Homo Rising: Humans in the Lower Paleolithic
1.2 million years ago. It is the beginning of the Stone Age, a time period known as the Lower Paleolithic.
The days are becoming drier and slightly hotter. Decreasing oceanic evaporation and the effects of the Quaternary glaciation are changing the land and, as a result, the hominids. Fruits relied upon by the Australopithecines as food sources are disappearing as savannahs encroach upon the forests of Africa.
They are now looking for new foods and, as a result, will further descend from the trees of their ancestors and continue to evolve into a new genus: Homo.
Homo habilis: "Handyman"
Approximately 2.4 million years ago, the first species of Homo appeared: Homo habilis, also known as “handy man.” Living in Kenya and Tanzania, Handy Man developed over a 1 million year span to become the first species with features kin to those of modern man. In comparison to his ancestors, the Australopithecines, Handy Man’s molars and premolars were smaller, his braincase slightly larger, and his cranial capacity about 640 cc. Additionally, his feet had a modern arch, as demonstrated by specimen OH 8, whose feet bones also showed signs of being attacked by a crocodile.
Handy Man was probably sexually dimorphic and retained the long arms and prognathic face of his ape ancestors. At adulthood, Handy Man was between 3 ft 4 in and 4 ft 5 in and weighed around 70 pounds. We know this based on several fossils, including KNM-ER 1813: an almost complete skull from the Turkana Basin.
Handy Man was partially arboreal. By retaining the long arms of his ape ancestors, he was still able to spend part of his life in the trees. But the trees were becoming less numerous as the savannah spread, so he was forced to spend part of his time on the ground foraging. He likely ate a flexible diet of leaves, woody plants, and animal tissues. Occasionally, he might have eaten brittle nuts and seeds, dried meat from carcasses, or hard tubers dug from the ground. Evidence from animal bones also suggests that Handy Man might have used stone tools to butcher carcasses or break bones to eat the marrow.
About midway through Handy Man’s existence came the next in the Homo line: Homo rudolfensis. Unfortunately, we don’t know much about H. rudolfensis – we only have one fossil to confirm his existence, and it is possible that this fossil is merely a mutated individual from the Australopithecus genus.
This fossil, KNM-ER 1470, dates to between 1.9 and 1.8 million years ago. It was found in Koobi Fora, Kenya. Physically, it is different from the Australopithecines and Handy Man. H. rudolfensis has larger, more thickly enameled teeth than Handy Man; a flatter and broader face; and more modern limb proportions. His braincase is 775 cc, which is quite large for the Australopithecines and Handy Man. These physical changes indicate that H. rudolfensis likely had a different diet, one that called for more powerful chewing, but that is all we know about him.
About the same time, however, human evolution made another leap: this time to Homo erectus. Homo erectus would live from 1.89 million years ago to 143,000 years ago. We have several fossils from H. erectus, including Turkana Boy (a well-preserved skeleton, except for the hand and foot bones, dating to 1.6 million years ago) and Peking Man.
These fossils are spread out over a larger area than any of his ancestors: H. erectus lived in Africa, Java, and China. This, in itself, is quite amazing. It means that during the over 1 million years of his existence, H. erectus spread out from Africa, appearing in Java 1.8 million years ago, Europe 1.7 million years ago, Asia 1.6 million years ago, and yet still inhabited Africa’s Olduvai Gorge at 1.2 million years ago.
Physically, H. erectus was quite different. The oldest known fossils show modern body proportions, with elongated legs and shorter arms suited for life on the ground. He was also very tall, between 4 ft 9 in and 6 ft 1 in, and weighed up to 150 pounds. His skull was generally long, low, and thickly walled with a flat frontal area and prominent brow ridges. He had smaller teeth, and was the first human ancestor to have third molars smaller than the first and second molars. In fact, from the neck down, he is practically indistinguishable from modern humans. H. erectus was also likely much smarter, as his cranial capacity was between 895 and 1040 cc.
These changes mean that H. erectus was better able to adapt to new environments quickly. He also required more energy (thus more calories per day) due to his taller stature and larger brain. Thus, his diet expanded rapidly to include underground tubers, honey, and more proteins. There is evidence that H. erectus was the first human to hunt. In Torralba and Ambrona, Spain, campsites show evidence of butchering elephants and large bone accumulations near water sources.
H. erectus was also a busy toolmaker. For example, at Monte Poggiolo near Forli, Italy, archaeologists have found thousands of stone tools dated to around 800,000 years ago. H. erectus developed the “core” tool technique, using a core of stone as his basic raw material for fashioning tools. He also developed the Acheulian tradition (named after the site it was first found at: St. Acheul, France), likely around 1.5 million years ago based on specimens in Tanzania. Most tools of this tradition had standardized designs and shapes, being made from large flint flakes struck off stone cores. Such tools have been found widely in Africa, Europe, and Western Asia near water sources, indicating camping centers were used as the center of group functions.
There is also evidence that H. erectus had begun to perform ritual acts. Some fossils, such as D3444 (an elderly male who had lost his teeth before death), indicate that H. erectus not only lived a longer life, but also cared for the elderly. There are also some burials of that show the remains being sprinkled with red ochre just before burial. In Zhoukoudian, China, there is also possible evidence of ritual cannibalism based on marks made into the bones.
Despite all this, it is not generally believed that H. erectus was our direct ancestor. So, who was?
Homo heidelbergensis: Our direct ancestor
About halfway through H. erectus’s reign, around 700,000 years ago, our direct ancestor appeared on the evolutionary tree: Homo heidelbergensis (whom I will call “Heidi”). Heidi would eventually spawn both the Neanderthal and Homo sapien lines of our family tree, dying out around 200,000 years ago.
Heidi lived in Africa, Europe, and possibly Asia. Physically, Heidi had a short, wide body – likely an adaptation to conserve heat as the Ice Age went into full swing. He had a large brow ridge, a larger braincase, and flatter face than older species of Homo. Males reached a height of 5 ft 9 in and a weight of 136 pounds, while females were about 5 ft 2 in and 112 pounds.
Heidi was the first to live in the colder climates of the Ice Age. It was these climatic changes that led to his use of controlled fire and wooden spears. Finds at Gesher Benot Ya-aqov in Israel indicate that by this time, Heidi was using fire-altered tools. These tools allowed him to become the first confirmed hunter of big game, killing wild deer, horses, elephants, hippos, and rhinos. At Schoningen, Germany, fossils indicate that Heidi was using spears and stone tools to butcher horses by 400,000 years ago.
Heidi was also the first to build shelters of wood and rock, such as those at Terra Amata, France. Nearby, in Atapuerca, Spain, archeological finds also indicate that Heidi engaged in rituals: around 400,000 years ago, the bones of 30 individuals were deliberately thrown into the Sima de los Huesos (“Pit of Bones”) along with a single, well-made, symmetrical hand axe. Such finds, combined with the large cranial capacity of Heidi, also lead some to believe that Heidi might have been the first to develop symbolic language – the earliest steps toward writing.
It is now 300,00 years ago: much closer to our age than when we started. We have traversed nearly 1 million years, watching our ancestors grow from the Austrolopithecines to the apex of Homo. We are now at a turning point from which only one of Heidi’s descendants will survive. Within the next 100,000 years, a profound evolutionary step will occur. It will define popular conceptions about the Stone Age as well as lead to some of the most heated debates in the history of science.
Right now, sometime between 300,000 and 200,000 years ago, a remarkable occasion is being marked: two separate births, both from members of Heidi’s species. One will mark the beginning of the Neanderthals. The other will mark the beginning of Homo sapien: the first modern human.
Next in this series: Life in the Middle Paleolithic