Craig S. Feibel

3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya

Human evolutionary scholars have long supposed that the earliest stone tools were made by the genus Homo and that this technological development was directly linked to climate change and the spread of savannah grasslands. New fieldwork in West Turkana, Kenya, has identified evidence of much earlier hominin technological behaviour. We report the discovery of Lomekwi 3, a 3.3-million-year-old archaeological site where in situ stone artefacts occur in spatiotemporal association with Pliocene hominin fossils in a wooded palaeoenvironment. The Lomekwi 3 knappers, with a developing understanding of stone’s fracture properties, combined core reduction with battering activities. Given the implications of the Lomekwi 3 assemblage for models aiming to converge environmental change, hominin evolution and technological origins, we propose for it the name ‘Lomekwian’, which predates the Oldowan by 700,000 years and marks a new beginning to the known archaeological record.

Early hominid stone tool production and technical skill 2.34 Myr ago in West Turkana, Kenya

Well-documented Pliocene archaeological sites are exceptional. At present they are known only in East Africa, in the Hadar, and Shungura formations of Ethiopia and in the Nachukui formation of Kenya. Intensive archeological survey and a series of test excavations conducted in the Nachukui formation since 1987 have led to the discovery of more than 25 archaeological sites whose ages range from 2.34 to 0.7 million years before present (Myr),, and to the extensive excavation of two 2.34-Myr sites, Lokalalei 1 in 1991 (refs 6, 7) and Lokalalei 2C in 1997. Lokalalei 2C yielded nearly 3,000 archaeological finds from a context of such good preservation that it was possible to reconstitute more than 60 sets of complementary matching stone artefacts. These refits, predating the Koobi Fora refits by 500 Kyr (ref. 8), are the oldest ever studied. Here we describe a technological analysis of the core reduction sequences, based on these refits, which allows unprecedented accuracy in the understanding of flake production processes. We can thus demonstrate greater cognitive capacity and motor skill than previously assumed for early hominids, and highlight the diversity of Pliocene technical behaviour.

Lothagam: a record of faunal change in the late Miocene of East Africa

ABSTRACT Lothagam is a richly fossiliferous late Miocene site near the western shore of Lake Turkana, northern Kenya. This site has yielded a diverse fauna documenting a chronological interval poorly known from elsewhere in Africa. Lothagam was first collected by an American research group in the late 1960s and early 1970s. Field studies by the National Museums of Kenya between 1989–1993 have recovered many additional vertebrate fossils, including species previously unknown from Lothagam. This contribution presents a revised, formal stratigraphic framework, initial results of a vertebrate systematic revision, and new interpretations of the paleoenvironmental setting. Analysis of the sedimentary facies and their fossil content indicates the presence of a large, slow moving, well-oxygenated perennial river with abundant backswamps and ponds. Comparisons with faunas from earlier middle to late Miocene Kenyan localities suggest that a major environmental change occurred at the end of the Miocene.

New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo

Since its discovery in 1972 (ref. 1), the cranium KNM-ER 1470 has been at the centre of the debate over the number of species of early Homo present in the early Pleistocene epoch of eastern Africa. KNM-ER 1470 stands out among other specimens attributed to early Homo because of its larger size, and its flat and subnasally orthognathic face with anteriorly placed maxillary zygomatic roots. This singular morphology and the incomplete preservation of the fossil have led to different views as to whether KNM-ER 1470 can be accommodated within a single species of early Homo that is highly variable because of sexual, geographical and temporal factors, or whether it provides evidence of species diversity marked by differences in cranial size and facial or masticatory adaptation. Here we report on three newly discovered fossils, aged between 1.78 and 1.95 million years (Myr) old, that clarify the anatomy and taxonomic status of KNM-ER 1470. KNM-ER 62000, a well-preserved face of a late juvenile hominin, closely resembles KNM-ER 1470 but is notably smaller. It preserves previously unknown morphology, including moderately sized, mesiodistally long postcanine teeth. The nearly complete mandible KNM-ER 60000 and mandibular fragment KNM-ER 62003 have a dental arcade that is short anteroposteriorly and flat across the front, with small incisors; these features are consistent with the arcade morphology of KNM-ER 1470 and KNM-ER 62000. The new fossils confirm the presence of two contemporary species of early Homo, in addition to Homo erectus, in the early Pleistocene of eastern Africa.

Numerical age control for the Miocene-Pliocene succession at Lothagam, a hominoid-bearing sequence in the northern Kenya Rift

Lothagam, located west of Lake Turkana in northern Kenya, is an uplifted fault block comprising a gently westward-dipping sequence of volcanic and sedimentary rocks. The lower part of the sequence, lavas and coarse volcaniclastic sediments of the Nabwal Arangan beds, was deposited mainly between 14 Ma and 12 Ma (Mid-Miocene), although the uppermost basalt has a K-Ar age of 9.1 Ma. The overlying fluvial sediments of the lower Nawata Formation have yielded ages on five tuffaceous horizons ranging from 7.4 ±0.1 to 6.5 ±0.1 Ma, Late Miocene. A tuffaceous horizon in the overlying Apak Member of the Nachukui Formation, yields an age of 4.22 ± 0.03 Ma; 40Ar-39Ar age spectra on the succeeding Lothagam Basalt indicate an age of 4.20 ± 0.03 Ma for its eruption. Much of the rich faunal assemblage from the Nawata Formation derives from the tightly dated lower intervals. Two hominoid teeth from higher in the formation can only be constrained to lie between 6.5 and 5 Ma old. The hominoid mandible, KNM-LT 329, from the lower Apak Member is older than 4.2 Ma and younger than 5.0 Ma.

