Overview
Often considered the African variant of Homo erectus, H. ergaster is best known from the "Turkana Boy" (KNM-WT 15000), the most complete early hominin skeleton ever found. This 1.6 MYA juvenile male stood approximately 160 cm tall and had modern body proportions with long legs and short arms, indicating full terrestrial adaptation. Brain size of approximately 900 cc represents a major advance. Associated with early Acheulean tool technology.
Key Fossils
KNM-WT 15000 ("Turkana Boy"), KNM-ER 3733, KNM-ER 992
Brain Anatomy
No Cranial Data Available
Tools & Technology
Associated Tool Traditions
Oldowan
Simple core-and-flake tools made by direct hard-hammer percussion. Includes choppers, scrapers, and sharp flakes used for cutting meat and processing plant foods.
Acheulean
Characterized by large bifacial tools, especially handaxes and cleavers. Represents a major advance in planning and symmetry. Lasted over 1.5 million years — the longest-lasting tool tradition.
Specific Tool Types
| Tool | Material | Function | Tradition |
|---|---|---|---|
| Flake tool | stone | Cutting meat, slicing plant material | Oldowan |
| Handaxe | stone | Multi-purpose: butchering, digging, woodworking | Acheulean |
| Cleaver | stone | Heavy-duty butchering and woodworking | Acheulean |
Diet & Food Sources
Omnivorous; significant meat consumption; possibly earliest cooking
| Food Source | Type | Evidence | Confidence |
|---|---|---|---|
| Tubers and roots (C3) | Tuber | Isotopic | Moderate |
Social Behavior
Acheulean large mammal procurement Probable
Butchery of large bovids
Evidence: Cut-marked megafauna at Acheulean sites
Phylogenetic Relationships
| Related Species | Relationship | Confidence | Notes |
|---|---|---|---|
| Homo erectus | Proposed ancestor | Strong | H. ergaster is widely considered the African form of or ancestor to Asian H. erectus |
| Homo habilis | Proposed ancestor | Moderate | H. habilis is the most likely ancestor of H. ergaster/erectus |
| Homo georgicus | Proposed ancestor | Moderate | H. georgicus may derive from an early H. ergaster/erectus dispersal |
Key Specimens
| Specimen | Name | Site | Year | Age (MYA) | Completeness | Significance |
|---|---|---|---|---|---|---|
| KNM-WT 15000 | Turkana Boy / Nariokotome Boy | West Turkana | 1984 | 1.56 | 80.00% | Most complete H. ergaster skeleton |
Life History
| Estimated Lifespan | ~42 years |
|---|---|
| Age at Maturity | ~14.0 years |
| Weaning Age | ~3.0 years |
| Interbirth Interval | ~3.8 years |
| Gestation | ~9.0 months |
| Dental Development | Similar to H. erectus juvenile schedules |
| Brain Growth | Rapid early brain growth vs apes |
| Growth Comparison | Intermediate between australopiths and modern humans |
| Confidence | Estimated from fossils |
Pathology & Healthcare Evidence
Periostitis
Affected: Femur KNM-ER 1808
Thick reactive bone on femoral shaft; interpreted as hypervitaminosis A (liver toxicity) vs infection (classic literature).
Survival: Subacute/chronic
Infection — KNM-WT 15000
Affected: Skeleton
Comparative row: juvenile skeletons sometimes show nonspecific lesions.
Survival: N/A
Comparative Anatomy
| Encephalization Quotient | 3.50 |
|---|---|
| Intermembral Index | 84.0 |
| Locomotion | Striding biped |
| Foramen Magnum | Anterior |
| Precision Grip | Developed |
| Pelvic Shape | Intermediate |
| Robusticity | Moderate |
| Big Toe | Fully adducted |
| Thorax | Intermediate |
H. ergaster/Turkana Boy body proportions near modern.
Isotope Analyses
| System | Value | Material | Site | Date (MYA) | Interpretation |
|---|---|---|---|---|---|
| delta C13 | -8.50 | Enamel | Koobi Fora | 1.600 | H. ergaster/early Homo: predominantly C3 ecosystems with mixed signatures. |
Dating Evidence
| Method | Date (MYA) | Uncertainty | Material | Site / Specimen |
|---|---|---|---|---|
| Ar Ar | 2.5000 | ± 0.0500 | Tuffs West Turkana | West Turkana |
| Ar Ar | 1.8000 | ± 0.0200 | Tuff I Bed I (crystal separates) | Olduvai Gorge |
| ESR | 1.8000 | ± 0.2000 | Tooth enamel (Swartkrans) | Swartkrans |
| K Ar | 1.7900 | ± 0.0500 | Basalt below OH 5 | Olduvai Gorge / OH 5 |
| Ar Ar | 1.5600 | ± 0.0200 | KBS Tuff (context) | Koobi Fora / KNM-WT 15000 |
| Ar Ar | 0.3200 | ± 0.0300 | Tephra correlations | Olorgesailie |