Just as we are beginning to appreciate the importance of our prehistoric and evolutionary roots to understanding the human condition, precious and irreplaceable information about them is in danger of being lost forever:
1. Languages. The 6,000 languages spoken on the planet hold information about prehistoric expansions and migrations, about universal constraints and learnable variation in the human language faculty, and about the art, social system, and knowledge of the people who speak it. Between 50% and 90% of those languages are expected to vanish in this century (because of cultural assimilation), most before they have been systematically studied.
2. Hunter-gatherers. Large-scale agriculture, cities, and other aspects of what we call "civilization" are recent inventions (< 10,000 years old), too young to have exerted significant evolutionary change on the human genome, and have led to cataclysmic changes in the human lifestyle. The best information about the ecological and social lifestyle to which our minds and bodies are biologically adapted lies in the few remaining foraging or hunting and gathering peoples. These peoples are now assimilating, being absorbed, being pushed off their lands, or dying of disease.
3. Genome diversity. The past decade has provided an unprecedented glimpse of recent human evolutionary history from analyses of diversity in mitochondrial and genomic DNA across aboriginal peoples. As aboriginal people increasingly intermarry with larger groups, this information is being lost (especially with the recent discovery that mitochondrial DNA, long thought to be inherited only along the female line, in fact shows signs of recombination).
4. Fossils. Vast stretches of human prehistory must be inferred from a small number of precious hominid fossils. The fossils aren't going anywhere, but political instability in east Africa closes down crucial areas of exploration, and because of a lack of resources existing sites are sometimes inadequately protected from erosion and vandalism.
5. Great apes in the wild. Information about the behavior of our closest living relatives, the bonobos, chimpanzees, gorillas, and orangutans, requires many years of intensive observation in inaccessible locations, but these animals and their habitats are rapidly being destroyed.
What these five areas of research have in common, aside from being precious and endangered, is that they require enormous dedication from individual researchers, they are underfunded (often running on a shoestring from private foundations), and have low prestige within their respective fields. A relatively small reallocation of priorities (either by expanding the pie or by diverting resources from juggernauts such as neuroscience and molecular biology, whose subject matter will still be around in ten years) could have an immeasurable payoff in our understanding of ourselves. How will we explain to students in 2020 that we permanently frittered away the opportunity to write our species' biography?