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The mechanisms by which options are generated for most decisions, however, are not well understood. We argue that understanding the origins of options is a crucial but untapped area for decision making research. We explore a number of factors which influence the generation of options, which fall broadly into two categories: psycho-biological and socio-cultural. The former category includes factors such as perceptual biases and associative memory networks.
The latter category relies on the incredible human capacity for culture and social learning, which doubtless shape not only our choices but the options available for choice. Our intention is to start a discussion that brings us closer toward understanding the origins of options.
Keywords: decision making, options, choice, goals, neuroeconomics, culture Introduction Neuroscientists and psychologists studying decision making generally follow a standard practice borrowed from economics, which is to assume a solitary decision maker who is presented with a set of options and asked to choose among them.
The quintessential mathematical formulations of choice, decision theory and game theory, deal exclusively with actors with a finite and completely known set of action choices, and this framework has allowed for the development of coherent formal theories of economic, political, and evolutionary organization. This practice has also been fruitful for the experimental sciences: we have learned much about the psychological factors that influence decisions in ways contrary to the rational ideal of Homo economicus, and have uncovered neurophysiological mechanisms by which we process and assess those options.
If we pull back from the domain of economic decision theory, however, we find that very few choices are made in this way. We are rarely given an explicit set of options from which to choose, or even an obvious goal toward which we can strive to optimize our choices. Rather, we make myriad decisions daily based on competing goals and options. Tupiguarani subsistence relied on cultivated plants and forest management. Microbotanical remains of maize and beans Phaseolus sp.
Consumption of maize has been attested by stable isotope data from human skeletal remains [ 62 ]. In addition, secondary vegetation in the surrounding of Tupiguarani settlements has been inferred from anthracological analyses [ 63 ]. Una and related phases. All the archaeological cultures discussed so far originated in Amazonia.
In the central Brazilian savanna cerrado , a separate focus of agriculture and ceramic diffusion is represented by the Una tradition [ 24 ]. The origins of Una expansion can be traced to ca. The earliest period is marked by a common settlement pattern, with the occupation of rock shelters in the cerrado and southern highlands [ 24 ]. Such a pattern is quite distinct from the tropical forest traditions reviewed so far. When compared to the Amazonian cultures, Una material culture is also characterized by its simplicity.
In later periods, however, larger and more permanent settlements appeared, including pit house villages associated with other types of earthen architecture like mounds and enclosures in the southern highlands [ 68 , 69 ] and ring villages in the cerrado and Atlantic coast [ 64 ]. In spite of the distinctiveness in its settlement patterns, the Una expansion has also been sustained by an agricultural base, as evidenced by the presence of maize in storage facilities since the earliest occupations in rock shelters, together with other domesticated plant remains like manioc and beans in later periods [ 70 , 71 ].
Microbotanical evidence of maize, beans and squash has also been recovered from southern Brazilian pit houses, where maize cultivation is further attested in the pollen record [ 72 — 74 ]. Importantly, ancient genomes point to a dispersal of certain lineages of maize in association with central Brazilian ring villages [ 75 ].
Possible correlations with language families. Direct connections between material culture, language and ethnicity in Amazonia are not without problems. Nevertheless, persistent associations of ceramic styles, settlement patterns and site architecture have been shown to pervade the Amazonian past, with strong links to historically recorded populations [ 33 ]. For example, the spread of the Saladoid-Barrancoid culture has been hypothesized for some time to reflect the expansion of Arawak languages [ 32 , 55 , 76 , 77 ].
Similarly, the Incised-Punctate expansion has been suggested to coincide with the spread of languages of the Carib family [ 32 , 78 ]. As for the Tupiguarani tradition, the very name given to the archaeological culture reflects the fact that its sites almost perfectly mirror the historical distribution of the Tupi-Guarani language family, one of the most widespread of South America [ 56 , 79 ]. Although we do not fully endorse perfect correspondences between material culture and language, we admit that, if demic expansions could be demonstrated to lie behind the archaeological phenomena in question, their association with language expansions in South America would be given further weight, fitting the expectations of the FLDH.
Materials and methods Compilation of radiocarbon dates Radiocarbon dates and associated coordinates were compiled from the published literature, academic theses and reports S1 Table. Information as complete and reliable as possible was recorded pertaining to cultural affiliation, site type, and potential problems with the date, when available.
Dates with standard errors larger than years were excluded. Although more precision would be desirable, retaining dates with even lower standard errors would lead to the exclusion of many dates published in the s and s. Using lower thresholds could also lead to the arbitrary removal of dates that are crucial for determining first arrival times in many regions [ 82 ].
Dates were calibrated using the ShCal13 curve [ 83 ]. Given that some sites are located north of the equator, an alternative approach would be to use the northern hemisphere curve for those cases, or to use a mixed curve to account for the mixing of atmospheric carbon from the two hemispheres caused by the annual displacement of the ITCZ over South America [ 84 ]. Considering that the difference between the southern and northern hemisphere curves is in the order of ca.