Revision of lithostratigraphic nomenclature in the Koobi Fora region, Kenya

Recent advances in our understanding of the Plio-Pleistocene sedimentary sequence northeast of Lake Turkana in northern Kenya has allowed a revision of the lithostratigraphic nomenclature and a more complete description of the deposits. As redefined, the Koobi Fora Formation encompasses the entire Plio-Pleistocene sedimentary sequence, and is subdivided into eight members. These members are delineated using volcanic ash horizons, which can be identified uniquely on the basis of chemical composition. The revised stratigraphy resolves all earlier conflicts with the biostratigraphic zonations based on vertebrate and molluscan studies. The sedimentary sequence of the Koobi Fora Formation attains an aggregate thickness of 560 m and spans the period from about 4.3 to 0.6 Ma. Detailed correlations have now been established to relate this sequence to other deposits within the Turkana Basin and to those at Hadar and in the Gulf of Aden.

Spatial Organization of Hominin Activities at Gesher Benot Ya’aqov, Israel

Home Is Where the Hearth Is One aspect of human intelligence is the ability to organize our living and working spaces. It was generally thought that this capability arose with modern humans in the past 100,000 years or so. However, Alperson-Afil et al. (p. 1677) found evidence of domestic organization 800,000 years ago at a Pleistocene hominin campsite in the Jordan Valley. Around patches of burnt debris, the remains of a wide range of plant and animal foodstuffs were found, including fruits and seeds, as well as remnants of turtles, elephants, and small rodents. Specific types of stone tools appear to have been made around the hearths, where there was also evidence of nut roasting and consumption of crabs and fish. In a more distant area there were signs of intensive flint knapping and food chopping. The spatial distribution of artifacts implies that living space was organized by use as early as 800,000 years ago. The spatial designation of discrete areas for different activities reflects formalized conceptualization of a living space. The results of spatial analyses of a Middle Pleistocene Acheulian archaeological horizon (about 750,000 years ago) at Gesher Benot Ya’aqov, Israel, indicate that hominins differentiated their activities (stone knapping, tool use, floral and faunal processing and consumption) across space. These were organized in two main areas, including multiple activities around a hearth. The diversity of human activities and the distinctive patterning with which they are organized implies advanced organizational skills of the Gesher Benot Ya’aqov hominins.

A geological history of the Turkana Basin.

The Turkana Basin preserves a long and detailed record of biotic evolution, cultural development, and rift valley geology in its sedimentary strata. Before the formation of the modern basin, Cretaceous fluvial systems, Paleogene lakes, and Oligo‐Miocene volcano‐sedimentary sequences left fossil‐bearing strata in the region. These deposits were in part related to an early system of rift basins that stretched from Sudan to the Indian Ocean. The present‐day basin has its origins in Pliocene tectonic developments of the modern rift, with subsidence making room for more than one kilometer of Plio‐Pleistocene strata. Much of this sequence belongs to the Omo Group, richly fossiliferous sediments associated with the ancestral Omo River and its tributaries. Modern Lake Turkana has a record stretching back more than 200 thousand years, with earlier lake phases throughout the Plio‐Pleistocene. The geologic history of the basin is one of dynamic landscapes responding to environmental influences, including tectonics, volcanic activity and climate.

Tephrostratigraphy and geological context in paleoanthropology

The fossiliferous and artifact‐rich sites of East Africa, which are central to our understanding of early hominid evolution, also preserve a detailed record of explosive volcanism. The products of these eruptions, ash, lapilli, and pumice, are collectively known as tephra. They drifted down from the skies or washed down rivers in later rainy seasons, and now provide a key to both dating and correlation, and with them the establishment of a geologic framework for evolution. While some tephra can be directly dated, particularly through mineral phases they contain, the glass component of most ashes has a geochemical fingerprint that is unique to a particular eruption. That fingerprint defines an isochronous marker, a layer in time. By identifying characteristic geochemical signatures from far‐flung localities, geologists can correlate sequences, establish relationships in time, and compile long‐term records from local sections. Much of our understanding of the pattern and timing of Plio‐Pleistocene evolution in East Africa is based on this tephrostratigraphic framework.

GRADUAL VERSUS PUNCTUATED EQUILIBRIUM EVOLUTION IN THE TURKANA BASIN MOLLUSCS: EVOLUTIONARY EVENTS OR BIOLOGICAL INVASIONS?

Abstract A running controversy in evolutionary thought was Eldredge and Goulds punctuated equilibrium model, which proposes long periods of morphological stasis interspersed with rapid bursts of dramatic evolutionary change. One of the earliest and most iconic pieces of research in support of punctuated equilibrium is the work of Williamson on the Plio-Pleistocene molluscs of the Turkana Basin. Williamson claimed to have found firm evidence for three episodes of rapid evolutionary change separated by long periods of stasis in a high-resolution sequence. Most of the discussions following this report centered on the topics of (eco)phenotypy versus genotypy and the possible presence of preservational and temporal artifacts. The debate proved inconclusive, leaving Williamsons reports as one of the empirical foundations of the paradigm of punctuated equilibrium. Here we conclusively show Williamsons original interpretations to be highly flawed. The supposed rapid bursts of punctuated evolutionary change represent artifacts resulting from the invasion of extrabasinal faunal elements in the Turkana palaeolakes during wet phases well known from elsewhere in Africa.