Prehistoric humans living more than 40,000 years ago had mastered the skills needed to catch fast-moving, deep ocean fish such as tuna, a remarkable new archaeological find has revealed.
In a small cave at the eastern end of East Timor, north of Australia, archaeologist Sue O'Connor from the Australian National University has unearthed the bones of more than 2,800 fish, some of which were caught as long as 42,000 years ago.
The find shows that the people living in the region had the sophisticated cognitive skills needed to haul in such a difficult catch, O'Connor says.
Her findings appeared in the journal .
"What the site has shown us is that early modern humans in island Southeast Asia had amazingly advanced maritime skills," she said.
"They were expert at catching the types of fish that would be challenging even today -- fish like tuna. It's a very exciting find."
It isn't clear exactly what techniques the people living in the area at the time used to catch these fish.
Tuna can be caught using nets or by trolling hooks on long lines through the water, O'Connor said.
"Either way it seems certain that these people were using quite sophisticated technology and watercraft to fish offshore."
The site where the discoveries were made, known as Jerimalai cave, is a small rock overhang hidden behind in foliage, a few hundred meters from the shore.
"When I discovered it in 2005, I didn't think that Jerimalai would tell us about the very early occupation of Timor," O'Connor said. "I was quite surprised when I found all these fish bones and turtle bones."
So far, she and her colleagues have only excavated two small test pits at the cave, which contained a number of stone artifacts, bone points, animal remains, shell beads and fish hooks.
In just one of those pits, 1 meter square and 2 meters deep, they found 39,000 fish bones.
They also unearthed another rare find -- a small piece of fishing hook made from a shell, which dates to between 23,000 and 16,000 years ago.
This is the earliest example of a fishing hook that has ever been found, the researchers say. They are hopeful that more extensive excavations might reveal more hooks at the site.
"I think Jerimalai gives us a window into what maritime coastal occupation was like 40,000 to 50,000 years ago that we don't really have anywhere else in the world," said O'Connor.