Modern Humans
Like all animals on earth, you and the others around you belong to a species. The one you belong to is known as Homo Sapiens. However, when did you, the modern human with all its representative features, first appear on Earth? The fossil evidence, the resultant morphological features, genetic evidence, and cultural artefacts we have do not coincide to give us a singular timeframe of when the modern human emerged. This indicates that there wasn’t some single point after which everyone became homo sapiens. Anatomically, modern humans can generally be characterised by lighter skeletal structures compared to earlier humans
As our anatomy changed, the ways we lived and the tools we created changed as well. In Africa, during a period of drastic climate change 300,000 years ago, humans made a leap in technology alongside evolving into homo sapiens. They crafted tools out of flaked points and attached them to handles and spear shafts to greatly improve hunting prowess. They also made scrapers and awls to refine hides for leather and process wood.
Humans started engaging with symbols around 100,000 years ago with flashes of artistic tendencies that lacked consistent expression. They also inhabited caves and rock shelters if these were available. One of the earliest deliberate burials of a modern human comes from Jebel Qafzeh in Israel, dating to 90,000 years old.
Where Humans Live: Evolved in Africa and currently all over the world.
When Humans Live: Around 300,000 years ago to present.
Homo Sapiens are deeply varied and do not have a true type specimen. Women have an average height of about 160 centimetres, while men are 175 centimetres tall. Modern humans have very large brains, which vary in size from population to population but average around 1300 cubic centimetres. Housing such a big grin involved the reorganisation of a thin-walled, high-vaulted skull with a flat vertical forehead. Modern human faces also show much less, if any, of the heavy brow ridges and prognathism of other early humans. Our jaws are also less heavily developed, with smaller teeth, and we’re the only species to have a protruding chin.
DNA evidence and fossils show that we are one of more than 200 species belonging to the order of Primates. Within that larger group, humans are nested within the great ape family. Although we did not evolve from any of the apes living today, we share characteristics with chimpanzees, gorillas, orangutans (the great apes), and other apes. We most likely evolved from Homo heidelbergensis, the common ancestor we share with Neanderthals, who are our closest extinct relatives.
More details
For millions of years, all humans, early and modern alike, had to find their own food. They spent much of each day gathering plants and hunting or scavenging animals. By 164,000 years ago, modern humans were collecting and cooking shellfish; by 90,000 years ago, modern humans had begun making special fishing tools. Then, within just the past 12,000 years, our species, Homo sapiens, transitioned to producing food and changing our surroundings. Humans found they could control the growth and breeding of certain plants and animals. This discovery led to farming and herding animals, activities that transformed Earth’s natural landscapes—first locally, then globally. As humans invested more time in producing food, they settled down. Villages became towns, and towns became cities. With more food available, the human population began to increase dramatically. Our species has been so successful that it has inadvertently created a turning point in the history of life on Earth.
Modern humans evolved a unique combination of physical and behavioural characteristics, many of which other early human species also possessed, though not to the same degree. The complex brains of modern humans enable them to interact with each other and with their surroundings in new and different ways. As the environment became more unpredictable, bigger brains helped our ancestors survive. They made specialised tools and used tools to make other tools, as described above; they ate a variety of animal and plant foods; they had control over fire; they lived in shelters; they built broad social networks, sometimes including people they have never even met; they exchanged resources over wide areas; and they created art, music, personal adornment, rituals, and a complex symbolic world. Modern humans have spread to every continent and vastly expanded their numbers. They have altered the world in ways that benefit them greatly. But this transformation has unintended consequences for other species as well as for ourselves, creating new survival challenges.
Morphological Features
The earliest Homo sapiens had bodies with short, slender trunks and long limbs. These body proportions are an adaptation for surviving in tropical regions due to the greater proportion of skin surface available for cooling the body. More stocky builds gradually evolved when populations spread to cooler regions as an adaptation that helped the body retain heat. Modern humans now have an average height of about 160 centimetres in females and 175 centimetres in males. Homo sapiens living today have an average brain size of about 1350 cubic centimetres, making up 2.2% of our body weight. Early Homo sapiens had slightly larger brains at nearly 1500 cubic centimetres. The earliest Homo sapiens had bodies with short, slender trunks and long limbs. These body proportions are an adaptation for surviving in tropical regions due to the greater proportion of skin surface available for cooling the body.
