Pre-Clovis occupation 14,550 years ago at the Page-Ladson site, Florida, and the peopling of the Americas

Halligan, Jessi; Waters, Michael R.; Perrotti, Angelina G.; Owens, Ivy J.; Feinberg, Joshua M.; Bourne, Mark D.; Fenerty, Brendan; Winsborough, Barbara; Carlson, David Lee; Fisher, Daniel C.; Stafford, Thomas W.; Dunbar, James S.

doi:10.1126/sciadv.1600375

Cited by 183 publications

(86 citation statements)

References 73 publications

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“…Clovis tools have only rarely been found in association with megafaunal remains. Evidence for pre-Clovis human occupation in the Americas includes locations in southern Chile (Dillehay et al, 2015), and the Florida panhandle where human occupation at~14.5 ka predated the Sporormiella decline by~2 kyr (Halligan et al, 2016), consistent with Sporormiella disappearance at~12.7 ka at another Florida panhandle location (Perrotti, 2018). Paucity of evidence for human occupation prior to~13 ka can be attributed to habitation being concentrated in coastal regions that were largely submerged during the subsequent (last) deglaciation, when sea level rise necessitated migration of humans and other terrestrial mammals into the continental interior.…”

Section: Reviews Of Geophysicsmentioning

confidence: 99%

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

Channell

Vigliotti

2019

Reviews of Geophysics

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It has long been speculated that biological evolution was influenced by ultraviolet radiation (UVR) reaching the Earth's surface, despite imprecise knowledge of the timing of both UVR flux and evolutionary events. The past strength of Earth's dipole field provides a proxy for UVR flux because of its role in maintaining stratospheric ozone. The timing of Quaternary evolutionary events has become better constrained by fossil finds, improved radiometric dating, use of dung fungi as proxies for herbivore populations, and improved ages for nodes in human phylogeny from human mitochondrial DNA and Y chromosomes. The demise of Neanderthals at ~41 ka can now be closely tied to the intensity minimum associated with the Laschamp magnetic excursion, and the survival of anatomically modern humans can be attributed to differences in the aryl hydrocarbon receptor that has a key role in the evolutionary response to UVR flux. Fossil occurrences and dung‐fungal proxies in Australia indicate that episodes of Late Quaternary extinction of mammalian megafauna occurred close to the Laschamp and Blake magnetic excursions. Fossil and dung fungal evidence for the age of the Late Quaternary extinction in North America (and Europe) coincide with a prominent decline in geomagnetic field intensity at ~13 ka. Over the last ~200 kyr, phylogeny based on mitochondrial DNA and Y chromosomes in modern humans yields nodes and bifurcations in evolution corresponding to geomagnetic intensity minima, which supports the proposition that UVR reaching Earth's surface influenced mammalian evolution with the loci of extinction controlled by the geometry of stratospheric ozone depletion.

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Section: Reviews Of Geophysicsmentioning

confidence: 99%

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

Channell

Vigliotti

2019

Reviews of Geophysics

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“…The gross features of the late (45-50 kya) out-of-Africa dispersal of Homo sapiens are reproduced [32], e.g. the colonization of Western Europe before 40 kya and that of South America before 14 kya [31]. As the upper plot in the right-hand panel of Fig 3 shows, for these ( r , D ) parameters, arrival times increase as T s ≥ 45 increases.…”

Section: World-wide Hominin Dispersalmentioning

confidence: 95%

A Stable Finite-Difference Scheme for Population Growth and Diffusion on a Map

et al. 2017

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We describe a general Godunov-type splitting for numerical simulations of the Fisher–Kolmogorov–Petrovski–Piskunov growth and diffusion equation on a world map with Neumann boundary conditions. The procedure is semi-implicit, hence quite stable. Our principal application for this solver is modeling human population dispersal over geographical maps with changing paleovegetation and paleoclimate in the late Pleistocene. As a proxy for carrying capacity we use Net Primary Productivity (NPP) to predict times for human arrival in the Americas.

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“…In addition to the number of geotagged responses (Geo) about a topic, there are several other aspects of the conversation that can be retrieved to represent different types of response to the two topics in urban areas. The numbers of Unique Users (UU) represents the number of users that responded to this topic (Kryvasheyeu et al 2016), and the average number of posts by unique users (Post-User) can be treated as the intensity of engagement from the users. Retweeting activities have been used in Twitter-based diffusion studies as the indicator of diffusion (Yang and Counts 2010;Suh et al 2010), and thus the total number of retweets (RT) and non-retweets (noRT) are included.…”

Section: Representing Conversation Aspectsmentioning

confidence: 99%

Reshaping the urban hierarchy: patterns of information diffusion on social media

Yang

Tsou

Janowicz

et al. 2019

Geo-spatial Information Science

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The spatial diffusion of information is a process governed by the flow of interpersonal communication. The emergence of the Internet and especially social media platforms has reshaped this process and previous research has studied how online social networks contribute to the diffusion of information. Understanding such processes can help devise methods to maximize or control the reach of information or even identify upcoming events and social movements. Yet activities in cyberspace are still confined to physical locations and this geographic connection tends to be overlooked. In this research, we focus on geographic regions instead of individuals and study how the underlying hierarchical structure of regions relates to their response to the information. We examined the top 30 populated cities and metropolitan areas in the U.S. and retrieved Twitter data related to two selected topics from these regions, the 2015 Nepal Earthquake and the #JesuisCharlie hashtag in response to the Paris attacks on the Charlie Hebdo offices. We analyzed the similarity among regions of their response using multiple statistical methods and three urban classifications. Our results indicate that the diffusion of information is impacted by the hierarchy of urban regions and that the Twitter responses act more similar when the populated regions are positioned at the same level in the urban hierarchy. ARTICLE HISTORY

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Pre-Clovis occupation 14,550 years ago at the Page-Ladson site, Florida, and the peopling of the Americas

Abstract: Page-Ladson, Florida, provides evidence of the oldest human occupation in the North American Gulf Coastal Plain at 14,550 B.P.

Cited by 183 publications

References 73 publications

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

A Stable Finite-Difference Scheme for Population Growth and Diffusion on a Map

Reshaping the urban hierarchy: patterns of information diffusion on social media

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