Afarensis

Awhile back Kambiz wrote a post about a recent paper by Mark Stoneking, during the course of which, Carleton Coon's book got mentioned. When first published The Origin of Races created considerable controversy and Coon was roundly vilified by a number of physical anthropologists.

About 12 years ago, while in college, I happened to buy a used copy of Coon's book, read about 60 pages and got sidetracked by other things. The post by Kambiz (and this one by Dienkes) caused me to pull the book out and read it in its entirety.

I will say at the outset that Carleton Coon was a pretty good writer. It took me a couple of days to get through The Origin of Races, but that is due more to length than style. There are a number of misconceptions about the book that I would like to clear up before going further. First, it has been claimed that Coon was not familiar with the "Modern Synthesis" - the melding of population genetics, biology, paleontology, and systematics (among others) that occurred during the 1930's-1950's (see this, justifiably disputed, Wikipedia article, for example). In reality this is flatly contradicted by actually reading the book - the bibliography reads like a veritable who's who of the modern synthesis. Mayr, Dobzhansky, Simpson, Rensch, Huxley, and Wright, among others put in appearances in the appropriate sections of the book. The second misconception that needs to be addressed is Coon's knowledge of the "New Anthropology." Certainly, Coon's relationships with some of the pioneers of the "New Anthropology", such as Washburn or Montagu were filled with animosity, but for all that he seemed to be quite familiar with where the field was heading. For example, Coon's use of primate behavior studies and hunter/gatherer studies to understand the evolution of early hominin behavior was a taste of things to come in the "New Anthroplogy".

With that in mind, what was the book about? In a nutshell, multiregional evolution - with some added surprises. Coon argued that Homo sapiens evolved in five separate regions of the world (an idea he took from studies of biogeography) from australopithicines (who, according to Coon, may have evolved somewhere in Asia and migrated to Africa - not unreasonable given that some of the Indonesian and Chinese material was originally considered to be australopithicine). Through a combination of migration (conquest and/or out breeding) and gene flow humans evolved through a Homo erectus stage into H. sapiens. In essence, then, this is multiregional continuity, the big difference being that Coon argued that subspecies (i.e. races) evolved before the species (thus explaining the regional features used by proponents of multiregional continuity more honestly) and that different groups reached the H. sapiens stage at different times (something else proponents of multiregional continuity need to be more honest about). So, how did he do that?

In Chapter One we get a your basic overview of the 'Modern Synthesis". Coon discusses taxonomy, the species concept, species and geographical differentiation, clines, polymorphisms, allometry, sexual dimorphism, the lifespans of mammalian species, and genetics.

Chapter Two focuses on geographical and environmental issues. Coon looks at biogeography, adaptations to heat, cold, humidity, etc

Chapter Three looks at social adaptations. Coon discusses the evolution of human behavior based on what was know about primate behavior and hunter/gatherer studies. He also looks at mating systems, island dwarfing, and the effects of social stress (the above linked Wikipedia mangles this somewhat. Coon doesn't say anything that you couldn't find, say, Mary West-Eberhard saying about the affects of hormones on evolution).

Chapter Four is a brief survey of modern primates.

Chapter Five situates humans among the primates. Coon looks at human posture, teeth, whether we were brachiators, embryology, postnatal growth (of apes and humans), biochemistry, and parasites (of apes and humans - kind of prescient.)

Chapter Six ranges from the origin of primates to the Pliocene.

Chapter Seven surveys all the, at that time, known australopithecines. Interesting tidbit from this chapter is that he disagreed with Dart's osteodontokeratic culture.

Chapter Eight is where Coon begins to go off the rails. In the preceding chapters Coon had given a pretty good review of evolutionary theory as it applies to humans, but in this, and following chapters it becomes apparent that he got a little carried away. Coon points out that the story of human evolution can be studied in four dimensions. Time, Space, Grade, and Line. The meaning of time and space are obvious in this context and no one can really argue with what he has to say about them here. Coon defines Line as follows:

A line is a lineage, a genetic continuum, a succession of animals in the process of phyletic evolution (evolution by succession), from the earliest distinguishable ancestor to the present form. A line may pass through several grades and a grade may include populations belonging through several lines.

Within lines populations could go extinct in any of three fashions. By dying out completely, by evolving into something else, or by hybridizing with, and being absorbed by, a genetically different population. For Coon the first never happens, the second happens occasionally, and the third is quite frequent. That leaves the concept of grade. For Coon, a grade is a stage of physical adaptation to a special way of life (for Coon this means an ecological niche). While most paleoanthropologists and paleontologists of the time worked with the concept of unilineal evolution where most change was anagenetic, rather than cladogenetic, Coon pushed the concept for all it was worth. Much further, in my opinion, than it was intended. Some of this may be due to the imperfections of the fossil record. For example, Coon argues that:

The monkeys of the New and Old Worlds moved from the prosimian to the simian grade independently of each other (Coon felt that platyrrhines evolved out of North American adapidae separately from the catarrhines - afarensis). each separately acquired stereoscopic color vision, and in both hemispheres some of them came to brachiate. In the Old World it is quite possible that at least the latter stages of adaptation for four-footed life on the ground were reached independently by the baboons and macaques. The gibbons and the living African apes also became aboreal separately. as probably did the Orang. Thus three lines of tailless apes independently moved into the pongid grade. If the hominid grade, with erect posture, was reached by a single animal only, this border-crossing constitutes a great exception.

