Two million-year-old hominin with human-like thumb knuckles was the first of our ancient ancestors to use its hands to grasp objects as well as climb trees, study shows

  • Australopithecus sediba is a distant relative that lived two million years ago 
  • Study claims its fingers were suited to climbing and grabbing branches 
  • But its thumb was well-suited to performing 'human-like precision grips'
An ancient human ancestor that lived two million years ago had hands that were able to perform some human-like movements as well as climb trees, a study has found. 
Australopithecus sediba is a distant relative of modern-day Homo sapiens that lived in what is now modern-day South Africa.  
Analysis of the hominin's well-preserved bones reveals the hand was a hybrid, still adapted to climbing trees like its predecessors and yet it was also able to perform human-like precise movements. 
It was suited to both activities, according to anthropologists from the University of Kent, which paints a complex picture of how human ancestors slowly ditched a life in the trees for a ground-based existence. 
Pictured, the fossilised hand bones of A. sediba. Analysis of the hominin's hand bones reveals the hand was a hybrid, not fully adapted to climbing trees or yet adept at performing precise movements
Pictured, the fossilised hand bones of A. sediba. Analysis of the hominin's hand bones reveals the hand was a hybrid, not fully adapted to climbing trees or yet adept at performing precise movements
Pictured, the hand of the A. sebida species in situ at the South African cave. The knuckles of Australopithecus sediba's fingers show the fingers were well-adapted and often used for tree climbing and branch grasping
Pictured, the hand of the A. sebida species in situ at the South African cave. The knuckles of Australopithecus sediba's fingers show the fingers were well-adapted and often used for tree climbing and branch grasping
The knuckles of Australopithecus sediba's fingers show the fingers were well-adapted and often used for tree climbing and branch grasping. 
However, the structure of the thumb knuckle is slightly different and is more consistent with human-like manipulation, the researchers say. 
This shows that A. sediba is different to other primitive hominins, including other Australopithecus species. 
Dr Christopher Dunmore, who led the research, said: 'Internal bone structures are shaped by frequent behaviours during life. 
'Therefore, our findings can support further research into the internal structure of hands in relation to stone tool use and production. 
Pictured, the skull of the ancient human ancestor, which lived around two million years ago. The study shows the species slowly adapted to walking on two legs
Pictured, the skull of the ancient human ancestor, which lived around two million years ago. The study shows the species slowly adapted to walking on two legs 

Australopithecus sediba gave birth 'relatively easily' 

Some ancient human relatives had far less difficulty giving birth than modern-day people, a study has found.   
Australopithecus sediba — an ancient hominin who lived around 2 million years ago — had wider birth canals than their modern equivalents.  
Modern human childbirth can be a difficult, painful and lengthy process.  
In contrast, some of our living distant relatives — like chimpanzees — have far easier labours, giving birth within a matter of hours with far less assistance.
Experts believe that the difficult nature of modern births stems from both large infant heads and a pelvis which has become narrower as humans evolved to walk upright, in turn narrowing the birth canal.
Researchers from the US created a digital model of an A. sediba pelvis, based on fossil specimens, to explore how labour would have been for our ancient relative.
To find out what childbirth might have been like for our ancient relatives, anthropologist Natalie Laudicina of Boston University in Massachusetts and colleagues created a 3D model of a female Australopithecus sediba's pelvi pelvis.
'This approach may also be used to investigate how other fossil hominin species moved around and to what degree climbing might have remained an important part of their lifestyle.'
Scientists have long sought to understand how and when ancient human ancestors moved away from climbing trees.
Professor Tracy Kivell said: 'The internal bone structure can reveal hidden evidence that gives us insight into how our fossil human relatives behaved. 
'We were really excited to see this particular hand-use pattern in Australopithecus sediba as it was so different from other australopiths. 
'The fossil record is revealing more and more diversity in the ways our ancestors moved around, and interacted with, their environments - the human evolutionary story is even more complex and interesting than we previously thought.'
Previous research has found that some species spent more time on the ground and, as a result, slowly began walking on two legs. 
Bipedalism, walking on two legs as opposed to four, was key in allowing modern humans to evolve as it signalled a change in lifestyle and allowed the sharing of food. 
Bipedalism coincided with an expanding brain capacity but made it harder to give birth.
Walking on two legs was already common among some early hominins, with estimates on the emergence of bipedalism dating back to up to six million years ago. 
However, the unique combination of functions seen in A. sediba reveals species adopted bipedalism at a different rate, and A. sediba gradually made the transition.   
Pictured, the site where the specimen was found. Malapa is a well-known archaeological site in South Africa
Pictured, the site where the specimen was found. Malapa is a well-known archaeological site in South Africa 

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