Behavioral modernity is a suite of behavioral and cognitive traits that distinguishes current H. sapiens from anatomically modern humans, hominins, and other primates. Although often debated, most scholars agree that modern human behavior can be characterized by abstract thinking, planning depth, symbolic behavior (e.g. art, ornamentation, music), exploitation of large game, blade technology, among others. Underlying these behaviors and technological innovations are cognitive and cultural foundations that have been documented experimentally and ethnographically. Some of these human universal patterns are cumulative cultural adaptation, social norms, language, cooperative breeding, and extensive help and cooperation beyond close kin. These traits have been viewed as largely responsible for the human replacement of Neanderthals in Western Europe and the peopling of the rest of the world.
Arising from differences in the archaeological record, a debate continues as to whether anatomically modern humans were behaviorally modern as well. There are many theories on the evolution of behavioral modernity. These generally fall into two camps: gradualist and cognitive approaches. The Later Upper Paleolithic Model refers to the idea that modern human behavior arose through cognitive, genetic changes abruptly around 40–50,000 years ago. Other models focus on how modern human behavior may have arisen through gradual steps; the archaeological signatures of such behavior only appearing through demographic or subsistence-based changes.
In order to classify what traits should be included in modern human behavior, it is necessary to define behaviors that are universal among living human groups. Examples of these human universals are abstract thought, planning, trade, cooperative labor, body decoration, control and use of fire, among others. Along with these traits, humans possess a heavy reliance on social learning. This cumulative cultural change or cultural "ratchet" separates human culture from social learning in animals. As well, a reliance on social learning may be responsible in part for humans' rapid adaptation to many environments outside of Africa.
There is also an important distinction to be made between when humans developed the ability to invent, in contrast to developing the ability to adopt, modern human behavior. As a modern analogy, there is no shortage of musicians in the world trying to compose new and original music, but only a handful every year that successfully manage to compose lasting world wide hit songs; yet essentially all of the other aspiring composer musicians can almost trivially learn to play those hit songs once they've heard them (with analogous undertakings in literature, art, science and technology etc.). A dramatic and sudden increase in complexity of human behavior is thus fully plausible even if significantly less than 1% of humanity developed the genetic ability to "invent", provided that the remaining 99% had no significant problems with "adopting" those inventions. There is potentially an evolutionary abyss between inventing and adopting; for instance, Homo erectus and Homo ergaster produced with little advancement essentially the same sharpened stone tools for over a million years, but there is no scientific evidence at hand that could prove that they were incapable of producing composite stone tools, such as spears, if shown how to do so.
It is thus not established if the early Homo sapiens had the genetic requirements to be able to adopt modern human behavior, such as religious beliefs, through cultural interaction. If indeed the early Homo sapiens had the ability to learn modern human behavior, once invented by other groups, there is no geographic restriction where modern behavior originated. However, if the early Homo sapiens hypothetically were genetically inhibited from adopting modern human behaviors, since cultural universals are found in all cultures including some of the most isolated indigenous groups, these traits must have evolved or have been invented in Africa prior to the exodus.
Archaeologically a number of empirical traits have been used as indicators of modern human behavior. While these are often debated a few are generally agreed upon. Archaeological evidence of behavioral modernity are:
- figurative art (cave paintings, petroglyphs, figurines)
- systematic use of pigment (such as ochre) and jewelry for decoration or self-ornamentation
- Using bone material for tools
- Transport of resources long distances
- Blade technology
- Diversity, standardization, and regionally distinct artifacts
- Composite tools
Several critiques have been placed against the traditional concept of behavioral modernity, both methodologically and philosophically. Shea (2011) outlines a variety of problems with this concept, arguing instead for "behavioral variability", which, according to the author, better describes the archaeological record. The use of trait lists, according to Shea (2011), runs the risk of taphonomic bias, where some sites may yield more artifacts than others despite similar populations; as well, trait lists can be ambiguous in how behaviors may be empirically recognized in the archaeological record. Shea (2011) in particular cautions that population pressure, cultural change, or optimality models, like those in human behavioral ecology, might better predict changes in tool types or subsistence strategies than a change from "archaic" to "modern" behavior. Some researchers argue that a greater emphasis should be placed on identifying only those artifacts which are unquestionably, or purely, symbolic as a metric for modern human behavior.
