We are now in a position to propose some very specific answers to the Overwhelming Question first raised in posts 182-194 (see Table of Contents, above): where do we come from? i.e, who were our ancestors and what were they like? or more precisely: what was HBP like? Prior to the advent of modern population genetics such a question would have seemed absurdly out of reach. But, amazingly enough, we now have more than sufficient evidence to formulate some very reasonable hypotheses.
Our method will be simple. Any attribute found to be shared by at least one group in each of the three populations with the deepest clades, i.e., Eastern Pygmies, Western Pygmies and Bushmen (EP, WP, Bu), should be taken seriously as a possible survival from the time the ancestors of all three groups were united as one -- the group I'm calling HBP. You could call this the "triangulation method."
Thus, for example, the short stature to be found in all three populations suggests that most or all HBP could also have been short. According to the Encyclopedia Britanicca, anthropologists define pygmies as any group whose adult males grow to less than 150 cm (4 feet 11 inches) in average height. Mbuti, according to the same source, average under 4 feet 6 inches in height. Some BaAka adults have been reported at exactly 4 feet in height. According to the 1911 edition of the Britanicca,
[t]he most striking feature of the Bushman's physique is shortness of stature. Gustav Fritsch in 1863-1866 found the average height of six grown men to be 4 ft. 9 in. Earlier, but less trustworthy, measurements make them still shorter. Among 150 measured by Sir John Barrow during the first British occupation of Cape Colony the tallest man was 4 ft. 9 in., the tallest woman 4 ft. 4 in.While it's also been reported that other Bushmen populations average to more or less "normal" height, the remarkable shortness of at least some such groups cannot be ignored. If WP, EP and certain Bu groups can thus be considered "pygmies" as far as height is concerned, then it does seem likely that their common ancestors, HBP, were also of "pygmy" height. This makes considerable sense when we realize first, that there is no real evidence that pygmy stature is necessarily an adaptation to rainforest conditions (though it could be); second, that HBP could have originated in the Central African rainforest in any case; third, that tallness seems a more likely adaptation, in strictly Darwinian terms, than shortness, since a larger person has certain very clear advantages over one who is smaller. (We must also remember that HBP is not necessarily representative of either the earliest "modern" humans or all their contemporaries. Thus, fossil evidence of early humans of normal or greater height would have no bearing on the height of HBP, who would have been, in all likelihood, only one of a great many modern humans living in Africa at the time.)
Biological research, as reported in Patterns of Human Growth, 1999, by Barry Bogin, suggests that pgymy size may be due to unusual endrocrine levels, produced by a "genetic defect in the cellular mechanisms for the production, release or cellular reception of IGF -1" (p. 375). Since levels of IGF-1 have been found to be significantly lower in pygmies, this hypothesis seems likely.
A recent study of Andamanese pygmies, by Jay Stock and Andrea Migliano, offering a very different and imo highly unlikely, explanation, based on recent historical factors (ala classic revisionist dogma) has been criticized for several reasons, the most decisive offered by Anthropologist Brian Shea of Northwestern University, who
calls such evidence “interesting but irrelevant to the origin of small body size in human pygmy groups.” Stock and Migliano document short-term, environmentally induced changes in height that would affect the size of any population, Shea contends. This process can’t explain the origin of pygmies, he says.I'm not sure whether the IGF-1 levels of Bushmen have been studied, but if they are also low, that would seem to settle the matter in favor of short stature as a trait inherited from a common ancestor by all three groups. Since HBP is the common ancestor, this means HBP would most likely have been of pygmy height as well. On the other hand, if Bushmen IGF-1 levels are found to be normal, then either the IGF-1 hypothesis is wrong, or Bushmen height is not inherited from HBP. If that were the case, then we would have no way of knowing whether HBP were short, tall or of medium height.
Turning to other phenotypical characteristics, steatopygia, an unusual degree of fat accumulation on the buttocks, has been noted in both Pygmies and Bushmen, making it likely that this condition was almost certainly inherited from HBP. In almost all other respects, however, Bushmen are morphologically very different from Pygmies, or indeed any other contemporary people. If HBP resembled today's Pygmies, then Bushmen morphology would represent a mutation or set of mutations from the HBP norm. On the other hand, if they resembled Bushmen, then the Pygmies would be the carriers of such mutations. It's possible they resembled neither, and as of now we seem to have no way of telling.*
A similar situation exists for language.
