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Journal of Anthropological 28 (2009) 1–13

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Journal of Anthropological Archaeology

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The diversity of North American projectile-point types, before and after the bow and

R. Lee Lyman *, Todd L. VanPool, Michael J. O’Brien

Department of Anthropology, University of Missouri, Columbia, MO 65211, USA article info abstract

Article history: Mimicking paleobiological studies of biodiversity, changes in the diversity of temporal types of North Received 4 March 2008 American projectile points are modeled to reveal evolutionary patterns of origination and extinction. Revision received 26 September 2008 Origination is modeled as rapid innovation of multiple point types (high diversity), and extinction is mod- Available online 21 January 2009 eled as gradual winnowing of less-efficient types. Introduction of the as a new weapon- delivery system is modeled as an increase in point diversity. Six sequences of points ( + arrow), six Keywords: sequences of dart points, and six sequences of arrow points from western North America best match Arrow-point types the model when the number of time periods P5 and the number of types is >3. Clade diversity Ó 2008 Elsevier Inc. All rights reserved. Cultural loss Dart-point types Extinction Innovation Origination Selection Stimulated variation Type diversity

Introduction goal is to determine if there is a consistent pattern in type diversity created by innovation and selection. The evolution of has been a mainstay of anthropo- Because we take our inspiration from paleobiology, we first logical and archaeological inquiry. Technological evolution has also sketch how that discipline explores biodiversity, along the way been studied by economists, historians, and others (e.g., Basalla, identifying concepts, analytical hurdles, and problem solutions 1988; Ziman, 2000). Archaeologists, however, have unique access that may be of use in archaeology. We then outline our theoretical to the temporally remote chapters of technological evolution and perspective and predictions regarding the history of technological also to uniquely long time spans. An archaeologist’s artifacts reveal diversity. Next, the particular analytical techniques we use are de- macroevolutionary patterns and processes accessible to no other scribed, followed by brief descriptions of the data sets we analyze. field of inquiry. Archaeologists should, for example, be able to Finally, the results of our analyses are presented and some sugges- determine if the rate of innovation is slower or faster or similar tions offered as to how analyses of technological history might be to the rate of cessation of innovation and discontinuance or extinc- expanded and improved. tion of some kinds of or . Similarly, the replacement of one kind of technology with another (e.g., the slide rule by the Paleobiology and biodiversity (and archaeology and pocket calculator) is an equally interesting evolutionary question; artidiversity) is the replacement slow or rapid, complete or partial? In this paper we explore these questions by applying analytical techniques ‘‘Biodiversity” usually signifies the number of taxa, but it can developed in paleobiology to projectile-point sequences. We mean a variety of other variables as (Maclaurin and Sterelny, examine the diversity of projectile points within the atlatl-and- 2008; Readka-Kudla et al., 1997). Conceptually and practically it is dart weapon-delivery system, within the bow-and-arrow weap- a ‘‘fundamentally multidimensional concept [that] cannot be re- on-delivery system, and within both systems combined in six chro- duced sensibly to a single number” (Purvis and Hector, 2000, p. nological sequences of points from the western . Our 212). When the term stands for the number of taxa, paleobiologists worry about how preservation, sampling, and identifications of pre- historic taxa and revisions thereof (e.g., Alroy, 2002; Dubois, 2003; * Corresponding author. Fax: +1 573 884 5450. Hughes and Labandeira, 1995; Khuroo et al., 2007; Westrop and E-mail address: [email protected] (R.L. Lyman). Adrain, 2001) influence measures of biodiversity (Erwin, 2008).

0278-4165/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jaa.2008.12.002 2 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13

The ‘‘metrics” paleobiologists use to measure biodiversity in- are two aspects to our answer—how the history of diversity is doc- clude taxonomic diversity (number of Linnean taxa, which are umented, and how appropriate units or metrics to measure taxo- not necessarily phylogenetically related), phylogenetic (clade) nomic diversity are created. diversity (number of taxa that share a common ancestor), morpho- ‘‘Spindle diagrams” document the history of the richness of taxa logical diversity (number of morphological variants irrespective of across geological time in graphic form (e.g., Newell, 1963; taxon and phylogeny), functional diversity (number of ecological Simpson, 1949; Valentine, 1978) and are given their name because roles irrespective of taxon), behavioral diversity, and developmen- they appear to depict the cross-section of spindles of various con- tal diversity (Erwin, 2008). Although we do not imply that biodi- figurations (Fig. 1). The wider the spindle, the more low-level Lin- versity and artidiversity (if we coin an equivalent term for artifact nean taxa there are within the high-level taxonomic group diversity) are empirically equivalent, we suggest that functional represented by the spindle, although spindle diagrams were drawn and behavioral diversity in artifacts might be examined by tallying as synthetic summaries without reference to explicit data. When in the number of classes of use wear displayed by stone , devel- the light of cladistic reasoning paleobiologists recognized that Lin- opmental diversity might be examined by tallying the number of nean taxa did not necessarily reflect phylogeny, spindle diagrams kinds of used to manufacture tools, and so on. We were replaced with clade-diversity diagrams (Raup and Gould, are particularly interested in taxonomic and phylogenetic diver- 1974; Raup et al., 1973). Clade-diversity diagrams can be similar sity, so how might we go about measuring artidiversity? There in appearance to spindle diagrams, but they depend on phyloge-

