The non-Austronesian-speaking headhunters of New Guinea were those whose languages possess the greatest number of Austronesian loanwords, indicating that the practice was introduced to the island by the prehistoric migrations of Austronesian speakers. Speaking an Austronesian language, therefore, once correlated strongly with decapitating other human beings. And we know that it's an Austronesian tradition, rather than one that spread in other ways, because Austronesian-speaking headhunters were once found in New Guinea and island Melanesia, areas cut off from later developments in island southeast Asia and connected only through shared origin.
Informants in different societies, however, gave surprisingly varied answers as to why they engaged in the practice. They did roughly the same thing, and their practices were clearly historically related, but appeared to do it for different reasons. Some said they did it because the ancestors told them to; others because heads ensured a bountiful harvest; still others because of grief caused by inter-communal violence and the rage accompanying it; because heads are like fruit, and a rich harvest of heads indicates the health of the community; because various supernatural entities demand heads to fill their barns just as humans fill their barns with rice; and so on. Some gave no explicit reason at all, and when pressed said that it was tradition. As it happens, I believe this is the most honest response and the closest to the truth.
Ethnographers were ready with their own interpretations, too. Some saw heads as manifesting 'soul substance' - something like Polynesian mana or Malay semangat - and others espoused an origin in ecology: Andrew Vayda, for instance, believed that Bornean headhunters took heads because this made them frightening to enemies, which gave them an edge in competing with other groups for fertile land. (As he didn't examine the issue in light of Austronesian ethnology, he was unaware that other Indo-Malaysian societies also practiced headhunting and that it had not recently evolved on Borneo; lack of awareness of the ethnological angle is actually quite common among investigators of headhunting.)
Rodney Needham claimed that skulls were believed to be causal agents of fertility in themselves, even without 'soul substances' and the like, and so their acquisition wasn't based on anything other than a belief in their intrinsic worth. This latter view may also be fairly close to the truth. It might be better to say that heads were valued because everyone believed that everyone else believed that heads were valuable due to their upbringing and the constant references to and images of skulls throughout life.
The tradition correlated strongly with speaking an Austronesian language, and therefore seems to be an authentically Austronesian tradition. But the headhunters themselves all gave different generic reasons for the practice, indicating that it was a mindless tradition instead of something done on the basis of reasons. But how could something persist for so long without any reason for it?
|An Atayal headhunting blade. Like many indigenous Taiwanese blades, it is single-edged and consists of a single piece of metal in a simple wooden sheath. h/t Swords and Antique Weapons. For some grisly images of Atayal headhunters and their booty, see here.|
This is less of a paradox than it seems, as long as we bear in mind that headhunting consisted of a series of individual acts instead of a single collective action inspired by an explicit, overarching motive. In order to explain it, we need a self-sustaining motive, not necessarily one bolstered by explicit religious or socio-political beliefs. We may find one in the combination of male ambition and the life-long perception of the importance of the head in the community.
It seems clear that despite the diversity of explicitly recognised motivations, the 'real' reason for Austronesian speakers taking heads is that they were heirs to a tradition of taking heads, and that taking heads was something men simply had to do. Each generation of children would see the men of the village receive plaudits for taking heads. They would see heads being used in ceremonies, hanging from poles or trees, being arranged neatly on wooden platforms, or being placed inside sacred houses. They would perceive the community's belief in the value of the human head before being able to articulate the reasons for it.
As they grew up, they might be given an explicit reason for taking heads, justified in terms of other practices and beliefs with which they were familiar, but by that point belief in the importance of taking heads may not have required much justification. Whatever the ultimate reason for taking heads (the reason proto-Austronesian speakers or their ancestors began taking heads), the principal reason for men in descendant Austronesian-speaking communities doing it was because men in Austronesian-speaking communities had always done it.
The ethnographies of almost all Austronesian headhunting societies from Taiwan to Timor and Sumatera to Malaita make it clear that if a man didn't take a head, he wouldn't get married or be tattooed. He wouldn't rise to chiefly office. He wouldn't acquire prestige or expensive trade products. He would forever be considered weak, shameful, and unmanly. A man had an interest in cutting off the heads of strangers in the belief that other people would consider him strong, manly, and worthy of marriage. Women would be told not to marry men until they had taken a head, just as some people in other societies would consider it unacceptable to marry before the man has a stable job and a home to live in. The belief in the power of human heads was self-sustaining because it had an impact on male ambition. Under such conditions, the only thing that could stop headhunting from taking place was an explicit, enforceable ban that had even greater consequences on ambition and success in headhunting communities.
|A Paiwan house in the Taidong Cultural Park, Taiwan. The Paiwan language is the closest Formosan language to the Malayo-Polynesian languages (i.e., the Austronesian languages found off Taiwan). Paiwan people were, until relatively recently, headhunters. Me, 2009.|
Incidentally, headhunters really would be wealthy and taking heads really was a good sign of the health of a village. This is because a headhunting raid was also a time for theft and slave-raiding. Animals, grain, slaves, and jewellery were all up for grabs, and these could be sold to other groups or used in one's own community. A raid was a time to enrich oneself. Headhunters would therefore be visibly wealth and worth emulating, and their home-coming would be accompanied by a surfeit of food for the community. In an early-twentieth century war between the two Ngadha clans Wogo and Wéré, for instance, the victorious Wogo clan stole twenty-three kerbau, several chickens, pigs, and dogs, in addition to rice, millet, and maize.
