Straw boats and the proverbial sea: a response to 'Island Archaeology: In Search of a New Horizon'

In a recent ISJ paper, “Island Archaeology: In Search of a New Horizon”, Boomert and Bright (2007) argue that the field of “island archaeology” should be replaced by an “archaeology of maritime identity”. We disagree and counter that although islands share many physical, biological, and cultural similarities with continental coasts, coastal zones also grade uninterruptedly into riverine, lacustrine, and terrestrial landscapes, raising questions about the validity of their concept of the archaeology of maritime identity. In our view, island archaeology (the application of archaeology to island settings), regardless of past biogeographical underpinnings, has made major contributions to understanding the historical ecology, human impacts, and cultural developments of islands around the world. A focus on islands by archaeologists has encouraged scholars to study the history of island and maritime societies within a comparative framework that is useful for breaking out of the often provincial focus on a single island or archipelago

Sea level, paleogeography, and archeology on California\u27s Northern Channel Islands

Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California\u27s Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early NewWorld coastal foragers. Sea level that was about 80–85m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution

Ecological consequences of human niche construction: Examining long-term anthropogenic shaping of global species distributions

The exhibition of increasingly intensive and complex niche construction behaviors through time is a key feature of human evolution, culminating in the advanced capacity for ecosystem engineering exhibited by Homo sapiens. A crucial outcome of such behaviors has been the dramatic reshaping of the global biosphere, a transformation whose early origins are increasingly apparent from cumulative archaeological and paleoecological datasets. Such data suggest that, by the Late Pleistocene, humans had begun to engage in activities that have led to alterations in the distributions of a vast array of species across most, if not all, taxonomic groups. Changes to biodiversity have included extinctions, extirpations, and shifts in species composition, diversity, and community structure. We outline key examples of these changes, highlighting findings from the study of new datasets, like ancient DNA (aDNA), stable isotopes, and microfossils, as well as the application of new statistical and computational methods to datasets that have accumulated significantly in recent decades. We focus on four major phases that witnessed broad anthropogenic alterations to biodiversity—the Late Pleistocene global human expansion, the Neolithic spread of agriculture, the era of island colonization, and the emergence of early urbanized societies and commercial networks. Archaeological evidence documents millennia of anthropogenic transformations that have created novel ecosystems around the world. This record has implications for ecological and evolutionary research, conservation strategies, and the maintenance of ecosystem services, pointing to a significant need for broader cross-disciplinary engagement between archaeology and the biological and environmental sciences

A Trans-Holocene Archaeological Record of Guadalupe Fur Seals (\u3ci\u3eArctocephalus townsendi\u3c/i\u3e) on the California Coast

Guadalupe fur seals (Arctocephalus townsendi) were decimated by 19th century commercial sealers in the northeastern Pacific and thought to be extinct until 1928 when commercial fishermen caught two adult males at Isla de Guadalupe from a group of up to 60 adults and pups (Wedgeforth 1928, Huey 1930). These two animals were brought to the San Diego Zoo, prompting several zoological expeditions to Isla de Guadalupe in the 1930s and 1940s, but none successfully located Guadalupe fur seals. In 1949, a single male was seen on San Nicolas Island, California (Bartholomew 1950), and in 1954, a small breeding group of animals was found in a cave at Isla de Guadalupe (Hubbs 1956). The population had grown to at least 500 animals in 1967, to about 7,400 animals in 1993, and to 12,176 in 2003, with breeding populations currently confined to Mexico’s Islas de Guadalupe and San Benito (Peterson et al. 1968, Gallo-Reynoso 1994, Gallo-Reynoso et al. 2005, Carretta et al. 2007). Although small numbers of Guadalupe fur seals haul out on the California Channel Islands today, including a female and single pup born on San Miguel Island in 1997, they are vastly outnumbered by California sea lions (Zalophus californianus), northern elephant seals (Mirounga angustirostris), northern fur seals (Callorhinus ursinus), and harbor seals (Phoca vitulina), all of which currently breed on San Miguel Island (Stewart et al. 1993, Melin and DeLong 1999, DeLong and Melin 2002). Archaeological and genetic data suggest, however, that the modern distribution and abundance of Guadalupe fur seals are very different from prehistoric distributions (Walker and Craig 1979, Colten 2002, Etnier 2002a, Walker et al. 2002, Weber et al. 2004)

Reply to Ellis et al.: human niche construction and evolutionary theory

We are pleased Ellis et al. found value in our recent synthesis of the deep history of human impacts on global ecosystems and agree that our paper should influence the current debate on if and how an Anthropocene epoch is defined. We also agree that the ecological consequences of human niche construction have profound and growing effects on the evolutionary trajectories of humans and other species living within human-altered ecosystems. Niche construction theory (NCT) provides an explicit framework for linking evolutionary and ecological processes into a coherent theory of biological evolution. Of special appeal to us as archaeologists is that NCT bridges biological and cultural evolution by including human culture and social learning within the mechanisms of evolutionary change, allowing scientists to address issues at the interface of human and natural systems. Some of us have contributed significantly to human NCT, addressing some of the very issues raised by Ellis et al. Finally, we agree that human transformations of ecosystems are inherently social processes—clearly humans are intensely social organisms—and that such processes result from long-term melding of biological and cultural evolution

Reply to Westaway and Lyman: emus, dingoes, and archaeology’s role in conservation biology

