Amazing stuff! The advantages of being an omnivore! 😊
"A new study ... reveals how millennia of human migration across Pacific islands led to the introduction of invasive pig species all over the Asia-Pacific region. ...
One notable exception is pigs. Pig populations occur on both sides of the Wallace Line and extend across Southeast Asia to New Caledonia, Vanuatu and remote Polynesia. Pigs are highly effective ecological invaders, and they are also culturally important across the region, raising a key question: what role did people play in their spread?
The new paper looked at the genome of over 700 pigs, including from living and archaeological specimens. This allowed the reconstruction of their movement across Southeast Asia and identify when they arrived on certain islands and how they might have interbred with various native pig species.
The researchers found that people of different cultures have moved pig species in the region for millennia. The earliest evidence points to people living in Sulawesi perhaps as early as 50,000 years ago, known to be the earliest cave painters, who both depicted and transported warty pig species as far away as Timor, possibly to establish future hunting stock.
The introduction of pigs in Island Southeast Asia dramatically accelerated, around 4,000 years ago, when early agricultural communities transported domestic pigs into the region.
Their journey began from Taiwan, extending across the Philippines, northern Indonesia (Maluku), into Papua New Guinea, and on to the outlying islands as far as Vanuatu, and remote Polynesia. The authors also found evidence for the introduction of pigs from Europe during the colonial period.
Many of these domestic pigs escaped, and became feral, in some cases, like on the Komodo islands, hybridizing with the warty pigs brought by people from Sulawesi thousands of years earlier. These hybrid pigs are now a major source of food for the endangered Komodo dragons.
The findings of this study highlight the dramatic and enduring impact of human activity on local ecosystems in the Pacific, raising conservation conundrums. Pigs in the region today have dramatically different statuses and impacts across islands: some are considered spiritual beings, others pests, while some are now so ingrained in local ecosystems that they could almost be considered native. ..."
From the editor's summary and abstract:
"Editor’s summary
Multiple species of pigs are endemic to Maritime Southeast Asia. Some of them exhibit a distinctive tooth shape and mitochondrial DNA haplogroups, but the history of pigs in this region is not clear. Stanton et al. collected genetic data from 117 modern, historic, and ancient individuals and examined morphometric data from over 700 modern and archeological samples. After comparing with 585 published mitochondrial genomes, the authors found that domestic pigs, which were likely introduced by Austronesian-speaking groups, contributed to most pigs found today from Hawaii to the Philippines. However, early specimens from these groups show no admixture with endemic species, mirroring the lack of mixture between these early human groups with local groups during their initial migrations. ...
Structured Abstract
INTRODUCTION
Humans have long moved animal species beyond their native ranges, drastically altering ecosystems, especially on islands. The translocation of vertebrates eastward across the Wallace Line into Wallacea, a biogeographic region between the Asian and Australasian biotas, has had major environmental impacts. For example, although the natural range of the genus Sus (pigs) is primarily located in Eurasia and Western Indonesia, free-living pigs are now widespread in Wallacea.
RATIONALE
The human-mediated translocation of pigs east of the Wallace Line most likely began with S. celebensis, a species native to Sulawesi, in pre-Neolithic times >4000 years ago.
S. scrofa (the ancestor of modern domestic pigs) populations were also likely introduced east of the Wallace Line between 4000 and 3000 years ago during the expansion of Austronesian speakers from mainland East Asia and Taiwan, through the Philippines and northern Wallacea, into Melanesia and Polynesia. The geographic origin and ancestry of these populations from Wallacea and Oceania, however, remain unknown.
To establish the geographic origins of the pig populations in Wallacea, Melanesia, Micronesia, and Polynesia and the potential dispersal routes along which they traveled alongside people, we sequenced 119 Sus nuclear genomes (including 63 historical and ancient genomes) and generated geometric morphometric data (from the third lower molar) from 401 modern and 307 archaeological individuals.
RESULTS
Ancestry analyses based on ancestry deconvolution, a process by which specific ancestries in admixed individuals can be identified and isolated using local ancestry inference, highlighted multiple pig-dispersal processes in Wallacea.
The initial dispersal was a natural and/or human-mediated translocation of Island Southeast Asian endemic pigs from Java (S. verrucosus) into present-day Bali. The indigenous suid on Sulawesi, S. celebensis, then dispersed over water to the Lesser Sunda Islands, including Flores and Timor, potentially as a result of hunter-gatherer translocations more than 4000 years ago.
More recently, domestic S. scrofa pigs from southern China and the Philippines were introduced across most islands of Wallacea and Oceania sometime after 3500 to 3000 years ago.
Many of these introduced pigs later became feral on islands across the region. Finally, during the colonial period, pigs with European ancestry were introduced broadly across the region, including in the Lesser Sundas and Papua New Guinea.
CONCLUSION
Our results demonstrate that non-native free-living pigs east of the Wallace Line have a complex ancestry that primarily reflects multiple intentional introductions by people. The most important of these events was the migration of Austronesian-speaking groups, ~4000 years ago, who moved from Southeast China and Taiwan via the Philippines and introduced domestic pigs across a vast geographical region from the Philippines to Hawai‘i, many of which became feral."
Genomic study reveals how people moved pigs across the Pacific
Map showing the dispersal of pigs into Wallacea, including deliberate introductions by people in Wallacea and the Pacific.
The numbers (1–4) on the arrows indicate the chronological order of these dispersal events, as per our analysis.