That's not the end of the story, by any means. People do, after all, like to justify what they do according to grander schemes. Moreover, if a tradition is followed for thousands of years, it is likely that it is carried alongside other traditions of similar antiquity. Language is one, but certain religious beliefs can also be among them.
In the case of Austronesian, belief in ancestors or ancestral spirits is common, and this influenced headhunting in several ways. Belief in powerful supernatural ancestors is an inherently conservative force that reinforces the idea that doing what has always been done is good. If you believe that the ancestors need to be placated because they can cause you to die a bad death, and you believe as well that the ancestors demand a harvest of heads, then that provides a pretty good reason for beheading a stranger and taking their head home.
Religious justifications are important, especially in determining how things actually played out in the constellation of practices we call 'headhunting'. In Solor, for instance, the war known as tikar bantal in Malay and ohã belone in Lamaholot (both meaning 'mat and pillow'), fought between representatives of two nominal alliances called Demon and Paji, was really a series of headhunting raids intended to placate two complementary deities (Lera Wulan and Tana Ekan) as well as the ancestors, and was enacted whenever there was a bad harvest, an epidemic, or something similar. This precise idea was not found elsewhere, and may reflect local religious ideas not present elsewhere.
|A map of the East Flores regency, Nusa Tenggara Timur, Indonesia. The colourful island in the top right is Adonara, still known as 'Murder Island', as headhunting is still practiced (to some extent). It is one of the most fertile islands in the province, and therefore provides an interesting counterpoint to theories of the ecological motivation for headhunting. h/t OrangFlores.|
Social structure also played an important role in how headhunting worked. In many areas, it was a way for men outside of direct succession to chiefly positions to achieve high status, and as such it could only really occur in that way in non-state societies, where attempts to acquire prestige through uncontrolled or clan-based violence wouldn't threaten the functioning of the state. The non-state nature of such societies also encouraged tit-for-tat violence, and headhunting is a perfect way of realising tit-for-tat violence - it even provides a convenient, durable means of keeping score. (You might note that Renato Rosaldo's theory of grief as causative of headhunting raids makes some sense of this, as does the view expressed by the Dutch anthropologist J. P. B. de Josselin de Jong that headhunting was partly to do with point-scoring and establishing parity between communities.)
We should expect headhunting to be absent from state societies, as it usually was. Headhunting was not found in the so-called 'Indianized' states of western Indonesia, for instance, and we can't attribute this entirely to religious change: the Toba Batak of Sumatera, who were inveterate headhunters, had experienced plenty of Indian religious influence but did not live in states as the Javanese and Malays did. Moreover, other aspects of traditional religious belief were synthesised with Indian religion, so it can't be assumed that religion alone is behind it. States are important here. In many areas, headhunting was used to legitimise and reinforce the state (or aspiring state), exapting the existing tradition for another end entirely (while still relying chiefly on male ambition, of course). This was certainly true of headhunting raids in late pre-colonial Timor, where warriors (meo, meaning 'cat') underwent rituals designed to tie their success to the ritual centre of the state, and it was true of island Melanesian chiefdoms, as well. It is notable that Dutch, Portuguese, and British colonial powers all used headhunters for imperial ends in their respective territories.
I suppose motivation for headhunting should be thought of in a similar way to motivation for crusading or . As Peter Frankopan noted in a recent blogpost, crusaders were motivated by the desire for prestige and wealth, by the desire to please, by the desire for fame and all the good things. They wanted wealth and the good life, just as headhunters did. They were also inspired by religion: by the genuine belief that the Muslim conquests in the Holy Land were bad and ought to be reversed, by the conviction that the Pope was right to call men to arms, and by the belief that going on crusade could enable them to spend less time in Purgatory atoning for their sins. Without these religious beliefs, it is hard to imagine crusades happening at all, but without the prospect of winning prestige and wealth, it is hard to imagine men volunteering to do it either. Headhunting is similar, in that the religious justification is not usually enough, on its own, to override basic practicality or ambition.
It should always be borne in mind that the beliefs and desires of individual human beings, even in cases of collective action, can be at variance to one another, and that searching for an ultimate reason behind amorphous, prestige-winning practices like headhunting is usually fruitless. It's not that headhunting is mindless, irrational activity. It's just that the vague, generic reasons mentioned by informants can sometimes be little more than post-hoc justification for a pre-existing practice, one justified primarily by the desire for advancement and the self-sustaining recursive set of beliefs, held by each individual in the community, that the community endorses it.
Headhunting was not exclusive to Austronesian speakers, and it was once found almost everywhere we care to look. Even in ancient China, we find that one of the ways of measuring the success of military units in the state of Qin was by the number of enemy heads it took in battle. So perhaps there is a deeper reason for the proliferation and spread of headhunting throughout the world based on the inherent features of the human head (for instance, heads are individual and recognisable; decapitation is invariably fatal; heads are portable; heads are therefore a good way to prove that you've killed an enemy and work perfectly as props in violence-based rites of passage; etc). You'll notice that I haven't concerned myself with the origin of headhunting, only with its transmission as a tradition in Austronesian-speaking communities. The former question is inherently more speculative, and I find it much less important to resolve the ultimate origin - which must have had something to do with conditions in Neolithic southern China - than the distribution of headhunting in the Indo-Pacific.