Modern Homo sapiens skulls have a number of distinctive features, including:
- A short base and a high braincase
- A broad top
- A fuller braincase with almost no post-orbital constriction
- A rounded back that indicates a reduction in neck muscles
- A reasonably small face with a projecting nose bone
- A limited brow ridge and a tall forehead
- Square orbits (eye sockets)
- Short jaws that result in an almost vertical face
- Usually no gap between the last molar teeth and the jaw bone
- Lightly built jaws with a protruding bony chin for added strength
- Relatively small teeth compared with earlier species, especially noticeable in the front incisor and canine teeth
- Two equal-sized cusps on the front premolar teeth in the lower jaw
They have a number of distinctive skeletal features, including thinner and less robust limb bones than earlier human species, indicating a reduction in muscle size. Legs are also relatively long compared with arms, which is an adaptation for efficient running. Finger and toe bones are straight, unlike earliest australopithecine ancestors, which had curved fingers and toes that were better adapted for tree climbing. The pelvis is narrower from side to side and has a deeper bowl shape from front to back than previous human species, which is thought to be an adaptation for bipedal locomotion.
Fossils
African fossils provide the best evidence for the evolutionary transition from Homo heidelbergensis to archaic Homo sapiens and then to early modern Homo sapiens. There is, however, some difficulty in placing many of the transitional specimens into a particular species because they have a mixture of intermediate features that are especially apparent in the sizes and shapes of the forehead, brow ridge and face. Late surviving populations of archaic Homo sapiens and Homo heidelbergensis lived alongside early modern Homo sapiens before disappearing from the fossil record about 100,000 years ago.
Key specimens that reveal an evolutionary transition from archaic to modern Homo sapiens include Florisbad cranium, LH18 from Laetoli, Omo 1 and 2 from Omo-Kibish, Herto skull from Ethiopia and Skhul 5 from Israel.
Archaic Homo sapiens
- Florisbad – a 260,000-year-old partial cranium discovered in 1932 in Florisbad, South Africa. This skull shows features intermediate between Homo heidelbergensis and early modern Homo sapiens. The face is broad and massive but still relatively flat, and the forehead is approaching the modern form.
- Omo 2 – a 195,000-year-old braincase discovered in 1967 in Omo-Kibish, Ethiopia. Like LH 18, this braincase shows a blend of primitive and modern features that places it as a member of a population transitional between Homo heidelbergensis and early modern Homo sapiens. Its primitive features include a heavier, more robust construction, an angled rather than rounded rear section, and a lower, sloping forehead. Refer to the Omo 1 specimen for interesting comparisons.
Early modern Homo sapiens
- Herto – a 160,000-year-old partial skull discovered in1997 in Herto, Ethiopia. This skull from an adult male and those of another adult and a child were found in 1997 and publicly announced in 2003. They are some of the oldest fossils of modern Homo sapiens yet discovered. Some scientists regard these fossils as a sub-species of modern humans (named Homo sapiens idàltu) because of some slight differences in their skull features. They show a suite of modern human traits mixed with archaic and early modern features. Also of significance are cut marks on the child’s skull. These were made when the bone was still fresh, indicating ritual practice. The skull also appeared ‘polished’ from repeated handling before it was laid on the ground.
- Omo 1 – a partial skull discovered in 1967 in Omo-Kibish, Ethiopia. A recently published date for this skull was about 195,000 years old, but this is disputed. However, it is still one of the oldest known fossils of early modern Homo sapiens. Features that show the transition from an archaic to an early modern Homo sapiens include a more rounded and expanded braincase and a high forehead. Now dated to the same age as Omo 2, it does raise interesting questions about why it appears to have slightly more advanced features than Omo 2. Were they from the same population?
- Skhul 5 – a 90,000-year-old skull discovered in 1932 in Skhul Cave, Mount Carmel, Israel. This skull of an adult male has developed relatively modern features, including a higher forehead, although it still retains some archaic features, including a brow ridge and a slightly projecting face. This specimen and others from the Middle East are the oldest known traces of modern humans outside of Africa. They prove that Homo sapiens had started to spread out of Africa. 100,000 years ago, although it may be that these remains represent a population that did not expand beyond this region – with migrations to the rest of the world occurring later, about 60-70,000 years ago.
Late modern Homo sapiens
Cro-Magnon 1 – a 32,000-year-old skull discovered in 1868 in Cro-Magnon rock shelter, Les Eyzies, France. This adult male represents the oldest known skull of a modern human from Western Europe. Cro-Magnon skeletons have proportions similar to those of modern Africans rather than modern Europeans. This suggests that the Cro-Magnons had migrated from a warmer climate and had a relatively recent African ancestry.