National Geographic News
Photo of Dr. Lee Berger at a dig in South Africa.

Dr. Lee Berger excavates a finger bone in South Africa in 1995.

Photograph by Kenneth Garrett, National Georgraphic

Andrew Howley

National Geographic

Published November 6, 2013

A harrowing expedition into the tiniest recesses of a cave system begins today in South Africa. The effort aims to recover recently discovered fossils of a yet-to-be-identified member of the human family.

Over the next several weeks, the expert team, directed by National Geographic Explorer-in-Residence Lee Berger of South Africa's University of Witwatersrand, will delve into the Rising Star cave system outside Johannesburg to carefully retrieve the fossils.

Berger's team made headlines in 2010 with the announcement of the discovery of two skeletons of a new, two-million-year-old hominid species the scientists named Australopithecus sediba. Those finds were made at a site called Malapa Cave, northwest of Johannesburg. (See "Malapa Fossils.")

Working under Berger’s direction, local cavers made the latest discovery at a site several miles from Malapa. The fossils will be excavated by a team made up of experienced caver-scientists from around the world. All have passed Berger's requirement of being small enough to fit into and out of cramped cave passages.

Without knowing exactly which species the bones come from, the team hopes their arduous recovery helps answer a broad list of deep questions about humanity's origins.

What Did Our Ancestors Look Like?

South African sites have long been important to understanding human evolution, beginning with the discovery near Taung of a little skull in 1924 by Raymond Dart, also of the University of Witwatersrand. Dart believed the skull was too primitive to be placed in our own genus Homo, so he gave it in a new genus name: Australopithecus, or “southern (as in Australia)  ape.”

Since then, many other specimens of Australopithecus have been recovered in southern and eastern Africa, dating from between four million and two million years ago. The most famous of these is "Lucy," a 2.8 million-year old skeleton discovered at Hadar in Ethiopia in 1974—still one of the most complete hominid skeletons ever found.

Like other australopithecines, Lucy’s species Australopithecus afarensis walked on two legs, but had much more primitive anatomy and smaller brains than members of our own genus Homo, which gets its name from the Latin for “same” (as in "homophones").

The earliest specimen of Homo, also from Hadar, is believed to be around 2.5 million years old. It evolved from one of the Australopithecus species, but there is much debate over which one. Many researchers contend that Australopithecus afarensis is the most recent ancestor to Homo. Recently, however, Berger and his colleagues have argued that A. sediba deserves that recognition.

Whichever australopithecine gave birth to Homo, its descendents eventually left Africa at least 1.9 million years ago. Fossils belonging to the species Homo erectus have been found in Africa and across Eurasia. Other than our own species Homo sapiens, the best known group within the Homo  lineage is the Neanderthals, who inhabited Europe and western Asia from as early as 600,000 years ago up until around 32,000 years ago.

Some scientists also refer to a third genus of hominid, called Paranthropus. The name combines "para" meaning "next to" or "not quite" (as in "paranormal") and "anthro" meaning "man" (as in "anthropology" or "android"). Paranthropus had huge, flat teeth and massive jaws. Other scientists prefer to group the Paranthropus specimens in with australopithecines with similar characteristics. Whatever you call these robust specimens, their lineage went extinct some 1.9 million years ago.

How Are We All Related?

Given all the hominids on the scene before our genus, how do we know which ones are actually ancestral to us?

Researchers have spent generations drawing and redrawing a family tree that could connect all the known hominid fossils. Each new find has the possibility of clarifying the picture—or further muddying the water.

Berger’s Australopithecus sediba fossils are without question among the most complete skeletons ever found, rivaling even Lucy. His contention that they are the best candidate to be the immediate ancestor of Homo is based on a suite of features, some even more humanlike than even those of Homo habilis, considered by many scientists to be the earliest member of our genus.

At the same time, A. sediba showed other similarities to much more primitive, tree-dwelling primates. (See "Human Ancestor May Put Twist in Origin Story.")

It was only the luck of finding the complete skeleton of a previously unknown species that made anyone consider such combinations of traits.

"[With A. sediba,] you have a heel bone and an ankle bone that if you found them independently, you'd put them in different taxa," said paleontologist Bernard Wood of George Washington University in Washington, D.C.