Fig. 1. A fictional spindle diagram (top) and a fictional clade-diversity diagram (bottom). In the spindle diagram, each letter denotes a high-level taxon, and the thickness of a layer (period) denotes its relative temporal duration. In the clade-diversity diagram each layer represents a stratum or period of equal duration. Note that diversity data are inexplicit and that diversity changes within a period in the spindle diagram whereas diversity data are explicit and diversity is static within a period/stratum in the clade- diversity diagram. R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 3 netic analyses and depict explicit tallies of taxa during individual phological diversity. Both type diversity and morphological diver- periods (Fig. 1). Paleobiologists are well aware that clade-diversity sity likely capture aspects of style (selectively neutral attributes) diagrams are based on hypothetical phylogenies that may be incor- and also of function (attributes subject to natural selection) (e.g., rect to some degree (Foote, 1996b), and they are also aware that Beck, 1995; Hughes, 1998). Temporal artifact types are thus much the taxa included in spindle diagrams and clade-diversity diagrams like the biological taxa tallied in paleobiology (e.g., Erwin, 2007, are likely not all equivalent units (Erwin, 2008). Taxon A may not 2008; Foote, 1996a) to create spindle diagrams and clade-diversity include as much morphological and functional diversity as taxon diagrams. B, or as much behavioral and developmental diversity as taxon C. A great deal of recent analytical effort has been devoted to Importantly, this has not precluded measuring biodiversity as the ascertaining if there is a particular shape that characterizes biolog- number of taxa or comparison of taxonomic diversity and morpho- ical clade-diversity diagrams (Foote, 2007 and references therein). logical diversity within lineages (Foote, 1993). Much of this work has been inductive because the historical pat- What we will hereafter refer to as clade-diversity diagrams tern of the diversity of life is largely unknown and different (realizing that the term is likely to be less than perfectly accurate researchers measure biodiversity with different metrics. Interest- [O’Brien and Lyman, 2003]) monitor two processes of evolution— ingly, and despite the many problems with the identification of the appearance of new forms or taxa and the extinction of old taxa, taxonomic revisions, and sample deficiencies, some recently forms or taxa (Lyman and O’Brien, 2000). This is an important compiled paleobiological clade-diversity diagrams have the observation for two reasons. First, scholars in various disciplines, archaeologically familiar unimodal ‘‘battleship-shape” of fre- including anthropology (Barnett, 1953) and archaeology (Schiffer, quency seriation (Foote et al., 2007). Similarities in the shape of 1996), have long studied technological innovation as an evolution- clade-diversity diagrams and archaeological battleship curves have ary process (Basalla, 1988; Farrell, 1993; Moykr, 1990; Petroski, been noted before (Gould et al., 1987), but there have been few ef- 1992; Ziman, 2000). Second, anthropologists have long argued that forts to examine artidiversity in the same way that biodiversity has cultural evolution is cumulative (e.g., Herskovits, 1948; Kroeber, been examined in paleobiology. 1953); indeed, Boyd and Richerson (1996) argue that a critical We have elsewhere examined artidiversity using metrics of definitive criterion of culture is that it is cumulative. That culture morphological variation within and between artifact types is accumulated over time is exemplified by Carneiro’s (1968, (Lyman et al., 2008). Here we examine typological diversity— 1970) argument that the more cultural traits held by a culture, how many types are there at any one time? We emphasize that the more evolutionarily advanced that culture is. Technological this does not contradict our pointing out elsewhere that tradi- innovation has received a great deal of attention from archaeolo- tional (in this case, temporal) artifact types are inappropriate gists and (to a lesser degree) other social scientists (e.g., Harrison for attaining some of the analytical goals of archaeologists (Ly- et al., 2002; Kingery, 2001; Lake and Venti, 2009; Spratt, 1982; man and O’Brien, 2002; O’Brien and Lyman, 2002). Our goal here van der Leeuw and Torrence, 1989). is to measure typological diversity over time as a proxy for both Technological loss, replacement, or obsolescence has received morphological and functional diversity; how revealing temporal less attention (see Schiffer, 2001 for a thoughtful exception) and types are with respect to evolutionary pattern and process re- so is less well understood than innovation. Cultural loss, or the mains to be determined. extinction of a cultural trait, was recognized early in anthropology Theory explaining patterns in biodiversity metrics is not well (e.g., Rivers, 1926) and has subsequently been discussed usually developed and is being written slowly (Foote, 1997; Gaston, only in passing (e.g., Bohannan, 1995; Goodenough, 1981; 2000), in part because historical patterns have not been rigorously Murdock, 1960). One of the most studied instances of cultural loss documented until recently (Foote, 2007 and references therein). in the archaeological record is the loss of tools in Tasmania The paucity of theory has contributed to research on prehistoric (Henrich, 2004; Jones, 1995; and references therein). Clade-diver- biodiversity being inductive. An explanation is sought for replicate sity diagrams document the history of diversity in a commonsen- patterns, and over time that explanation becomes more rigorous sical graphic form and allow rates of origination and extinction and more firmly theoretically grounded. The same is true for arti- to be statistically evaluated. Once the pattern(s) of innovation diversity (Schiffer, 2001), although evolutionary archaeologists are and loss are documented, explanatory models of the processes beginning to reach the point where they can propose general pat- can be tested. terns of evolutionary diversity (e.g., Lyman et al., 2008; Neiman, The other critical aspect of how we measure and analyze arti- 1995). Much of our knowledge of technological innovation con- diversity concerns choosing a metric, or unit, to tally diversity. cerns industrial or mechanized technologies rather than primitive We suggest that the ‘‘temporal types” designed by archaeologists technologies (e.g., Schiffer, 1996, 2001; Ziman, 2000). Our case may serve that purpose well for four reasons. First, they mark study thus begins with some theoretically founded expectations the passage of time because each occupies a unique (spatio) tem- and predictions, but these are general for want of well-developed poral range—this is the definition of a temporal type. Both innova- theory. The empirical evaluation of our predictions presented here tion and extinction take place over time, and temporal types is, in our view, a necessary early step toward building robust the- display a spatio-temporal pattern of distribution that implies the ory (see also Kingery, 2001). innovation (first appearance of a type) and extinction (last appear- ance of a type) processes. Second, temporal types have been largely Atlatl and dart, bow and arrow designed by trial-and-error to measure the passage of time. They are ideational rather than empirical units (Dunnell, 1971) and as Diversity of evolving phenomena can be studied at the scale of such solve a fundamental conundrum in that they allow us to taxonomic diversity (the number of taxa represented, or type rich- study a continuous process (evolutionary change) with discontinu- ness) and at the scale of morphological diversity (within individual ous units (Dunnell, 1995). Evolutionary change is marked by taxa) (Foote, 1993). Elsewhere we examined the history of mor- changes in frequencies of kinds rather than by changes of kinds. phological diversity in arrow points and in dart points and found Third, specimens of each temporal type were made over spans of that prehistoric artisans experimented more when arrow points time so that each type reflects a cultural tradition and thus cultural were first manufactured than they did subsequently (Lyman transmission, a major process of cultural evolution that results in et al., 2008). Here, we examine taxonomic diversity manifest as persistence of cultural traits. The fourth reason temporal types the richness of undifferentiated point types, of dart-point types, may be a good metric of artidiversity is that they do measure mor- and of arrow-point types in North American sequences in order 4 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 to determine if patterns can be detected in artidiversity at the scale Studies of modern material culture have found inventive activ- of (temporal) type. ities ‘‘discernible as a clustering in time and space of similar inven- The projectile points we discuss here are the only archaeologi- tions”—literally, a ‘‘burst of variation,” termed stimulated variation cally surviving pieces of complex, compound weapon-delivery sys- (Schiffer, 1996, p. 656). Perceived deficiencies in requisite perfor- tems. The atlatl-and-dart system includes minimally the atlatl mance characteristics of a category of artifacts result in a prolifer- itself, perhaps a , the dart shaft and foreshaft, the (pre- ation of variation (Basalla, 1988; Petroski, 1992). Often, these sumably) fletched proximal shaft, mastic and binding, and the bursts of variation are associated with underlying technological point (e.g., Couch et al., 1999; Perkins, 1992; Raymond, 1986). or social changes that make possible new approaches to mitigating The bow-and-arrow system includes minimally the bow ( the perceived deficiencies—a process Schiffer (2005) labels as the type and form [long, recurved, backed]), string (sinew, plant fiber), cascade effect. Changes in the context of cultural transmission, of- arrow shaft, perhaps a foreshaft and fletching, mastic and binding, ten including the introduction of new cultural traits or shifts in and the point (e.g., Bergman and McEwen, 1997). Fine tuning of all previously unrelated or marginally related cultural traits, funda- parts in concert such that all perform efficiently together likely mentally alter artifact traditions and their selective environments. prolongs the perfection process (e.g., Kingery, 2001; Schiffer, This creates new adaptive spaces in which artifact traditions 2001; Zeanah and Elston, 2001). Thus when we say ‘‘winnowing change in response to new selective pressures. of less-efficient forms” we do not mean to imply a point is efficient A particular temporal dynamic attends stimulated variation. or it is not; efficiency is not a dichotomy but a lengthy continuum. Initially, variation increases relatively rapidly as artisans experi- The strength of selective forces will consequently vary from in- ment with designing effective forms; subsequently, variation de- stance to instance. Efficient (but slightly imperfect) points that creases slowly as less-efficient variants cease to be replicated work most of the time will have weaker selective forces working (VanPool, 2001). Thus, type richness will initially be high and then on them than inefficient points that work only some of the time. decrease to only those forms that are increasingly well suited for The atlatl and dart were used during the Old World’s Upper their specific selective environments, until another change in the and the New World’s Paleoindian and Early Archaic eras selective environment and its associated stimulated variation oc- (Cotterell and Kamminga, 1992, p. 166; Dixon, 1999, pp. 151–153; cur (O’Brien and Holland, 1992; VanPool, 2002; West-Eberhard, Mildner, 1974, pp. 20–21). As-yet-unpublished evidence suggests 1992). the bow and arrow appeared as early as 4000 14C BP (uncalibrated) What are the archaeological patterns that we expect to find gi- in eastern Washington (K.M. Ames, personal communication, Sep- ven the evolutionary processes we have outlined? We do not know tember 2008) and in southern , eastern Oregon, and northern when the first atlatl and darts were made, but they appeared in Utah about 2500–3000 14CBP(Yoh, 1998). The atlatl and dart con- North America during the terminal . We therefore pre- tinued to be used for some time subsequent to that appearance dict that the richness of dart-point classes, which together form a (Blitz, 1988; Bradbury, 1997; Fawcett, 1998; Nassaney and Pyle, clade, will initially be high but then eventually (and gradually) de- 1999; VanPool, 2003). Introduction of the bow and arrow influ- crease as more-effective dart-point classes develop (Shott, 1996; enced projectile-point shape because of differences in the perfor- VanPool, 2001, 2003). Whether this is visible in the particular se- mance requirements of the weapon systems (Hughes, 1998; quences of points examined will likely depend on how much of VanPool, 2003, 2006). Archaeologists have long recognized mor- the early history of the clade is represented. If only the late portion phological differences between dart and arrow points (e.g., Corliss, is represented, the richness of dart points may be limited and rel- 1972; Fenenga, 1953), but the impact of the introduction of the atively stable. The dart-point clade may also appear to be diverse bow and arrow on morphological variation reflected through the when the bow and arrow are introduced because the first arrow richness of both dart- and arrow-point classes remains a largely points will likely be modified dart points that artisans were exper- unexplored research domain. Introduction of the bow and arrow imenting with to produce effective arrow points. Archaeologists and eventual discard of the previously dominant atlatl and dart won’t be able to distinguish between the arrow and dart points represent fundamental shifts in the adaptive space and attendant for reasons outlined by Shott (1997) and discussed below, likely niche construction related to projectile points. creating the pattern of diversity illustrated in Fig. 2. Because of mechanical differences between the bow and arrow Theoretical perspective and expectations and the atlatl and dart (Cotterell and Kamminga, 1992, pp. 166– 175, 180–188), attributes of dart points, especially those related Our perspective is based on the premise that cultural traits to size (arrow points are smaller than dart points) and , evolve in concordance with Darwinian evolution, which is a prob- had to be experimented with to find combinations that served to abilistic rather than a deterministic process (Shanahan, 2003). create effective arrow points (e.g., Beck, 1995, 1998; Hughes, This means that predictions based on the operation of evolution- 1998; Musil, 1988). The diversity of arrow points should initially ary forces apply to the general structure of populations but not to be high but subsequently decrease as less-effective kinds are win- specific individuals (Mills and Beatty, 1994). Four axioms follow nowed out. We expect diversity to be greatest relatively early in from this premise. First, cultural transmission creates artifact tra- the history of the arrow-point clade. The overall diversity of projec- ditions, or clades (Lipo et al., 2006; Lycett and Gowlett, 2008; tile-point classes (dart points + arrow points) will be greatest near Neiman, 1995; Tehrani and Riede, 2008). Second, the persistence the temporal middle of the clade as the limited diversity of dart of artifact classes monitors cultural transmission and heritability points is augmented by substantial richness of arrow points. Great- (Neiman, 1995; O’Brien, 2008; Thompson, 1956). Third, variation er richness relative to the preceding era, when only dart points is introduced by copying error (intentional or not) and experi- were present, may continue later in time as a result of the simulta- mentation (Eerkens and Lipo, 2005, 2007; Schiffer, 1996). Fourth, neous (relatively late) occurrence of both weapon systems (Fig. 2). selection reduces or stabilizes variation (Dunnell, 1980; O’Brien and Lyman, 2000; VanPool, 2001; Wilhelmsen, 2001). As a result Assumptions and caveats of the last two axioms, there is descent with modification of cul- tural traits, in which some forms continue whereas others do not, We assume that the first arrow point was a descendant of an and new forms appear. The rate of change in the inventory of ex- atlatl point within each sequence we examine. That is, we assume tant forms can vary considerably based on particular historical that the artisans did not copy an arrow point they somehow came circumstances. to possess (there was little or no horizontal transmission). Evi- R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 5

