Tarefa para casa de Evolução Humana 101 para Marcelo Gleiser

sábado, fevereiro 26, 2011

Ape or Human? Fossils' Link to Evolution Questioned
Natalie Wolchover, Life's Little Mysteries Staff Writer
Date: 23 February 2011 Time: 09:10 PM ET

In a paper published Feb. 19 in the science journal Nature, two paleoanthropologists argue that some recently discovered primate fossils may not be as human as everyone thinks. While the authors maintain that humans did, of course, evolve from apes, their contentions highlight the difficulty of using 7-million-year-old bone fragments to piece together the full story of human evolution.

The fossils in question — corresponding to species named Orrorin tugenensisSahelanthropus tchadensis and Ardipithecus ramidus — have all made headlines in recent years for filling in gaps in the evolution from apes to humans. Though they've been hailed as remnants of some of our earliest hominin ancestors, paleoanthropologists Bernard Wood of George Washington University and Terry Harrison of New York University say they're probably just non-hominin ape bones.

"The problem is that a number of features that have been identified as being related to humans may be interpreted in different ways," Harrison told Life's Little Mysteries, a sister site to LiveScience.

For example, all that has been found ofSahelanthropus, the oldest genus widely believed to have been a hominin, is a 7-million-year-old partial skull. And yet, from its shape, paleoanthropologists have concluded that the specimen must have walked upright. "The position of its foramen magnum"—the spot where the brain connects to the spinal cord—"has historically been argued to be associated with bipedalism," said Harrison. "However, we see from comparative anatomy that that's not always the case."

In 2008, Orrorin, the second-oldest alleged hominin, was also argued to be bipedal in an article in Science by William Jungers at Stony Brook University and his colleagues. But Harrison and Wood argue that Orrorin might not have walked upright either.

And of the famous 4.4-million-year-old Ardipithecus partial skeleton found in 2009, Harrison said, "It's a remarkable find. It's really incredible to have such an old skeleton of a potential human ancestor. But we would argue it seems to look like many of the forms of the apes we have seen from that period."

Skepticism regarding these famous primate fossil finds seems to call into question the rigor of the scientific process within the field of paleoanthropology. Wood's and Harrison's paper certainly makes one wonder: Are these isolated incidents of misinterpretation followed by media hype, or does the problem pervade the whole branch of science? Is the human evolutionary fossil record a crapshoot?

"No," said Harrison. There are reasons why this branch of science may seem messier than most, he said, but all things considered, it is doing extremely well.


Read more here: Live Science



Marcelo Gleiser afirmou recentemente no seu artigo Defendendo a ciência, publicado na Folha de São Paulo, que a questão da evolução humana já estava cientificamente estabelecida: registro fóssil, genômica y otras cositas mais. Nada mais falso. 

A área da paleoantropologia é uma das áreas científicas onde os egos são inchados pela possível glória de entrar para o panteão da ciência se o elo perdido for encontrado. Há muitas disputas internas nesta ciência. Mas o que eles têm de evidência é circunstancial e não resiste ao rigor de pesquisas científicas como essa aqui.

Tarefa para casa de Evolução Humana 101 para Marcelo Gleiser: 

Escrever 1.000 vezes - "O fato, Fato, FATO da evolução humana ainda não foi cientificamente estabelecido."