Fossil technician Sipho Makhele deep underground in the darkness of the Sterkfontein Caves near Johannesburg. The caves are part of the Cradle of Humankind, one of South Africa’s 12 Unesco World Heritage Sites. (Photo: Ihsaan Haffejee)

11 July 2025 • Photos and text by Ihsaan Haffejee

Itumeleng Molefe remembers the day neighbours came rushing into his family’s home in Rustenburg, a town northwest of Johannesburg. His father was famous because they had just seen him on TV, they said. “People were screaming, yelling and celebrating. It was very cool to experience.”

Nkwane Molefe, Molefe’s father, and his colleague Stephen Motsumi had just made one of the greatest discoveries in our bid to understand human origins. Fossil technicians at the Sterkfontein Caves, the pair worked under paleoanthropologist Ron Clarke to unearth the fossil skeleton of an ancient hominin known as Little Foot.

Discovered in the 1990s, it is the most complete hominin fossil yet found, with 90% of the skeleton unearthed. Little Foot was a female Australopithecus who died nearly four million years ago. Her brain was about the size of a chimpanzee’s but she walked upright on the ground, like us.

The Sterkfontein Caves near Johannesburg lie within the Cradle of Humankind, one of South Africa’s 12 Unesco World Heritage Sites. Some of the science’s most important fossils have been discovered there.

Fossil technician Itumeleng Molefe working in the Sterkfontein Caves, as his father did before him. (Photo: Ihsaan Haffejee)

Today Molefe continues the work of his now-retired father. He too is a fossil technician in the caves, searching for fossils that may help unlock the mysteries of our past.

“Our work is important,” he said. “It helps our understanding and knowledge of the world we live in. The best part of my job is that we are constantly learning, discovering new things.” He added: “You have to have passion for this job to do it well, because it’s not easy.”

Fossil technicians play a vital role in Sterkfontein, doing far more than just extracting rocks. They spend hours painstakingly separating fossil from rock without damaging the fossil. They then cast replicas of the fossils for scientists to study, with the precious originals stored away for safekeeping. They also catalogue the finds, making sure everything is properly labelled and organised.

Fossil technician Abel Molepolle with an undated photo of his father David Molepolle, who joined the Sterkfontein Caves team in 1967. (Photo: Ihsaan Haffejee)

Many of the fossil technicians have been doing this job for decades, amassing huge knowledge of the caves and their fossils.

Dr Job Kibii, head of the Sterkfontein Caves, said the technicians’ knowledge and experience was an invaluable resource for researchers. “These guys might not have degrees, but they actually know everything. In fact, a number of them have actually taught the professors and researchers who come to the site.

“They show them how to distinguish between different fossils: which are from [non-human] animals, and which are from hominins. And then the professors eventually would go ahead and do the description. But initially they learned from these guys that this is what you should be looking for.”

Fossil technician Abel Molepolle casting a replica of a fossil from the Sterkfontein Caves. (Photo: Ihsaan Haffejee)

The legacy of colonialism and the skewed power dynamics of race and class have meant that, over the years, the work of fossil technicians – often black and with no formal higher education – has not been recognised. Their important contributions have been relegated to the footnotes of the pages that document their findings.

Technician Andrew Phaswana with fossil casts. Phaswana and his team create moulds from the original fossils and then cast replicas. These are used for scientific study while the precious originals are stored for safekeeping. (Photo: Ihsaan Haffejee)

‘It is an academic contribution’

Kibii said the scientific community’s lack of recognition had been a disservice to fossil technicians. He is now actively working to educate scientists doing research at the site on the importance of the technicians’ work.

“I want them to be included in the actual publications, in the actual descriptions of those specimens, so they can be recognised with academic contribution,” he said. “Because it is an academic contribution.”

Sipho Makhele excavates in the Sterkfontein Caves’ Silberberg Grotto, close to where the Australopithecus fossil Little Foot was discovered. (Photo: Ihsaan Haffejee)

“We are not asking for much,” said technician Sipho Makhele. “We are just asking to be acknowledged for the work we do.”

Makhele too has family ties to the site, as the third generation to work in the caves. It may go on to a fourth. “Now my young daughter is also interested and has begun her university studies in anthropology,” he said.

“So, we will keep digging and digging. There’s still plenty to find down there.”

An undated old photo of fossil technicians at the Sterkfontein Caves. Itumeleng Molefe’s’s father, Nkwane Molefe, is second from right. Steven Motsumi is fifth from right. The pair unearthed the famous Australopithecus fossil Little Foot while working under paleoanthropologist Ron Clarke.

Inside the Sterkfontein Caves, where some of the world’s most important human fossils have been discovered. (Photo: Ihsaan Haffejee)

Originally published by GroundUp on 30 June 2025.
© 2025 GroundUp. This article is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.