That the genetic evidence has significant meaning for the study of cultural history has been noted by several geneticists, though the possibilities have not yet been widely explored. Since the pioneering work of Cavalli-Sforza, there has been an effort to correlate the genetic findings with those of historical linguistics, but the results have not always been consistent, for obvious reasons, since languages can easily change in a very short time, due to historical factors. We know this to be the case in Africa, since the spread of Bantu languages is almost certainly due to the relatively recent (ca 3,000 ya) Bantu expansion.
Sarah Tishkoff et al. alluded to the linguistic evidence as follows, in their recent Science article on Africans and African Americans:
The shared ancestry, identified here, of Khoesan-speaking populations with the Pygmies of central Africa suggests the possibility that Pygmies, who lost their indigenous language, may have originally spoken a Khoesan-related language, consistent with shared music styles between the SAK (Southern African Khoesan) and Pygmies (p. 1041).Since, as Tishkoff notes, all Pygmy groups lost their original languages (assuming they had any to begin with) and now speak languages related for the most part to those of their agriculturalist neighbors, we have no way of knowing what sort of language was spoken by HBP, or indeed if they had any language at all. As Tishkoff implies, the same is not true of music, since there are "shared music styles between the SAK (Southern African Khoesan) and Pygmies" (a specific reference to Lomax's work). If the lack of a shared verbal language can be seen as a serious drawback to any attempt to connect EP, WP and Bu culturally, the presence of shared musical styles easily makes up for it. Because music too is a language, though much neglected by anthropologists, for reasons already discussed at some length in earlier posts.
Much of my blog has been devoted to this very point, but in my next post I'll review the all important musical evidence, for the benefit of latecomers.
* [added at 2:32 PM, same day] I just had a bit of a brainstorm on the question of whether HBP would have been closest in morphology to Bushmen or Pygmies. If we take another look at the phylogenetic trees in the previous post, it's apparent, in all three cases, that the Bushmen occupy the deepest clades. Moreover, all these clades are dead ends. If the deepest clades are occupied by haplogroups found largely today among Bushmen, that strongly suggests that the ancestral group (HBP) could have resembled Bushmen. If that were the case, then the oldest ancestors of the Pygmies would have been the first group to diverge from the ancestral group, which is consistent with Chen's finding that the Biaka Pygmies were the first to diverge.
We would then have the following historic sequence: 1. A proto-HBP group either resembling today's Bushmen morphologically, or evolving in that direction, until we reach 2. HBP, resembling Bushmen; 3. the development and divergence of the first Pygmy or Proto-Pygmy (PP) population from HBP, due possibly to a population bottleneck or some other type of founder effect (due to banishment, accidental isolation, etc.); 4. the gradual expansion and migration of the original HBP population until it populates most or all of southern Africa with Bushmen-like people -- since all or most of the Bushmen clades are dead ends, the evidence suggests that HBP did not give rise to any other non-Bushmen populations, but remained relatively static (we are admittedly hampered here by a lack of Hottentot DNA, a serious gap since the Hottentots are generally thought to have been a Bushmen derivation); 5. the migration of the proto-Pygmy group (PP) into the Central African Forest, where it expands to eventually produce all the Pygmy groups we know today; 6. the development and divergence of a Proto-Bantu population from a Pygmy group, roughly 18,000 years ago, according to the genetic evidence.
If we assume, on the other hand, that HBP were more Pygmy-like, this would, first of all be inconsistent with current genetic evidence placing Bushmen at the deepest clades. If that were nevertheless the case, then we might have the following sequence, which would in fact be fully consistent with Chen's table: 1. A proto-Pygmy group, ancestral to the WP (Biaka), is the first to diverge, ca 70,000 to 100,000 years ago; 2. a proto-Bushmen group, ancestral to the !Kung, develops from HBP, due to some sort of founder effect or population bottleneck and diverges from the ancestral group between 41,000 and 54,000 years ago; 3. yet another Pygmy group, ancestral to the EP (Mbuti), diverges from HBP roughly between 14,000 and 19,000 years ago. If the ancestries of EP and WP are so completely separate from one another, by such a long time span, it's very hard to understand how both groups would have made their way separately into the Tropical Forest. Which tells us either that this second scenario is highly unlikely, or that HBP developed originally within the Tropical Forest, from which PB ultimately migrated.