Revista Scientific American Marzo 2016. Inglés
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Revista Scientific American Marzo 2016. Inglés
ISSN: 0036-8733
Descripción
Controversy and Excitement Swirl around New Human Species
An astonishing trove of fossils has scientists, and the media, in a tizzy over our origins
By Kate Wong
In the brand-new fossil vault at the University of the Witwatersrand, Johannesburg, in South Africa, shelf space is already running out. The glass-doored cabinets lining the room brim with bones of early human relatives found over the past 92 years in the many caves of the famed Cradle of Humankind region, just 40 kilometers northwest of here. The country’s store of extinct humans has long ranked among the most extensive collections in the world. But recently its holdings doubled with the discovery of hundreds of specimens in a cave system known as Rising Star. According to paleoanthropologist Lee Berger and his colleagues, who unearthed and analyzed the remains, they represent a new species of human Homo naledi, for “star” in the local Sotho language that could overturn some deeply entrenched ideas about the origin and evolution of our genus, Homo.
The Brain’s Waste-Disposal System May Be Enlisted to Treat Alzheimer’s and Other Brain Illnesses
An internal plumbing system rids the brain of toxic wastes. Sleep is when this cleanup ritual occurs
By Maiken Nedergaard, Steven A. Goldman
The human brain weighs only about three pounds, or roughly 2 percent of the average adult body mass. Yet its cells consume 20 to 25 percent of the body’s total energy. In the process, inordinate amounts of potentially toxic protein wastes and biological debris are generated.Each day, the adult brain eliminates seven grams of worn-out proteins that must be replaced with newly made ones, a figure that translates into the replacement of about half a pound of detritus a month and nearly six pounds, twice the brain’s own weight, over the course of a year.
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Revista Scientific American Marzo 2016. Inglés
ISSN: 0036-8733
Descripción
Controversy and Excitement Swirl around New Human Species
An astonishing trove of fossils has scientists, and the media, in a tizzy over our origins
By Kate Wong
In the brand-new fossil vault at the University of the Witwatersrand, Johannesburg, in South Africa, shelf space is already running out. The glass-doored cabinets lining the room brim with bones of early human relatives found over the past 92 years in the many caves of the famed Cradle of Humankind region, just 40 kilometers northwest of here. The country’s store of extinct humans has long ranked among the most extensive collections in the world. But recently its holdings doubled with the discovery of hundreds of specimens in a cave system known as Rising Star. According to paleoanthropologist Lee Berger and his colleagues, who unearthed and analyzed the remains, they represent a new species of human Homo naledi, for “star” in the local Sotho language that could overturn some deeply entrenched ideas about the origin and evolution of our genus, Homo.
The Brain’s Waste-Disposal System May Be Enlisted to Treat Alzheimer’s and Other Brain Illnesses
An internal plumbing system rids the brain of toxic wastes. Sleep is when this cleanup ritual occurs
By Maiken Nedergaard, Steven A. Goldman
The human brain weighs only about three pounds, or roughly 2 percent of the average adult body mass. Yet its cells consume 20 to 25 percent of the body’s total energy. In the process, inordinate amounts of potentially toxic protein wastes and biological debris are generated.Each day, the adult brain eliminates seven grams of worn-out proteins that must be replaced with newly made ones, a figure that translates into the replacement of about half a pound of detritus a month and nearly six pounds, twice the brain’s own weight, over the course of a year.