Luson, Bisaya & Mindanao

For this blog, I’m basically looking at the peopling of the Philippines; where did the Filipinos come from and who are the modern day Filipinos? Additionally, in order to explore the topic, we need to look at Southeast Asia as a whole.

The Ice Age

Before we embark on our journey, the basic understanding of a great event that peaked at least twice during the migration of our ancestors should first be understood. Theories surrounding the causes of ice ages are still up for debate. The Earth’s wobble and the amount of greenhouse gases are the main theories linked with the occurrence of the ice ages. Ice ages are marked by two periods, the glacial and interglacial. Glacial periods are the period of colder temperatures while Interglacial are the relatively warmer periods.

A glacial maxima happens during a glacial period when the temperatures are at its lowest point; in essence it is the peak of an ice age. Interglacial is basically the period between glacial maximas. As the temperatures decrease, the Earth’s water accumulates as glaciers in the northern and southern hemispheres; it is at these times when the polar ice caps get closest to the equator. The source of water that form these glaciers are mainly from the ocean, hence at a glacial maxima, the sea level is at its lowest point which gives rise to shallow seabed and becomes what scientists calls “land bridges”. The increase in ice in the European and Asian continents and the emergence of land bridges especially in between continents, as scientists know today, played a major role in the peopling of the world.

The last two glacial maxima had been estimated to be between 25,000 to 15,000 BP and 175,000 to 125,000 BP (Kaplan et al. 2005).

Timeframe

Another important vocabulary we need to have a basic understanding of is about the two epochs. Geological epochs are geologic stratifications/timescales involving different rock layers that form the Earth’s crust; the significance of which is the present and last epochs provided many fossil finds that helps in the understanding of the peopling of the world. The Pleistocene epoch spans approximately 1.6 million BP to 10,000 BP. The next epoch is the Holocene and spans up to the present time. The last two glacial maxima that happened in the late Pleistocene and early Holocene may have played a significant role in the peopling of the world.

Models of Migration in Southeast Asia

As scientists have explained, there are at least two great migrations to the Philippines; the Itas and the Malay speakers. Gaillard and Mallari compiled the various theories behind the peopling of the Philippines and of course it touched on the surrounding areas within Southeast Asia. From what I observed, the PASNP may support Manuel’s and Bellwood’s theories where the origins of the Malay speakers may have been from mainland South China; more specifically, I believe we are from Southwest China.

Ita ang Unang Tao sa Luson, Bisaya, at Mindanao

Itas are the first people to settle Luson, Bisaya, & Mindanao

The Itas (Negritos) were the first to settle Island Southeast Asia (ISEA). The famous Tabon Man was discovered by Dr. Robert B. Fox in 1962 in the Tabon Caves of Palawan island is one proof; it was dated at 22.5K BP. Although Scott states in his book that the Tabon Man is not Ita I believe the opposite is true. My reasoning is simply by process of elimination; all of the archeological findings that links to the Austronesian speaking people (Nusantao) in ISEA have never been more than 5.5K years old (Bellwood). If not the Itas nor the Nusantao, who else can the Tabon Man be? Aside from the Tabon Man, a new discovery by Dr. Armand Salvador B. Mijares of what may be the oldest human fossil find in Southeast Asia called the Callao Man; the Callao Man has been dated 67K BP and scientists describes part of the bones found to be similar to modern Itas. There are also other sites from other islands as shown in Table 1; this table shows the various archaeological finds in Southeast Asia linked to the Itas.

BTW: I call the Negritos, Tasmanians, Orang Asli (Negritos), Australoids, Australo-Melanesian, & Melanesoid as Ita including all other group of people with the phenotype pigmented skin, frizzy/curly hair and typically shorter in stature than the average East Asian population. Ita is a term that my parent and my parents parents thought us who these people were/are (at least in the Philippines at the time). This is what what the Northern Itas call themselves also; the spelling may have evolved over time. I have Ita blood myself and Itas are part of the fabric that makes a Malay.

Since there are no known land bridges that can connect Palawan to mainland Luson (see satellite image from Google), we can infer that, at least for the Itas in the Philippines (except Palawan), they have reached the islands by means of a raft or some sort.

Figure 1: Snapshot of Philippines with the visible but submerged land bridges connecting Palawan to the Sunda shelf (from Google maps). The added highlights shows where humans would need a raft of some sort to cross to the next island and reach Luson.

Table 1: List of Archaeological Finds Linked to the Itas

Number	Date (BP in thousand)	Item	Site	Island	Country	Reference	Remarks
1	65.7	human third metatarsal bone	Callao Cave	Luson	Philippines	Mijares et al. 2010	"Negrito"
2	40	deep skull	Niah Cave	Kalamintan	Malaysia	Kennedy 1977	"Tasmanians"
3	37	human tibia	Tabon Cave	Palawan	Philippines	Détroit et al. 2004, Fox 1970	"Melanesoid"
4	25.5	flaked artefacts and charcoal	Callao Cave	Luson	Philippines	Mijares 2007, 2008
5	22	charcoal	Tabon Cave	Palawan	Philippines	Fox 1970
6	14.5	frontal bone	Tabon Cave	Palawan	Philippines	Dizon et al. 2002, Fox 1970
7	13.9	small flake assemblage	Ille Cave	Palawan	Philippines	Lewis et al. 2008
8	10.7	projectile points made of bone and stingray spine	Niah Cave	Kalamintan	Malaysia	Barton et al. 2009
9	10	twenty-seven burial remains	Gua Cha	Peninsular	Malaysia	Sieveking 1954, Adi 1985	"Melanesian"
10	10	male skeleton	Gua Gunung Runtuh	Peninsular	Malaysia	Zuraina 1994	"Australo-Melanesian"
11	7.5	twelve disturbed skeletons	Sukajadi Pasar	Sumatra	Indonesia	Budhisampurno 1985	"Australo-Melanesian"
12	6.5	burials	Moh Khiew Cave	Peninsular	Malaysia		"Australo-Melanesian"
13	6.5	red painted bones, two skulls	Wajak	Java	Indonesia	Dubois 1890	"Australo-Melanesian" ?

