Another branch of the human family tree has been discovered, with a new species of early humans unearthed in a cave in the Philippines, in the same part of the world as the famous "hobbit" Homo floresiensis.
And researchers believe this may still be the tip of the iceberg in terms of the discoveries about the increasingly complex history of the human species scattered across the south Pacific.
The new species has been named Homo luzonensis by the international team, after it was found in Callao Cave on Luzon Island in the northern Philippines in 2010.
At that time, the team discovered some foot bones after extended digs in the cave site, and eventually uncovered a partial femur and teeth from three individuals.
Professor Philip Piper, a zooarchaeologist with Australian National University, was at the time working at the University of the Philippines.
"I remember Mandy (lead researcher Armand Mijares) dumped the bones on my desk and I took them home," Dr Piper said.
"We had no idea it was a hominin at that time, but what was important to us was that irrespective of that it was the oldest human remains ever recovered from the Philippines."
Previously, the oldest human remains discovered in the area were anatomically modern Homo sapiens remains, dated to 30,000 to 40,000 years ago, discovered on Palawan Island.
Professor Rainer Grün, director of Griffith University's Australian Research Centre for Human Evolution, said their team had dated the fossils to be at least 50,000 years old, possibly older.
"We use a laser to sample a very small amount of material into a mass spectrometer and we get an age estimate from that," Dr Grün said.
"The method only gives you minimum age estimates, but we tested the teeth and got a minimum age of 50,000 years."
Dr Grün and the Griffith team had previously worked on dating examples of Homo floresiensis, which was found on the island of Flores in Indonesia, placing them in a similar time period of around 50,000 to 60,000 years ago at the latest.
Homo luzonensis would have been a similar size to the "hobbits" of Flores at a little over a metre tall, but would likely have looked different to them, having some characteristics which resemble older types of hominin such as Australopithecus.
Dr Piper said the discovery made the fascinating case for a diverse range of ancient human species which evolved separately at the same time across the islands of south-east Asia.
"This basically opens up Pandora's Box- we already know there's 200,000-year-old stone tools on Sulawesi, and it's probably only a matter of time before we have a hominin species there as well," he said.
"Think about the Galapagos Islands, and species like the Galapagos tortoise; there's no reason you can't see archipelago speciation in terms of hominins. It's incredible.
"They've arrived on the island and been isolated from each other and evolved into all these different species."
Dr Grün said there was possibly up to four known human species living in the region at the same time - Homo luzonensis, Homo floresiensis, Homo erectus in Indonesia and possibly anatomically modern humans as well.
"You compare with Europe where there has been systematic archaeological investigation for 200 years, compared to the last 10 years or so in south-east Asia," he said
"I think with the systematic investigation which is really taking off in southeast Asia, there will be more and more really interesting things coming out."
The discovery of Homo floresiensis in 2004 caused a sensation due to the fundamental re-writing of human history, while another human species, Homo naledi, has been discovered in South Africa since then.
An article on the findings has been published in the journal Nature this week.
- The Brisbane Times