Fig. 2. Modeled expectations of dart-point and arrow-point richness over time. Bar width signifies ordinal-scale richness; stratum thickness is modeled as interval scale such that all strata are of the same duration. Note that it is probable that many early arrow points will be misclassified as dart points and a few dart points will be misclassified as arrow points (denoted by ‘‘experimental”).

dence concerning the timing of appearance of arrow points sum- point forms may therefore occur several times within a marized above suggests that this assumption is false, but we begin generation. The initial winnowing of arrow-point variation may with it because evidence suggests that aspects of the reduction be quick, in that much of the initial rapidly created variation will technology used to produce dart points were transferred to the produce that are unworkable and hence have poor replica- manufacture of the first arrow points (Yoh, 1998). Thus arrow tive success. Natural selection may then continue limiting varia- points observed or obtained elsewhere were not simply cloned or tion through time as the points and the rest of the weapon copied. Rather, familiar technologies produced what likely was system become more finely tuned to the selective environment, an imperfectly understood element of a complex tool. but the initial formation of workable arrow points may be obtained We statistically analyze each sequence of points as if the earli- very early. Archaeological temporal control may be too poor to est period represented is the one in which dart points first appear, fully document this pattern. We cannot always escape the effects which probably is not always the case. Similarly, both clades of of time averaging (the results of >1 temporally distinct events projectile points (dart and arrow) are truncated in the early his- are blended together and cannot be analytically separated). Many toric period (sixteenth and seventeenth centuries AD) because of artifact assemblages from distinct strata likely are time averaged demographic and cultural change resulting from European influ- ‘‘cumulative palimpsests” (Bailey, 2007). As in paleobiology (e.g., ence in the New World. There may not always have been enough Kowalewski et al., 1998), this may not be a problem with respect time for selection and other evolutionary processes to produce to monitoring the history of taxonomic richness, depending on the patterns of artidiversity we predict, and in some cases the early the rate of fluctuation of projectile-point class richness relative to or late end of clade history may not be represented. Missing ends the rate of deposition. However, it may also cause bursts of innova- of clades are a common problem in paleobiology, but it has not tion and the subsequent elimination of much variation to be ob- precluded analysis of clade diversity. scure if the analytical temporal periods are excessively long. Further, some individual points are likely to be incorrectly clas- On a related note, some archaeologists are concerned that tem- sified. Archaeologists typically distinguish dart points from arrow poral types of points may give false chronometric readings because points using weight (dart points > 3 gm > arrow points; e.g., of post-fracture reworking (Flenniken and Wilke, 1989). Although Hughes, 1998; VanPool, 2003) or shoulder width (dart points > 2 c- we do not deny that such may create a bit of typological and chro- m > arrow points; e.g., Thomas, 1978), but comparisons with haf- nological noise, the chronometric properties of the temporal types ted examples from archaeological contexts (e.g., Shott, 1997) used in our analyses are sufficiently robust to significantly mute have shown that these are not infallible criteria. Early arrow points that noise (Bettinger et al., 1991; Hockett, 1995; O’Connell and Ino- modeled on effective dart points may be particularly prone to way, 1994). Further, archaeological data supporting the so-called incorrect classification and thus suggest greater diversity of dart ‘‘rejuvenation hypothesis” are essentially nonexistent (e.g., points than actually exists (Fig. 2). As a result, much of the initial Rondeau, 1996), and experimental replication studies suggest that variation in arrow points may also be analytically invisible to retooling broken dart points likely was uncommon prehistorically archaeologists because of the trouble with distinguishing between because it was not an economically efficient practice (Zeanah and dart and large arrow points. Elston, 2001). Cultural evolution is on the whole much more rapid than hu- How can we test our modeled predictions (Fig. 2) given these man genetic evolution, and change in the diversity of projectile- caveats? Our tests could be considered less than ideal, but the 6 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 problems we face (e.g., imperfect analytic units, time averaging see also Gilinsky et al., 1989; Kitchell and MacLeod, 1989) and problems) are general to studies of diversity. None of them under- use Student’s t to determine whether observed CG values are sig- mines our fundamental ability to undertake paleobiodiversity nificantly greater or less than 0.5 (SD = 0.032 for n = 1000 random studies. Despite the issues outlined above, archaeologists can still simulations). All p values are for one-tailed tests based on our pre- have a reasonable expectation that the general patterns of varia- dictions regarding the history of projectile-point diversity. Our pre- tion will be reflected in the richness of artifact classes in the dictions regarding the diversity or richness of projectile-point archaeological record. Our analysis is virtually the first of its kind classes are summarized and cast in terms of clade diversity in Ta- in archaeology and thus is exploratory. The data we use are per- ble 1. haps sometimes less than ideal, but less than ideal does not neces- To assist with interpreting the empirical record when graphed sarily equate with poor. Poor data should yield random behavior in as a clade-diversity diagram, we adapt our model (Fig. 2) to each terms of class frequencies per stratum. Using multiple assem- individual case. The main reason for doing this is that the position blages, we should be able to evaluate whether the data are ade- of greatest diversity in a clade-diversity diagram may be a function quately robust to evaluate our proposed model and whether the of the portion of the stratigraphic column (and the included por- proposed model fits. Identifying data weaknesses will point the tion of an artifact tradition) represented by a site. Although our way to better data, as well as to realistic predictions. model concerns whether a clade-diversity diagram is top heavy, Finally, explanatory theory is still being written in paleobiology, symmetrical, or bottom heavy, the CG statistic does not account where our inspiration for this study resides, and shortcomings in for the portion of a clade that is represented but instead assumes our analysis may point the way to better theory there and also in the complete clade is present. This makes interpretation of a CG archaeology. In short, we find analytical shortcomings to be as by itself tenuous. For example, assume two assemblages vary as important as analytical successes. predicted by our model, but one represents only the last period of the dart-point developmental sequence but a long portion of Analytical methods the arrow-point developmental sequence, whereas the other in- cludes the entire sequence of dart-point development but only To monitor change in class richness statistically, we use clade- the start of the arrow-point developmental sequence. The first diversity diagrams and center-of-gravity statistics (Gould et al., assemblage will graphically and statistically have a CG of about 1977, 1987). A clade-diversity diagram displays fluctuations in tax- 0.5 because the period of greatest variation, associated with the onomic richness (here the number of projectile-point classes rep- development of arrow points, will be toward the center of the dis- resented in a collection) within a clade over time (Fig. 1, lower). tribution. The second assemblage will appear hourglass shaped be- Time passes from the bottom to the top of the diagram, and verti- cause it will have considerable variation at the bottom, which cally stacked, horizontally centered bars of varying widths signify represents dart-point development, and also at the top, which rep- class richness. Initial diversity is always zero until the first member resents the development of arrow points. Despite the fact that both of a clade appears; diversity never falls below zero during the his- assemblages vary in accord with our proposed model, they will ap- tory of a clade; and final diversity is zero when the taxon goes ex- pear graphically and statistically different for reasons of sampling. tinct. Over time, ‘‘diversity is Markovian (diversity at any time Comparison of a case-adjusted version of our model with each par- t + dt depends in part upon the diversity at previous time t)” ticular case allows us to visually evaluate goodness-of-fit between (Gilinsky and Bambach, 1986, p. 251). the empirical record and how we think that record should appear. A clade-diversity diagram’s ‘‘center of gravity” refers to the ‘‘rel- ative position in time of the mean diversity” of a clade (Gould et al., Materials 1977, p. 26; Gould et al., 1987, p. 1438). The duration of a clade is measured on a scale from zero—the time period immediately prior We use data from six sites in the western United States to test to the period when the clade first appears—to one—the time period our predictions regarding the diversity of projectile points. immediately following the period of clade extinction. An equilat- Gatecliff Shelter is in central Nevada (Thomas, 1983), part of the eral diamond-shaped clade-diversity diagram is symmetrical and Great Basin culture area (D’Azevedo, 1986; Grayson, 1993). The has a center of gravity of 0.5; a tear-drop-shaped, or bottom-heavy, 10-m-thick sedimentary record comprises 56 individual strata, diagram is asymmetrical and has a center of gravity of less than among which the excavators identified 16 cultural horizons that 0.5; an inverted tear-drop-shaped, or top-heavy, diagram has a span approximately the last 5500 14C years. Four-hundred and se- center of gravity of greater than 0.5. The center-of-gravity value ven projectile points were distributed among 13 of the cultural is calculated with the formula horizons (Table 2). Three classes of arrow points and seven classes of dart points are represented (Thomas, 1978, 1981; Thomas and CG ¼ðRNiti=RNiÞ Bierwirth, 1983). All were classified by the original investigators where N is richness per time interval (i) and t is the temporal posi- according to the modern Great Basin typology of temporal types. tion of the richness measure. The midpoint of each time interval is used for N, which is measured as a proportion of the complete dura- tion of the sequence. We scale class richness during each period according to the duration of that period. Calculation of what we Table 1 hereafter refer to as temporally scaled CG accommodates temporal Predictions of the history of projectile-point diversity (see Fig. 2). Rows are arranged gaps in the sequence by assuming that the elapsed time represented in superposed temporal order (oldest at the bottom, youngest at the top) to facilitate by the gaps is equally distributed between the immediately adja- integration with analysis of clade-diversity and center-of-gravity analysis (top heavy, symmetrical, bottom heavy). cent earlier and later strata. Symmetrical clades suggest that diversity increased and then Sequence Projectile-point clade Dart-point clade Arrow-point (ordinal scale) (clade symmetrical (clade symmetrical clade (clade decreased at a similar rate. Bottom-heavy clades suggest processes or top heavy) or bottom heavy) bottom heavy) such as stimulated variation rapidly created variation early in a 4 (youngest) Diversity decreasing Diversity decreasing Diversity clade’s history and that sorting processes such as selection gradu- decreasing ally winnowed out less-effective kinds over a large portion of clade 3 (arrow appears) Diversity great Diversity great Diversity great history. Top-heavy clades suggest most variation was generated 2 Diversity decreasing Diversity decreasing – late in a clade’s history. We follow Kitchell and MacLeod (1988); 1 (oldest) Diversity great Diversity great – R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 7

