(Related: "Neandertals Had Long Childhoods, Tooth Study Suggests" [September 20, 2005].)
Similar signs of interrupted growth have been noted in Neandertal remains discovered elsewhere.
The likely cause of this malnutrition was either food shortages due to climatic conditions, Rosas said—"probably because the weather was very cold or the other possibility is that they were suffering from some sort of illness.
"What is clear is that their growth was stopped, for whatever reason," he added.
The new study is the first to indicate that Neandertals in one region looked different from Neandertals in other areas, Rosas says.
Jawbone remains from the Spanish cave site, which is near the northwestern town of Oviedo (Spain map), helped paint the portrait for the researchers.
"What we have seen in this sample is that the southern Neandertals had their faces a little bit broader and shorter" than those of Neandertals living farther north, Rosas said.
Using the bone finds from the cave site, called El Sidrón, as a guide, the study team identified two main Neandertal populations based on known facial features.
One group inhabited southwest Asia and southern Europe, including Spain, the scientists say. The other lived in the northern area of the Neandertals' range.
The study team says these two varieties probably existed largely in isolation, with each group perhaps evolving slightly different features.
"Probably climatic conditions had a strong influence on the anatomy of these fellows," Rosas said.
The team notes that DNA analysis of Neandertal remains supports the idea of different lineages within the Neandertal gene pool. They add that the evolution of this human species produced a "regional diversity of populations."
(Related: "Neandertal DNA Partially Mapped, Studies Show" [November 15, 2006].)
Erik Trinkaus, an anthropologist at Washington University in St. Louis, Missouri, comments that the study shows Neandertals were more diverse than previously believed.
"Neandertals are variable, and some of that variation is geographically patterned," he said.
More evidence for physical differences are likely to emerge as more Neandertals fossils are recovered and studied, Trinkaus says.
"The type of separation we're talking about is what's called isolation by distance," he added.
"It doesn't mean that there are necessarily any [geographical] barriers. But where there are barriers, like mountain ranges, that accentuates it."
Trinkaus agrees that contrasting living conditions possibly account for altered features in the two population groups. For instance, he says, the northern Neandertals may have had a larger internal nose for heating up the colder air they breathed.
But, he added, "We don't have the fossils to show that at present."
Rosas, who led the study, says there's a big question mark looming over the Neandertal bone cave at El Sidrón.
The cannibalized remains were found together, but no dismemberment tools or animal remains were in evidence. This, Rosas said, is "very peculiar."
"What is the meaning of this?" he asked. "Some specific behavior is going on." Perhaps a ritual of some kind?
Washington University's Trinkaus argues that there's little mystery about the underlying reasons for outbreaks of Neandertal cannibalism.
"I think it's just these people were hungry," he said.
"They had periods of seasonal starvation, and on occasion, when they are really starving and members of their social group are already dead, they consumed their remains."
"It's what I call survival cannibalism," Trinkaus added, comparing these episodes to cases of cannibalism in recent human history.
Cases, for instance, resulting "from airplane crashes in high mountains." (See "Alive! Retracing the Survivors' Daring Escape".)
"I think that's the kind of stuff we're looking at."
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