The first humans to reach the Americas are likely to have come via a coastal route

SUMMARY: 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.

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.

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.

The intensive commercial exploitation of California sheephead (Semicossyphus pulcher) has become a complex, multimillion-dollar industry. The fishery is of concern because of high harvest levels and potential indirect impacts of sheephead removals on the structure and function of kelp forest ecosystems. California sheephead are protogynous hermaphrodites that, as predators of sea urchins and other invertebrates, are critical components of kelp forest ecosystems in the northeast Pacific. Overfishing can trigger trophic cascades and widespread ecological dysfunction when other urchin predators are also lost from the system. Little is known about the ecology and abundance of sheephead before commercial exploitation. Lack of a historical perspective creates a gap for evaluating fisheries management measures and marine reserves that seek to rebuild sheephead populations to historical baseline conditions. We use population abundance and size structure data from the zooarchaeological record, in concert with isotopic data, to evaluate the long-term health and viability of sheephead fisheries in southern California. Our results indicate that the importance of sheephead to the diet of native Chumash people varied spatially across the Channel Islands, reflecting modern biogeographic patterns. Comparing ancient (~10,000 calibrated years before the present to 1825 CE) and modern samples, we observed variability and significant declines in the relative abundance of sheephead, reductions in size frequency distributions, and shifts in the dietary niche between ancient and modern collections. These results highlight how size-selective fishing can alter the ecological role of key predators and how zooarchaeological data can inform fisheries management by establishing historical baselines that aid future conservation.