I have visited a couple of 'lost tribes' who's first contact with Western civilization has been during my lifetime, i.e. since 1960. I wish I could say it is an uplifting experience, but it was quite the opposite.
THE MANGYAN, Mindoro, Phillipines
I've visited Mangyan villages a few times, since 1985. The Filipinos- fisherfolk, weavers and small scale farmers- basically live around the coast in Mindoro- the Interior is dense jungle, and Mangyan country. It was basically assumed back then that there were several Mangyan tribes that would have had absolutely no contact with the West, or even the Filipino's. Those that lived close to the Filipino's had obviously had contact though, and there were and are several Mangyan villages scattered in the hinterland, behind where the Filipino's inhabited. They were considered sub human by the townspeople, prolly still are, and were the butt of much humour.
I was curious to see them, and theres a couple of villages within an hour of Puerto Galera- a tourist destination. Not much nice to report. They lived in absolute filth and squalor. The kids were filthy, barefoot, naked from the waist down. So were many of the women, although the blokes thankfully kept their knobs covered. Such things as a spoon, a lighter or a metal blade were luxuries to these people- oh, and they loved cigarettes. Local townfolk, being aware of this fact, would head up to a Mangyan village, usually pissed with a few mates, and bring a couple of lighters, cigs or grubby old spoons which they would give out. In return for Blow Jobs. Yes, I was offered one.
The only reason I came back was to bring them a few things like old T shirts, Spoons, lighters- that sort of thing. This was both uplifting, and pathetic. The gratitude on their faces was indeed uplifting- the rather obvious gestures offering oral sex & whatever else in return, saddening. My Filipina business partner, who accompanied me, found it all quite bemusing- in fact she got them to bring out some of their younger, prettier ones, to see if I could be tempted into a BJ. My then girlfriend (a Beauty) refused to come- associating with Mangyans was looked down upon.
They basically existed outside the system. I could be wrong, but I don't think you ever saw Mangyans outside of their villages and the jungle. They didn't go to the town markets to sell produce, or anything like that. For a Mangyan woman to be seen in a town, or on a road, was an open invitation to rape or worse anyway- the law didn't apply to them, no more than it applies to a monkey.
I hope their lot has improved.
In short, I do not think that contact with modern civilisation has been anything but bad for these people. They were better off as they were, and the ones that live in the remote jungles are better off than the ones that inhabit the squalid hinterland villages. The same applies to the Bushmen, Hottentots, many New Guinea and Amazonian tribes, even the Australian Aborigines.
I like the sound of this Funai Foundation, although their's is probably a hopeless cause in the long run. I'll try to find out more about them.