September 08, 2011

Australopithecus sediba in Science

From the press release.
Researchers have confirmed the age of possibly our oldest direct human ancestor at 1.98 million years old.

The discovery was made after researchers conducted further dating of the early human fossils, Australopithecus sediba, found in South Africa last year.

A series of studies carried out on newly exposed cave sediments at the Malapa Cave site in South Africa, where the fossils were found, has assisted researchers to determine their more precise age at 1.98 million years old, making the Malapa site one of the best dated early human sites in the world.

...

"Knowing the age of the fossils is critical to placing them in our family tree, and this new age means that Australopithecus sediba is the current best candidate for our most distant human ancestor."

"The results of these studies present arguably the most precise dates ever achieved for any early human fossils," she said.

It appears the fossils were deposited in the Malapa Cave during a 3,000-year period around 1.98 million years when the Earth's magnetic field reversed itself by 180 degrees and back again.

List of papers in Science. Judging by the list of co-authors, I would hazard a guess that this research was funded and supported (directly or not) by public money from institutions across several continents. This may have been money well-spent in advancing science, but it is Science that will now profit from it, for nothing more than providing a glorified web-hosting service. The public must pay once more, either directly to Science or by inconveniencing itself with a trip to a Science-subscribing library, if there is one nearby.

This is as good a place as any to plu the open science Malapa Soft Tissue Project.

9 comments:

eurologist said...

"Australopithecus sediba is the current best candidate for our most distant human ancestor"

Not sure how they come to that conclusion, given the mix of old and modern signatures. If anything, it just shows that around 2 million years ago and before the dominance of erectus there were many different lineages, and we don't really know which one eventually contributed to humans.

eurologist said...

The authors' interpretations and conclusions are pretty frustrating to me. Here you have a number of quite different fossil finds all within several hundreds of thousands of years (rather short, actually), showing different modern feature combinations, and all they can come up with is homoplasy.

Have we learned nothing from archaic-AMH interbreeding? Obviously, several regions in Africa where innovation geology- and climate-driven hot-houses during that time. The most logical hypothesis should be that interbreeding selected the best innovations, while initially saving peculiar adaptations for local niches - until a better all-rounder (erectus) evolved who also was capable of some sort of group defense, rather than fleeing into the trees.

Onur said...

It isn't surprising for such very late australopith (=genus Australopithecus) specimens to show anatomical features transitional between australopiths and humans (=genus Homo), as they are from a time when humans already existed in the forms currently classified as "Homo rudolfensis", "Homo gautengensis", "Homo habilis" and "Homo ergaster". Such transitional australopiths must have existed already before the emergence of humans. The 2.5 million years old "Australopithecus garhi" is a prime example of them.

Onur said...

Researchers have confirmed the age of possibly our oldest direct human ancestor at 1.98 million years old.

"Knowing the age of the fossils is critical to placing them in our family tree, and this new age means that Australopithecus sediba is the current best candidate for our most distant human ancestor."


Pure sensationalist statements and nothing else.

terryt said...

"it just shows that around 2 million years ago and before the dominance of erectus there were many different lineages, and we don't really know which one eventually contributed to humans."

Given the 'multiregionalism' that seems to be re-developing we could probably assume that it is not our 'only' ancestor from that period. As a result I'm in complete sympathy with:

"Have we learned nothing from archaic-AMH interbreeding?"

Interbreeding around that period would explain 'the mix of old and modern signatures'. The 'modern' signatures have come from several different 'species' over the period of our evolution.

eurologist said...

Interbreeding around that period would explain 'the mix of old and modern signatures'. The 'modern' signatures have come from several different 'species' over the period of our evolution.

I agree - in my first post I meant to say "which ones."

PS said...

Pure sensationalist statements and nothing else.

Folks, this is Lee Berger writing about his own discovery (you will note his name on all of the papers). I'm not sure why everyone is acting so astonished that he'd pump up the importance of the find.

Onur said...

Folks, this is Lee Berger writing about his own discovery (you will note his name on all of the papers). I'm not sure why everyone is acting so astonished that he'd pump up the importance of the find.

It is the press presentation that is sensationalist, probably not the papers themselves judging by their abstracts.

terryt said...

"Folks, this is Lee Berger writing about his own discovery"

Years ago I read a book by Berger in which he claimed he had presented a paper showing northern and southern Australopithecus were different. This would hardly be surprising but I've heard no more about it. He claimed southern versions had shorter legs and arms but larger heads while nothern ones had longer arms and legs and smaller heads. If true that would be very interesting.

"in my first post I meant to say 'which ones'."

That is the all-important question.