Almost everyone arrives in northern Tanzania with the same list, and that list is made of animals. It is an excellent list and it leaves out something that is literally on the same map: two of the world's most important sites on human origins.
They are not in another region and they do not require another trip. Olduvai Gorge is inside the Ngorongoro conservation area, and Laetoli is about 45 kilometres from it. Anyone going to the crater passes close by without noticing.
01 Two sites inside the circuit
The gorge is about 48 kilometres long and reaches 90 metres deep, cut by erosion into Pleistocene lake sediments. It is in Ngorongoro district, inside Arusha Region.
That it sits inside the conservation area is the logistical key to this whole article. You do not need to mount an expedition: you need to decide to give half a day of the itinerary you already have, and to do it knowing what you will find.
02 What came out of Olduvai
Systematic excavations began in 1931, led by Mary and Louis Leakey. The two finds that changed the field arrived a year apart and in the same stretch of gorge.
In 1959, Mary Leakey found at the FLK site the skull of a Paranthropus boisei, initially known as Zinjanthropus. In 1960, Jonathan Leakey found at FLK North-North the mandible that became the type specimen of Homo habilis.
A type specimen is not just another fossil: it is the reference against which an entire species is defined. That the one for Homo habilis came out of this gorge makes the site more than an important dig.
03 Why it can be dated precisely
Here is what makes Olduvai unique and what you enjoy most if you arrive understanding it. The deposits span from 1.89 million years ago to about 17,000 years ago. A range like that is only useful if each layer can be dated.
And it can be, thanks to something that has nothing to do with the bones: volcanic ash from Olmoti and Kerimasi, interleaved between the sediments. That ash can be dated by radiometric methods such as potassium-argon.
Which is to say: the reason this place is an archive and not a pile of loose finds is that a couple of local volcanoes kept marking time with ash layers for two million years. Without volcanoes, there would be no chronology.
What dates the Olduvai fossils is not the fossils: it is the ash from the volcanoes next door.
04 Laetoli and the important warning
About 45 kilometres from the gorge lies Laetoli, and what was found there is probably the most moving find in all of palaeoanthropology: a trail of footprints 3.7 million years old.
Mary Leakey's team discovered them in 1976 and they were fully excavated by 1978. There are three individuals, one of them stepping in another's prints, on a main trackway of about 24 metres with around seventy impressions. The species usually proposed is Australopithecus afarensis.
They were preserved because a layer of volcanic ash about fifteen centimetres thick took a soft rain that cemented it into tuff without erasing the prints. And what they prove is enormous: that bipedalism came before brain enlargement, roughly a million years before the first stone tools.
And now the warning, because it is the reason this article exists. The original trackway was reburied in 1979 to preserve it, protective layers were added in 1993 and it remains covered. It cannot be seen.
05 What you actually see today
It is worth being explicit about this because it marks the difference between a memorable visit and a disappointment. What there is at Olduvai today is the gorge — visible in full from the rim, with its bands of sediment and ash — and a museum.
That museum, sitting on the gorge rim and about five kilometres from the main monument, is considered one of the largest onsite museums in Africa. It is not a small annexe: it is the centrepiece of the visit.
And there is something you do see that makes up for the absent footprints: the cut of the ground itself. From the viewpoint you can make out the horizontal bands on the walls, which are the stacked layers of sediment and ash. You are looking at two million years arranged from the bottom up.
06 If this describes you
The useful question is not whether fossils interest you, but whether a site interests you knowing that most of what made it famous is in museums in other cities or buried under protective layers. Anyone who answers yes will find here one of the most meaningful stops on the continent.
And if you are travelling with people who came exclusively for the wildlife, say so before booking. This stop takes half a day and has no animals: it is a dry gorge, a museum and an idea. For anyone who gets it, it is the best half day of the trip; for anyone who does not, it is a long detour.
