jueves, 4 de mayo de 2017

Debate on dating Little Foot continues

Ron Clarke working on the “Little Foot” skeleton. Source: Maropeng
Wits University Palaeontologist, Professor Francis Thackeray says he stands by the original findings regarding dating Australopithecus fossil, Little Foot.

This comes after new findings by University of Johannesburg’s Prof Jan Kramers and Australia's James Cook University’s Prof Paul Dirks revealed that the fossil was much younger than originally thought.

Little foot was an Australopithecus individual, who lived more than two million years ago in Southern Africa. Australopithecus is an extinct group of the human species.

The fossil is one of a few complete skeletons that has been found of this general group of species.

The age of “Little Foot” has been hotly debated ever since its discovery at the Sterkfontein Caves at the Cradle of Humankind world heritage area.

Little Foot was named for the four ankle bones which were found in 1980. The remainder of the skeleton was uncovered from 1997 onwards.

Thackeray says the original date of 3,7 million was based on a sample of nine rocks... (Audios) SABC News

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Early culture shaped by migration and population growth

Image credit: Getty Images
Bursts of cultural advance are usually assumed to result from climate or biological changes. A new theory digs into how humans innovate, and suggests such bursts could be the result of population dynamics and culture itself.

Something odd happened in the transition from the Middle to the Upper Paleolithic, around 50,000 years ago. Modern humans and their immediate ancestors had been using tools for a few million years prior, but the repertoire was limited. Then, all of sudden, there was an explosion of new tools, art and other cultural artifacts.

What caused that change has been the subject of much debate. Maybe brainpower reached a critical threshold. Maybe climate change forced our prehistoric kin to innovate or die. Maybe it was aliens.

Or maybe it was the result of populations growing and spreading throughout the land, Stanford researchers write in Royal Society Interface. That certainly could explain some other curious features of Paleolithic culture – and it could mean that a number of paleontologists’ inferences about our genetic and environmental past are, if not wrong, not as well supported as they had thought. [...] Stanford News

The Size Of This Gorilla Bone Holds The Secret Of Ancient Human Sex Practices

The sagittal crest can be seen running along the top of this male gorilla skull. Image: ANU.

What was sex like for ancient humans? Fossils can only tell us so much about the lives of our ancestors, but it turns out that a certain bone may reveal a secret about extinct mating practices.

The key to the mystery is part of a gorilla or orangutan skull called the sagittal crest, a ridge of bone running from front to back at the top of the cranium that sort of looks like a tiny bone mohawk. Certain animals have these crests, and so did some prehistoric human relatives. Although scientists have believed the bone protrusion is linked to eating — assisting the muscles that connect all the way down to the jaw to help in chewing — new research suggests it plays a sexual role too.

For a study in the Journal of Anatomy, scientists analyzed how the size of the sagittal crest increased with age and how its development is related to sex differences. For gorillas and orangutans, the crest’s size “cannot be solely explained” by chewing needs and they may “form in response to sexual selection and may play a role in social signaling.” [...] ibtimes.com / Link 2 

Actualización: Hayan pistas sobre la vida sexual de los ancestros del hombre | DiarioPuntual
Al analizar los cráneos de gorilas y orangutanes machos, los científicos están aprendiendo acerca de las estructuras sociales creadas por nuestros parientes homínidos extintos. Los investigadores afirman que la cresta ósea vista en los cráneos de algunas especies podría ser el resultado de la selección sexual -e identificar crestas similares en nuestros antepasados ​​podría revelar cómo interactuaban, especialmente cuando se trataba de jerarquías sociales y selección de pareja.

En un estudio publicado en el Journal of Anatomy, en abril, investigadores liderados por Katharine Balolia, de la Universidad Nacional de Australia, examinaron las crestas sagitales -un arco óseo en la parte superior del cráneo- de grandes simios y gibones.

Los humanos modernos no tienen crestas sagitales porque no tenemos que masticar alimentos duros como los monos o nuestros antepasados. Mientras que nuestros músculos de la mandíbula terminan justo debajo de la oreja, en una especie con una cresta sagital, esta se extendería hacia arriba, dándoles el poder extra que necesitan para comer.

Pero los investigadores dicen que esto no es toda la historia. En su estudio, el equipo analizó las exploraciones 3D de los cráneos de cuatro especies de simios. Examinaron el tamaño de la cresta y la compararon con la madurez dental y en qué etapa de la vida se desarrolló la cresta. También miraron a machos y hembras para ver si había una diferencia entre los sexos...

Water tubing accidents, table run-ins cause Neandertal-like injuries

Battered bone. Neandertal injuries include an upper right arm bone (bottom) sheared off just above the elbow (at right), perhaps because of an emergency amputation. An intact upper left arm bone (top) from the same individual, who lived as early as about 45,000 years in what’s now Iraq, appears for comparison.

Analysis shows that comparing ancient and modern bone breaks yields little insight into hominids’ everyday dangers

NEW ORLEANS — Rodeo riders’ recent scientific reputation, as the best modern examples of a Neandertal pattern of excess head knocks, has taken a tumble. Taking their place: People who like to be dragged behind powerboats on big inner tubes, among others.

An exhaustive comparison of Neandertals’ injuries to those of people today finds that water tubing and mishaps involving tables, not rodeo riding, result in top-heavy fracture patterns most similar to those observed on Neandertal fossils. This analysis illustrates just how little modern evidence reveals about ways in which our evolutionary relatives ended up so battered, said anthropologist Libby Cowgill of the University of Missouri in Columbia. She presented data highlighting the mystery of Neandertals’ many preserved bone fractures on April 22 at the annual meeting of the American Association of Physical Anthropologists.

Her study, conducted with Missouri anthropologist James Bain, was inspired by an influential 1995 report that Neandertals, like modern rodeo riders, suffered lots of head and above-the-waist injuries and little hip and leg damage. Authors of the 1995 study explained their finding by suggesting that, unlike rodeo riders who get catapulted off bucking broncos, Neandertals’ hard knocks came during violent, up-close clashes with large prey. [...] Science News

Ancient humans: What we know and still don’t know about them

In recent weeks, we have explored the brain of a species called Homo naledi, speculated on the idea that Neanderthals might have made it to North America deep in prehistory, and found signs of Denisovan DNA in layers of dirt in a Siberian cave that don’t actually contain any fossil bones.

But who were these ancient humans? And what about the other species that pop up in the news on a regular basis? Here is New Scientist’s primer to help you understand a little bit more about seven of the most important human species in our evolutionary tree. [...] New Scientist

ActualizaciónDesde ‘Lucy’ hasta el hombre moderno: la historia de la evolución humana | N+1
En las últimas semanas, la ciencia ha calculado por fin la edad de una especie ancestral humana llamada Homo naledi, y especulado sobre la idea de que los neandertales podrían haber llegado a Norteamérica mucho antes de lo que se pensaba. Sabemos que los restos del ancestro más antiguo del hombre, homo sapiens, son los de Lucy, una australopithecus afarensis de 3,2 millones de años de antigüedad hallada en 1974 en Etiopía. Pero desde esta primera humana ¿sabemos cuántas especies han existido, evolucionado y se han relacionado entre ellos para dar lugar al ser humano moderno? Esto es, a grandes rasgos, lo que conocemos, hasta ahora, de la evolución humana. No te preocupes si no tarda en quedarse obsoleto, significará que cada vez estamos más cerca de desentrañar nuestra historia...