Theories and Models
Late Upper Paleolithic Model or "Revolution"
The Late Upper Paleolithic Model, or Upper Paleolithic Revolution, refers to the idea that, though anatomically modern humans first appear around 150,000 years ago, they were not cognitively or behaviorally "modern" until around 50,000 years ago, leading to their expansion into Europe and Asia. These authors note that traits used as a metric for behavioral modernity do not appear as a package until around 40–50,000. Klein (1995) specifically describes evidence of fishing, bone shaped as a tool, hearths, significant artifact diversity, and elaborate graves are all absent before this point. Although assemblages before 50,000 years ago show some diversity the only distinctly modern tool assemblages appear in Europe at 48,000. According to these authors, art only becomes common beyond this switching point, signifying a change from archaic to modern humans. Most researchers argue that a neurological or genetic change, perhaps one for complex language, caused this revolutionary change in our species.
Contrasted with this view of a spontaneous leap in cognition among ancient humans, some authors, primarily working in African archaeology, point to the gradual accumulation of "modern" behaviors, starting well before the 50,000 year benchmark of the Upper Paleolithic Revolution models. Howiesons Poort, Blombos, and other South African archaeological sites, for example, show evidence of marine resource acquisition, trade, and abstract ornamentation at least by 80,000 years ago. Given evidence from Africa and the Middle East, a variety of hypotheses have been put forth to describe an earlier, gradual transition from simple to more complex human behavior. Some authors have pushed back the appearance of fully modern behavior to around 80,000 years ago in order to incorporate the South African data.
Others focus on the slow accumulation of different technologies and behaviors across time. These researchers describe how anatomically modern humans could have been cognitively the same and what we define as behavioral modernity is just the result of thousands of years of cultural adaptation and learning. D'Errico and others have looked at Neanderthal culture rather than early human behavior for clues into behavioral modernity. Noting that Neanderthal assemblages often portray similar traits as those listed for modern human behavior, researchers stress that the foundations for behavioral modernity may in fact lay deeper in our hominin ancestors. If both modern humans and Neanderthals express abstract art and complex tools then "modern human behavior" cannot be a derived trait for our species.
Cultural evolutionary models may also shed light on why although evidence of behavioral modernity exists before 50,000 years ago it is not expressed consistently until that point. With small population sizes, human groups would have been affected by demographic and cultural evolutionary forces that may not have allowed for complex cultural traits. According to some authors until population density became significantly high, complex traits could not have been maintained effectively. It is worth noting that some genetic evidence supports a dramatic increase in population size before human migration out of Africa. High local extinction rates within a population also can significantly decrease the amount of diversity in neutral cultural traits, regardless of cognitive ability.
Before the "Out of Africa" theory was generally accepted, there was no consensus on where our species evolved and, consequently, where modern human behavior arose. Now, however, African archaeology has become extremely important in discovering where our species began. Since human expansion into Europe around 48,000 years ago is generally accepted as already "modern", the question becomes whether behavioral modernity appeared in Africa well before 50,000 years ago as a late Upper Paleolithic "revolution" which prompted migration out of Africa, or arose outside Africa and diffused back.
A variety of evidence of abstract imagery, widened subsistence strategies, and other "modern" behaviors have been discovered in Africa, especially South Africa. The Blombos Cave site in South Africa, for example, is famous for rectangular slabs of ochre engraved with geometric designs. Using multiple dating techniques, the site was confirmed to be around 77,000 years old. Beads and other personal ornamentation have been found from Morocco which might be as old as 130,000 years old; as well, the Cave of Hearths in South Africa has yielded a number of beads significantly before 50,000 years ago.
