Correction on 7): The Batak are Philippine Batak who live in Palawan Island, and not Sumatran Batak. They are about 20% Aeta (brown component). This would suggest that the Aeta likely arrived in the Philippines via Palawan from Borneo.
Elaborating on point 5): The Polynesian green component emerges early in the admixture analysis at K=5, even prior to the Aeta (North Philippine Negrito) brown component emerging at K=6, and the Native American dark yellow component emerging at K=7. The authors of the study explain that it is likely due to genetic drift.
From K = 5, Polynesians take their own ancestry (green), which, like their deflection on the PCA plot, is most likely due to genetic drift or, alternatively, cryptic relatedness or extreme inbreeding in studied populations. However, the latter is unlikely due to the lack of close relatives (up to third-degree, inclusive) in four Polynesian groups, and normal range of inbreeding coefficients when comparing to other human populations (FIS, Supplementary Table S6).
More on 9): The South Asian (STU) as mentioned earlier are about 60% European (CEU), 12-15% East Asian (light yellow component), and about 15-17% Pre-Austronesian Southeast Asian (cyan component). Their Australoid component (Aeta, New Guinea, and New Britain) combined is less than 10%. I find this interesting. The Ancient South Indian (ASI) component from my understanding is supposed to be largely an Australoid component, but this admixture analysis seems to show that South Asian's Australoid component is very small (less than 10%). In my opinion, the Pre-Austronesian Southeast Asian cyan component is what is likely absorbing a lot of the Australoid since Southeast Asians are part Australoid. Although there have been Southeast Asians migrating to South Asia for several thousands of years, and a part of that 15-17% Pre-Austronesian Southeast Asian cyan component may actually be from those Southeast Asian migrations, but a large portion of it could actually be something else (an indigenous South Asian Australoid component) that happens to have a strong affinity to the Australoid component of Southeast Asians. The indigenous South Asian Australoid component is not the same as that of the Southeast Asian Australoid component, but they have an affinity to one another, hence why in this study the South Asians have a lot of the cyan component (Pre-Austronesian Southeast Asian).
Again more on 9): So the indigenous South Asian Australoid component has an affinity to the Pre-Austronesian Southeast Asian component (cyan component) rather than the brown component of the Aeta, or the light purple component of the New Guinea Papuan, or the dark purple component of the New Britain Oceanian, or the green component of the Polynesian. I find this very interesting. As mentioned earlier, the Pre-Austronesian Southeast Asian component (cyan component) is partly Australoid in nature and partly Mongoloid also, and this cyan component is found in all Mongoloids (sampled in this study) at varying degrees and also among many Polynesians, which suggest that the indigenous South Asian Australoid component may be closely related to the Australoid component that virtually all Mongoloids carry since it is closer related to any other Australoid component in this study!!!
As mentioned in my previous post, part of that could be from the Southeast Asian and East Asian migrations into India in the past 10,000 or so years, but it's likely that the indigenous Australoid component of South Asia (at least prior to the arrival of Southeast Asians or East Asians in the past 10,000 years)could actually already have been closely related to the Australoid component that resided in the Far East (north of Southeast Asia)!!!
A lot of scenarios can be played out here as to how or why this happened. There could have been an even earlier large migration or migrations (prior to 10,000 years ago) of Far East Asians (coming from north of Southeast Asia, and most possibly from China) migrating into India, or it could be the other way around. But what's interesting is that these two regions may have interacted more with each other than with Southeast Asia and Oceania, at least in the far past (before 10,000 years ago). If we look at historical times (in the last 2,000 years), we know that many Far East Asian groups migrated into India especially Northeast India, and we also have the Mongol and Turkic invasions and migrations into India coming through Northwest India, and then you have the Tibeto-Burman speakers at the Himalayan borders of Northern India, and those that reside in Bhutan and Nepal.
