It's hard to think of human beings as primitive creatures when so many traits separate us from
the rest of the animal kingdom. We’re the only species to maintain a completely upright posture,
for example, even amongst other primates. We boast a unique dexterity with our hands, and increased
brain volume and intelligence, too. It all allows us to distinguish ourselves via the use of speech,
the development of tools, the use of fire, and so on… to grow to where we are today; large,
mass civilizations spanning every corner of the globe. However, humankind hasn’t always been quite
so unique and complex. In fact, in a time not that long ago, relative to the age of the universe,
our human ancestors had more in common with the modern squirrel than with modern people.
So how did a small rodent-like tree climber evolve into the dominating species of today?
This is Unveiled, and today we're answering the extraordinary question;
How was the first human born?
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The story of human evolution begins with the extinction of the dinosaurs.
When an asteroid struck land sixty-six million years ago (as per the most commonly held theory)
it may have rained death down upon the reptiles… but it also allowed a new class of animals to rise
out of their shadowed holes. With most of the world’s biggest creatures gone - and around 75%
of Earth's total flora and fauna at the time, by most counts - whole ecosystems collapsed,
and the food chain was thrown into turmoil. But the catastrophe left massive empty niches and key
environmental roles just waiting to be filled. And so, it was the mammals that rose to become the
dominating class. And, because there were so many positions to fill, a rich and diverse evolutionary
boom occurred across a relatively short period of time. Within the next ten million years,
it’s thought that between three and five thousand species of mammals emerged on planet Earth,
including the earliest classes of whales, bats, rodents and, crucially for the human story,
monkey-like primates… our earliest ancestors. These prehistoric primates then went through
many changes very quickly… with the first significant development happening around
sixty million years ago, when the evolutionary line divided into strepsirrhines (also called
the wet-nosed primates) and haplorrhines (the dry-nosed primates). This was a key moment in
the slow progression toward Homo sapiens, as while the strepsirrhines remained primarily nocturnal
and reliant on their sense of smell, the diurnal haplorrhines developed larger brains and were
therefore able to rely on their vision; thereby already showing two more human-like attributes.
From there, the haplorrhines continued to diverge for millions of years, with several of our primate
cousins branching off the family tree. However, it wasn't until about twenty million years ago that
another major development took place; the arrival of the first ape, known as Proconsul. While still
quite monkey-like in behaviour, the earliest apes began taking on physical attributes that were,
again, increasingly human to today’s eyes. Importantly, they were significantly
larger than their ancestors, weighing up to 110 pounds, while they notably lacked a tail. Still
millions of years ago, and the apes continued their variation, branching into the Great and
Lesser Apes and gradually giving birth to some of our other evolutionary cousins such as gibbons,
orangutans, and gorillas - all of which had developed before the earliest humans came to be.
As for our closest cousins, the chimpanzees and bonobos, they arrived much later…
around seven million years ago, only. But what of the human ancestral branch itself?
One of the first big steps in our transcendence from ape to human came with the evolution
of the Ardipithecus, the first genuinely bipedal genus. Despite remaining a primarily
tree-climbing species - with opposable big toes, small cutting teeth, and a brain size very similar
to an ape - the Ardipithecus developed the breakthrough ability to walk on two legs.
From here it took massive strides through the evolutionary timetable, and within about two
million years - that’s now around four million years ago - the first Australopithecus evolved.
Australopithecus retained apelike features (including long arms and short legs)
but they were becoming significantly more human still, largely thanks to one change… the
opposable big toes present in earlier species had now moved to face forward on their feet.
This meant they became more adjusted to walking reliably, which freed their hands
for the earliest known use of stone tools. The Australopithecus thrived until around
two million years ago, when evolution evolved along two more distinct directions. While one
group is said to have developed stronger jaws to better help them to eat the nuts and vegetation
specifically available at that time… another evolved with weaker jaws but with larger brains.
While both branches survived for a significant period, those with the larger brain proved to be
more adaptable in the long run… and they ultimately gave rise to the genus Homo,
taken from the Latin for man, and here is where human history is said to truly begin.
The first member of the Homo genus was Homo habilis. Colloquially known as "Handy Man”,
the progression of habilis is most notable for its ever-widening use of tools which, again,
led to many major evolutionary advancements happening quickly. In fact, within just 500,000
years - so, we’re now about 1.9 million years ago - Homo habilis had given rise to another new
classification, Homo erectus, to make possibly the most crucial evolutionary leap toward modern man.
Homo erectus was the first to closely resemble the proportions of a current human body. They
had relatively elongated legs and shorter arms compared to the size of their torso, which was
the result of their being fully adapted to living on the ground (rather than in trees). Homo erectus
had a slightly larger brain size, too, although it was still only about 60% the size of a modern
human’s… and they were the first to use fire as a tool. This, along with their bipedalism, enabled
them to migrate outside of Africa, to become the first group to be widespread across Europe, Asia,
and Africa. Finally, according to fossil evidence, Homo erectus not only gathered in social groups,
but they actually cared for their old and weak - something that was virtually unheard of until this
point. It’s believed that they had empathy and were emotionally developed as well as physically,
something which allowed them to survive and even eventually thrive alongside modern humans… before
going extinct just 110,000 years ago. Over this period between 1.9 million
years ago and 100,000 years ago, and as a result of Homo erectus' migratory patterns,
new members of the Homo genus began springing up all across the world map. As each new species
evolved to adapt to different environments, these various human groups began to diverge and cross
over at various historical points, causing an intricate web of evolutionary lines. This has made
it difficult to precisely know from which line after Homo erectus we (modern humans) find our
origins. We may have evolved directly from Homo erectus or from one of the several species that
branched off before or after it. Nevertheless, we do know that we were neither the first nor the
last species to evolve along our branch… it’s just that we’re the ones that remain today.
First appearing around 300,000 years ago, Homo sapiens are (and were) distinguishable from
other Homo groups most significantly by their having much larger brains, an adapted skull
shape to house those larger brains, and a lighter skeletal frame. As a result, ancient Homo sapiens
go down as being an exceptionally innovative group, developing advanced tools like fishhooks
for hunting, bows, arrows and spears (also for hunting), sewing needles (for clothing),
and various building materials and methods (for shelter). This ensured that sapiens would outlast
all other Homo types… with the last Neanderthal, for example, dying out about 40,000 years ago.
But, while that’s the human story so far, evolution is far from being done. And as
much as we tend to assume that we’re the ultimate, end-of-the-line model,
it will actually continue to alter us well into the future. In the past 100,000 years,
for example, the average height of Homo sapiens is thought to have shrunk slightly… although
we do appear to have grown slightly taller in just the past couple of centuries. Meanwhile,
although brains had been getting progressively larger throughout evolution up until this point,
ours have actually decreased in size over the past 30,000 years or so... with it commonly said
that a modern human has lost about a tennis ball’s worth of brain size compared to earlier sapiens.
Luckily for us, we remain a reasonably intelligent species…
but who’s to say what could happen in the future. For now, that’s how the first human was born.
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