African fossils put new spin on human origins story (BBC)

[eppur_se_muova]

By Jonathan Amos
Science correspondent, BBC News

The ancient remains of two human-like creatures found in South Africa could change the way we view our origins.

The 1.9-million-year-old fossils were first described in 2010, and given the species name Australopithecus sediba.

But the team behind the discovery has now come back with a deeper analysis.

It tells Science magazine that features seen in the brain, feet, hands and pelvis of A. sediba all suggest this species was on the direct evolutionary line to us - Homo sapiens.

"We have examined the critical areas of anatomy that have been used consistently for identifying the uniqueness of human beings," said Professor Lee Berger from the University of the Witwatersrand in Johannesburg
***
more: http://www.bbc.co.uk/news/science-environment-14824435

[xchrom]

1. recommend

[Tikki]

2. Being a human is an amazing thing...

Tikki

[ladjf]

3. The most amazing thing about the human race is that it is on track

to having the shortest tenure of Earth of any known species. We've been around for less that 500,000 years and already on the brink of self-annilhilation. nt

[Exultant Democracy]

4. Humans aren't the problem. They got along fine untill the last 10k years or so, its civilization

or the dominate civilization to which we are a part of that is the problem. Even today there are indigenous people around the world whose cultural practices are completely sustainable in their local ecosystems.

[Odin2005]

6. The "sustainable" reputation of traditional societies is exaggerated, IMO.

Whenever modern humans first moved into a region a mass extinction of the megafauna followed soon after. Sustainable practices only developed after the initial ecological massacre out of necessity.

[Exultant Democracy]

8. The science is still conflicted over the megafaunal extinctions

while they have been linked pretty well to human activity in Australia and in parts of central Asia there are a number of scientist that argue that the megafaunal extinctions were caused by rapid environmental changes.

Even is we take the extinctions as being caused by humans then we still have about 30k years between the extinctions and when man next started in on mass destruction with agriculturalists and pastoralists. And of course we still have plenty of tribes eve today that have still not adopted either practice. We can't compare the moderate effect that these indigenous people have as lifeforms on their environments and the damage that we modern people due.

[Odin2005]

9. I think its quite clear that most of them were caused by humans.

Humans come in, mega-fauna go extinct. IMO that is pretty damning. The only continent spared extinctions was Africa, because the big animals there evolved with us.

I think a lot of people are in denial and want to hold on to romantic notions of "noble savages at one with nature", thus people denying that humans had anything to do with the extinctions.

North America used to have 2 species of mammoth. It used to have lions. It used to have cheetahs (that's why pronghorn antelope are so fast). It used to have camels. It used to have horses. Soon after humans arrived, they were gone.

The extinction of the mammoths, by human hands, transformed the ecology of the sub-arctic regions. Had the mammoths survived, the boreal forests today would be much more open and have a higher biological productivity.

[ladjf]

11. When I used the term "extinction" in my original OP, I was referring

to the extinction of the human race itself. nt

[ladjf]

10. Good point! To be more specific, I believe that the downfall

began when humans move away from their natural hunter/gatherer role and began amasing wealth in the form of land, grain storage and other forms of wealth consolidation. Instinctive self-interests morphed into pathological greed, a trend which is currently at an alltime peak of destruction.

[Odin2005]

5. Yikes, the taxonomic mess at the base of the genus Homo just got messier.

I have believed for a while that "Homo" habilis was not on the line to us, but one of several descendants of Australopithecus Africanus, only one of which gave rise to our genus, the rest were dead ends.

[starroute]

7. I don't find it convincing

There is evidence that primitive Homo erectus were present in the Caucasus Mountains by 1.85 million years ago. And there was an article just last week saying that an Acheulian handaxe of the type associated with H.erecus has been found near Lake Turkana in Kenya and dated at 1.76 MY. (http://popular-archaeology.com/issue/june-2011/article/early-humans-made-stone-handaxes-earlier-than-previously-thought-study-says)

The article cited in the OP says, "Whereas original estimates had put the age of the remains at somewhere between 1.78 and 1.95 million years old, the new analysis has narrowed this window of uncertainty to just 3,000 years. The new age is now between 1.977 and 1.98 million years old. The refined dating is important, says the team, because it puts A. sediba deep enough in time to be a realistic ancestor to H. erectus."

Realistic? Hardly. On one side, you have a tiny-brained pre-human with some semi-modern characteristics in its hands, feet, and pelvis -- but also "powerful muscles for grasping, suggesting A. sediba spent a lot of time clambering through the branches of trees" and "a distinctive type of walk when the creature was not climbing in trees." And on the other, you have H. erectus, which was almost modern in its anatomy from the neck down, fully ground-dwelling, and capable of making relatively sophisticated tools. And they want us to believe that it was possible to get from one to the other -- and from South Africa to the Caucasus -- in just over 100,000 years?

I think it's more likely that once the Australopithecines had become bipedal when on the ground, there was a general evolutionary tendency to refine the ability to walk erect and use the hands for new tasks. But A. sediba is in the wrong time and the wrong place to be a plausible candidate for the next step.