New human-like species
discovered in S Africa
By Pallab GhoshScience
correspondent, BBC News, Johannesburg
10 September 2015, From the section Science
& Environment
Scientists have discovered a new human-like species in a burial chamber deep in a cave system in South Africa. The discovery of 15 partial skeletons is the largest single discovery of its type in Africa. The researchers claim that the discovery will change ideas about our human ancestors. The studies which have been published in the journal Elife also indicate that these individuals were capable of ritual behaviour.
The
species, which has been named naledi, has been classified in the grouping, or
genus, Homo, to which modern humans belong. The researchers who made the find
have not been able to find out how long ago these creatures lived - but the
scientist who led the team, Prof Lee Berger, told BBC News that he believed
they could be among the first of our kind (genus Homo) and could have lived in Africa up to three million years ago.
"What
we are seeing is more and more species of creatures that suggests that nature
was experimenting with how to evolve humans, thus giving rise to several
different types of human-like creatures originating in parallel in different
parts of Africa. Only one line eventually
survived to give rise to us," he told BBC News.
I
went to see the bones which are kept in a secure room at Witwatersrand University.
The door to the room looks like one that would seal a bank vault. As Prof
Berger turned the large lever on the door, he told me that our knowledge of
very early humans is based on partial skeletons and the occasional skull.
The
haul of 15 partial skeletons includes both males and females of varying ages -
from infants to elderly. The discovery is unprecedented in Africa
and will shed more light on how the first humans evolved.
"We
are going to know everything about this species," Prof Berger told me as
we walked over to the remains of H. naledi.
"We
are going to know when its children were weaned, when they were born, how they
developed, the speed at which they developed, the difference between males and
females at every developmental stage from infancy, to childhood to teens to how
they aged and how they died."
A
chronology of human evolution
Ardipithecus
ramidus (4.4 million years ago) : Fossils were discovered in Ethiopia in the
1990s. Pelvis shows adaptations to both tree climbing and upright walking.
Australopithecus
afarensis (3.9 - 2.9 million years ago) : The famous "Lucy" skeleton
belongs to this species of human relative. So far, fossils of this species have
only been found in East Africa. Several traits
in the skeleton suggest afarensis walked upright, but they may have spent some
time in the trees.
Homo
habilis (2.8 - 1.5 million years ago) : This human relative had a slightly
larger braincase and smaller teeth than the australopithecines or older
species, but retains many more primitive features such as long arms.
Homo
naledi (Of unknown age, but researchers say it could be as old as three million
years) : The new discovery has small, modern-looking teeth, human-like feet but
more primitive fingers and a small braincase.
Homo
erectus (1.9 million years - unknown) : Homo erectus had a modern body plan
that was almost indistinguishable from ours. But it had a smaller brain than a
modern person's combined with a more primitive face.
Homo
neanderthalensis (200,000 years - 40,000 years) The Neanderthals were a
side-group to modern humans, inhabiting western Eurasia before our species left
Africa. They were shorter and more muscular
than modern people but had slightly larger brains.
Homo
sapiens (200,000 years - present) Modern humans evolved in Africa
from a predecessor species known as Homo heidelbergensis. A small group of Homo
sapiens left Africa 60,000 years ago and
settled the rest of the world, replacing the other human species they
encountered (with a small amount of interbreeding).
I
was astonished to see how well preserved the bones were. The skull, teeth and
feet looked as if they belonged to a human child - even though the skeleton was
that of an elderly female.
Its
hand looked human-like too, up to its fingers which curl around a bit like
those of an ape.
Homo
naledi is unlike any primitive human found in Africa.
It has a tiny brain - about the size of a gorilla's and a primitive pelvis and
shoulders. But it is put into the same genus as humans because of the more
progressive shape of its skull, relatively small teeth, characteristic long
legs and modern-looking feet.
"It
was a moment that 25 years as a paleoanthropologist had not prepared me
for."
One
of the most intriguing questions raised by the find is how the remains got there.
I
visited the site of the find, the Rising Star cave, an hour's drive from the
university in an area known as the Cradle of Humankind. The cave leads to a
narrow underground tunnel through which some of Prof Berger's team crawled in
an expedition funded by the National
Geographic Society.
Small
women were chosen because the tunnel was so narrow. They crawled through
darkness lit only by their head torches on a precarious 20 minute-long journey
to find a chamber containing hundreds of bones.
Among
them was Marina Elliott. She showed me the narrow entrance to the cave and then
described how she felt when she first saw the chamber.
"The
first time I went to the excavation site I likened it to the feeling that
Howard Carter must have had when he opened Tutankhamen's tomb - that you are in
a very confined space and then it opens up and all of a sudden all you can see
are all these wonderful things - it was incredible," she said.
Ms
Elliott and her colleagues believe that they have found a burial chamber. The Homo
naledi people appear to have carried individuals deep into the cave system and
deposited them in the chamber - possibly over generations.
If
that is correct, it suggests naledi was capable of ritual behaviour and possibly
symbolic thought - something that until now had only been associated with much
later humans within the last 200,000 years.
Prof
Berger said: "We are going to have to contemplate some very deep things
about what it is to be human. Have we been wrong all along about this kind of
behaviour that we thought was unique to modern humans?
"Did
we inherit that behaviour from deep time and is it something that (the earliest
humans) have always been able to do?"
Prof Berger believes that the discovery of a creature that has such a mix of modern and primitive features should make scientists rethink the definition of what it is to be human - so much so that he himself is reluctant to describe naledi as human.
Other
researchers working in the field, such as Prof Stringer, believe that naledi
should be described as a primitive human. But he agrees that current theories
need to be re-evaluated and that we have only just scratched the surface of the
rich and complex story of human evolution.
Who...What am I?!!