Expanding subsistence strategies beyond big-game hunting and the consequential diversity in tool types has been noted as signs of behavioral modernity. A number of South African sites have shown an early reliance on aquatic resources from fish to shellfish. Pinnacle Point, in particular, shows exploitation of marine resources as early as 120,000 years ago, perhaps in response to more arid conditions inland. Establishing a reliance on predictable shellfish deposits, for example, could reduce mobility and facilitate complex social systems and symbolic behavior. Blombos Cave and Site 440 in Sudan both show evidence of fishing as well. Taphonomic change in fish skeletons from Blombos Cave have been interpreted as capture of live fish, clearly an intentional human behavior.
While traditionally described as evidence for the later Upper Paleolithic Model, European archaeology has shown that the issue is more complex. A variety of stone tool technologies are present at the time of human expansion into Europe and show evidence of modern behavior. Despite the problems of conflating specific tools with cultural groups, the Aurignacian tool complex, for example, is generally taken as a purely modern human signature. The discovery of "transitional" complexes, like "proto-Aurignacian", have been taken as evidence of human groups progressing through "steps of innovation". If, as this might suggest, human groups were already migrating into eastern Europe around 40,000 years and only afterword show evidence of behavioral modernity, then either the cognitive change must have diffused back into Africa or was already present before migration.
In light of a growing body of evidence of Neanderthal culture and tool complexes some researchers have put forth a "multiple species model" for behavioral modernity. Neanderthals were often cited as being an evolutionary dead-end, apish cousins who were less advanced than their human contemporaries. Personal ornaments were relegated as trinkets or poor imitations compared the cave art produced by H. sapiens. Despite this, European evidence has shown a variety of personal ornaments and artistic artifacts produced by Neanderthals; for example, the Neanderthal site of Grotte du Renne has produced grooved bear, wolf, and fox incisors, ochre and other symbolic artifacts. Though burials are few and controversial, there have been circumstantial evidence of Neanderthal ritual burials. There are two options to describe this symbolic behavior among Neanderthals: they copied cultural traits from arriving modern humans or they had their own cultural traditions comparative with behavioral modernity. If they just copied cultural traditions, which is debated by several authors, they still possessed the capacity for complex culture described by behavioral modernity. As discussed above, if Neanderthals also were "behaviorally modern" then it cannot be a species-specific derived trait.
Most debates surrounding behavioral modernity have been focused on Africa or Europe but an increasing amount of focus has been placed on East Asia. This region offers a unique opportunity to test hypotheses of multi-regionalism, replacement, and demographic effects. Unlike Europe, where initial migration occurred around 50,000 years ago, human remains have been dated in China to around 100,000 years ago. This early evidence of human expansion calls into question behavioral modernity as an impetus for migration.
Stone tool technology is particularly of interest in East Asia. Following Homo erectus migrations out of Africa, Acheulean technology never seems to appear beyond present-day India and into China. Analogously, Mode 3, or Levallois technology, is not apparent in China following later hominin dispersals. This lack of more advanced technology has been explained by serial founder effects and low population densities out of Africa. Though tool complexes comparative to Europe are missing or fragmentary, other archaeological evidence shows behavioral modernity. For example, the peopling of the Japanese archipelago offers an opportunity to investigate the early use of watercraft. Though one site, Kanedori in Honshu, does suggest the use of watercraft as early as 84,000 years ago, there is no other evidence of hominins in Japan until 50,000 years ago.
The Zhoukoudian cave system near Beijing has been excavated since the 1930s and has yielded precious data on early human behavior in East Asia. Though disputed, there is evidence of possible human burials and interred remains in the cave dated to around 34-20,000 years ago. These remains have associated personal ornaments in the form of beads and worked shell, suggesting symbolic behavior. Along with possible burials, numerous other symbolic objects like punctured animal teeth and beads, some dyed in red ochre, have all been found at Zhoukoudian. Though fragmentary, the archaeological record of eastern Asia shows evidence of behavioral modernity before 50,000 years ago but, like the African record, it is not fully apparent until that time.
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