Early Hominids 2

Diagnostic features, the species, timescale, "Out of Africa" or "Multiregional hypotheses".

Homo - diagnostic features

NB. Some features are behavioural (language, society, ritual, art)

• Large brain (beware, must take into account body size)
• Large cranial vault
• Face tucked underneath
• Prominent nose
• Bony spine at centre of base of nose
• Short base of skull
• Folded base of skull
• Throat remodelled for language (lower voice box)
• Thin mandible
• Chin
• Small teeth
• Slow tooth eruption
• Slow development
• Late sexual maturity
• Long life (survive after reproductive age - cultural skill transmission value?)
• Hip joint modifications
• Light skeleton (perhaps only H. sapiens)

Homo habilis

2.4mya, eastern & southern Africa. Coincides with the appearance of "Oldowan" style stone tools. 7500-800ml cranial capacity, comparatively small molar teeth. Two classic crania from Koobi Fora: KNM-ER 1470 and KNM-ER 1813. Referred to as large and small form H. habilis. Argument about whether 2 different species (large form = H. rudolfensis) or male and female examples (c.f. A. afarensis).

Homo erectus

1.8mya, in eastern Africa. Persisted for over 1my and spread to Asia. Asian form used to be known as Pithecanthropus erectus, but this is no longer the general opinion. Earliest examples from Koobi Fora (e.g. KNM-ER 3733) and West Turkana (KNM-WT 15000). Brain size: 800-900ml. Long low skull with broad base, prominent brow ridges. Generally much larger than H. habilis and with more pronounced nose. Nariokotome boy, although still an adolescent (unfused epiphyses on long bones) was 168cm (5ft 6in) tall and heavily built.

Later H. erectus from Olduvai (e.g. OH 9, 1.2 mya) have cranial capacities of over 1000ml and are very robust. But even later forms are much later: an extreme variant or a different species? At about 1mya, H. erectus was certainly present in Asia (recent dates indicate that they may have been there since 1.5mya or even earlier). These are the 'Java Man' of the 19th century and the 'Peking Man' of the 1920's and 1930's. Lots of Peking man skulls were lost in transit by the American air-force as they were being flown out of China to stop them falling into the hands of the Japanese. Asian forms seem to have survived much later than African forms (200,000 ya compared to 500,000 ya).

H. erectus is found associated with "Acheulean" style stone tools and also with wooded tools. There is also evidence of fire use, and extended cave occupancy.

'Archaic Homo sapiens'

About 500,000 ya there is sufficient anatomical change to indicate the emergence of a new species. This is loosely described as Archaic Homo sapiens, but may also be H. heidelbergensis (Boxgrove tibia and Heidelburg jaw), or even H. rhodensiensis (Broken Hill skull at Kabwe). These creatures have larger brains (1100 - 1300 ml) with a concurrent expanded parietal region. There is a reduction in buttressing, with a more prominent nose and face. There are also changes in the basicranium that may be linked to an elaboration of the larynx.

The fossils dated from 500,000ya to 200,000ya that are arguably fitted into the categories of either archaic sapiens or advanced erectus. These are found throughout Africa, Asia and for the first time Europe.

Neanderthals

About 200,000ya, the European fossils first showed the appearance of "Neanderthal Man" (Homo sapiens neanderthalensis, or more commonly now, Homo neanderthalensis) first found in the Neander valley in Germany. Most specimens date from 130,000 to 30,000 ya. The indications seem to be that Neanderthals were very advanced, with larger brains than modern humans (1200 to 1750, but they had larger bodies too), but were probably an offshoot, and not directly ancestral to modern humans (though they did live sympatrically for considerable periods of time). They were heavy, but short - perhaps an adaptation to the cold climate. They had large noses and robust skulls with supra-orbital ridges and an occipital bun, due, perhaps, to the enlargement of the occipital region of the brain. Early Neanderthals are associated with "Mousterian" stone tool industries (Middle Palaeolithic - limited cultural evidence: looking after infirm and ritual burial)

Modern humans

Also about 200,000ya, the first "anatomically modern humans" (Homo sapiens sapiens) appeared. Depending on conflicting dates, these were either eastern African or Middle Eastern (East African forms probably winning here). These animals have less prominent brow-ridges, higher, shorter, more rounded skulls, shorter jaws and a well-developed chin (missing in Neanderthals). They are taller and less robust, with modern-type hip joints and pelvic bones.

Behaviourally, they seem to be very similar to the Neanderthals but the European forms seem to be associated with Upper Palaeolithic industries (Neanderthals re associated with Middle Palaeolithic, mostly). Upper Palaeolithic society seems considerably more complex: tools used ivory and bone; cave paintings; sculpture.

The origin of modern humans is much argued. There are 2 main theories: the "multi-regional hypothesis" which suggests that H. erectus gradually evolved into H. sapiens sapiens throughout its range, with rapid genetic exchange; and the "out of Africa" hypothesis which suggests that H. erectus underwent a speciation event in eastern Africa to produce H. sapiens sapiens and then migrated throughout the rest of the world, displacing other forms of Homo with little or no genetic exchange. The molecular evidence (Mitochondrial Eve and more recent Y-chromosome studies) support the latter model, but until some recent re-evaluation of dates, the morphological evidence supported the former. Currently, it looks like "Out of Africa" is more likely to be correct.

Bibliography

Library

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