About 1.9 million years ago in Africa, a massive turning point arrived in the history of human evolution. Passing the era of Australopithecus, who moved back and forth between trees, a being finally appeared that strode confidently on two legs upon the ground.
The protagonist of this story is Homo ergaster, the first early human to possess body proportions most similar to modern humans. What did these “Workmen” look like, and what abilities did they possess?
1. Appearance: 180cm Tall Long-Legs, But a Short Childhood
The fossil that best reveals Homo ergaster is the ‘Turkana Boy’ (KNM-WT 15000), discovered in 1984 west of Lake Turkana in Kenya. This fossil astonished anthropologists.
A Physique Just Like Modern Humans
This boy possessed long legs, a narrow pelvis, and short arms. This indicates that, unlike previous hominins who climbed trees, he was completely adapted to life on the ground. A narrow pelvis and long legs constitute a physique optimized for walking or running while efficiently dissipating heat under the scorching sun of tropical Africa .
Surprisingly Rapid Growth
Even more surprising is their ‘growth rate.’ Analysis of dental development suggests this boy was only about 8 to 11 years old at the time of death. However, his height had already reached 160 cm, and his skeletal maturity was comparable to a modern 15-year-old adolescent. Had he reached adulthood, he would likely have stood 185 cm tall and weighed 68 kg.
In other words, Homo ergaster grew slower than apes but much faster than modern humans. Their childhood was much shorter than ours, and they had to become adults quickly to survive.
2. Ability 1: Ancestor of Olympic Marathoners, The Origin of the ‘Apple Hip’
Homo ergaster did not merely walk. Professors Bramble and Lieberman argue that they were ‘born marathoners’ .
A Body Evolved for Running
There are features in our bodies that are not strictly necessary for walking but are critical for running. Homo ergaster was the first human to possess these traits.
- Achilles Tendon and Arch of the Foot: These act as springs that store energy and absorb shock when pushing off the ground .
- Nuchal Ligament: This ligament at the back of the neck, found in running animals like dogs or horses, holds the head steady while running. This tissue, absent in chimpanzees, first appeared during the Homo ergaster era.
- Expansion of the Gluteus Maximus: This is the muscle often referred to as the ‘apple hip.’ While not heavily used during walking, it plays a decisive role in preventing the upper body from pitching forward while running.
It is highly likely that they engaged in ‘persistence hunting,’ chasing prey under the midday sun until the animal collapsed from exhaustion .
3. Ability 2: The First Swiss Army Knife and the Coexistence of Technology
Homo ergaster also brought about a revolution in tool-making technology. Going beyond the simple Oldowan tools of the past, they created the sophisticated Acheulian handaxe.
High-Tech from 1.76 Million Years Ago
At the Kokiselei 4 site in Turkana, Kenya, Acheulian stone tools dating back approximately 1.76 million years were discovered. This implies that these humans possessed the intelligence to plan and the dexterity to craft tools with precision.
Using Smartphones and Pagers Together?
An interesting point is that the cutting-edge Acheulian tools and the old-fashioned Oldowan tools were discovered simultaneously in the same era and region. This suggests that groups possessing the technology and those without it lived together, or that the two types of tools were used for different purposes. This also provides a clue to the mystery of why the Homo erectus groups that migrated to Asia earlier did not take handaxes with them (potentially leaving before the technology became widespread) .
4. The Mystery: Could They Speak?
With a brain capacity enlarged to 800–900 cc, did Homo ergaster converse like us? The fossil of the Turkana Boy provides a negative clue regarding this.
The Secret of the Narrow Vertebral Canal
The vertebrae of the Turkana Boy, particularly the vertebral canal in the thoracic region, were much narrower than those of modern humans. This means the bundle of nerves controlling the fine movements of the rib cage was smaller . To speak, one must control breathing very precisely; however, the anatomical structure of Homo ergaster suggests it is highly likely that they were incapable of the breath control necessary for complex language.
Perhaps they roamed the African grasslands communicating through eye contact, gestures, and simple sounds.
5. Conclusion: The First Adventurer to Step Out into the World
Homo ergaster (or early African Homo erectus) represents the true ‘starting point’ of human evolution. They conquered the savanna out of the forests, enjoyed a meat-based diet, and expanded beyond Africa into the Eurasian continent with their exceptional legs.
Although they could not speak fluently like us and their childhoods were short, the legacy they left behind—large brains, running ability, and tool-making—remains intact in our bodies and behaviors today. Homo ergaster was not a mere ape, but the first ‘human-like human.’
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