In a rejoinder to Gill et alia (2021), Martin (2022) accuses us of perpetuating misconceptions about human nutrition and erroneously describing geophytes as a dietary staple. We provide authoritative definitions for the terms “essential” and “dietary staple” to show that it is Martin who mischaracterizes and misunderstands the foundational role of geophytes and other plant foods to human diets and subsistence economies in Native North America outside of the Arctic. Recent data demonstrate that carbohydrate-rich geophytes were abundant, regularly utilized, and essential resources on the Northern Channel Islands, a dietary staple that was a rich source of calories and complemented the protein-rich shellfish and finfish that were also staple foods for the Island Chumash.

The places in which people live and spend time are steeped in history, memory, and meaning from the intersection of daily life, environmental interactions, cultural practices, and ritual. Geologic features, plants, animals, and ecosystems merge with these cultural histories, forming critical parts of the landscape and areas of “high cultural salience,” or “cultural keystone places” (CKPs). We identify Kumqaq’ (Point Conception) and the surrounding area in California as a Chumash CKP. Ethnohistoric accounts and contemporary Chumash community members have long demonstrated the importance of Point Conception in Chumash worldview and identity, whereas biologists, ecologists, and conservationists reference the area's rich biodiversity and significance as a biogeographical boundary. Recent archaeological survey of the coastline surrounding Kumqaq’ highlights these connections, identifying over 50 archaeological sites—including shell middens, villages, lithic scatters, and rock art—with at least 9,000 years of occupation. Ongoing collaborations among archaeologists, the Nature Conservancy, and Chumash community members help document and understand the long-term linkages between cultural and biological diversity and how integrating these perspectives can help ensure the resilience of this nexus of human and natural history in the Anthropocene future.

There is growing evidence for human use of geophytes long before the advent of agriculture. Rich in carbohydrates, geophytes were important in many coastal areas where protein-rich marine foods are abundant. On California's Channel Islands, scholars have long questioned how maritime peoples sustained themselves for millennia with limited plant resources. Recent research demonstrates that geophytes were heavily used on the islands for 10,000 years, and here we describe geophyte and other archaeobotanical remains from an approximately 11,500-year-old site on Santa Rosa Island. Currently the earliest evidence for geophyte consumption in North America, our data extend geophyte use on the Channel Islands by roughly 1,500 years and document a diverse and balanced economy for early Paleocoastal peoples. Experimental return rates for a key island geophyte support archaeological evidence that the corms of blue dicks (Dipterostemon capitatus) were a high-ranked staple resource throughout the Holocene.

High-resolution Chirp sub-bottom data were obtained offshore from the Northern Channel Islands (NCI), California, to image submerged paleoshorelines and assess local uplift rates. Although modern bathymetry is often used for modeling paleoshorelines, Chirp data image paleoshorelines buried beneath sediment that obscures their seafloor expression. The NCI were a unified landmass during the last glacial maximum (LGM; ~20 ka), when eustatic sea level was ~120 m lower than present. We identified seven paleoshorelines, ranging from ~28 to 104 m in depth, across this now-submerged LGM platform. Paleoshoreline depths were compared to local sea-level curves to estimate ages, which suggest that some were reoccupied over multiple sea-level cycles. Additionally, previous studies determined conflicting uplift rates for the NCI, ranging from 0.16 to 1.5 m/ka. Our results suggest that a rate on the lower end of this range better fits the observed submerged paleoshorelines. Using the uplift rate of ~0.16 m/ka, we estimate that paleoshorelines formed during Marine Oxygen Isotope Stage 3, the LGM, and the Younger Dryas stade are preserved on the NCI platform. These results help clarify uplift rates for the NCI and illustrate the importance of sub-bottom data for mapping submerged paleoshorelines.

Forty years ago, Knut Fladmark (1979) argued that the Pacific Coast offered a viable alternative to the ice-free corridor model for the initial peopling of the Americas—one of the first to support a “coastal migration theory” that remained marginal for decades. Today, the pre-Clovis occupation at the Monte Verde site is widely accepted, several other pre-Clovis sites are well documented, investigations of terminal Pleistocene subaerial and submerged Pacific Coast landscapes have increased, and multiple lines of evidence are helping decode the nature of early human dispersals into the Americas. Misconceptions remain, however, about the state of knowledge, productivity, and deglaciation chronology of Pleistocene coastlines and possible technological connections around the Pacific Rim. We review current evidence for several significant clusters of early Pacific Coast archaeological sites in North and South America that include sites as old or older than Clovis. We argue that stemmed points, foliate points, and crescents (lunates) found around the Pacific Rim may corroborate genomic studies that support an early Pacific Coast dispersal route into the Americas. Still, much remains to be learned about the Pleistocene colonization of the Americas, and multiple working hypotheses are warranted.

In the desert of southeastern California, the geological and archaeological remnants of a once massive lake, Lake Cahuilla, are still visible. One of the most distinctive features marking Lake Cahuilla's relic shorelines is a series of rock fish trap features that, in some cases, stretch across thousands of square meters. These fish traps are severely understudied, and systematic archaeological survey can help scientists reconstruct the dynamic human-environmental history of the region. The large number of fish traps along with the rocky desert terrain, however, make traditional pedestrian archaeological surveys both difficult and inefficient. We used unmanned aerial vehicle (UAV) technology along with traditional archaeological methods to conduct surveys and identify patterning in the shapes, orientations, and frequencies of fish traps. Our study demonstrates the potential of emerging archaeological field technology to better understand the nature of human-environmental ecodynamics through time and space.

