Lake Turkana - Mankind's Origins

See also our evolutionary family tree (until further notice!), the Dancing Stones of Namoratunga, and the mysterious 'cup-marks' of Rukinga and Chomoto, in the Taita Hills. There are lots of good websites on prehistory and palaeontology. A couple of recommendations: PaleoAnthropology: A Short Journey Through Time, and Talk Origins.
In this page:
Australopithecus afarensis
Homo habilis
Australopithecus robustus (A. africanus)
Australopithecus boisei
Australopithecus aethiopicus
Australopithecus anamensis
Homo erectus


Fossilized monkeyIt is an irony that in this bare land, where man now struggles to survive, the past was neither waterless nor barren. Ample fossil evidence indicates that the lake's shores were teeming with wildlife, including prehistoric elephants and three-toed ancestors of the horse, and before them some truly enormous dinosaurs such as the 50-tonne, 25-metre long Diplodocus, a fossil of which was found near Lokitaung on the west side of the lake. Other animal fossil finds include both black and white rhino, the extinct giant otter, hippo and the extinct pygmy hippo, elephant, monkeys, wild camels and lion. But most remarkable, and the reason for Turkana's worldwide fame as the purported 'Cradle of Mankind', are the finds of early hominids, including remains of various Australopithecus species, Homo habilis, Homo erectus and Homo sapiens.

Although Lake Turkana and adjacent parts of the Rift may not necessarily be the only - or even the earliest - cradle of mankind, the abundance of the fossil record here has been taken by many to support the 'Out of Africa' or 'African Eve' theories of human origin, which postulate that mankind began life in Africa, from where it began fanning out across the rest of the world. Whether or not mankind originated in East Africa, the path of human evolution, from the first faltering steps of Australopithecus some four and a half million years ago, to the first tools shaped by Homo habilis three million years ago, through Homo erectus and Homo sapiens ("knowledgeable man") to ourselves - Homo sapiens sapiens ("too-clever-by-half man"?) - can be traced through the fossils that have been unearthed along the shores of Lake Turkana.

Incidentally, I have stubbornly ignored any mention of the genus Paranthropus, which is how some experts have classed our friends Australopithecus aethiopicus, A. boisei and A. robustus, for the simple reason that I don't want to confuse anyone any more than I'm confused already. Anyhow, the whole structure changes in any case with every fresh discovery... If you really miss Paranthropus, you'll find him on the evolutionary family tree.

Lucy, world superstar
Australopithecus afarensis - Jaw Mandible
Ardipithecus (Australopithecus?) ramidus

Australopithecus afarensis

(2,500,000-3,500,000 BP)

Since 1967, when the palaeontologist Richard Leakey unearthed some stone tools on the eastern shore of the lake and became curious, several sites on both sides of the lake, most famously at Koobi Fora on the east, have yielded an astonishing quantity of proto-human fossils. Since then, further important finds have also been made in Tanzania and in Ethiopia, most famously the Australopithecus afarensis skeleton called "Lucy" - nearly half of the bones of a 3.2 million year old australopithecine woman which were uncovered in 1974 at Hadar in the Afar Triangle of Ethiopia. From this comes her scientific name, "southern ape of the Afar", and it is Lucy who, in the popular imagination, is our very own great grandmother several thousand times removed: the African Eve.
   Forgetting that rather simplistic image for a moment, the upshot of all this is that relatively intelligent, upright, tool-using ancestors of modern man lived in eastern Africa as early as 2.5 million or 3.6 million years ago, or almost twice the time span of previous estimates. They also ate meat, unlike A. boisei which appeared much later.
   Whether australopithecus afarensis itself was our direct ancestor is, however, an entirely different matter, although the discovery of a male A. afarensis skull ("Lucy's Grandson") supports the theory. The 1994 discovery of much older 4.4 million year old fragments in Ethiopia also gave hope to this theory, although their discoverers revised the name they initially gave this new species from Australopithecus ramidus (ramid meaning root in the local Afar language) to Ardipithecus ramidus, when they realized that the animal was really much more similar to chimps than humans. Nonetheless, ramidus hasn't yet been completely ruled out of contention as a human ancestor.

Skull 1470 Homo habilis
ER 1813 Homo habilis?

Homo habilis

(2,500,000-2,600,000 BP)

Following the first discoveries of Australopithecus afarensis, Leakey began arguing that the two other main australopithecine forms then known (A. robustus and A. boisei) eventually died out and that the stone-tool using Homo habilis ("handy man") evolved into Homo erectus (see below), the direct ancestor of Homo sapiens, which begat homo sapiens sapiens, modern human beings. Of particular importance is the Homo habilis skull, prosaically called "Skull 1470", which was found in 1972 at Koobi Fora, and reconstructed from almost 300 different pieces. This creature lived about 2,600,000 years ago and is believed to be a direct ancestor of modern man. The discovery of Skull 1470 caused great controversy in the scientific community because it lacked the pronounced brow of other hominid skulls and had a cranial capacity nearly twice that of Australopithecus and more than half that of modern humans. Many believe Homo habilis is one of the earliest examples of modern humans which developed the skills to make and use basic tools, and this probably led to their success. Was this the 'missing link'?

Taung Child

Australopithecus robustus (A. africanus)

(2,000,000-2,500,000 BP)

As far as I can gather, Australopithecus africanus, which was first found in the Taung Caves in South Africa (and is called the "Taung child"), has not been found in Kenya. Still, he's important to us as he's a 2.5 million year old example of the Australopithecus robustus species, from which A. boisei is presumed to have evolved (see below), and to which A. aethiopicus is related. They are all known as robust australopithecines, because their skulls in particular are more heavily built.
   The Taung child was a significant find at the time since the skull indicated a spinal cord entering from below rather than behind - a good sign that the owner walked upright.