Table 2 Dirty Shame Rockshelter is in southeast Oregon (Aikens et al., Gatecliff shelter, Nevada, projectile-point history. nsp, number of specimens. 1977), part of the Great Basin culture area. The 4.5-m-thick deposit 14 Cultural Age No. of dart-point No. of arrow-point included six strata spanning the last 9500 C years; a depositional horizon (yr BP) classes (nsp) classes (nsp) and occupational hiatus occurred between about 5900 and 2700 14 1 700–500 1 (1) 2 (19) C BP. One hundred and forty-five arrow points and dart points 2 700 1 (1) 3 (22) were recovered (Hanes, 1977). As with Hogup and Dry Creek 3 1300–700 1 (3) 3 (26) Rockshelter, we reclassified the points according to the modern 4 1900–? 3 (67) 1 (1) Great Basin typology of temporal types (Table 5). 5 ? 3 (100) 0 6 3250–? 4 (57) 1 (3) Windust Cave is in southeastern Washington (Rice, 1965), with- 7 3300–3250 3 (39) 0 in the Columbia–Fraser Plateau culture area (Walker, 1998). The 8 3350–3300 3 (38) 0 deposit consisted of 10 strata, three of which produced no cultural 9 3450–3350 4 (17) 0 remains. Ages of the strata were estimated based on included pro- 10 4100–3450 1 (1) 0 11 4300–4150 0 0 jectile-point classes, typological cross-dating, and geochronology 12 5050–4300 1 (5) 0 (e.g., Lyman, 2000). Two hundred and thirty-eight projectile points 13 5150–5050 0 0 were recovered (Table 6). We classified points based on the overall 14 5300–5150 2 (6) 0 point descriptions given by the original analyst (Rice, 1965) in or- 15 5400–5300 1 (1) 0 der to approximate the local temporal types (Leonhardy and Rice, 16 5550–5400 0 0 1970). In two cases we lumped adjacent strata to increase sample sizes (2–3, 4–5), and in another we retained a stratigraphic subdi- vision (6A, 6B). is in northwestern Utah (Aikens, 1970), part of the Cave is in northwestern Wyoming (Wedel et al., 1968), Great Basin culture area. The 4-m-thick deposit comprises 16 stra- within the (northern) Great Plains culture area (Frison and ta spanning the last 8500 years. Two hundred and eighty projectile Mainfort, 1996). The 8-m-thick deposits were laid down over the points representing both arrow points and dart points were dis- last 9200 14C years and consisted of more than 50 distinct strata, tributed among the strata (Table 3). These points were reported approximately half of which produced cultural material (Husted using a typology that has since been discarded (Aikens, 1970p. and Edgar, 2002). The projectile points were analyzed by Hughes 34), and we classified the points according to the modern Great (1998), who provided us with her unpublished data on point clas- Basin typology of temporal types (e.g., Thomas, 1981, 1983; Tho- ses. Three hundred and thirty-one projectile points recovered from mas and Bierwirth, 1983). Class richness and sample-size data the site were sufficiently complete to be classified and used in our per stratum were lumped in several instances to increase the sam- analysis (Table 7). We classified individual points as either arrow ple size per temporal unit. points or dart points based on the culture-historical classes recog- Dry Creek Rockshelter is in southwestern Idaho (Webster, 1978, nized by Hughes (unpublished data) and on other morphometric 1980), usually considered part of the Great Basin culture area. The attributes. We lumped some adjacent strata to increase sample 2.5-m-thick deposit comprises 13 strata, several of which did not sizes. contain artifacts, and spans the last 4150 14C years. One hundred arrow points and dart points were recovered (Webster, 1978, Results 1980). We reclassified all points according to the modern Great Ba- sin typology of temporal types (Table 4). In an earlier study of the Gatecliff Shelter projectile points we found a correlation between the number of projectile points and the richness of classes of points per cultural horizon (r = 0.744, Table 3 Hogup Cave, Utah, projectile-point history. nsp, number of specimens.

Stratum Age No. of dart-point No. of arrow-point Table 5 classes (nsp) classes (nsp) Dirty Shame Rockshelter, Oregon, projectile-point history. nsp, number of specimens. 15–16 A.D. 1350–1850 0 2 (5) Stratum Age (14C yr BP) No. of dart-point No. of arrow-point 14 ?–A.D. 1350 1 (6) 3 (16) classes (nsp) classes (nsp) 12–13 A.D. 400–? 1 (9) 2 (22) I 1100–400 5 (19) 2 (42) 10–11 ?–A.D. 400 2 (8) 1 (12) II 2700–1100 5 (10) 1 (11) 9 1250 B.C.–? 8 (23) 3 (5) III 6300–5900 9 (28) 1 (1) 8 ?–1250 B.C. 12 (48) 2 (3) IV 6800–6300 7 (10) 0 6–7 ? 9 (42) 1 (1) V 7900–6800 7 (9) 0 5 ? 9 (41) 0 VI 9500–7900 8 (15) 0 4 ? 9 (19) 0 1–3 6400 B.C.–? 8 (20) 0

Table 6 Windust Cave, Washington, projectile-point history. nsp, number of specimens. Table 4 Stratum Age (yr BP) No. of dart-point No. of arrow-point Dry Creek Rockshelter, Idaho, projectile-point history. nsp, number of specimens. classes (nsp) classes (nsp) 14 Stratum Age ( C yr BP) No. of dart-point No. of arrow-point 10a 200–50 0 0 classes (nsp) classes (nsp) 9 2000–200 0 4 (65) a 3 1410–1300 0 1 (2) 8 2500–2000 0 0 5 1550–1450 1 (2) 1 (11) 7 5700–2500 5 (32) 0 7 1710–1550 1 (3) 1 (16) 6B 6500–5700 4 (25) 0 8–9 1950–1710 4 (15) 1 (8) 6A 7500–6500 4 (35) 0 10 2400–1950 5 (15) 1 (6) 4–5 9000–7500 12 (66) 0 11 2500–2400 3 (5) 1 (1) 2–3 10,000?–9000 3 (15) 0 a 12 3300–2550 6 (10) 1 (1) 1 >10,000 0 0 13 4150–3300 1 (5) 0 a No cultural remains recovered. 8 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13

