Friday, May 9, 2008

Human ancestors at waterside, Kelp highway

map of Monte Verde, Chile

Chile coast, medicine hut with seaweed cuds

WASHINGTON — Remains of meals that included seaweed are helping confirm the date of a settlement in southern Chile that may offer the earliest evidence of humans in the Americas.

Researchers date the seaweed found at Monte Verde to more than 14,000 years ago, 1,000 years earlier than the well-studied Clovis culture. And the report comes just a month after other scientists announced they had found coprolites - fossilized human feces - dating to about 14,000 years ago in a cave in Oregon.

See pictures: map, medicine hut, seaweed quids

Kelp Iodine scavenges reactive oxygen species
FC K�pper et al.2008 PNAS 105:6954-8
Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry

Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodo-carbons in the coastal atmosphere. Nevertheless, the chemical state & biological significance of accumulated iodine have remained unknown to this date.

Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic anti-oxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface & in the apoplast, iodide detoxifies both aqueous oxidants & ozone, the latter resulting in the release of high levels of molecular iodine & the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human
blood cells.

Early chicken in South America not Polynesian

Blue highway: African Rift - Blue Nile
(University of Texas at Austin anthropologist) John Kappelman presented this counterintuitive idea October 19 in a talk titled “Blue Highways,” which followed his fossil digs along the Blue Nile tributaries in Ethiopia. Early humans are thought to have taken one of two routes out of Africa: along the Red Sea, or along the Nile Valley and out across Eurasia.

But “there’s been very little testing on the ground, recovering fossils and sites that actually permit us to evaluate either one of those two hypothetical migration events,” Kappelman said.

(British naturalist) Samuel Barker noticed something key: The rivers are dry for most of the year, but every summer the water rushes back “like freight cars,” Kappelman said. The torrent of water gouged out deep holes that retained water even during the dry season, leaving a necklace of isolated pools.

And the pools were full of fish. “The fish were literally in a bucket,” Kappelman says.

Kappelman and his team found double-edged blades that were probably used as arrow heads and evidence of hearth fires in several sites around the Nile.

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