The dataset was further filtered for unreliable dates whose association with the archaeological context or cultural affiliation was questionable. Dates that were considered unreliable by the researchers who obtained them or that were found to be unreliable by later reviews were also excluded. Nevertheless, not all cases could be resolved in such a manner and therefore, given the scope of the dataset and the lack of consensus on cultural taxonomies in the archaeology of lowland South America, S1 Table also lists the sites excluded from the filtered dataset.
We annotated the reasons for removal so as to make our decisions as transparent as possible. In what follows, we explain our choices regarding the most important controversies. The long chronology places the origins of Saladoid ceramics at ca.
The Barrancoid style, on the other hand, is commonly accepted to have begun ca. Given the lack of consensus, and supported by the recently obtained dates for the Saladero phase, which show that the development of that ceramic style fits poorly in the short chronology [ 46 ], here we provide an analysis using the long chronology. Nevertheless, for the sake of methodological integrity, we decided to run separate regression analyses and simulations also adopting the Orinoco short chronology.
For running these models, we removed the earliest dates reported by Roosevelt [ 38 ] for La Gruta ceramics. Koriabo sites, however, have been included in spite of doubts about their broader affiliation [ 88 ], since the ceramics show much clearer affinities with lower Amazonian complexes [ 89 , 90 ]. Regardless of our decision, the Koriabo culture is recent, and excluding its dates from the analysis would not substantially affect the results. The Tupiguarani chronology is surrounded by controversies.
The dates published by Miller [ 93 ], some earlier than cal BP, are often cited as confirmation of a southwestern Amazonian origin [ 14 , 56 ]. Beyond the contextual problems that such dates pose, the cradle of the Tupi-Guarani language family not the Tupi stock is clearly located in eastern not southwestern Amazon [ 19 , 94 , 95 ].
Another difficulty in Tupiguarani chronology is represented by recently published dates from the coast of Rio de Janeiro state, inexplicably early when compared to other Tupiguarani occupations outside of Amazonia [ 59 , 96 ]. In light of those numerous problems, we used a conservative approach and excluded all the dates for which some objection could be raised, thus removing outliers from southwestern Amazon [ 91 , 92 , 97 ], central Brazilian rock shelters [ 98 ], and the coast [ 59 ].
Regression analysis To assess the relationship between chronology and geographical dispersion, we followed the well-established practice of performing linear regression of dates versus great-circle distances from hypothetical origins [ 6 , 8 , 35 , 82 , 99 , ]. Ordinary least squares OLS is commonly adopted for such ends, with regression of dates versus distances following the assumption that the former variable contains most of the error, whereas the latter is, in principle, known with certainty [ 8 , 82 , ].
Given that de facto travelled distances were probably not linear, this assumption is problematic. Here, we prefer the alternative of using reduced major axis RMA regression. While OLS assumes that the independent variable is measured without error, RMA assumes a symmetrical distribution of error between both variables [ 99 , ]. RMA has been shown to perform better at identifying the true relationship between two error-prone variables, being robust to outliers and preserving the underlying slope even when the dataset is reduced [ ].
We adopted the standard practice of measuring great-circle distances from the site with the earliest date discovered so far, which is assumed to be the probable center of origin [ 6 ]. This procedure, however, may be inadequate in certain cases, such as when the earliest date does not correspond to the beginning of the expansion [ 36 ]. In addition, given potential research biases in the location of the earliest dates, other locations should be considered [ 35 ].
Thus, although we primarily rely on the regression of dates and distances from the earliest site, we also tested for other possible origins by iterating over all sites. The inclusion of all available dates per site for line-fitting has been considered problematic, given the distortion caused when early sites also have more recent dates [ ]. The most commonly employed solution is to include only the earliest date available for each site, assuming they reflect the event of first arrival in a given location [ 6 , , ].
Additionally, to account for biases in the regional distribution of dates, some form of spatial filtering is frequently employed. One approach is to cluster sites into spatial bins defined by regular distance intervals measured from the center of origin [ 7 , 35 , 99 ].
This approach is more adequate for estimation of front speeds due to the fact that, in theory, the number of sites is correlated with time and distance from origin for a population expanding at a constant rate [ 99 ]. The bin size must offer a compromise between maximizing the number of sites included in the analysis and ensuring a minimum distance for the identification of underlying trends [ 35 ].
Here, we tested a range of spatial bin widths from to km in intervals of km, excluding those cases where fewer than 5 dates were retained after filtering. One of the difficulties inherent in analyzing radiocarbon dates as a function of distance is the use of point values for dates.
The modal values of uncalibrated 14C dates and the medians of calibrated probability distributions have commonly been utilized for that end [ 6 , 99 , ].
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