Table 7 strata 15 and 16, which compresses the top of the clade and ana- , Wyoming, projectile-point history. nsp, number of specimens. lytically creates symmetry. Stratum Age (14C yr BP) No. of dart-point No. of arrow-point The richness of all projectile-point classes per stratum from classes (nsp) classes (nsp) Dry Creek Rockshelter (Table 4) does not correlate with the num- 1 370 0 3 (11) ber of points per stratum (r = 0.49, p > 0.2), and thus sample-size 2 ? 0 2 (11) effects on clade diversity should be minimal. The CG for the time- 3 1230 0 1 (64) scaled collection of all points is 0.563 (t = 1.968, p < 0.025), indi- 4–5 2820–2050 2 (35) 0 cating the clade is top heavy, as predicted. The richness of dart- 6–7 4420–4090 7 (72) 0 8–9 5390–4640 13 (78) 1 (1) point classes per stratum is correlated with the number of dart 10–12 6780–5600 5 (27) 0 points per stratum (r = 0.802, p = 0.03), indicating richness may 13–17 8150–7630 6 (12) 0 be influenced by sample size. The dart-point clade has a time- 18–23 9250–8200 3 (20) 0 scaled CG of 0.553 (t = 1.655, p < 0.05), suggesting the clade is top heavy, not as we predicted. Deleting stratum 13, with only p < 0.001), suggesting that temporal fluctuation in point diversity one class and thus perhaps not representative, dart-point richness may be a function of sample size (Lyman and O’Brien, 2000). Scal- is not a function of sample size (r = 0.8, p > 0.05), and the time- ing time based on the duration of each horizon at Gatecliff Shelter scaled CG is 0.442 (t = 1.812, p < 0.05). The dart-point clade is sig- (Table 2), the CG value is 0.615 (t = 3.592, p < 0.001), indicating the nificantly bottom heavy, as we predicted. Further, given that the projectile-point clade is top heavy, as predicted (Table 1). Sample bow and arrow appear in the Great Basin coincident with the size, however, may be causing the shape of the clade. deposition of stratum 7, the fact that the richness of dart points Because of small samples in the early horizons, we calculated decreases with the deposition of stratum 7 meets our predictions. the CG for dart points only in horizons 1–9 (richness and sample The diversity of arrow points does not change from 1.0 across the size are not correlated, r = 0.612, p = 0.08). The time-scaled CG for stratigraphic sequence, precluding calculation of a CG statistic for the dart-point clade is 0.344 (t = 4.85, p < 0.001), indicating that the clade. Stasis in typological richness of arrow points does not the clade is bottom heavy and likely undergoing stabilizing selec- meet our prediction. tion (Fig. 3). This is consistent with our predictions. The bow and The richness of all projectile-point classes per stratum from arrow first appeared in the central and southern Great Basin about Dirty Shame Rockshelter (Table 5) does not correlate with the AD 400 (Beck, 1995; Bettinger and Eerkens, 1999; Bettinger et al., number of points per stratum (r = 0.063, p = 0.9), indicating class 1991; Holmer, 1986; Kelly, 1997; Yoh, 1998). We therefore con- richness in the clade is not being influenced by sample size. To cal- clude that the presence of the three arrow points in cultural hori- culate temporally scaled CG values, we distributed the temporal zon 6 is likely the result of stratigraphic mixing or the hiatus between strata II and III (5900–2700 14C BP) equally be- 1 misclassification of dart points , so we eliminate it from analysis. tween the two strata. The CG for the time-scaled collection of all The time-scaled CG for the arrow-point clade as represented by points is 0.45 (t = 1.562, p > 0.05), indicating the clade is symmet- horizons 4–1 (we assume arrows first appear as cultural horizon rical, meeting our prediction. The richness of dart-point classes 4 was being deposited) is 0.718 (t = 6.809, p < 0.001). The arrow- per stratum is not correlated with the number of dart points per point clade is top heavy, not as predicted (Fig. 3), but richness stratum (r = 0.48, p > 0.3). The time-scaled CG for the dart clade and sample size in horizons 1–4 are correlated (r = 0.95, p < 0.06). is 0.417 (t = 2.592, p < 0.005), indicating the clade is bottom heavy, Clade diversity could thus be a function of sample size, i.e., the which meets our prediction. Assuming that the presence of an ar- more recent layers appear to be more diverse for no reason other row point in stratum III is a result of stratigraphic mixing or mis- than they produced larger samples. classification of a dart point as an arrow point, the occurrence of The richness of all projectile-point classes per stratum from arrow points in only two strata precludes statistical assessment Hogup Cave (Table 3) correlates with the number of points per of the history of diversity of this clade. The richness of arrow-point stratum (r = 0.7, p = 0.024), suggesting that type diversity may be types increases from stratum II to stratum I, and thus does not a function of sample size. The time-scaled CG for all points is meet our prediction, but arrow-point richness in strata II and I 0.475 (t = 0.781, p > 0.2), indicating that clade diversity is symmet- may be a function of sample size. rical, meeting our prediction. The richness of dart-point classes per The richness of projectile-point types per stratum from Windust stratum is correlated with the number of dart points per stratum Cave (Table 6) does not correlate with the number of points per (r = 0.87, p = 0.0025), suggesting sample size may be influencing stratum (r = 0.646, p > 0.15; culturally sterile strata 1, 8, and 10 ex- dart-point class richness. The time-scaled CG for the dart-point cluded), indicating type richness is not being influenced by sample clade is 0.438 (t = 1.937, p < 0.05), indicating that diversity is bot- size. To calculate time-scaled CGs, we omitted strata 1, and 10 from tom heavy (Fig. 4), which meets our prediction. We aren’t sure consideration because they produced no points and divided the when strata 9 and 10–11 were deposited, but evidence indicates time represented by stratum 8 (500 yr) equally between strata 7 that stratum 8 predates the arrival of the bow and arrow at about and 9. The time-scaled CG for all points is 0.402 (t = 3.061, AD 400. Arrow points in stratum 8 and lower likely are the result of p < 0.005), indicating the clade is bottom heavy, which does not stratigraphic mixing or misclassification of dart points as arrow meet our prediction. The paucity of the arrow-point record is likely points. We therefore consider only strata 9–16 when examining the cause of this. The richness of dart-point types per stratum and the arrow-point clade. The richness of arrow-point classes per stra- number of dart points per stratum are correlated (r = 0.959, tum and the number of arrow points per stratum are not correlated p < 0.01), suggesting the richness of dart points is being influenced (r = 0.123, p > 0.8; strata 6–7 and 8 omitted because arrow points by sample size. The time-scaled CG for the dart-point clade is 0.417 are like to be intrusive or misclassified). The time-scaled CG for ar- (t = 2.592, p < 0.005), indicating the clade is bottom heavy. This row points is 0.558 (t = 1.812, p > 0.2), indicating that the arrow- meets our prediction. Because only one stratum produced arrow point clade is symmetrical. This does not match our prediction points, we cannot evaluate the history of diversity of the arrow- and may be a result of the time averaging that attends lumping point clade at Windust Cave. The richness of projectile-point classes per stratum at Mummy Cave (Table 7) does not correlate with the number of points per 1 Given a misclassification rate of 23% as determined by Shott (1997), we would expect up to 14 misclassified dart points in cultural horizon 6 alone. It is surprising stratum (r = 0.543, p > 0.1), indicating class richness is not being there are so few (see Table 2). influenced by sample size. The time-scaled CG for the entire collec- R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 9

Fig. 3. Modeled (left) and observed (right) clade-diversity diagrams for dart points and arrow points in the nine most-recent strata at Gatecliff Shelter. Vertical thickness of bar indicates temporal duration of horizon. Unshaded bar represents intrusive or misclassified specimens. Note the modeled misclassification of arrow points as dart points in the left column of the model.

Fig. 4. Modeled (left) and observed (right) clade-diversity diagrams for dart points and arrow points at Hogup Cave. Vertical thickness of bar indicates temporal duration of stratum. Unshaded bars represent intrusive or misclassified specimens. Note the modeled misclassification of arrow points as dart points in the left column of the model.

tion of points is 0.495 (t = 0.156, p > 0.4), indicating the clade is ing our prediction. We suspect that the single arrow point in stra- symmetrical, thus meeting our prediction (Fig. 5). The frequency tum 8–9 is intrusive from overlying strata or was misclassified. of dart-point classes per stratum is not correlated with the fre- Only three strata (1–3) produced arrow points, and arrow-point quency of dart points per stratum (r = 0.723, p > 0.1). The time- richness for the three is not correlated with the number of arrow scaled CG value for the dart point clade is 0.503 (t = 0.094, points per stratum (r = 0.866, p > 0.3). The time-scaled CG value p > 0.4), indicating the diversity of the clade is symmetrical, meet- for the arrow points in strata 1–3 is 0.663 (t = 3.529, p < 0.001), 10 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13

