I've come up with certain possibilities:
1) Austronesians arriving from the West (about 3500 years ago, with 'proto-Austronesian numbers', already invented) married into, and converted some local tribes to speak their language, but the locals retained much of their original language, and the numbering systems that they'd always used before, merely adopting new Austronesian pidgin names for them.
The Austronesian speakers' systems regressed.
2) Austronesian speakers were already resident some time before that, and were (and still are) in the process of forming their own numbering systems, from scratch.
The systems progressed, (and are still doing so).
I see indications of this in the strange numbering systems used by the Manus islanders, the Motu aound Port Moresby, the 4-base system of the Schouten islands, further West in Irian Jaya, and so on.
In addition, the Papuan languages in the interior of Cape Finistere (the bump above the tail) are much more sophisticated (ie tending towards decimalisation) than other non-Austronesian languages. I'll discuss each of these in later posts.
I have found three such groups; the Sissano, the Dawawa, and the Kuni, widely separated.
Neither the Sissano nor the Kuni have any more number names than 1, 2, and a few, and perhaps many. The Dawawa and some of their neighbours have names for only 1 and 2, and make up all bigger number combo-names from these two alone.
Sissano: 1 = pontanen, 2 = entin, and many = tartar.
Kuni has only kaona, lua, and koi.
Dawawa has only 1 = tegana, and 2 = rabui. 5 is rabui rabui be tenagu.
The number names in Sissano resemble nothing else at all, in either the local Papuan languages or the Austronesian. The
Kuni names are recognisably 'Austronesian', and the Dawawa names are used by a number of other An groups in their area.
The Rev Dr Strong wrote this of the Kuni a century ago:
"There is one quite exceptional Melanesian-speaking people who are strangely deficient as regards counting. In 1905 I was in their country. They live on the south coast in the Kuni district, inland from Hall Sound. These people have, or at least in 1905 had, no trace of any numeral beyond three. For "two" they used lua, and for " three" koi. These words are both obviously of Melanesian origin.
In 1905 I was using a Motu-speaking Kuni native as guide. On asking him how many times we would have to sleep on the road in going from Mafulu to Kabadi, he replied in Motuan, " three times, toi. Like many of the people around Hall Sound he was unable to say a "t" and pronounced all his "t's" as "k's." So his pronunciation of the Motuan word toi was really koi.
On my asking the names of the places we had to sleep at, he correctly mentioned five names, and these names I afterwards verified. On asking him to explain why he said we had to sleep koi times and yet gave five names, he seemed quite unaware that the fact required explanation.
At the time, I discussed this with some of the missionaries who could talk the Kuni language, and they confirmed the fact that in practice the Kuni people used the word koi to mean a few.
The Kuni people, in fact, really only counted one, two, a few, many.
The Kuni are the only Melanesian-speaking people in British New Guinea who have gone far inland. Their language is obviously a regular Melanesian one, very closely allied indeed to the Motu of Port Moresby, which has a well-defined system of numeration, going at least up to a thousand.
It is very difficult to see how the Kuni people can have lost numerals like " five," if they ever had them.
I feel rather driven to the conclusion that the Melanesian numerals above toi are a comparatively recent introduction, subsequent to the arrival of the Melanesians in New Guinea.
The Kuni natives are by no means deficient in intelligence. The Kuni guide I had was quite intelligent and particularly energetic". [He needed to be, if he was going to stop for 5 nights, but only sleep 3].
Some Personal Experiences in British New Guinea. W. M. Strong
The Journal of the Royal Anthropological Institute of Great Britain and Ireland, Vol. 49. (Jul. -Dec., 1919), pp. 292-308. Available at JSTOR
Note: At that time, Austronesian speakers in New Guinea and around about, were called 'Melanesians'.
In fact, the Motu have a very strange numbering system, where 5 = ima (An), but 6 = 'a bit more' 7 = 6 +1, 8 = other 4, and 9 = 8+1, but they were active traders along the coast, and needed sophisticated numbers for just that.
But how could Austronesian immigrants, with inherited, and very simple, proto-Austronesian numbers, possibly have regressed?
I don't think that Austronesian immigrants came with ready-made numbers at all. The numbers developed around New Guinea, and were taken back to the West, and on to the East, together with a host of cultural characters we like to think of as 'pure' Austronesian.
There simply wasn't a simple 'Express Train' migration from Taiwan to Polynesia.
There is, confusingly, a third possibility.
New Guineans, during the last two centuries, have been overwhelmed by a 'superior' culture, that has introduced new languages, customs, mores, and a monetary economy. The hundreds of small groups, each speaking their own language, have travelled away from their own areas to work, stopped headhunting, and, however painfully, are being absorbed into a larger entity.
Most of all, though, they had to become more number conscious now that they were trading more widely, and , for the first time in some 40,000 years of human presence in New Guinea, were being gainfully employed, for money.
The New Guineans first invented a pidgin, that has now developed into a fully-formed creole language of its own: Tok Pisin, with elements of 'Papuan', English, some German, and even some of a world-wide lingua franca, Nautical Pidgin.
Almost all New Guineans have adopted the new numbers: wan, tu, tri, foa, faiv, sikis, seven, et, nain, ten, with 11 = wanpela ten wan
But most still employ their own native numbers, from 1 to 5, in everyday use, just as my neighbours here in Siargao do: qesa, duhá, tuyú, qepát, lima, but then the 'Spanish' sais, siete, otso, nueve, jeis.
In Siargao, all the native numbers above nine have been completely forgotten, except for isa ka gatus (100), which is used by fishermen for depth-sounding, and by the locals for 100 pesos ($2), which is a lot of money around here.
It is therefore possible that the Sissano, Dawawa and Kuni have just completely forgotten their old number systems. But if that's happened, why have all the others not done the same?
I prefer to think that they are just the outlying remnants of the area where number systems first developed, and that, somewhere in the area in between them, simple number systems evolved.
But then, in some mysterious area, the 'proto-Austronesian higher numerals' were invented, and were brought back, though not to the whole area, or indeed, to very much at all of Melanesia.
PS The Sissano have had a very raw deal, and it is surprising that their language survives at all - see coming post.