavior started Gondwana was just beginning to break apart (that would be between 130 and 110 million years ago)
and these turtles were just swimming across the narrow strait to lay their eggs. Each year the swim was a little longer– maybe an inch or so– but who could notice that. Eventually they were crossing the ocean to lay their eggs, having no idea, of course, why they would do such an extravagant thing.

Out of 25 females studied in the new
research, three migratory routes were
identified – including one 7,563km
journey straight across the South Atlantic
from Africa to South America.
And are there, or rather what are the “extravagant things” that we all do without knowing why?