Fig. 5. Modeled (left) and observed (right) clade-diversity diagrams for dart points and arrow points at Mummy Cave. Vertical thickness of bar indicates temporal duration of stratum. Unshaded bar represents intrusive or misclassified specimens. Note the modeled misclassification of arrow points as dart points in the left column of the model. indicating the arrow-point clade is top heavy, contrary to our pre- ysis, two of them (Hogup Cave and Gatecliff Shelter) appear to re- diction. This is likely the result of the truncated recent history of flect a relationship between sample size and richness, which the lineage. produced a symmetrical clade at Hogup Cave and a top-heavy clade at Gatecliff Shelter that may not accurately reflect diversity Discussion in point types through time. The third (Mummy Cave) is signifi- cantly top heavy and thus does not match our predictions. Further, In general, our predictions are met for most of the combined ar- two arrow-point clades not amenable to statistical analyses—Dry row- and dart-point assemblages, and for the dart-point assem- Creek Rockshelter and Dirty Shame Rockshelter—appear (literally, blages independent of arrow points (Table 8). Clade diversity in visually) to not meet our prediction of a bottom-heavy clade. five of six point (dart + arrow) clades is either symmetrical (3) or What is causing the poor fit between our expectations and the top heavy (2), as predicted. The nearly equal distribution of clades arrow-point assemblages? Obviously the lack of correspondence as symmetrical or top heavy highlights the probabilistic nature of between our expectations and the assemblages from Hogup Cave, evolution. Five dart-point clades are significantly bottom heavy, Gatecliff Shelter, and Dirty Shame Rockshelter may relate to sam- and while all six meet our predictions (are bottom heavy or sym- ple-size issues, which is a common problem in archaeological anal- metrical), three may do so as a result of sample size. However, ysis. The pattern at Dry Creek Rockshelter and Mummy Cave are the arrow-point assemblages do not clearly meet our expectations. more interesting. Dry Creek Rockshelter is characterized by unifor- Of the three sequences sufficiently robust to allow statistical anal- mity with a single arrow-point type in each stratum. An explana- tion we find likely is that the earliest arrow points reflect the transmission of types already developed elsewhere, in particular, eastern Washington. The diversity of arrow-point types corre- Table 8 CG values for clades sponding with experimentation thus is not reflected at Dry Creek Rockshelter, which instead reflects the continuation of a previously Site Projectile Dart points Arrow points points developed point type. The top-heavy arrow-point clade at Mummy Cave could reflect a similar phenomenon, in that the initial lack of Gatecliff Shelter 0.615a (p < 0.001) M 0.344a (p < 0.001) M 0.718a (p < 0.001) variation could reflect the transmission from elsewhere of a com- Hogup Cave 0.475a (ns) M 0.438a (p < 0.05) M 0.558 (ns) plete bow-and-arrow weapon system that was then modified, cre- Dry Creek Rockshelter 0.563 (p < 0.025) M 0.442 (p < 0.05) M –b ating increased variation through time. b Dirty Shame 0.45 (ns) M 0.417 (p < 0.005) M – Perhaps arrow points have so few performance constraints that Rockshelter Windust Cave 0.402 (p < 0.005) 0.417a (p < 0.005) M – variation in them is effectively random relative to natural selec- Mummy Cave 0.495 (ns) M 0.503 (ns) M 0.663 tion. Although arrow points are a great way to modify and regulate (p < 0.001) an arrow’s spine, arrows don’t need stone points to work (sharp- a Richness is correlated with nsp. ns, not statistically significant. M, prediction ened wooden tips were used ethnographically); the most signifi- (Table 1) met. cant performance characteristic of arrows is a sharp tip to b Statistical analysis not possible but prediction apparently not met. facilitate penetration (although some groups used bunts [dull woo- R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 11 den tips] for birds and small animals) (VanPool, 2003). As time. The diversity of dart points decreased over time at Gatecliff long as the point is light enough, arrows can be tipped with almost Shelter, Hogup Cave, Dry Creek Rockshelter, and Dirty Shame anything. This being the case, after the initial burst of variation, Rockshelter after the introduction of the bow and arrow. Arrow- most of which would result in (arrow) points being misclassified point clades provided unsatisfactory tests of our predictions for a by archaeologists as dart points, fluctuation in the number of ar- variety of reasons. Our analyses suggest two things about future row-point types may reflect attributes such as individual choice, analyses of clade diversity. First, most statistically significant re- emblemic style, and random variation. sults that matched our predictions were for all points (darts + ar- Some years ago it was suggested that the change from to rows) and for dart points. Dart-point diversity averaged 4.95 atlatl and dart occurred when western North American projectile types across all 42 assemblages, but arrow-point diversity aver- points shifted from fluted and stemmed to notched points, the lat- aged only 2.05 types per assemblage across 18 assemblages, a sta- ter representing adoption of the atlatl and dart (reviewed in tistically significant difference (Student’s t = 2.69, p < 0.02). The Holmer, 1986). This may indeed have occurred, but evidence today statistical significance of a center of gravity was readily deter- suggests it is unlikely. As noted earlier, the atlatl and dart were mined with larger inventories of types. The second thing of note used by Paleoindians who manufactured fluted and stemmed is that arrow-point diversity was measured over an average of 3 points (Dixon, 1999). Some archaeologists have suggested that a periods per site whereas dart-point diversity was measured over shift from hunting mega-mammals of the terminal Pleistocene to an average of 7 periods per site, another statistically significant dif- more-diverse smaller taxa during the may have ference (t = 15.49, p < 0.0001). Determination of a center of gravity prompted an early shift in projectile-point diversity (reviewed in was facilitated when the number of time periods represented in a Musil, 1988), whereas a change in smaller prey exploited during sequence was P5. Thus we have learned two important things the Holocene prompted a later shift in projectile-point types about the analysis of clade diversity: The overall patterns of clade (e.g., Carlson and Magne, 2008). Again, there seems to be little evi- diversity we predict are more often than not evident among the dence of change in prey corresponding with change in projectile- point assemblages with >3 types and P5 periods. point type, as many point styles discussed here have been found The model in Fig. 2 may be typical of the evolution of projectile associated with many animal taxa. Further, paleoenvironmental points in general and perhaps other manifestations of material cul- data for Gatecliff Shelter (Thomas, 1983), Hogup Cave (Madsen ture. A robust test of the model using good data is mandatory prior et al., 2001), Dirty Shame Rockshelter (Grayson, 1993), Windust to its general adoption. If and when that model is confirmed, com- Cave (Chatters, 1998), and Mummy Cave (Brunelle et al., 2005; parisons of typological diversity with morphological diversity may, Millspaugh et al., 2004) indicate that while some changes in pro- as in paleobiology, reveal much about the patterns and processes jectile-point type inventories correspond with changes in environ- of cultural innovation and extinction as manifest in artidiversity. ment or prey, there are also many changes in type inventories that do not correlate with a change in environment or prey. Acknowledgments Ultimately then, our model accurately predicts the variation in dart assemblages and in assemblages containing both dart and ar- We thank Susan Hughes for providing the Mummy Cave data, row points, but is unsuccessful when dealing with arrow-point Ken Ames for allowing us to mention his unpublished work on pro- assemblages. We suspect that there are many reasons for stasis, jectile points, and two very demanding reviewers for comments. variation, and change in projectile-point types and that sorting out which process(es) is responsible in any given case will demand References more-detailed data and analyses than we have presented here.

Identifying these processes has not been our goal. Instead, we have Aikens, C.M., 1970. Hogup Cave. University of Utah Anthropological Papers No. 93. sought to determine if the diversity of projectile-point types dis- Salt Lake City. plays a patterned history (Fig. 2). Our results have been mixed Aikens, C.M., Cole, D.L., Stuckenrath, R., 1977. Excavations at Dirty Shame Rockshelter, Southeastern Oregon. Tebiwa, Miscellaneous Papers of the Idaho for various reasons, including the possibility of stratigraphic mix- State University Museum of Natural History, No. 4. Pocatello. ing, sample-size influences, and misclassification of specimens as Alroy, J., 2002. How many named species are valid? Proceedings of the National dart points or arrow points. These problems are not fatal to our Academy of Sciences 99, 3706–3711. analysis, but they do suggest that if a rigorous test of our model Bailey, G., 2007. Time perspectives, palimpsests and the archaeology of time. Journal of Anthropological Archaeology 26, 198–223. is to be performed, steep data requirements must be met. These in- Barnett, H.G., 1953. Innovation: The Basis of Cultural Change. McGraw-Hill, New clude paying close attention to the stratigraphic context of each York. individual point, omitting from analysis those that are in disturbed Basalla, G., 1988. The Evolution of Technology. Cambridge University Press, Cambridge. contexts, evaluating sample representativeness (see discussion and Beck, C., 1995. Functional analysis and the differential persistence of Great Basin references in Lyman and Ames, 2007), and evaluating how points dart forms. Journal of California and Great Basin Anthropology 17, 222–243. were classified to type and assigned to the dart- and arrow-point Beck, C., 1998. Projectile point types as valid chronological units. In: Ramenofsky, A.F., Steffen, A. (Eds.), Unit Issues in Archaeology: Measuring Time, Space, and categories. Material. University of Utah Press, Salt Lake City, pp. 21–40. Regarding the last, we find it curious that there are many (up to Bergman, C.A., McEwen, E., 1997. Sinew-reinforced and composite bows: 12) dart-point types during a period but never more than 4 arrow- technology, function, and social implications. In: Knecht, H. (Ed.), Projectile Technology. Plenum, New York, pp. 143–160. point types at any one time. This observation makes us wonder if Bettinger, R.L., Eerkens, J., 1999. Point typologies, cultural transmission, and the each type captures an equivalent amount of morphological varia- spread of bow-and-arrow technology in the prehistoric Great Basin. American tion (whatever the cause of that variation) and makes us suspect Antiquity 64, 231–242. Bettinger, R.L., O’Connell, J.F., Thomas, D.H., 1991. Projectile points as time markers that the types do not. If our suspicion is correct, then temporal in the Great Basin. American Anthropologist 93, 166–172. types may not be good measures of artidiversity despite the prop- Blitz, J.H., 1988. Adoption of the bow in prehistoric North America. North American erties they share with paleobiological taxa. Archaeologist 9, 123–145. Bohannan, P., 1995. How Culture Works. Free Press, New York. Boyd, R., Richerson, P.J., 1996. Why culture is common, but cultural evolution is Conclusion rare. Proceedings of the British Academy 88, 77–93. Bradbury, A.P., 1997. The bow and arrow in the Eastern Woodlands: evidence for an Among six collections of projectile points the richness of types archaic origin. North American Archaeologist 18, 207–233. Brunelle, A., Whitlock, C., Bartlein, P., Kipfmueller, K., 2005. Holocene fire and of points sometimes changed in predictable ways. The diversity vegetation along environmental gradients in the Northern Rocky Mountains. of all point types either was symmetrical or bottom heavy over Quaternary Science Reviews 24, 2281–2300. 12 R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13