We have learned quite a bit about primate evolution since Coon wrote these words (incidentally, the edition I have is the fourth printing from 1966) and we know that large sections of that statement are wrong. The important point here is that Coon pushes the concept of grade until it almost sounds like the evolutionary ladder of life and the great chain of being. When it comes to H. sapiens Coon pushes the concept of grade into the realm of culture.

In man the making of tools, the use of fire, and the manufacture of houses and clothing are all cultural adaptations that provide the basis of ecological grades, through which, or through some of which, different human lines have passed. Ecological grades in human populations involve man's relationships with the land on which he lives and with other men.

So, if humans passed through one or more grades on the way to , well, us (and by us I mean H. sapiens), how did that occur and when? Better yet, how can you tell one grade from another, and how many are there? For Coon, there are two grades - H. erectus and H. sapiens and he spends about 40 pages discussing the threshold between the two. Factors involved include brain size, cranial form, tooth size (and the effects of tooth size of facial prognathism), population differences in tooth shape and various traits of the tooth, evolution of the chin (not something unique to H. sapiens), and facial flatness. For Coon, these latter two, tooth morphology and facial flatness, refer to lines of descent rather than grade and are what allow him to allow him to examine the origins of "racial differentiation".

The next four chapters are Coon's attempts to do exactly that.

In Chapter Nine Coon looks at Pithcanthropus and the Australoids and examines every scrap of skeletal evidence he can find from Jave, Solo, Ngandong, Wadjek, Keilor, Niah Cave, and Mapa - plus some others I have never heard of such as Aitape, Talgai, and Cohuna. In Chapter Ten Coon looks at Sinanthropus and the Mongoloids and examines every scrap of skeletal material he can find in China. Chapter Eleven does the same for Europe while Chapter Twelve looks at Africa. A book review of this nature, and this is already much longer than I had originally planned, can not do full justice to the extensive discussion in those four chapters (which covers something like 280 pages of text). One interesting bit, that I would like to quote (and it is a rather long quote) gives some insight into how Coon's theory works. It also refutes notions of racial purity:

The ancestors of Caucasoids who, as we suppose, evolved there could have been in direct peripheral contact with frontier populations of three of the four other subspecies: the Australoid in India, the Capoid in North Africa, and possibly the Congoid in southern Arabia if not also in Africa...

It is safest to say that during most of the 500,000 years of man's known existence the Mongoloids were in a position to exchange genes with only one other subspecies, the Australoid. The Congoids were in possible contact with two (certainly Capoid and possibly Caucasoid); the Capoids with two (Congoid and Caucasoid); and the Caucasoids with three, as stated above.

The geographical situation gave the Mongoloids the isolation necessary to retain their extreme racial peculiarities while evolving from a lower to a higher grade. At the same time it placed the Caucasoids in a central position in which they could accept genes directly and simultaneously from the other three subspecies; process these new genes by exposing them to natural selection for climate and culture, in a zoologically central area; and pass the product back to peripheral populations separately. In the same way, to a correspondingly lesser extent, the Mongoloids could deal with Australoid genes.

Peripheral gene exchanges between the five subspecies in their formative periods need not have been extensive in order to have stimulated general evolutionary change, i.e. grade-crossing, in populations which received the new genes. Had the exchanges been much greater than they were, swampings might have occurred and some lineages might have ceased to exist except in mixture.

In some respects Coon is facing head on, an issue that multiregional continuity advocates leave implicit. As regional populations adapt to their local environment they experience gene flow from the center to the edge - this is what allows regional traits to continue while the populations at the same time evolved into H. sapiens. Coon would argue that given the vast distances involved, the diverse environments, and cultural differences, this means that this transition could not have happened in all regions at the same time. Which is of course, one of the things that got him in trouble.

Coon, though, makes one of the same mistakes that I think that multiregional continuity advocates make. This involves the traits that are invoked in say, Java and Australia to establish that continuity. Although Coon gives lip service to clines and things like cold, heat, or humidity adaptations, when discussing regional traits this all goes by the wayside and Coon, and the multiregional continuists, mistake convergence for ancestry.

Despite Coon's mention of the species concept and his frequent mention of the need to understand the variability of populations, there is a certain typological element to his thinking. It would be interesting to see a historian of science tackle the book.

When Coon's book was first published, and even slightly before, there was a controversy surrounding the book. Many felt, and still feel, that Coon was a racist and certainly, as this article demonstrates, Coon kept some pretty questionable company. It is very possible that he was. There are a number of cynical comments scattered throughout the book that make me think Coon didn't think much of modern humans or their culture - but that could have been a pose.