Steven A. LeBlanc, an archaeologist with Harvard’s Peabody Museum, has written a significant book, Constant Battles: Why We Fight (2004). Like another controversial archaeologist Lawrence H. Keeley who I have mentioned in previous notes, LeBlanc strives to bring some clarity to the stubborn myth of the universally peaceful hunter-gatherer living in ecological balance with their surroundings. As far back as we can tell from the archaeological record, writes LeBlanc, human societies have over-run their resource bases, denuded the land, extinguished other species who shared their territories, then moved on to do the same elsewhere. He shows that ecological imbalance has always been the primary cause of fighting and war.

“The one common thread I found with all this warfare . . . was that it correlated with people exceeding their area’s carrying capacity. Ecological imbalance, I believe, is the fundamental cause of warfare.”

This makes eminent sense to me. The outcome of most warfare, whether it is conducted against other human societies or against forests and their denizens, is that the victor claims the carrying capacity that had until recently been used by those that have been defeated. As others like Steven Pinker have pointed out, the incidence of warfare has declined enormously during the 20 century (aside from a couple of unfortunate lapses). Pinker is eager to propose an idealistic reason for this, pointing to the supposed birth of a “better nature” in the human animal. The reality, I suspect, is far more prosaic and materialist – in line with LeBlanc’s suggestion above. Given the turmoil building in the world today, it is also far more concerning.

My proposition can be stated in one sentence:

A key factor in the recent decline of warfare is that we finally developed enough social organization, technology and energy to allow us to steal carrying capacity previously used by plant and animal life and redirect it to human use.

As in any war, to the victor go the spoils. Waging the equivalent of low-cost war on plants and animals gave enormous returns in conquered carrying capacity. This greatly reduced the ecological pressure on human beings. In fact, it reduced the pressure enough that we didn’t need to wage nearly as many high-cost wars on other humans to try and confiscate their carrying capacity (which people tend to defend to the death, because not doing so means certain death…)

Agriculture and its associated deforestation are the main strategies we have used in this war on non-human species. Using mechanized troops armed with tractors, harvesters and chainsaws as well as chemical weapons such as pesticides, defoliants and ammonia-based fertilizers, we have easily won this war against our unarmed opponents. The spoils of victory have included endless wheat fields, vast cattle ranches, pig farms and palm oil plantations. The redirection of this liberated carrying capacity is what has allowed our population to triple since the end of WWII.

During the 70 years since the end of WWII humanity has lost on average one-hundredth of one percent (0.01%) of our population to warfare each year, not including interna genocides and famines. This is less than a tenth of of the average warfare-related death rate of the previous 150 years (0.11%). These numbers are based on the highest estimates of death tolls from warfare over the last two thousand years as recorded in Wikipedia. Estimates given by Keeley for death rates from warfare before 1900 range up 100 times higher than we have experienced since the end of WWII.

If my proposition is correct, these halcyon days may be numbered. The planet’s ability to supply carrying capacity is being reduced through climate change and pollution. The amount of energy we have at our disposal to facilitate the ongoing theft of carrying capacity from other species may be about to decline. Our social organization is beginning to fray. And all the while our numbers are climbing by 80 million a year. The carrying capacity we have available may soon not be sufficient for us, and we will be forced back into the time-honoured tradition of stealing it from other people.

During our major growth phase over the last century or two, the carrying capacity we could draw on was apparently increasing, so warfare died down. The obvious implication is that as we begin our descent, the reverse will happen. We will become very eager to steal carrying capacity from any place we can find it. This will result in the further and more complete extinction of wildlife as well as a dramatic and long-term rise in the level of warfare.

Our big brains have given us some extraordinary gifts. One is the problem-solving ability that lets us keep growing when perhaps we should take a break. The other is our incredible social adaptability. We can be competitive or cooperative, selfish or altruistic as the situation seems to call for, and we can switch from one to the other at the drop of a hat. This seems connected to our perceptions of surplus or shortage. In a situation of perceived surplus, both individuals and nations tend to be cooperative, altruistic and peaceful. When the perception of shortage rears its head, people and pull in their horns, becoming more competitive, selfish and combative.

This view explains quite well the relative low level of warfare since the end of WWII, as humanity entered the period of greatest perceived surplus in our history. However, more people are now becoming subliminally aware that we are near the limits, and that results in more people exhibiting attitudes of selfishness, insularity and xenophobia. Such personal attitudes also colour the cultural tone when they are exhibited by public opinion leaders. When such leaders accede to the levers of national power, warfare is the invariable result.

To call on the agriculture-as-war image one last time, we have sowed the wind, and we are about to reap the whirlwind.