Hunters and gatherers living in tropical forests represent an important part of the total range of variation among contemporary hunting and gathering societies. Studies of tropical forest hunting and gathering peoples have contributed to our perceptions of the foraging way of life. Yet no peoples have ever been directly observed living independently of agriculture in tropical rain forest. This article tests the hypothesis that humans do not exist nor have ever existed independently of agriculture in tropical rain forest. We find no convincing ethnographic evidence and, with the possible exception of Malaysia, no archeological evidence for pure foragers in undisturbed tropical rain forests. Negative evidence cannot be conclusive, but it suggests that we need to carefully reexamine common assumptions concerning the recent history of tropical forest dwellers, the adaptability of preagricultural humans, the geographic and environmental range of hominids, and the form and consequences of selection pressures acting on humans in warm, humid environments. The overriding purpose of this article is to stimulate further ecological and archeological research in the neglected tropical forest areas of the world.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.The geographic expansion of Tiwanaku people and culture (cal A.D. 500-1150) in the south-central Andes can be viewed as a two-staged diaspora. This article defines and categorizes diasporas, suggests archaeological correlates and theoretical implications, and reconstructs the Tiwanaku diaspora. The first stage was a colonizing diaspora in the context of the functioning Tiwanaku state, limited to a few mid-elevation places such as the middle Osmore drainage near Moquegua and probably Cochabamba. The second stage was a much more extensive victim/refugee diaspora driven by the violent disintegration of the colonies around A.D. 1000, in conjunction with either the collapse of Tiwanaku or its radical reorientation by a militaristic elite. Second-stage diaspora populations that settled in sparsely populated areas such as the upper Osmore drainage or the Carumas-Calacoa region established dispersed, small, defensible villages. Those that settled among a larger or more established host population such as the Chiribaya in the coastal Osmore Valley integrated as a marked, lowerstatus minority. This explosive collapse suggests that Tiwanaku was composed of multiple groups whose differing interests could not be contained. Supporting evidence is drawn primarily from the Osmore drainage, especially the coastal segment. Se puede ver la extension geogrdfica de la gente y cultura Tiwanaku (500-1150 d.C.) en los Andes sur-centrales como una didspora de dos etapas. Este articulo define y clasifica didsporas, sugiera correlativos arqueol6gicos y consecuencias te6ricas, y reconstruye la didspora Tiwanakota. La primera etapafue una didspora colonizadora, en el contexto del estado Tiwanaku en marcha. Esta fue limitada a unos sitios de altura intermedia, como la cuenca media del Osmore cerca a Moquegua, y probablemente Cochabamba. La segunda etapafue una didspora mucho mds extensa, del tipo victima/refugiado. Fue impulsada por la desintegraci6n violenta de las colonias alrededor de 1000 d.C., contempordneo con el colapso de Tiwanaku o su reorientacion radical por un elite militar Poblaciones de la segunda etapa que se asentaron en dreas poco pobladas, como la cuenca superior del Osmore o la region de Carumas-Calacoa, establecieron aldeas pequehias, dispersas, y defendibles. Los que se asentaron entre una poblacion mayor o mejor establecida, como los Chiribaya en el Osmore costero, integraron como una minoria marcada, de menor estatus. Este colapso explosivo sugiere que Tiwanaku era compuesto de grupos mdltiples cuyos intereses diversos no podian ser contenidos. Datos en apoyo provienen principalmente de la cuenca Osmore, especialmente el Osmore costero.

Transposable elements (TEs) are drivers of evolution resulting in episodic surges of genetic innovation and genomic reorganization (Oliver KR, Greene WK. 2009. TEs: powerful facilitators of evolution. Bioessays 31:703-714.), but there is little evidence of the timescale in which this process has occurred (Gingerich PD. 2009. Rates of evolution. Ann Rev Ecol Evol Syst. 40:657-675.). The paleontological and archaeological records provide direct evidence for how evolution has proceeded in the past, which can be accessed through ancient DNA to examine genomes using high-throughput sequencing technologies (Palmer SA, Smith O, Allaby RG. 2011. The blossoming of plant archaeogenetics. Ann Anat. 194:146-156.). In this study, we report shotgun sequencing of four archaeological samples of cotton using the GS 454 FLX platform, which enabled reconstruction of the TE composition of these past genomes and species identification. From this, a picture of lineage specific evolutionary patterns emerged, even over the relatively short timescale of a few thousand years. Genomic stability was observed between South American Gossypium barbadense samples separated by over 2,000 miles and 3,000 years. In contrast, the TE composition of ancient Nubian cotton, identified as G. herbaceum, differed dramatically from that of modern G. herbaceum and resembled closely the A genome of the New World tetraploids. Our analysis has directly shown that considerable genomic reorganization has occurred within the history of a domesticated plant species while genomic stability has occurred in closely related species. A pattern of episodes of rapid change and periods of stability is expected of punctuated evolution. This observation is important to understanding the process of evolution under domestication.

Can.

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