In the face of environmental uncertainty due to anthropogenic climate change, islands are at the front lines of global change, threatened by sea level rise, habitat alteration, extinctions and declining biodiversity. Islands also stand at the forefront of scientific study for understanding the deep history of human ecodynamics and to build sustainable future systems. We summarize the long history of human interactions with Polynesian, Mediterranean, Californian and Caribbean island ecosystems, documenting the effects of various waves of human settlement and socioeconomic systems, from hunter–gatherer–fishers, to agriculturalists, to globalized colonial interests. We identify degradation of island environments resulting from human activities, as well as cases of human management of resources to enhance productivity and create more sustainable systems. These case studies suggest that within a general global pattern of progressive island degradation, there was no single trajectory of human impact, but rather complex effects based on variable island physiographies, human subsistence strategies, population densities, technologies, sociopolitical organization and decision-making.

The island fox (Urocyon littoralis) is one of few reportedly endemic terrestrial mammals on California's Channel Islands. Questions remain about how and when foxes first colonized the islands, with researchers speculating on a natural, human-assisted, or combined dispersal during the late Pleistocene and/or Holocene. A natural dispersal of foxes to the northern Channel Islands has been supported by reports of a few fox bones from late Pleistocene paleontological localities. Direct AMS 14C dating of these “fossil” fox bones produced dates ranging from ∼ 6400 to 200 cal yr BP, however, postdating human colonization of the islands by several millennia. Although one of these specimens is the earliest securely dated fox from the islands, these new data support the hypothesis that Native Americans introduced foxes to all the Channel Islands in the early to middle Holocene. However, a natural dispersal for the original island colonization cannot be ruled out until further paleontological, archaeological, and genetic studies (especially aDNA [ancient DNA]) are conducted.

Glassow’s (2015) synthesis of “red abalone middens” on California’s Santa Cruz Island does not include the broader geographic, chronologic, and ecological context to this phenomenon. We explore the wider distribution of these site types and emphasize their importance for addressing modern fisheries management issues.

I thank all the authors for their thoughtful responses to my paper. I believe they effectively highlight some of the diverse opinions about the concept of the Anthropocene and underscore the challenges faced by the ICS subcommission.

The concept of the Anthropocene has become increasingly prominent in recent years, but is it best defined as a geological period or as part of a longer-term pattern of human actions? And when did it begin? Todd Braje launches this Debate feature by arguing for a shift away from definitions and toward an emphasis on the human causes and consequences. This piece is followed by a series of reactions from geologists and anthropologists, with a concluding reply from the author.

California's Northern Channel Islands have long been an epicenter of specialized fishing economies dating from 13,000 yr ago to the mid-19th century. With thousands of well-preserved shell middens, some dominated by single shellfish species and little to no material culture, it can be difficult to distinguish between specialized prehistoric and historical deposits at some site types. Beginning at least in the Early Holocene and continuing into the Historic period, California mussels, turban snails, and abalone were targeted for specialized collection and processing by Native Americans and later Chinese and Euro-American fishers. Here, we demonstrate how selective accelerator mass spectrometry (AMS) radiocarbon dating of specialized abalone processing camps can help distinguish between prehistoric and historical sites. While unconventional, our case study demonstrates the utility of 14C dating at sites less than 300 yr old.

For at least 100,000 yr, marine shell beads have been important ornamental and symbolic artifacts intimately associated with the behavior of anatomically modern humans. In California, giant rock scallop (Hinnites multirugosus) beads were once thought to have been used only for the last 1000 yr, where they were considered to be markers of high social status among the Chumash Indians of the Santa Barbara Channel region. Direct accelerator mass spectrometry (AMS) radiocarbon dating of 1 giant rock scallop ornament and 2 beads from San Miguel Island extends the use of this shell for personal adornment to at least 8000 cal BP. Our study emphasizes the importance of direct AMS 14C dating of artifacts to enhance cultural chronologies and clarify the antiquity of various technologies and associated behaviors. Our results also caution archaeologists when equating artifact rarity with sociopolitical complexity.

Within the broad framework of historical and behavioral ecology, we analyzed faunal remains from a large habitation site (CA-SRI-147) on Santa Rosa Island to explore a 7,000 year record of coastal subsistence, nearshore ecological dynamics, and human impacts on shellfish populations. This long, stratified sequence provides a rare opportunity to study the effects of prolonged human predation on local intertidal and nearshore habitats. During the past 7,000 years, the Island Chumash and their predecessors had significant impacts on nearshore ecosystems, caused by growing human populations and depletion of marine and terrestrial ecosystems. At CA-SRI-147, local depletion of higher ranked shellfish species stimulated dietary expansion and a heavier reliance on lower-ranked shellfish taxa and more intensive exploitation of nearshore and pelagic fishes. In the Late Holocene, as local ecosystems were increasingly depleted, the Island Chumash relied increasingly on craft specialization and trade to meet their subsistence needs. Native peoples clearly impacted Channel Island ecosystems, but data from CA-SRI-147 suggest that they adjusted their subsistence strategies toward productive fisheries that sustained the high population densities and sociopolitical complexity recorded by early Spanish chroniclers at European contact.

California's San Miguel Island contains over 600 archaeological sites, some occupied as early as 12,000 yr ago and most located along the island's north coast. Archaeologists have long believed the south coast to have been marginal or largely uninhabited. Burial of some landforms by sand dunes deposited after historical overgrazing, the lack of systematic survey, and a dearth of radiocarbon dating have also contributed to an underestimation of the intensity of human land use along the south coast of San Miguel Island. Our recent reconnaissance and dating of shell middens on the island's south coast indicate more intensive occupation than previously thought, with numerous south coast sites spanning at least the past 9000 yr, and demonstrate the utility of combining systematic archaeological reconnaissance and radiometrics in reconstructions of human settlement and historical ecology in coastal environments.