So does that make it more or less likely to be our ancestor?

"These sorts of issues really need to be worked out by finding a suite of fossils that have some time depth to them," said Rick Potts, director of the Smithsonian's Human Origins Program.

Then "you can begin to understand what sort of combination of traits would occur in a small isolated group," or that would be found in "a lineage with integrity to it [that] you see over and over again for generations."

These issues are present in a lesser degree for almost all hominid fossils. Each have unique combinations of traits that make them seem so close and yet so far from being a definite ancestor for us. This brings up the next big question.

Who Exactly Were Our Ancestors?

The story of human evolution was once pitched as a search for the "missing link," an ancient creature that would exhibit traits somewhat like a human, but somewhat like the other great apes. (Also see "New Studies Shake Up Human Tree.")

After a century of discoveries, it's clear there wasn't just a missing link, but rather a whole continuum of different forms, only some of which are directly ancestral to us. Like all species, those in our family tree were shaped by their environments.

"There are multiple places within sub-Saharan Africa that were probably undergoing quite a complex series of responses to environmental variability," said Potts. It was not just gradual climate change, but rather the kind of instability that is now seen as playing a critical role in driving adaptation and speciation (the formation of new species).

The environmental instability of the time "creates a much more experimental world," Potts added. "Not a 'cradle of humankind'—that's too nurturing. I now prefer the term 'cauldron of humankind.'

"And it's much more of a series of broiling events and a churning process full of this sort of experimentation."

As the landscape changed, diversifying populations could meet back up and essentially jump back into the gene pool together, creating hybrids.

Potts doesn't suggest hybridization explains all the mixed characteristics in fossils like A. sediba, but says it's a piece of the puzzle that shouldn't be forgotten when trying to trace which species absolutely did or did not contribute to the human family line.

What Don't We Know?

The final driver for continued pursuit of early hominid fossils is the growing awareness of just how much we don't know.

A. sediba was not only an unknown species until a few years ago, but the place it was discovered also was considered exhausted of all fossils. Berger stresses that our understanding of human evolution is nowhere near complete. We haven't even finished looking at the things we thought we knew, he says.

"It's not just a question of finding more fossils," says GWU’s Bernard Wood. "We need a better understanding of how reliable morphology is for telling us about relationships."

Follow the New Expedition

The latest chapter in the search for answers is about to kick off in the Rising Star caves, but for now the emphasis is wholly on the search.

"Our aim is to get the fossils out carefully, study them, compare them to other fossil material from around the world, and then proceed to analyze and describe them," said Berger. He hopes to publish the team's findings in late 2014. A National Geographic/NOVA documentary will tell the full story of discovery and analysis next fall.

Follow the team's progress on our Explorers Journal blog.

44 comments
Maxim Dynin
Maxim Dynin

"homo" in "homophones" is a Greek prefix meaning "same" and has nothing to do with "homo" in Latin (with the root homin-), which simply means "man". For instance, the word "hominid" comes from the latter.

BILL STULL
BILL STULL

If  science is right about mankind. They should tell us what the climate was like. That would help to determine what early homo sapiens were like. Cold weather means one thing, jungle another, savanna etc.,

Rosemary Bortz
Rosemary Bortz

God will only let you discover what he wants you to know but it is very interesting to read and see other peeps comments

sumit roy
sumit roy

Amazing! is it possible to retrieve any genetic material for study?


James Johnson
James Johnson

Where we came from and what we will be in the next few centuries... very interesting subjects for me.

Margaret Myers
Margaret Myers

I think this fascinating and I want to see more of this. 

Shermin Nasiri
Shermin Nasiri

I wish I was there
This would exploration of historical photographs.

Deborah Bice
Deborah Bice

I live in Utah and there is so much here, fossils, dinosaur tracks etc . I would love to be a part of a working site.

Paul Sutton
Paul Sutton

Since my first class in paleontology with Dr. Wood at Stockton State College I have been fascinated by the search for the origin of man. I became so interested in the work of Jane Goodall and all the subsequent investigation of current primates and the link with our past, the connection with our evolution. 