There are many surprising results regarding the Itas from a previous blog which I will expand here. First, there seems to be at least four unique Ita populations in Southeast Asia.

1.     Orang Asli (Malaysian Itas: Kensui and Jehai)

2.     Ati Ita (Philippine Itas: Ayta, Ati, Agta, & Iraya, North Ita)

3.     Mamanwa Ita (Philippine Ita, South Ita)

4.     Papuan

Table 2: Ita Populations Relative Fst

Figure 2: PC1 vs PC2 Plot (Zoomed)

These separations are demonstrated through the genetic distance produced by Admixture, the correlation analysis, principal component analysis and dendrogram. These large Ita separation is likely a very long period of separation from each other. It is odd though that the obvious phenotypes did not change much (pigmented skin and curly/frizzy hair – another topic for another blog J ). Initially, the Itas populated Southeast Asia including ISEA through land bridges that appeared as an effect of ice ages. These land bridges lasted for a very long time since population movements are not as quick as it is today; we’re talking about thousands of years. Then later, the sea level rose and the land bridges disappeared to where they are today. Since the Itas and most people in the world did not have the technology to travel long distance by sea; the genetic separation began and since the genetic distances are large, it must have been thousands of years (long period).
I have updated the dendrogram from the previous blog using “complete” method. The “ward” method gave results inconsistent with the Fst table. I have also added some cluster box equal to 9, representing the 9 cluster populations.

Figure 3: PASNP Dendrogram (K=19)

The same can be said with the separation for the two groups of Itas in the Philippines, the Mamanwa and North Itas. We can probably deduce from this that the separation of the two Philippine Ita populations was due to at least two major island groups that formed the Philippines during those ice ages. If we look carefully at the Philippine map including the seabed, you can almost make out at least two island groups. The Luzon – North Bisaya island and the South Bisaya - Mindanao island. Again, these long period of physical separation probably also caused the large genetic distance.

It’s interesting that the Papuans and Atis are close to each other; I would have expected the Atis and Mamanwas would be closer due to proximity. Perhaps the Mamanwas had a “bottle neck” founder populations similar to the Mlabri, meaning, the founders of the Mamanwa before the separation came from a small group of the bigger Ita group (bottle neck).

Figure 4: Ita Admixture

The Mamanwa and the Ati Itas have significant admixture with each other (Figure 5). Mamanwa also have admixture with the 2nd group of migrants, the Malay speakers; it shows an admixture range from 1.2% to 1.5% for the Ilokano, Bisaya, & Tagalog samples while the Manobo (Mindanao Nusantao) clearly admixed with Mamanwa at a higher percentage, 6.6%. The Ati Itas & Mamanwa gene is present (albeit small amount) with all the countries in Southeast Asia (Indonesia, Malaysia, Thailand, South China, Indian) in the PASNP data. This gene presence is probably proof that they have once lived among the mainland East Asians – Mon-Khmer, Nusantao, Tai-Kadai, & Sino-Tibetan, at the least and South Asians (Indians). Note that there is a paper out there shows the South Indians (Dravada speakers) to be another Ita group. (Vedoid) but the 4 Ita groups in Southeast Asia are definitely distinct from the ancient Dravada speakers.

Figure 5: Mamanwa Gene Percentage

Figure 6: Mamanwa Gene Prevalence

Figure 7: Ati Gene Percentage

Figure 8: Ati Gene Prevalence

Figure 9 & Figure 10 bring in some inferences. The Ati & Mamanwa groups have only recently admixed with the Malay speakers (Nusantao). This is likely since the archaeological evidence of Malay settlements to ISEA are less than 5.5K BP. The significant Papuan presence in the Ati samples is a surprise. As mentioned, the four Ita groups have large separation. If it is true then the Papuan content is of recent admixture. Were the Papuans and/or Atis able to develop maritime technology (sea worthy ships)? The other possibility is that the Ati’s were the founder source for the Papuans (and perhaps the Mamanwas); given the relatively greater Ati diversity. Note the Mamanwas has 1.1% Papuan content. The Papuans, on the other hand, has 99.2% Papuan, 0.5% Ati, & 0.3% Mamanwa. Whatever the possibilities are, the Papuans, Mamanwas & Atis have significant interactions in Luson, Bisaya, & Mindanao.

Note: Although percentage less than 0.25% maybe be a margin of error in admixture analysis, I would not completely dismiss these results since we are only comparing 55,000 SNPs compared to the millions unidentified. For the moment, I will most likely not explore percentage less than 0.25%.

Figure 9: Mamanwa Admixture

Figure 10: Ati Admixture

Figure 11: Papuan Gene Percentage

Figure 12: Papuan Gene Prevalence

Figure 13: Malaysia Ita Gene Prevalence

Figure 14: Malaysian Ita Admixture

  

References

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