ER 406 A. Boisei
Australopithecus boisei - Nutcracker Man

Australopithecus boisei

(1,100,000-2,100,000 BP)

The Koobi Fora area represents one of the richest locations of hominid fossils ever found. The finds - most spectacularly a complete skeleton and several skulls - provide evidence which, alongside other African finds, points to a species called Australopithecus boisei, which is estimated to have lived from around 1,100,000 to 2,100,000 years ago. Its diet was strictly vegetarian, and it is a variant of Australopithecus robustus, the remains of which were first recovered in South Africa (see A. africanus above). It is generally believed that A. boisei was not our ancestor, and that the species eventually died out.

The Black Skull

Australopithecus aethiopicus

(2,500,000 BP)

Despite initial excitement in the 1920s, Australopithecus had been discounted as a possible human ancestor by the 1940s, and out it stayed in the cold until the 1990s, when fresh research and discoveries at Lake Turkana put new life into the old debate.
   Until the 1990s, the theory which was gaining increasing acceptance was based on the 1970s discoveries, whose implications seemed pretty simple: Homo habilis evolved into Homo erectus, and both lived in East Africa. Homo erectus in turn evolved into the modern human, which then fanned out across the world. Meanwhile, the australopithecines had died out and so could not be our ancestors.
   However, further discoveries in the 1980s and 1990s have confused the issue, creating heated and often vindictive debate among archaeologists, palaeontologists and anthropologists. But any firm conclusions - and they seem to be as numerous as the 'experts' expounding them - can only be speculation. So remember that, before you get confused!
   The first problem (the second was Australopithecus anamensis, below) was the mid-1980s discovery in west Turkana of an australopithecine cranium (KNM-WT 17000) which appears to be very different from the robust australopithecines known so far (A. robustus and A. boisei). This new specimen, which has been classed as Australopithecus aethiopicus and is more commonly known as "The Black Skull", may be evidence showing that evolution not only leads to divergence, but possibly convergence.

Australopithecus anamensis

Australopithecus anamensis

(3,900,000-4,400,000 BP)

The next key discovery, which really turned things upside down, was the mid-1990s find of the remains of about 21 Australopithecus individuals in Alia Bay on the east shore of Lake Turkana, and at Kanapoi on the west shore. Consisting mainly of leg and arm bones and a few jaws, the fossils have been dated to between 3.9 and 4.4 million years, and show conclusively that, although ape-like in some regards, these hominids walked upright. Australopithecus anamensis (anam is the Turkana word for lake) is thus the earliest bipedal hominid yet found, and the discovery has only started to fuel more controversy about whether australopithecus could indeed have been our direct ancestor. If yes, then A. anamensis is our oldest-known ancestor to date.
   The first remains of Australopithecus anamensis, incidentally, were discovered at Kanapoi in 1965, but were not properly classified as such until the 1990s discoveries.

ER 3733 Homo erectus
Turkana Boy
Turkana Boy skull profile

Homo erectus

(1,600,000-1,800,000 BP)

Enough of australopithecines! Homo erectus is an altogether easier matter, as the experts are in rare unanimity that H. erectus was definitely our ancestor. Apart from walking upright, H. erectus was also the first hominid to emigrate from Africa, at least 1.8 million years ago, spreading all the way to China and Indonesia. Then, at some point - for reasons still mysterious - the lineage diverged, with one branch leading to Neanderthals and another to modern humans. H. erectus was a tool maker, which provided the ability to obtain meat from relatively large grazing animals.
   Of several Kenyan specimens that clearly belong to Homo erectus, a cranium from Koobi Fora (KNM-ER 3733) is one of the most ancient and best-preserved Homo erectus fossils discovered anywhere in Africa. On the northwestern shore of the lake, excavations at Nariokotome came up with another almost complete skeleton of a slender adolescent Homo erectus male, catalogued as KNM-WT 15000 but more popularly known as "Turkana Boy". He was about 12 years old when he died, some 1.6 million years ago, and now lives in a display case in Nairobi's National Museum. As an adult, he would have grown to about six feet tall (1.80m), not unlike the present-day Turkana.


I'll keep it simple. Until the 1980s, things seemed pretty clear cut: Homo habilis evolved into Homo erectus, and both lived in East Africa. Homo erectus in turn evolved into the modern human, which then fanned out across the world. Meanwhile, the australopithecines had died out and were not our ancestors.
   However, the subsequent discoveries of bipedal Australopithecus anamensis, bearing signs of modern characteristics and dated to around 4 to 4.5 million years, threw the simplistic step-by-step evolutionary theories into disarray.
   Since these finds belong to a species much older than the 1970s fossils, and moreover to a species which was long believed simply to have died out, researchers are now faced with a radical rethinking of human evolution, especially as most had discounted the idea that Australopithecus could have been our ancestors.
   The idea currently favoured is that several different hominid species may have coexisted in the same periods, of which only one could presumably have any direct relation to ourselves. The answer, of course, is which? And this leads one to question whether and how these different species of hominid interacted with each other. Did they compete, or were their diets different? Did they fight each other? Did they simply ignore each other? Or even, did they interbreed and 'converge', as the "Black Skull" (Australopithecus aethiopicus KNM-WT 17000) might suggest?

Leakey and his team have said that they are currently studying two 5.5 million-year-old hominid teeth and a similarly ancient jaw fragment with an embedded tooth from a site in northern Kenya, whilst another group has announced that it is working on Ethiopian fossils dated about the same age, either of which may change all these theories once again.

The only thing that's certain is that palaeontologists have only begun to scratch the surface of the story of human evolution: Lake Turkana almost certainly has a few more surprises in store, just to confuse us all once again, but always for the better!


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also by Jens Finke
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