More on 3): Anyone find it interesting that at K=9 that the Kankanaey are all cyan (pre-Austronesian Southeast Asian), and have no other colors not even the light yellow (East Asian) component. Not only are the Kankanaey the best population for the original Austronesians (blue component at K=10), they may actually be the best pre-Austronesian Southeast Asian population sample!!!
What this also suggest to me is that the Kankanaey (and the original Austronesians) were originally a Pre-Austronesian Southeast Asian population that diverged from the other Pre-Austronesian Southeast Asian populations, hence the all blue color at K=10 for Kankanaey. I'm not a population geneticist, but my guess is that the Kankanaey genetically diverged from other Pre-Austronesian Southeast Asian populations before any other Pre-Austronesian Southeast Asian population were able to genetically diverge??? Hence at K=10, the blue component emerges (before any other color emerges among the Southeast Asian groups) with the Kankanaey being the best example for it, but also being wholly blue with no other admixture. Is my guess correct that the Kankanaey are the first Pre-Austronesian Southeast Asians to genetically diverge from other Pre-Austronesian Southeast Asian populations?
The fact that the Kankanaey (and the original Austronesians) have no light yellow at either K=9 or K=10 suggest that the Austronesian expansion began before the East Asian (light yellow component) arrived in China, in particular, Southern China and Coastal China. I've been using the term East Asian for the light yellow component, but perhaps a more accurate term would be Northern East Asian. Therefore the Austronesian expansion began on its own volition which is what most great or large scale migrations are caused by. It was Austronesians themselves that were motivated to go beyond their original homelands and into the islands of East and Southeast Asia, Mainland Southeast Asia, and beyond into Oceania, the Pacific, Australia, Sri Lanka and South and East India, Madagascar and East Africa, and elsewhere.
After collectingDNAfrom the study participants — a huge endeavor that included radio advertisements and in-person meetings in Polynesia — the scientists teased apart which snippets of DNA came from Indigenous Polynesian ancestry and which snippets came from outside sources, such as from European or African descent. (The graphic below is a helpful illustration of this.) In other words, after establishing a background "reference," the scientists knew which DNA sequences came from which populations.
Each group of colored dots shows where DNA was sampled for this project. For instance, the yellow dots signify Southern Native Americans. The below bar shows what percentages of DNA from different populations were found in each individual. For example, the light blue represents Polynesian DNA while the hot pink represents European DNA sequences. The team also charted the wind and ocean currents to see how ancient people may have traveled across the Pacific. (Image credit: Ioannidis et al., Nature)
In particular, the team zeroed in on Native American sequences found in Polynesian genomes. A previous 2014 study in the journalCurrent Biologyhad shown that Native American DNA became part of some Polynesians genomes from about 1300 to 1500, but that research didn't pinpoint which region of South America those Indigneous people came from. In the current study, the researchers identified that the Indigenous signal was similar to that of the Zenu, a Native American group that lives in Colombia.
The team then used several statistical methods to figure out when in history the Polynesians had coupled with the Native Americans. "All of those dating methods gave the same date, which is the Middle Ages, around 1200," Ioannidis said. "That was long before Europeans came onto the scene."
This is an important detail, the researchers said, as thousands of Pacific Islanders, including 1,407 Rapa Nui individuals, were kidnapped during the Peruvian slave raids of 1862-1863. Of those captured, about 20 returned to Rapa Nui. In addition, Rapa Nui became a Chilean territory in 1888. It's possible that these events prompted Polynesian-Native American coupling, which would have introduced Native American DNA into the following generations' genomes. Some people have argued that such couplings would explain why some Polynesians have Native American DNA, Ioannidis said.
In contrast to those recent dates, the new results indicate that the Polynesian-Native American coupling was a single event in the deep past that involved multiple couples. After that event, the Polyesians' descendants, who carried Native American DNA in them, went on to explore distant Polynesian islands, including Rapa Nui. As a result, their descendants still carry some Native American DNA.
However, not all modern Polynesians carry Native American ancestry; the researchers found the signal predominantly on several eastern Polynesian islands, which were likely settled after the coupling event happened, the researchers said.
480w, 
