In late 2016, researchers discovered a genetic gap in the DNA of Melanesians from Papua New Guinea, a gap which indicates a third, previously unknown ancestor of the Melanesian people. Needless to say, the scientific world immediately began to speculate different theories as to who provided the missing link in Melanesian DNA. Already a highly isolated area featuring some of the world's most obscure countries, the Melanesian people developed a culture distinctively their own, including a number of unique methods of mummy-making. Now they also boast one of the most unique genetic footprints of any other population, leading many to theorize the possible ancestry of the Melanesians.
The search for the link within Melanesian DNA revealed a number of other strange and exciting facts about Melanesian peoples. They each possess genes from Neanderthals and Denisovans alike, and their genes also appear in American populations, meaning they traveled far beyond the realm of Oceania. Even all of this new information only gives researchers a limited number of answers, as most, like the Melanesian people's third genetic ancestor, remain lost to time.
Four major groups of Pacific Islanders – Malaysians, Melanesians, Polynesians, and Micronesians – were identified during the 19th century, with theorists asserting they shared the same origins and DNA. During the early 21st century, however, DNA evidence proved Polynesians and Micronesians share little in common with Melanesians in terms of genetics. Only after both Polynesians and Melanesians established themselves in Oceania did they meet and mix DNA with one another.
In 2010, the genetic identity of Melanesians revealed itself to be even more obscure than expected. Research discovered that Melanesians were linked to not only European Neanderthals but also to Denisovans, their eastern cousins. Scientists knew Neanderthals migrated throughout the world thousands of years ago, but the appearance of their cousins' DNA in Melanesians was particularly surprising.
The discovery of Neanderthal and Denisovan ancestry in Melanesia upturned the genome world. Using new data which indicated that Melanesian DNA was comprised of anywhere from 3-6% of Denisovan DNA, scientists determined that the Denisovans most likely migrated out of Africa and into east Asia approximately 300,000 years ago. There, they came in contact with the ancestors of the Melanesian people.
When scientists reassessed Melanesian DNA in 2016, they found a smaller contribution of Denisovan genetic material than anticipated. With less Denisovan ancestry present, another percentage of Melanesian DNA was up for grabs. Scientists posited that there must be a new and unidentified ancestor adding to the Melanesian mix.
Unfortunately, no remains of this third ancestor exist in the known fossil record. Experts only know of the Denisovan because of a single pinky finger bone discovered in a Siberian cave.
With Denisovan DNA found in Siberia and Melanesia, the migratory activities of these groups may be extrapolated to a certain extent. Given that no archeological evidence exists of this third genetic ancestor either, asserting absolutes about its origins will prove difficult.