Newsgroup: it.politica.internazionale
Titolo: Umani e Scimpanze' si sono incrociati per milioni di anni (Reuters)

 Dedicato a quei campioni cattolici dell'Umano che hanno irriso la 
legislazione di Zapatero per la protezione dei Grandi Primati.
Am.
Genetic study reveals surprises in human evolution
 Wed May 17, 4:12 PM ET
LONDON (Reuters) - Humans' evolutionary split from their closest 
relatives, chimpanzees, may have been more complicated, taken longer and 
probably occurred more recently than previously thought, scientists said 
on Wednesday.
After comparing the genomes, or genetic codes, of the two species they 
suggest the initial split took place no more than 6.3 million years ago 
and probably less than 5.4 million years ago.
The process of separation may have taken about 4 million years and there 
could have been some inter-breeding before the final break.
"The study gave unexpected results about how we separated from our 
closest relatives, the chimpanzees," said David Reich of the Broad 
Institute and Harvard Medical School's Department of Genetics in 
Massachusetts.
Instead of analyzing genetic differences between humans and chimpanzees, 
Reich and researchers from the Massachusetts Institute of Technology 
(MIT) and the Broad Institute of Harvard and MIT looked at variations in 
the degree of divergence between the two in different regions of the 
genomes.
The analysis, published in the journal Nature, shows some regions in the 
human genome are older than others which means they trace back to 
different times in the common ancestral population of the two species.
The youngest regions are unexpectedly recent, according to the 
researchers, which means the separation between the two species was more 
recent than previously thought.
"A hybridization event between human and chimpanzee ancestors could help 
explain both the wide range of divergence times seen across our genomes, 
as well as the relatively similar X chromosomes," Reich explained.
Hybridization refers to the initial separation of two species followed 
by interbreeding and then the final split.
The findings also raise questions about the 7 million year old fossil of 
a skull called "Toumai" which was thought to be the earliest member of 
the human family.
The skull, which has a mixture of primitive and human-like features and 
dates, was hailed as probably the most important fossil discovery in 
living memory because it was thought to belong to an ancient ancestor of 
modern humans.
Some scientists had argued it was a fossil of a female ape.
"It is possible that the Toumai fossil is more recent than previously 
thought," said Nick Patterson, of the Broad Institute and a co-author of 
the study.
"But if the dating is correct, the Toumai fossil would precede the 
human-chimp split. The fact that it has human-like features suggest that 
human-chimp speciation (separation) may have occurred over a long period 
with episodes of hybridization between the emerging species," he added.

e poi "finalmente" nacque l'ibrido amalric.
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