I posted recently about the types of descent that can be found in human societies. Descent is often very important in societies without states, as it forms one of several ways in which humans can group together, achieve shared aims, respond to threats, acquire land and possessions, fight battles, organize agriculture, engage in ritual, and much else. It's a really important principle. Alliance, usually based on marriage (but sometimes based on other things, like blood brotherhood) is also important. This is how non-state societies work, or can work: through kin bonds, through so-called 'fictive' kinship, through marriage, blood brotherhood, and so on. All of these things have formal properties that can and should be studied, and which are different enough from state, industrial, and post-industrial social structure to require a separate discipline that specialises in them.
And let's be super clear: most people throughout history have lived in societies without states, or in societies with very weak states such that non-state principles (like kin bonds) are still vital. If you want to say that you study the diversity of humankind then you simply cannot neglect these people, whose actions were guided by principles different to those of people who live in states. Moreover, studying descent and alliance is quite hard, or at least it requires some nous and knowledge. So it's important to have some group of people studying these things. We've got political scientists, sociologists, and economists, among many others, studying aspects of industrial and post-industrial life. We need someone to study non-state, non-industrial life, I think.
So what is that (sub-?)discipline? It used to be social anthropology, which taught students how to understand non-state societies through such ideas as descent and alliance. Students were taught about the different forms of descent, the different kinds of alliance (bilateral cross-cousin marriage, for instance), and how different societies work. When these students went on fieldwork, in the early days, they still encountered people who lived in more-or-less non-state situations - people for whom the state that nominally governed them was distant and impotent. They could then see these effectively non-state societies working as they do. These anthropologists actually saw descent and alliance in action.
As the twentieth century wore on, more and more people came under the sway of states, reasonably powerful ones, and so they found themselves relying less and less on clans and kindreds. States tend to break the power of clans. It's not that descent disappears (it doesn't), but it becomes something else entirely, and a political dynasty in a democracy isn't the same as a clan.
On top of that, anthropology became conflated with a particular method - the so-called ethnographic method, a form of qualitative research in which the researcher directly observes life and events and writes about them. This led to calls to apply 'anthropology' - viz, the ethnographic method, originally devised as a last resort to study societies that produced no statistics or literature of their own - to post-industrial societies. As a result of these two trends, many, if not now most, anthropologists never see descent and alliance in action. They never see the negotiations for bridewealth payments, or the avoidance of using the left hand near a mother's brother.
These things began to seem quaint, colonial, and, more to the point, difficult to understand. As anthropologists proliferated, their original subject matter dwindled. Now anthropology is primarily associated with a method, rather than a subject matter; its method attracts artistic people rather than those who find value in formal understanding; its students never see the phenomena its earlier students used to study. That's where we're at.
There are some societies in the world where descent and alliance are still key - you won't be able to understand many areas of eastern Indonesia without understanding descent and alliance, for instance - but most commuities are not based around such things anymore. Given that the ethnographic method is almost entirely about the present, anthropologists now study people who live in states. They study how states impact people's lives, which is important stuff, and they study how industrialisation causes changes in how people think about time and family and so forth, which is also important. But the study of descent groups and marriage alliances is a minority pursuit, so much so that it is rarely found on anthropology courses as a core aspect. Questions about alliance and descent no longer appear on exam papers, which they used to.
Which would be fine if it were useless to study descent and alliance, and if non-state social structure had turned out to be a figment of the colonial imagination. But that simply isn't the case. There's now a hole in the academy where anthropology used to be. You can no longer take up a subject at university and study non-state social structure and social dynamics, unless you're willing to put in a lot of time studying something hard that won't even end up on your exams. Which students aren't.
I think there's plenty to be said for anthropology as you find it in universities today, although the science-phobia, bullshit theoretical background (seriously - Gilles Deleuze?), appalling writing, and prescriptive focus do not endear it to me. The idea of studying human life by witnessing it up close is just an extension of something people have been doing for thousands of years, and it is worthwhile to find out what people do and why they do it in the modern age.
But states are new, non-state societies are fascinating, and there is plenty of documentation of them that still exists from before anthropologists changed tack. There's a vast and detailed literature on all aspects. And the way we think about stateless people informs to a large extent the way we think of humans and 'human nature' in general. You can't say that it is now impossible to study such things, or that they are not important, or that they aren't part of the academy. It's just that studying them requires different skills to the ethnographic method (which really should change its name).
I find it all a little disappointing. I'm disappointed that there's a whole area of study that is the purview of a tiny minority of people. And, being a minority interest, there is always the danger that it will succumb to poor interpretation and bad argument. The neglect of non-state social structure isn't the result of some shift for the better in anthropology. It's just a kind of laziness combined with a kind of myopia, and it's not a good thing.