Noticias

Stone Spear Tips Surprisingly Old—"Like Finding iPods in Ancient Rome"

Ker Than

for National Geographic News

Published November 16, 2012

Some of our early human ancestors may have been smarter, and deadlier, than we thought, according to a new study of what may be Earth's oldest stone spear points.

If the dating is correct, it suggests our evolutionary forebears mastered the art of the stone-tipped spear half a million years ago—some 250,000 years earlier than previously thought.

Discovering that the world's oldest known spear points may come from a Homo heidelbergensis site is "like finding an iPod in a Roman Empire site," said paleoanthropologist John Shea, who wasn't part of the study. "It's that level of weirdness."

But it isn't weird to imagine these stocky big-game hunters using stone tools or even wooden spears in what's now South Africa. Until now, though, there's been no evidence H. heidelbergensis had the know-how to put the two together.

To fasten a handle to a blade—a technique called hafting—a prehistoric hunter likely would have had to procure a stone blade, a wooden shaft, twine woven from plants or animal sinew, and glue made from tree resin. The glue itself may have required a mastery of fire, to liquefy the resin, said Shea, of New York's Stony Brook University.

Supplies in hand, the toolmaker would have had to assemble the spear sturdily, "so you don't get killed the first time you use it on a Cape buffalo," Shea said. 

Video Relacionado "Spear-Wielding Chimps Studied"

"Lucy's Baby" a Born Climber, Hinting Human Ancestors Lingered in Trees

James Owen

for National Geographic News

Published October 26, 2012

What made us human? Part of the answer may rest on the shoulders of a 3.3-million-year-old toddler.

Like "Lucy," the fossil child was a member of the species Australopithecus afarensis, pioneers of upright walking. Yet her apelike shoulder blades hint that our forebears may have taken longer than we thought to fully come down to earth, a new study says.

Figuring out when the tree-to-ground transition took place is immensely important to understanding how we became who we are. Bipedalism, after all, gave prehumans a literal head's-up on approaching predators and freed up hands for stone tools, which in turn gave access to more types of food, including brain-boosting animal proteins—among other advantages.

The tiny fossils—including the only known complete A. afarensis scapula, or shoulder blade—add to evidence that that giant stride was more a series of faltering steps.

"What we're showing is that bipedalism wasn't this sudden change that took shape in an early common ancestor," said study co-author David Green, an anatomy professor at Midwestern University in Downers Grove, Illinois.

"As bipedalism was developing, there were other forms of locomotion that were still important."

(See an interactive time line of human evolution.)

Clinging to the Branches of the Human Family Tree?

"Selam," or "Lucy's baby," or "Dikika baby"—as the A. afarensis three-year-old has been variously nicknamed—spent millions of years encased in rock in Ethiopia's Dikika region, where the shady forests she knew have long since given way to desert. (See pictures of the Dikika baby.)

After discovering Selam in 2000, Zeresenay Alemseged spent 11 years flecking away sandstone to free what remained of her bones. For the new study, the California Academy of Sciences anthropologist and colleagues compared her fossils with those of living apes, humans, and other early human species.

The team found that the sockets of Selam's shoulder joints point upward, as they do in apes. Likewise, the bony ridge that runs along her shoulder blades is set at a similar angle as in chimpanzees.