World population history | a story of two halves

World population history is sensational.

Any human alive before the invention of agriculture 10,000 years ago or even those who were around before the fossil fuel powered agricultural revolution of the 19th century would have thought the world an under-populated place.

Everywhere people were few.

What evidence we have suggests that hunter-gatherer communities were small, a necessity dictated by the available food supply.

Unlike the grazing herbivores of the savannas, early humans survived on small amounts of resource rich foods that being widely spaced and often seasonal, they needed to spend a lot of time finding. Not for them the ‘munch along steadily on low quality nosh’ option.

Given that food supply was patchy it was also hard to stay in one place. Perhaps it was only possible in the prized real estate on the shores of lakes and seas. Everywhere else people had to move around just to keep everyone fed.

So for a very long time — almost the entirety of human existence — world population history was predictable. There were low numbers of people meandering around in small groups to find food occasionally marching further afield in times of need. Starvation and strife were common and there were likely many intense interactions with other species and human rivals.  

Upright posture that conferred the ability to run steadily for long periods might have been the key to beating the competition on the savannas but it was smarts and cooperation that helped survive threats from the many bigger, faster predators [humans ought to have been easy meat for lions]

Spreading out

At the start all this meandering and predator avoidance happened in Africa.

It was not until humans crossed the land bridge to Asia that the meandering began to resemble a march. With more space available the wanderings opened up new opportunities and the ability of fast-learning humans to adapt meant they persisted in novel habitats.

Anthropologists call this the great leap forward.

It was a propensity to move [that was either pushed by a drying climate in Africa or facilitated by lower sea levels] combined with the ability to persist in new and unusual places. And it meant that humans quite quickly spread across most of Europe and Asia.

This period of world population history was sensational in its scope.

Most species have a localized distribution. Even the migratory birds that traverse the planet to catch the summer do so into specific habitat types. To have a wide distribution requires that preferred habitat is also widely spread — there are not many cheetah in dense forests — or the species is able to handle many different conditions [adaptable].

It is also important to have mixing over time. Isolation tends to let evolution proceed to fit generations of residents to their local conditions. In short, speciation happens.

Humans adapted and mixed. This allowed a rapid and extensive spread across most of the globe.

But numbers remained low.

Adaptability and smarts allowed for expansion but people still lived from hand to mouth. Hunting and gathering meant food was always the priority [together with avoiding the dangers that came with finding it].  It was risky to stay put and hard to carry the old and the sick. Nobody had a pension.

And this went on for millennia.

Then — and very recently in the scheme of things — everything changed.

world population history | African savanna

Open savanna, like this mopane woodland in northern Botswana was an important habitat for humans before agrculture

Surplus food

World population growth was slow at best during this time of hand to mouth. Any increase in global numbers came from expansion into new lands and is believed to have remained below 15 million, more often around 3 million. 

And everywhere population density — people per unit area — remained low.

None of the big epidemics were around [bubonic plague, smallpox, influenza and measles all came later] but poor nutrition, predation, exposure, water shortages, starvation in poor years were hazards enough.

Then smarts and circumstance came together. At some time around 10,000 years ago people domesticated plants and animals — they started farms.

In the Fertile Crescent through Egypt to the Persian Gulf and perhaps independently elsewhere people began to cultivate grains that they harvested for food. They kept animals for milk, blood and meat. Agriculture began.

It would have been slow at first, experiments that failed more often than not. Only the consequences of success were profound. If there was enough food to stay in one place then that place could be made more comfortable with robust shelters. And, more importantly, it could be fortified. People were able to acquire goods beyond those they could carry and with food growing they could use their time for endless mischief.   

Most of all they could start living together in bigger groups.

Imagine after millions of generations of living in groups the size of an extended family, the village was possible; and before long the town. It was quite a shock.

And the consequence for world population history was that numbers started a phase of exponential growth. 

Surplus food meant better nutrition that kept more babies alive. Birthrates rose and survival improved. So long as food supply persisted people procreated and became more numerous.

Villagers in the highlands of Papua New Guinea

Living together

Clearly it was not all damper and lamb shanks. 

Living together had its drawbacks. Not least the arrival of epidemic diseases many of which jumped from the newly domesticated animals to people. And rapidly from person to person given they were now close by.  

The importance of agriculture became acute.

Reliance on a crop was more risky that reliance on mobility to source food. Crops could fail, get sick or be raided. Water supply was critical too.

Some of the early towns faltered when crops failed or the water supply ran out. But where there was certainty, such as in the annual flood of the River Nile, great cultures emerged.

