In 1931, at the age of 28, Louis Leakey made his first trip to Olduvai Gorge, in what is now Tanzania. His goal: to prove that Africa – specifically East Africa, where he had been born and grown up – was the so-called “cradle of humanity”.

It was, he had been told, a fool’s errand. “There’s nothing of significance to be found there,” one of his professors at the University of Cambridge reportedly advised. “If you really want to spend your life studying early man, do it in Asia.”

Leakey, however, stuck to his guns – and within months, he had been proven right. With his discovery of a few primitive hand axes buried in ancient sediment, Olduvai Gorge was officially put on the map as a place of significance in the history of humankind.

In the decades since that first dig, its importance has only increased.

An ancient controversy

Leakey was not the first to investigate Olduvai Gorge. In fact, his curiosity about the site had initially been piqued by the earlier work of Hans Reck, a German geologist who, in 1913, had discovered hominin remains in the Gorge that he claimed were about half a million years old.

Reck was wrong about the fossils’ age – radiocarbon dating would later confirm that they were only around 17,000 years old, but had been buried in much older sediment. His general conclusion, however – that Olduvai would ultimately challenge everything scientists of the time knew about the history of humanity – was correct.

It would just take a few decades of work.

In 1964, Leakey and his colleagues – by this point including his wife Mary, who arguably made most of the actual finds associated with the Leakey name, and his son Jonathan – made a controversial announcement. The fossils they had collected in Olduvai a few years earlier belonged, they said, to a previously unknown species of hominin. 

They called it Homo habilis, or the “handy man”, due to the presence of stone tools near its remains – tools which, the Leakeys said, the ancient human had crafted themselves. Even more shockingly, it had been revealed by cutting-edge dating techniques as being more than 1.75 million years old.

“The announcement of Homo habilis was a turning point in palaeoanthropology,” wrote Bernard Wood, a palaeoanthropologist at George Washington University in Washington DC, in a 2014 article for Nature. “It shifted the search for the first humans from Asia to Africa and began a controversy that endures to this day.”

As stubborn as Leakey was that this was a new species, other anthropologists were equally sure that it could not be. “Some thought that the fossils were too similar to Australopithecus africanus to justify a new species,” Wood explained. “John Robinson, a leading authority on australopiths, suggested that H. habilis was a mix of earlier A. africanus and later H. erectus bones.” 

“Other researchers agreed that the species was new,” he wrote, but “[v]ery few accepted that it was the earliest human.”

Even today, many anthropologists are loathe to accept H. habilis into the immediate family. Its features are too ape-like, they argue; its brain too small. They were likely scavengers rather than hunters, and as for their claim of being the first toolmakers – well, even that was controversial from the beginning.

The workshop of humankind

H. habilis may be the most infamous ancient hominin to have been found in Olduvai Gorge, but it’s far from the only one. Indeed, from the very start, their name may have been a case of stolen valor: “Louis and Mary Leakey were looking for the maker of the stone tools they had found,” explained Fred Spoor, a Research Leader in human evolution at the Natural History Museum. 

“First, they found a rather bizarre heavily built creature with a very flat, upright face not at all like modern humans. It quickly got the nickname “Nutcracker Man”. They thought this must be the toolmaker.”

They gave this ancient hominin the name Zinjanthropus boisei, claiming that it was a brand-new genus. Today, it’s considered a species of australopithecine, and generally known as Paranthropus boisei – though some anthropologists would argue that even this is unnecessarily divisive, and prefer the classification Australopithecus boisei.

The idea that Nutcracker Man may have been responsible for the tools around them, though, was quickly dismissed after the Leakeys discovered H. habilis – a species with smaller, more human-like teeth, a potentially larger brain, and crucially, hand fossils, Spoor explained. 

It wasn’t until 2023 that the poor Paranthropus was potentially vindicated, when some of the oldest stone tools ever discovered were found near Nutcracker remains – suggesting that these ancient ape-men weren’t as dim-witted as previously thought. And in fact, modern research in Olduvai Gorge has borne out this idea of humanity’s endless skill for invention, with the site providing evidence of millions of years’ worth of evolving adaptation.

“Taken together, the data we gathered presents the earliest evidence for human activity in the Olduvai Gorge: about 2 million years ago,” wrote Julio Mercader Florin, a Professor in the Department of Anthropology and Archaeology at the University of Calgary, in a 2021 article for The Conversation. “It also shows that early humans used a great diversity of habitats as they adjusted to constant change.”

“This is a clear sign that 2 million years ago humans were not constrained technologically and already had the capacity to expand geographic range, as they were ready to exploit a multitude of habitats within Africa – and, possibly, beyond.”

Why Olduvai?

It’s clear, then, that Olduvai Gorge is a priceless resource for the study of humanity’s origins. But what about it makes this place so rich in history?

Perhaps surprisingly, it’s the area’s unique geography that might be key. “Olduvai Gorge is in East Africa,” Florin explained in a 2021 episode of The Conversation Weekly podcast, “and if you think of it as a region, there is this rift that is splitting the crust of the earth that is allowing volcanoes to spit out lava and ash.” 

“But at the same time […] it’s making the terrain sink,” he said. “And when that happens, you have water building up, and that forms lakes and rivers and swamps. And because of that, biodiversity tends to be really, really high, because nature is really productive in this kind of rift context.”

Just like any other animal in the region, he explained, the earliest humans were drawn towards this bounty of resources – but the geological processes that gave so much would, ultimately, also be their downfall.

“[L]ife near volcanoes was preserved because the eruptions and the sediments covered that up and then archaeologists exposed it,” Florin said. “[I]magine an African Pompeii. But […] much older; it is two million years [ago]. And instead of Romans, you want to imagine […] early humans, several species.”

It’s thanks to this enormous tectonic quirk, therefore, that Olduvai Gorge has cemented its place in the story of human evolution. And by all accounts, it is a pretty stunning region for our species to have grown up: “[T]he gorge is like a canyon, it’s like a small version of the Grand Canyon,” Florin explained. “And because there is like a scar in the terrain, you can see the fossils in the remains, popping out from the walls that create the canyon.”

“[T]o sum it up, Olduvai Gorge is important because many aspects of early human life have been buried, covered and preserved for posterity,” he said. “And it’s not only the human fossils, but what we humans did on a daily basis, our activities.”