Carlson, R.L., Magne, M.P.R., 2008. Projectile points and in northwestern Henrich, J., 2004. Demography and cultural evolution: how adaptive cultural North America. In: Carlson, R.L., Magne, M.P.R. (Eds.), Projectile Point Sequences processes can produce maladaptive losses—the Tasmanian case. American in Northwestern North America. Publication No. 35. Department of Antiquity 69, 197–214. Archaeology, Simon Fraser University, Burnaby, BC, pp. 353–362. Herskovits, M.J., 1948. Man and His Works. Knopf, New York. Carneiro, R.L., 1968. Ascertaining, testing, and interpreting sequences of cultural Hockett, B.S., 1995. Chronology of Elko series and split stemmed points from development. Southwestern Journal of Anthropology 24, 354–374. northeastern Nevada. Journal of California and Great Basin Anthropology 17, Carneiro, R.L., 1970. Scale analysis, evolutionary sequences, and the rating of 41–53. cultures. In: Naroll, R., Cohen, R. (Eds.), A Handbook of Method in Cultural Holmer, R.N., 1986. Common projectile points of the intermountain west. In: Anthropology. Columbia University Press, New York, pp. 834–871. Condie, C.J., Fowler, D.D. (Eds.), Anthropology of the Desert West: Essays in Chatters, J.C., 1998. Environment. In: Walker, D.E., Jr. (Ed.), Handbook of North Honor of Jesse D. Jennings. University of Utah Anthropological Papers, No. 110. American Indians, Plateau, vol. 12. Smithsonian Institution, Washington, DC, pp. Salt Lake City, pp. 89–115. 29–48. Hughes, S.S., 1998. Getting to the point: evolutionary change in prehistoric Corliss, D.W., 1972. Neck Width of Projectile Points: An Index of Culture Continuity weaponry. Journal of Archaeological Method and Theory 5, 345–408. and Change. Occasional Papers of the Idaho State University Museum, No. 29. Hughes, N.C., Labandeira, C.C., 1995. The stability of species in taxonomy. Pocatello. Paleobiology 21, 401–403. Cotterell, B., Kamminga, J., 1992. Mechanics of Pre-industrial Technology. Husted, W.M., Edgar, R., 2002. The Archeology of Mummy Cave, Wyoming: An Cambridge University Press, Cambridge, MA. Introduction to Shoshonean Prehistory. Midwest Couch, J.S., Stropes, T.A., Schroth, A.B., 1999. The effect of projectile point size on Archeological Center, Special Report, No. 4. Lincoln, NE. atlatl dart efficiency. 24, 27–37. Jones, R., 1995. Tasmanian archaeology: establishing the sequence. Annual Review D’Azevedo, W.L. (Ed.), 1986. Great Basin, Handbook of North American Indians, vol. of Anthropology 24, 423–446. 11. Smithsonian Institution, Washington, DC. Kelly, R.L., 1997. Late Holocene Great Basin prehistory. Journal of World Prehistory Dixon, E.J., 1999. , Boats and Bison: Archaeology of the First Colonization of 11, 1–49. Western North America. University of New Press, Albuquerque. Khuroo, A.A., Dar, G.H., Khan, Z.S., Malik, A.H., 2007. Exploring an inherent interface Dubois, A., 2003. The relationships between taxonomy and conservation biology in between taxonomy and biodiversity: current problems and future challenges. the century of extinctions. Comptes Rendus Biologies 326, S9–S21. Journal for Nature Conservation 15, 256–261. Dunnell, R.C., 1971. Systematics in Prehistory. Free Press, New York. Kingery, W.D., 2001. The design process as a critical component of the anthropology Dunnell, R.C., 1980. Evolutionary theory and archaeology. In: Schiffer, M.B. (Ed.), of technology. In: Schiffer, M.B. (Ed.), Anthropological Perspectives on Advances in Archaeological Method and Theory, vol. 3. Academic Press, New Technology. University of New Mexico Press, Albuquerque, pp. 123–138. York, pp. 35–99. Kitchell, J.A., MacLeod, N., 1988. Macroevolutionary interpretations of symmetry Dunnell, R.C., 1995. What is it that actually evolves? In: Teltser, P.A. (Ed.), and synchroneity in the fossil record. Science 240, 1190–1193. Evolutionary Archaeology: Methodological Issues. University of Arizona Press, Kitchell, J.A., MacLeod, N., 1989. Response to Gilinsky et al. Science 243, 1614–1615. Tucson, pp. 33–50. Kowalewski, M., Goodfriend, G.A., Flessa, K.W., 1998. High-resolution estimates of Eerkens, J.W., Lipo, C.P., 2005. Cultural transmission, copying errors, and the temporal mixing within shell beds: the evils and virtues of time-averaging. generation of variation in material culture and the archaeological record. Paleobiology 24, 287–304. Journal of Anthropological Archaeology 24, 316–334. Kroeber, A.L., 1953. The Nature of Culture. University of Chicago Press, Chicago. Eerkens, J.W., Lipo, C.P., 2007. Cultural transmission theory and the archaeological Lake, M.W., Venti, J., 2009. Quantitative analysis of macroevolutionary patterning in record: providing context to understanding variation and temporal changes in technological evolution: bicycle design from 1800 to 2000. In: Shennan, S.J. material culture. Journal of Archaeological Research 15, 239–274. (Ed.), Pattern and Process in Cultural Evolution. University of California Press, Erwin, D.H., 2007. Disparity: morphological pattern and developmental context. Berkeley. Palaeontology 50, 57–73. Leonhardy, F.C., Rice, D.G., 1970. A proposed cultural typology for the Lower Snake Erwin, D.H., 2008. Extinction as the loss of evolutionary history. Proceedings of the River Region, southeastern Washington. Northwest Anthropological Research National Academy of Sciences 105, 11512–11519. Notes 4, 1–29. Farrell, C.J., 1993. A theory of technological progress. Technological Forecasting and Lipo, C.P., O’Brien, M.J., Collard, M., Shennan, S.L. (Eds.), 2006. Mapping Our Social Change 44, 161–178. Ancestors: Phylogenetic Approaches in Anthropology and Prehistory. Aldine Fawcett, W.B., 1998. Chronology and projectile point neck-width: an Idaho Transaction, New Brunswick, NJ. example. North American Archaeologist 19, 59–85. Lycett, S.J., Gowlett, J.A.J., 2008. On questions surrounding the Acheulian ‘tradition’. Fenenga, F., 1953. The weight of chipped stone points: a clue to their function. World Archaeology 40, 295–315. Southwest Journal of Anthropology 9, 309–323. Lyman, R.L., 2000. Building cultural chronology in eastern Washington: the Flenniken, J.J., Wilke, P.J., 1989. Typology, technology, and chronology of Great Basin influence of geochronology, index fossils, and radiocarbon dating. dart points. American Anthropologist 91, 149–158. Geoarchaeology 15, 609–648. Foote, M., 1993. Discordance and concordance between morphological and Lyman, R.L., Ames, K.M., 2007. On the use of species-area curves to detect the effects taxonomic diversity. Paleobiology 19, 185–204. of sample size. Journal of Archaeological Science 34, 1985–1990. Foote, M., 1996a. Models of morphological diversification. In: Jablonski, D., Erwin, Lyman, R.L., O’Brien, M.J., 2000. Measuring and explaining change in artifact D.H., Lipps, J.H. (Eds.), Evolutionary Paleobiology. University of Chicago Press, variation with clade-diversity diagrams. Journal of Anthropological Archaeology Chicago, pp. 62–86. 19, 39–74. Foote, M., 1996b. Perspective: evolutionary patterns in the fossil record. Evolution Lyman, R.L., O’Brien, M.J., 2002. Classification. In: Hart, J.P., Terrell, J.E. (Eds.), Darwin 50, 1–11. and Archaeology: A Handbook of Key Concepts. Bergin and Garvey, Westport, Foote, M., 1997. The evolution of morphological disparity. Annual Review of Ecology CT, pp. 69–88. and Systematics 28, 129–152. Lyman, R.L., VanPool, T.L., O’Brien, M.J., 2008. Variation in North American dart Foote, M., 2007. Symmetric waxing and waning of marine invertebrate genera. points and arrow points when one or both are present. Journal of Archaeological Paleobiology 33, 517–529. Science 35, 2805–2812. Foote, M., Crampton, J.S., Beu, A.G., Marshall, B.A., Cooper, R.A., Maxwell, P.A., Maclaurin, J., Sterelny, K., 2008. What is Biodiversity? University of Chicago Press, Matcham, I., 2007. Rise and fall of species occupancy in Cenozoic fossil Chicago. mollusks. Science 318, 1131–1134. Madsen, D.B., Rhode, D., Grayson, D.K., Broughton, J.M., Livingston, S.D., Hunt, J., Frison, G.C., Mainfort, R.C. (Eds.), 1996. Archeological and Bioarcheological Quade, J., Schmitt, D.N., Shaver III, M.W., 2001. Late quaternary environmental Resources of the Northern Plains. Arkansas Archeological Survey Research change in the Bonneville Basin, western USA. Palaeogeography, Series No. 47. Fayetteville. Palaeoclimatology, Palaeoecology 167, 243–271. Gaston, K.J., 2000. Global patterns in biodiversity. Nature 405, 220–227. Mildner, M.P., 1974. Descriptive and distributional notes on atlatls and atlatl Gilinsky, N.L., Bambach, R.K., 1986. The evolutionary bootstrap: a new approach to weights in the Great Basin. In: Hester, T.R., Mildner, M.P., Spencer, L. (Eds.), the study of taxonomic diversity. Paleobiology 12, 251–268. Great Basin Atlatl Studies. Ballena Press, Ramona, CA, pp. 7–17. Gilinsky, N.L., Gould, S.J., German, R.Z., 1989. Asymmetries of clade shape and the Mills, S.K., Beatty, J.H., 1994. The propensity interpretation of fitness. In: Sober, E. direction of evolutionary time. Science 243, 1613–1614. (Ed.), Conceptual Issues in Evolutionary Biology, second ed. Massachusetts Goodenough, W.H., 1981. Culture, Language, and Society. Benjamin/Cummings, Institute of Technology, Cambridge, MA, pp. 3–23. Menlo Park, CA. Millspaugh, S.H., Whitlock, C., Bartlein, P.J., 2004. Postglacial fire, vegetation, and climate Gould, S.J., Raup, D.M., Sepkoski Jr., J.J., Schopf, T.J.M., Simberloff, D.S., 1977. The shape history of the Yellowstone–Lamar and Central Plateau Provinces, Yellowstone of evolution: a comparison of real and random clades. Paleobiology 3, 23–40. National Park. In: Wallace, L.L. (Ed.), After the Fires: The Ecology of Change in Gould, S.J., Gilinsky, N.L., German, R.Z., 1987. Asymmetry of lineages and the Yellowstone National Park. Yale University Press, New Haven, CT, pp. 10–28. direction of evolutionary time. Science 236, 1437–1441. Moykr, J., 1990. Punctuated equilibria and technological progress. American Grayson, D.K., 1993. The Desert’s Past: A Natural Prehistory of the Great Basin. Economic Review 80, 350–354. Smithsonian Institution Press, Washington, DC. Murdock, G.P., 1960. How culture changes. In: Shapiro, H.L. (Ed.), Man, Culture and Hanes, R.C., 1977. Lithic Tools of the Dirty Shame Rockshelter: Typology and Society. Oxford University Press, New York, pp. 247–260. Distribution. Tebiwa, Miscellaneous Papers of the Idaho State University Musil, R.R., 1988. Functional efficiency and technological change: a hafting tradition Museum of Natural History, No. 6. Pocatello. model for prehistoric North America. In: Willig, J.A., Aikens, C.M., Fagan, J.L. Harrison, R., Gillespie, M., Peuramaki-Brown, M. (Eds.), 2002. Eureka: The (Eds.), Early Human Occupation in Far Western North America: The Clovis– Archaeology of Innovation and Science. Archaeological Association of the Archaic Interface. Nevada State Museum Anthropological Papers, No. 21. Reno, University of Calgary, Calgary, Alberta. pp. 373–387. R. Lee Lyman et al. / Journal of Anthropological Archaeology 28 (2009) 1–13 13