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MARY ALEXANDER • 8 DECEMBER 2018

An artist’s impression of the earth’s surface billions of years ago. The planet had almost zero oxygen in its atmosphere, but there was still life: microorganisms living in the globe-spanning ocean, long before today’s continents were formed.  (National Geographic – The Story of Earth)

Life on earth needs oxygen to survive, right? Maybe not. A South African scientist and his colleagues have discovered the remains of giant bacteria that flourished on our planet billions of years ago – breathing sulphur.

Fossils of the bacteria were found in a thick layer of extremely hard and ancient black rock in South Africa’s Northern Cape province. They have been dated as 2.52-billion years old. Earth itself is 4.5-billion years old.

At the time these bacteria lived, there was just a trace of oxygen in our planet’s atmosphere – less than one-thousandth of one percent of what there is now. The air we breathe today is about 21% oxygen.

The fossils were discovered and analysed by a research team that included Professor Nicolas Beukes, a geologist at Cimera. He and his colleague Andrew Czaja of the University of Cincinnati published their research in the December 2016 issue of the journal Geology.

The ancient bacteria were exceptionally large – much larger than most modern bacteria – sphere-shaped, and smooth-walled. They were similar to modern single-celled creatures that live in the sulphur-rich waters of the deep oceans, where even now there is almost no oxygen.

ABOVE: A 3-D digital image showing the wrinkled surface of the compressed fossil, which was originally round. With a diameter of about 200 microns – 0.2 millimetres – these creatures were massive for bacteria.

Deep and dark waters

“These fossils represent the oldest known organisms that lived in a very dark, deep-water environment,” says Czaja. “These bacteria existed 2-billion years before plants and trees, which evolved about 450-million years ago. We discovered these microfossils preserved in a layer of hard silica-rich rock called chert located within the Kaapvaal craton of South Africa.”

The first half of our 4.5-billion-year-old planet’s history was an important time for the development and evolution of ancient bacteria. But there is little evidence of these life forms, or of how they survived with virtually no oxygen.

The bacteria thrived in deep areas of the ocean in a geologic time, 2.8- to 2.5-billion years ago, known as the Neoarchean Eon.

Because the atmosphere then had only traces of oxygen, scientists thought there could have been creatures that didn’t need sunlight or oxygen, living in the mud at the depths of the ocean. But there was no evidence, until now.

What makes these ancient South African fossil bacteria even more remarkable was not only that they breathed sulphur gas, but they also lived 2.5-billion years ago – more than 2.2-billion years before the dinosaurs first put in an appearance. (Andrew Czaja, University of Cincinnati)

The oxygen revolution

While the giant bacteria were thriving in the deep ocean, other species of micro-organism were living in shallower waters, closer to sunlight. These survived with photosynthesis, converting the sun’s energy into chemical energy – and releasing oxygen as a by-product. As these bacteria multiplied, so the oxygen levels in the earth’s atmosphere increased.

“We refer to this period as the Great Oxidation Event of 2.4- to 2.2-billion years ago,” says Czaja. This, he says, was “a time of major atmospheric evolution”.

Ancient rocks such as those containing the giant fossil bacteria are extremely rare today. So scientists’ understanding of the Neoarchean Eon is based on samples found in a handful of geographic areas, including South Africa’s Northern Cape.

Scientists theorise that South Africa and Western Australia were once part of an ancient supercontinent called Vaalbara. Then a shifting and upending of tectonic plates during a major change in the Earth’s surface split them apart.

In search of ancient bacteria … The scientists on a 2014 excursion to collect fossils near the town of Kuruman in South Africa’s Northern Cape province. From left: Clark Johnson, University of Wisconsin, Madison; Aaron Satkoski, University of Wisconsin, Madison; Nicolas Beukes, University of Johannesburg, South Africa; Breana Hashman, University of Wisconsin, Madison; and Kira Lorber, University of Cincinnati. (Andrew Czaja, University of Cincinnati)

‘Doing something remarkable’

According to the research by Beukes and Czaja, the Neoarchean bacteria, living deep in muddy sediment on the ocean floor, were processing hydrogen sulphide, the gas that gives off a rotten egg smell. They then emitted sulphate, a gas with no smell. He says this is the same process that goes on today as modern bacteria recycle decaying organic matter into minerals and gases.

“While I can’t claim that these early bacteria are the same ones we have today, we surmise that they may have been doing the same thing as some of our current bacteria,” says Czaja. The bacteria probably consumed dissolved sulphur-rich minerals from land rocks that had eroded and washed out to sea, or from old volcanic lava on the ocean floor.

There is an ongoing debate about when sulphur-oxidising bacteria arose and how that fits into the earth’s evolution of life.

“But these fossils tell us that sulphur-oxidising bacteria were there 2.52-billion years ago,” Czaja says, “and they were doing something remarkable.”

Comments? Email mary1alexander@gmail.com

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