This September a new member was added to our family tree1. His
name is Homo naledi. He was found,
two years ago, buried in the damp dark depths of the Dinaledi chamber of the
Rising Star cave system in the archaeological hotspot known as the Cradle of
Humankind in South Africa.
Two cavers while exploring in the caves accidentally broke through a
crevice and discovered buried fossils of a human-like creature 30 metres below
ground level. They took their news to Lee Berger, a paleoanthropologist and
archaeologist at the University of the
Witwatersrand in Johannesburg. Lee Berger was intrigued, but his large frame
could never get through the 20 cm wide opening into the chambers were the fossils
lay buried. But he had a plan.
Paleoanthropologists are generally thought of as secretive scientists
who shy away from limelight and conduct their research in dark obscure spaces,
slowly and painstakingly brushing away the dust of millennia to uncover
fragments of fossils that may tell a tantalizing story about our past. But
Berger had a different style. When Berger realized he needed help with the
excavation underground, he shot off an advertisement on Facebook® inviting people with archaeological, paleontological or excavation skills to come
join his excavation; but he had other conditions, they should not be
claustrophobic or afraid of the dark and they should be small.
The excavators he selected from the many who applied
were six slender young women, who came to be known to the discovery team as the
‘Underground Astronauts’. They crawled through narrow openings, climbed up
ragged walled caves and dropped down a chute into dark damp chambers where they
for hours together excavated the fossils: gently, carefully,
painstakingly. They worked in 6 hour
shifts for 21 days to uncover, surface-scan, photograph, clear the soil, label
and pack the remains one by one to be send up to the base camp. A group of senior palaeontologists, anthropologists and archaeologists had
assembled in an over-the-ground base camp to guide the below-ground excavators.
The activity below was monitored through cameras and microphones and lights and
scanners that fed into computers in the base camp.
What the ‘Underground Astronauts’ brought up were nearly 1550 fossils
that are thought to belong to 15 or more individuals of different ages of a
species long gone. A large team of scientists assembled to study the remains.
Each part of the body had specialists who were experts on that structure e.g.
hands, head, feet and so on. The team of scientists released the conclusions of
their analysis this September to describe a human-like creature. He had
remarkable arched feet for balance, just like ours, suggesting he walked
upright. He had agile fingers like ours with well developed thumb muscles for
fine manipulation of tools. But, unlike ours, his long curved fingers could also
help him grasp and climb like more primitive hominins. He stood as tall as us
but his brain was less than half our size. So, why is this discovery creating
the ripples in the news?
Homo sapiens, our species, is thought to have emerged around 200,000
years ago2. But the hominins, the larger group to which we belong,
emerged around 7 million years ago. Australopithecus and Paranthropus groups,
both more ancient than us, were more ape-like in their behaviour. They climbed trees and but were beginning to
walk upright; their brains though were much smaller suggesting lack of
sophistication.
The genus Homo, containing perhaps
our direct ancestors, Homo habilis, Homo
rudolfensis, Homo erectus and Homo
heidelbergensis existed in the last 1-2 million years. The more recent
members of the Homo genus emerged somewhere in the last half million years of
so. The Homo genus were committed to
walking upright and are not known to climb trees having lost the adaptations
for climbing and grasping.
One of our most recent cousins, the Neanderthals (Homo neanderthalensis) lived in Europe during the last ice age.
Well adapted to the cold, they wore clothing, used tools and had cultural
practices such as burying their dead. They were larger than us and their brains
were as big as ours and sometimes bigger. Scientists believe that until their
extinction around 40,000 years ago they coexisted, interacted and perhaps even
interbred with humans in the cold climes of Europe. There are traces in our DNA
that might have come from our Neanderthal cousins and mates.
Remains of another cousin of ours, Homo
florensis, who perhaps also overlapped with modern humans, was discovered
only a few years back on the Indonesian Island of Flores. The adult Homo florensis were no taller than a 3
year-old human child and had a brain one-third of ours. But they could hunt
pigmy elephants with tools they made, make fire and cook meat. They lived successfully
on the island till as late as 13,000 years ago, while the surrounding mainland
was already inhabited by humans. But perhaps isolated from the surrounding
mainland by kilometres of treacherous sea, humans and the Homo florensis never met.
So, what about Homo naledi?
Did they ever meet us humans? Were they recent inhabitants of earth who
retained their love for trees even as they walked and hunted on the ground? Or
were they ancient cousins who came before the Homo genus descended from the trees? We do not know the answers to
these questions. We do not know because, it has been very difficult to estimate
the age of the Dinaledi fossils. Usually fossils are dated by the geological
layer they are found in. The rock layers can be traced back to various volcanic
eruptions, droughts, ice ages and other such major events on earth. But the Homo naledi was found in a deep cave in
loose damp earth, with not even bones of other creatures nearby, which might
have helped us guess at the era they lived in. Scientists are prepared for the
long haul to determine the age of these fossils.
Until then we will be left wondering how did these creatures get inside
a cave that is so inaccessible from the surface. They could not have
accidentally strayed into a place so out of the way. Were they entombed there
as part of some ancient burial ritual? How could creatures with half our brain
size have concepts of afterlife and have cultural practices and burial rituals?
Did they coexist with some other more intelligent species of the Homo genus? Did these compatriots dump
them there, perhaps?
Like all scientific discoveries, this one finding opens up many more
interesting, exciting questions. And like always the human mind will weave its
stories about its own past, the only species that can encompass the whole past,
present and future in its 1 kilo brain.
References
This article appeared in the ACE Academy magazine TRUMP in October 2015.
No comments:
Post a Comment