Nassaney, M.S., Pyle, K., 1999. The adoption of the bow and arrow in eastern North Thomas, D.H., 1978. and atlatl darts: how the stones got the shaft. America: a view from central Arkansas. American Antiquity 64, 243–263. American Antiquity 43, 461–472. Neiman, F.D., 1995. Stylistic variation in evolutionary perspective: inferences from Thomas, D.H., 1981. How to classify the projectile points from monitor valley, decorative diversity and interassemblage distance in Illinois Woodland ceramic Nevada. Journal of California and Great Basin Anthropology 3, 7–43. assemblages. American Antiquity 60, 7–36. Thomas, D.H., 1983. The Archaeology of Monitor Valley 2: Gatecliff Shelter. Newell, N.D., 1963. Crises in the history of life. Scientific American 208 (2), 76–92. American Museum of Natural History Anthropological Papers 59(1). New York. O’Brien, M.J. (Ed.), 2008. Cultural Transmission and Archaeology: Issues and Case Thomas, D.H., Bierwirth, S.L., 1983. Material culture of Gatecliff shelter: projectile Studies. Society for American Archaeology, Washington, DC. points. In: Thomas, D.H. (Ed.), The Archaeology of Monitor Valley 2: Gatecliff O’Brien, M.J., Holland, T.D., 1992. The role of adaptation in archaeological Shelter. American Museum of Natural History Anthropological Papers 59(1). explanation. American Antiquity 57, 3–59. New York, pp. 177–211. O’Brien, M.J., Lyman, R.L., 2000. Applying Evolutionary Archaeology: A Systematic An archaeological approach to the study of cultural stability, 1956. In: Thompson, Approach. Kluwer Academic/Plenum Press, New York. R.H., Wauchope, R. (Eds.). Seminars in Archaeology: 1955, Memoir, vol. 11. O’Brien, M.J., Lyman, R.L., 2002. The epistemological nature of archaeological units. Society for American Archaeology, pp. 31–57. Anthropological Theory 2, 37–57. Valentine, J.W., 1978. The evolution of multicellular plants and animals. Scientific O’Brien, M.J., Lyman, R.L., 2003. Cladistics and Archaeology. University of Utah Press, American 239 (3), 140–158. Salt Lake. van der Leeuw, S.E., Torrence, R. (Eds.), 1989. What’s New? A Closer Look at the O’Connell, J.F., Inoway, C.M., 1994. Surprise Valley projectile points and their Process of Innovation. Unwin Hyman, London. chronological implications. Journal of California and Great Basin Anthropology VanPool, T.L., 2001. Style, function, and variation: identifying the evolutionary 16, 162–198. importance of traits in the archaeological record. In: Hurt, T.D., Rakita, G.F.M. Perkins, W.R., 1992. The weighted atlatl and dart: a deceptively complicated (Eds.), Style and Function: Conceptual Issues in Evolutionary Archaeology. mechanical system. Archaeology in Montana 33, 65–77. Bergin and Garvey, Westport, CT, pp. 119–140. Petroski, H., 1992. The Evolution of Useful Things. Vintage Books, New York. VanPool, T.L., 2002. Adaptation. In: Hart, J.P., Terrell, J.E. (Eds.), Darwin and Purvis, A., Hector, A., 2000. Getting the measure of biodiversity. Nature 405, 212–219. Archaeology: A Handbook of Key Concepts. Bergin and Garvey, Westport, CT, Raup, D.M., Gould, S.J., 1974. Stochastic simulation and evolution of morphology— pp. 15–28. towards a nomothetic paleontology. Systematic Zoology 23, 305–322. VanPool, T.L., 2003. Explaining Changes in Projectile Point Morphology: A Case Raup, D.M., Gould, S.J., Schopf, T.J.M., Simberloff, D.S., 1973. Stochastic models of Study from , Arizona. Doctoral Dissertation, University of New phylogeny and the evolution of diversity. Journal of Geology 81, 525–542. Mexico, Albuquerque. Raymond, A., 1986. Experiments with the function and performance of the VanPool, T.L., 2006. The survival of archaic technology in an agricultural world: how weighted atlatl. World Archaeology 18, 153–177. the atlatl and dart endured in the North American Southwest. 71, Readka-Kudla, M.L., Wilson, D.E., Wilson, E.O. (Eds.), 1997. Biodiversity II: 429–452. Understanding and Protecting Our Biological Resources. Joseph Henry Press, Walker, D.E. (Ed.), 1998. Plateau. Handbook of North American Indians, vol. 12. Washington, DC. Smithsonian Institution, Washington, DC. Rice, H.S., 1965. The Cultural Sequence at Windust . Unpublished Masters Webster, G.S., 1978. Dry Creek Rockshelter: Cultural Chronology in the Western Thesis, Department of Anthropology, Washington State University. Pullman. Snake River Region of Idaho, ca. 4150 B.P. – 1300 B.P. Tebiwa, Miscellaneous Rivers, W.H.R., 1926. The disappearance of useful arts. In: Rivers, W.H.R. (Ed.), Papers of the Idaho State University Museum of Natural History, No. 15. Psychology and Ethnology. Kegan Paul, Trench, Trubner, London (originally Pocatello. published in 1912). Webster, G.S., 1980. Recent data bearing on the question of the origins of the bow Rondeau, M.F., 1996. When is an Elko? In: Odell, G.H. (Ed.), Stone Tools: Theoretical and arrow in the Great Basin. American Antiquity 45, 63–66. Insights into Human Prehistory. Plenum, New York, pp. 229–243. Wedel, W.R., Husted, W.M., Moss, J.H., 1968. Mummy Cave: prehistoric record from Schiffer, M.B., 1996. Some relationships between behavioral and evolutionary Rocky Mountains of Wyoming. Science 160, 184–186. archaeologies. American Antiquity 61, 643–662. West-Eberhard, M.J., 1992. Adaptation: current usages. In: Keller, E.F., Lloyd, E.A. Schiffer, M.B., 2001. The explanation of long-term technological change. In: Schiffer, (Eds.), Keywords in Evolutionary Biology. Harvard University Press, Cambridge, M.B. (Ed.), Anthropological Perspectives on Technology. University of New MA, pp. 13–18. Mexico Press, Albuquerque, pp. 215–235. Westrop, S.R., Adrain, J.M., 2001. Sampling at the species level: impact of spatial Schiffer, M.B., 2005. The devil is in the details: the cascade model of invention biases on diversity gradients. Geology 29, 93–906. processes. American Antiquity 70, 485–502. Wilhelmsen, K.H., 2001. Building the framework for an evolutionary explanation of Shanahan, T., 2003. The evolutionary indeterminism thesis. Bioscience 53, 163–169. projectile point variation: an example from the central Mississippi River Valley. Shott, M.J., 1996. Innovation and selection in prehistory: a case study from the In: Hunt, T.L., Lipo, C.P., Sterling, S.I. (Eds.), Posing Questions for a Scientific . In: Odell, G.H. (Ed.), Stone Tools: Theoretical Insights into Archaeology. Bergin and Garvey, Westport, CT, pp. 97–144. Human Prehistory. Plenum Press, New York, pp. 279–309. Yohe II, R.M., 1998. The introduction of the bow and arrow and lithic resource use at Shott, M.J., 1997. Stones and shaft redux: the metric discrimination of chipped- rose spring (CA-INY-372). Journal of California and Great Basin Anthropology stone dart and arrow points. American Antiquity 62, 86–102. 20, 26–52. Simpson, G.G., 1949. The Meaning of Evolution. Yale University Press, New Haven, CT. Zeanah, D.W., Elston, R.G., 2001. Testing a simply hypothesis concerning the Spratt, D.A., 1982. The analysis of innovation processes. Journal of Archaeological resilience of dart point styles to hafting element repair. Journal of California and Science 9, 79–94. Great Basin Anthropology 23, 93–124. Tehrani, J.J., Riede, F., 2008. Towards an archaeology of pedagogy: learning, teaching Ziman, J. (Ed.), 2000. Technological Innovation as an Evolutionary Process. and the generation of material culture traditions. World Archaeology 40, 316–331. Cambridge University Press, Cambridge.