Lake Turkana - Mankind's Origins

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.

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'?

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.

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.

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

---

(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.

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.