One thing about human beings is true whatever the view of history. We are extraordinary innovators. It did not take long for the wheel, plough, selective breeding of crop plants and the use of fertilizers to make farms more efficient. More food freed people to invent markets, complex societies and money.

But for world population history this was still the early phase of the period of expansion. The invention of agriculture started the exponential growth in human numbers but it needed energy to really get it going.

For a long time agriculture was limited by human and animal labour. It needed a subsidy to really achieve yields from the land. Enter fossil fuels as draft power to clear vegetation and till the soil and as an energy source to manufacture artificial fertilizers. 

One man with a tractor and a budget could grow enough grain to feed a regiment. And so they did.

Before long there was enough food to support many more people.

Since the first use of commercial fertilizers in the 1850s human population expanded dramatically, doubling every few decades to reach over 7 billion in 200 years.

World population history is really all about modern agriculture. 

Some more Ask Alloporus pages related to world population history... world population growth | over population | human population control

Housing development in Gaborone, Botswana

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The Bushman

By saying nothing Art had everyone's attention, communicating more powerfully than he knew. Eventually, his eyes sharpened and he spoke softly into the microphone.

“Dumela borra et bomma,” he paused to move his eyes across the entire audience. “I came to talk about the history of wildlife hunting in this thirsty land, but I feel strangely compelled to first tell you a story I heard from a !Xau elder I met many years ago.” He paused again repeating the gaze. “I was just a boy. It was long ago, a very long time ago. I was alone on the hot sand of the desert walking as I did when my father took me on his official visits. I was walking and I met an old bushman. Where he came from I do not know. How I understood him I do not know only that he spoke with a smile. He told me that once, when he was a young hunter about my size, he had for three days tracked a herd of eland. Many times he had come close enough to fire his poison arrow to bring down a cow, but could not bring himself to shoot. At the end of the third day, the biggest bull in the herd had walked directly towards him. The bushman said, with a proud chuckle, that he was the hunter, invisible, being just as small as a mongoose hidden behind a thicket, so the bull could not have seen him, but it came closer still, and he had a clear shot, the great animal towering over him as he crouched like the mongoose. He said that he could see the marks on the elegant spiral horns that adorned the great one and proclaimed its power, and he could smell the contents of the great ones stomach. The old man said he raised his bow, poison arrow already drawn from his quiver, and the bull looked straight him. Yet again he hesitated. I can still remember the old bushman's eyes as he told me. He was in awe of this animal, this powerful being, this life force. Then the bushman said that the eland spoke to him in his own tongue and asked him to shoot. It stood still and waited for the arrow. But again he couldn’t shoot. So the eland asked him again if he would release the arrow and turned to provide an even easier target. They old man said that he did not let go of the string but still the arrow shot the short distance into the eland. It pierced the skin on the haunch then dropped to the ground.

‘Fire back in his eyes, the old man said he ran like the wind after the bull as it bolted. He followed the spoor for two hours before he caught up with the poisoned animal, as it lay exhausted under a bush. The hunter said that he stood over the huge bull with his spear ready, and thanked the great beast for giving his life to feed his own family, a ritual passed down through generations of !Xau. Then he stopped telling me his story, looked up at the sky and held out his hands. Just like you or I might do if it had just started to rain. He stayed like this for several minutes his only movement a shuffling of his bare feet, as though he needed to feel the sand move between his toes. And then he said that the bull spoke to him again and it said ‘it was his honour to supply nourishment to his kind, as his own ancestors had done. But be wary, for soon a day will come when honour will be lost.’  Then they eland died, so the old man said he did not need his spear.”

The audience was still, expectant as Art paused. “I saw a mixture of fear and pride in the bushman's expression at the end of his tale,” Art said. “A look that masked the usual cheerful disposition of the !Xau. I felt his mood so strongly that I gasped and, for a moment, I found it hard to breathe. As a young one I was scared. I thought this man had put muti on me. I recovered my senses and wanted to ask more questions but the old man grinned, and then turned away and trotted off into the bush. I never saw him again.” 

Art clasped the podium. Every soul in the room was listening and had heard each word in Arts story. A story that came from a time now lost.

Art was silent again. His body slumped as though he needed to hold onto the podium to stay upright. Eyes cast down he looked sad, dejected by the implication of what he had recounted. Eventually, he looked up and said, “I have not told that story before, not even to my sons. Somehow it protected itself, although I recall the words as vividly as if I had heard them this morning. So now I have told them to you and I feel sad, but also strangely relieved. Make of these words what you will.” 

The room was still as it is in the time before dusk when the sun has just fallen below the tree line. Abruptly, as if to break his own spell, Art Chambers stood taller, coughed and delivered his prepared speech.