In a curious comment on our PNAS Perspective, Westaway and Lyman offer two Australian zooarchaeological case studies—one involving eggshells and the other dingoes—that they argue undercut one of our main points: that archaeological data and deep time perspectives have much to offer conservation biology. Neither example provides a specific substantive critique of our perspective: there are no dingoes in our article, no eggshells, and we mention the long and rich record of human management and alteration of Australian environments only briefly. Nor do we suggest that all archaeological assemblages can effectively inform current conservation biology efforts. Such datasets obviously vary in their quality and potential applicability to modern situations. When considered more closely, both of Westaway and Lyman’s case studies underscore rather than undercut the importance of archaeological and paleoecological data in conservation biology initiatives

Oregon 2100: projected climatic and ecological changes

Greenhouse climatic warming is underway and exacerbated by human activities. Future outcomes of these processes can be projected using computer models checked against climatic changes during comparable past atmospheric compositions. This study gives concise quantitative predictions for future climate, landscapes, soils, vegetation, and marine and terrestrial animals of Oregon. Fossil fuel burning and other human activities by the year 2100 are projected to yield atmospheric CO2 levels of about 600-850 ppm (SRES A1B and B1), well above current levels of 400 ppm and preindustrial levels of 280 ppm. Such a greenhouse climate was last recorded in Oregon during the middle Miocene, some 16 million years ago. Oregon’s future may be guided by fossil records of the middle Miocene, as well as ongoing studies on the environmental tolerances of Oregon plants and animals, and experiments on the biological effects of global warming. As carbon dioxide levels increase, Oregon’s climate will move toward warm temperate, humid in the west and semiarid to subhumid to the east, with increased summer and winter drought in the west. Western Oregon lowlands will become less suitable for temperate fruits and nuts and Pinot Noir grapes, but its hills will remain a productive softwood forest resource. Improved pasture and winter wheat crops will become more widespread in eastern Oregon. Tsunamis and stronger storms will exacerbate marine erosion along the Oregon Coast, with significant damage to coastal properties and cultural resources

Wildfire and Abrupt Ecosystem Disruption on California\u27s Northern Channel Islands at the Allerod-Younger Dryas Boundary (13.0-12.9 ka)

Sedimentary records from California\u27s Northern Channel Islands and the adjacent Santa Barbara Basin (SBB) indicate intense regional biomass burning (wildfire) at the Ållerød–Younger Dryas boundary (~13.0–12.9 ka) (All age ranges in this paper are expressed in thousands of calendar years before present [ka]. Radiocarbon ages will be identified and clearly marked “14C years”.). Multiproxy records in SBB Ocean Drilling Project (ODP) Site 893 indicate that these wildfires coincided with the onset of regional cooling and an abrupt vegetational shift from closed montane forest to more open habitats. Abrupt ecosystem disruption is evident on the Northern Channel Islands at the Ållerød–Younger Dryas boundary with the onset of biomass burning and resulting mass sediment wasting of the landscape. These wildfires coincide with the extinction of Mammuthus exilis [pygmy mammoth]. The earliest evidence for human presence on these islands at 13.1–12.9 ka (~11,000–10,900 14C years) is followed by an apparent 600–800 year gap in the archaeological record, which is followed by indications of a larger-scale colonization after 12.2 ka. Although a number of processes could have contributed to a post 18 ka decline in M. exilis populations (e.g., reduction of habitat due to sea-level rise and human exploitation of limited insular populations), we argue that the ultimate demise of M. exilis was more likely a result of continental scale ecosystem disruption that registered across North America at the onset of the Younger Dryas cooling episode, contemporaneous with the extinction of other megafaunal taxa. Evidence for ecosystem disruption at 13–12.9 ka on these offshore islands is consistent with the Younger Dryas boundary cosmic impact hypothesis [Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch, T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett, D.J., Erlandson, J.M., Dickenson, O.J., Goodyear, A.A., Harris, R.S., Howard, G.A., Kloosterman, J.B., Lechler, P., Mayewski, P.A., Montgomery, J., Poreda, R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W., Wittke, J.H. Wolbach, W.S., 2007. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and Younger Dryas cooling. Proceedings of the National Academy of Sciences 104, 16016–16021.]

An Anthropocene Without Archaeology—Should We Care?

For more than a decade, a movement has been gathering steam among geoscientists to designate an Anthropocene Epoch and formally recognize that we have entered a new geological age in which Earth’s systems are dominated by humans. Chemists, climatologists, and other scientists have entered the discussion, and there is a growing consensus that we are living in the Anthropocene. Nobel Prize-winning atmospheric chemist Paul Crutzen (2002a, 2002b; Crutzen and Stoermer 2000) coined the term, but the idea that humans are a driver of our planet’s climate and ecosystems has much deeper roots. Italian geologist Antonio Stoppani wrote of the “anthropozoic era” in 1873 (Crutzen 2002a), and many others have proposed similar ideas, including journalist Andrew Revkin’s (1992) reference to the “Anthrocene” and Vitousek and colleagues (1997) article about human domination of earth’s ecosystems. It was not until Crutzen (2002a, 2002b) proposed that the Anthropocene began with increased atmospheric carbon levels caused by the Industrial Revolution in the late eighteenth century (including the invention of the steam engine in A.D. 1784), however, that the concept began to gain serious traction among scientists and inspire debate