It is great to be able to have insight to the very current exploration of new finds and to have access to the researcher's ideas and interpretations. YOU GO NAT GEO!! LOVE IT

C Victor R hONEY
C Victor R hONEY

Wonderful, exciting! It's good to share the enthusiasm of those working at the site. GO WELL

Paul Landry
Paul Landry

The real origins of humankind may never be fully understood but every new discovery provides the basis for a new hypothesis.  All these new discoveries encourage  anthropologists to continue searching for new evidence of our origin.  It make for very interesting reading.

Farah Khoury
Farah Khoury

In the history there was Ge ants ( big human pieces ) their  grave  was like the baby before born , do you discover some thing like this ?

thanks for you. 

Gerard Verhoeven
Gerard Verhoeven

It looks as if the theories of Zecharia Sitchin, such as the creation of mankind by the Anunnaki/Nephilim of the planet Nibiru, are step by step nearing the real truth.




Srikanth Ramachandra
Srikanth Ramachandra

Its just so awesome, so many open questions and so much more to find out...thanks and keep up the good work...

Herbert Moyo
Herbert Moyo

Have not bothered much about fossils and stuff before but this sounds interesting will keep close to the proseedings.

Jack Kilmon
Jack Kilmon

One small correction. The Genus HOMO is Latin for MAN.  It is in Greek that HOMO is "same."  HOMO sapiens means "thinking MAN."

Garima Poonia
Garima Poonia

I haven't been able to watch Nat Geo on T.V. for years. And I am insanely glad to be back here! 

Gary Proffitt
Gary Proffitt

I have a picture that I took on a recent trip and  I didn't realise that a skull was in the ground, you can only just make it out but i wondered if any experts could verify what it might be?

Stephanie Foster
Stephanie Foster

My "Fossil Evidence of Human Evolution" course is taught by Dr. de Ruiter, who is on this team. Exciting! :D

Larry Coleman
Larry Coleman

Whichever australopithecine gave birth to Homo, its descendents eventually left Africa at least 1.9 million years ago. Fossils belonging to the species Homo erectus have been found in Africa and across Eurasia. Other than our own species Homo sapiens, the best known group within the Homo  lineage is the Neanderthals, who inhabited Europe and western Asia from as early as 600,000 years ago up until around 32,000 years ago."-- I had this very discussion earlier today on Facebook!

Clayton Douglass
Clayton Douglass

This makes perfect sense. As members of a genus separate and reunite at a later time,it stands to reason that individuals would seek out members of the opposite sex with the most desirable traits to mate with,thereby creating "hybrids" or offspring with the best features of both parents. This is how nature works,and how the strong survive.

David Phinney
David Phinney

I love reading NG...I don't like eggheads who argue about the Latin and Greek meanings of the word homo. I think those who do the arguing are homo ...if you get my meaning.

Robert Schwendau
Robert Schwendau

Under the section titled "What Did Our Ancestors Look Like?... third paragraph...

It is stated that the word "homo" is the Latin for "same."   Incorrect!   The Latin word "homo" is best translated as man/human person.

The Greek-based word "homo" means "same."


Greg Wiens
Greg Wiens

I love national geographic, it truly is my favorite magazine and website on science, geology and culture (except articles on beetles, I just don't care about beetles). 

I especially enjoy the articles like this one which are on world views, and religion. 

Endre Polyak
Endre Polyak

The more we discover about ourselves, the more we realize how little we know.

:Peter Tarr
:Peter Tarr

This site makes the 11th Plio-Pleistocene hominin site in South Africa (by my count)

Michael Morris
Michael Morris

This is all wonderful stuff to be thought about and analyzed but, where does Al Sharpton fit in?

Ben Creisler
Ben Creisler

Interesting story. However, the derivation for Homo should be the Latin noun homo (hominis), meaning "human being, man"--not the Greek adjective homos "same"...

Ben Creisler
Ben Creisler

The article reads:  "our own genus Homo, which gets its name from the Latin for 'same' (as in 'homophones')."

The derivation given from Homo is wrong. It comes from the Latin noun homo (hominis) "human being, man"--not from the  Greek adjective homos "same" found in "homophones."



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