September 16, 2021

I, Science

The science magazine of Imperial College

Human population continues to grow, but how long can we survive with our limited resources? ...


Approximately 30,000 years ago, our Homo erectus ancestors died out leaving us Homo sapiens as the only ‘humans’ remaining on the planet. Some believe that we all evolved in Africa and spread from there to China, Asia, and Europe, whilst others think that we developed simultaneously all over the globe. Either way humans, as we exist today, have inhabited the planet for the last 30,000 years.

Population has not remained stagnant over this time; we reached five million in 8000 BC, but by 1 AD we were around 100 million strong. Growth continued steadily until the year 1800, by which time the global population had reached one billion.

After the Industrial Revolution, the population boomed and each successive billion was reached faster than the last— three billion within 30 years, four billion within 15 years, and five billion after another 13 years. We reached seven billion in 2012 and are predicted to reach eight billion by 2024.

There are clear reasons behind these trends in population growth. In our early years, we lived a hunter-gatherer or nomadic lifestyle: food was often in short supply and infanticide was a common way to combat this. The Black Death, although it appeared in Britain in the 14th century, first emerged in 542 AD in Western Asia. It is thought to have killed half of the Byzantine Empire—nearly 100 million people—and such pandemics are a key reason behind the stagnation of population levels.

The population boom of the Industrial Revolution was due to faster food production and better living conditions. Although infant mortality remained high because of poor sanitation in cities, healthcare began to improve and when infant mortality rates started to fall as a consequence, the population surged further. Improving healthcare has also had an effect on longevity, and males born today are expected to live to 79 years of age, while female life expectancy is 83. By contrast, in 1901 the life expectancy was 45 and 49, respectively. In 2032, it is predicted to be even higher: 83 and 87 respectively.

The latest prediction shows we’re not able to sustain the rate of increase and life expectancy is expected to plateau— at least for the near future. With such a great population boom coupled with no signs of slowing down energy or material consumption, our finite resources are becoming increasingly strained.

It could be that the almost exponential rate of the population increase may indeed become an issue in terms of resource management and possible effects on the climate. The future of the global population is simply a numbers game, but ours may be about to run out.

IMAGE: Plus Magazine