Mark Hardiman

Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards

Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the discovery of cryptotephra deposits (volcanic ash layers that are not visible to the naked eye) in archaeological cave sequences. They enable us to synchronize archaeological and paleoclimatic records through the period of transition from Neanderthal to the earliest anatomically modern human populations in Europe. Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.

Fire history on the California Channel Islands spanning human arrival in the Americas

Recent studies have suggested that the first arrival of humans in the Americas during the end of the last Ice Age is associated with marked anthropogenic influences on landscape; in particular, with the use of fire which, would have given even small populations the ability to have broad impacts on the landscape. Understanding the impact of these early people is complicated by the dramatic changes in climate occurring with the shift from glacial to interglacial conditions. Despite these difficulties, we here attempt to test the extent of anthropogenic influence using the California Channel Islands as a smaller, landscape-scale test bed. These islands are famous for the discovery of the ‘Arlington Springs Man’, which are some of the earliest human remains in the Americas. A unifying sedimentary charcoal record is presented from Arlington Canyon, Santa Rosa Island, based on over 20 detailed sedimentary sections from eight key localities. Radiocarbon dating was based on thin, fragile, long fragments of charcoal in order to avoid the ‘inbuilt’ age problem. Radiocarbon dating of 49 such fragments has allowed inferences regarding the fire and landscape history of the Canyon ca 19–11 ka BP. A significant period of charcoal deposition is identified approximately 14–12.5 ka BP and bears remarkable closeness to an estimated age range of the first human arrival on the islands. This article is part of the themed issue ‘The interaction of fire and mankind’.

Inconsistent redefining of the carbon spherule “impact” proxy

The recent article by Israde-Alcantara et al. (1) outlined a wide array of purported impact proxies from a lacustrine paleo-record in Lake Cuitzeo, Mexico. These findings were used to support the suggestion of a Younger Dryas (YD) impact event/s. Although most of the purported impact proxies have been described in previous publications (2, 3), this new work extended the range of such markers to Mexico. The article also allowed the proponents of the YD Impact Hypothesis [YDIH] to respond to the many critiques of the YDIH.

Did Nanodiamonds Rain from the Sky as Woolly Mammoths Fell in their Tracks Across North America 12,900 Years Ago?

1. Institute for Materials Science and Engineering, Washington University, St. Louis, MO, USA. 2. Department of Physics, Laboratory for Space Sciences, Washington University, St. Louis, MO, USA. 3. Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, UK. 4. Department of Geography, University of Portsmouth, Portsmouth, UK. 5. Department of Earth and Planetary Sciences, University of California Davis, Davis CA, USA. 6. School of Earth Sciences and Environmental Sustainability, Northern Arizona U., Flagstaff, AZ, USA.