Now, of the ten plagues, the eighth one was that of locusts. Moses warned the Pharaoh that God will send so many locusts that they will "cover each and every tree of the land and eat all that is there to be eaten". Every time the Pharaoh refused, a fresh plague was inflicted upon his kingdom. (Exodus 10:3-6)
A concern and eventually a worldview originated in me with a simple question as to how and why locusts swarm. Finding out that locusts are grasshoppers when not swarming led to wondering whether the phenotypic switch of these and other polyphenic animals is possible in humans. Polyphenic means many appearances, where a phenotype is a specific physical characteristic. Locusts are a phenotype of certain species of grasshopper, but they look notably different, usually they are darker, stronger and display more desert-like colors. They have unique physical and behavioral expressions and yet they are the same species with the same genes. Polyphenic animals’ DNA perform an if-then condition calculation from the environment to the body expression of the individual. If there are too many grasshoppers we need to express a locust form to best survive. A summer coat or even a tan is a small version of this. Changing body expression into a locust results from significant endocrine signaling changes and coincides with significant behavioral changes1. It seems plausible to have phenotypes predominately in behaviors without dramatic shifts in form.
The locusts’ transformation is triggered by an impending resource scarcity as detected by the frequency of contacts to the hind leg of each individual. Behavioral effects of the transition include migration, increased metabolism2, increased sociality and cannibalism. Yes, cannibalism. The locust swarm essentially becomes a body, and that body eats itself as it travels. Much like a body of cells does when an organism has insufficient nutrients. In an algorithmic sense, traveling facilitated by swarming with cannibalism can be seen as an elegant search operation to find new and distant environments with water and vegetation. Distance required might be vast and include expanses of desert and other arid geographies. Reversion of the swarm from locust-form to grasshopper-form requires a massive diminution of population density. That asymmetry in environmental signals defines how plentiful the destination environment needs to be relative to the remaining locusts for the search to end. The new environment needs to allow for multiple generations of grasshoppers before the next swarm.
What relevance to us, the supposedly wise species? Do humans also exhibit polyphenic traits? At least a few examples of other species have well known cannibalism triggered by resource scarcity and stress. It is also well known that lab rats and lab mice mothers cannibalize a significant portion of their children due to the stresses of being trapped in a lab. While not exactly a phenotypic transition, the behavior is ecologically induced through the mammalian nervous system. Not bringing a child to term under extreme stress is clearly an adaptive feature humans also have, and following birth all parents' level of investment is ultimately as variable as the local environment allows.
We find even more behavioral evidence and behavioral gradation in our wide spread domesticate: gallus gallus domesticus, the domesticated chicken. Chickens, as well as many other wild and domesticated species, peck at and if permitted will cannibalize their kin in accord with the hierarchical manner we frequently use in the metaphor of a “pecking order”. The poultry industry wants to control and prevent such feather picking and cannibalistic behaviors, because it’s bad for business. In a later section we will discuss how relevant such research on animals’ internal and external environments will relate to human behavior.
Yet, behaviorally we can already see similarities between locusts with emergent violent mobs. We have well known examples from the Arab Spring where mobs arose when food prices got too high. Bodies in those societies could feel famine set in. Some of those experiencing the stress didn’t just demonstrate. A significant number of young men formed new military groups that went on to topple, or try to topple regimes. So we might ask, how close to swarm behavior and pecking orders are the sweeping conquests of Alexander the Great, Ghengis Khan, Napoleon and many others? I suggest very close; close enough to be biologically equivalent. War-like bands and emergent angry mobs are our swarms of locusts.
In appearance, the locusts looked like horses prepared for battle. They had what seemed to be crowns of gold on their heads, and their faces were like human faces. They had hair like women’s hair, and their teeth were like lions’ teeth. They had breastplates like iron breastplates, and the sound of their wings was like the noise of many horse-drawn chariots charging into battle. They have tails like scorpions’ tails, and stings as well, and their tails have the power to harm people for five months. (Revelation 9:7)
The New Testament has a fascinating metaphoric or linguistic confirmation of this argument emerging from a vision. The vision of the author described in the book of revelation tells of another type of locusts, those locusts were men of war. From my reading he describes mounted men with biting spears, long hair, so maybe foreigners, and requiring a lengthy recovery from a confrontation. The conceptual correlation of both mounted invaders and insect locusts in a lifetime of experience would be common enough to a person in the middle east, and perhaps much of humanity. Humans would experience famine at the same time as animals in their environment. The struggle for caloric resources after droughts would be within and among various species.
A full or organized army would be similar, but even more adaptive than a mob in the sense of preventing local violence and taking the resource conflict elsewhere. In that light, the social drive to war can be seen as an emergent evolutionary mechanism. Effective soldiering requires a submission of self into the hierarchy. If a soldier is lucky and effective they will participate in the bounty and booty including opportunistic fathering3. At a minimum they reduce their chances of being put to death or starving locally.
Those killed by the sword are better off than those who die of famine; racked with hunger, they waste away for lack of food from the field. (Lamentations 4:9)
The evolutionary objective of expansionary wars is now seen to manage the resource stress from too many hungry mouths and to search for fertile pastures, wombs, and grain stores. Particularly troublesome is the hunger of young and potentially rebellious men. Wise leaders and societies would do well to preempt their own demise by supporting expansionary efforts. Conflict is unavoidable. The big men of history are only the pawns, albeit clever pawns, of an unstoppable force of nature.
The metabolic basis of war and its relation to politics is important for the dynamics of our current times. Political institutions live atop of a population’s aggregate of personalities, driven by their biological evaluation of resources. Those institutions, like those that facilitate war, are biological resource allocation mechanisms. More peaceful institutions emerge in less precarious times. They emerge when and where the environment can support sufficient incentives, temperaments, and time for discourse based allocations. To say another way: sufficient health, wealth, and security allows for non-authoritarian modes of governance or resource allocation. Our typical western ideological desire to share democracy is understandable, but it is causally backwards.
Perhaps the behavioral effects of caloric deprivation are localized to young men, but I suspect not. War serves as one of many practical exams for sexual selection. In evolutionary conditions, violent conflict will also enact a sorting out of a smaller number of more capable men4. The local aggregate of fertile women’s incentives are served regardless of victory. Women’s famine and war time strategy might first be to encourage or support it. A more stressful time would involve higher catecholamines and a higher estrogen ratio. Higher relative estrogen is associated with seeking men that are perhaps less reliable, but more survivable in high risk situations. It seems ecologically plausible as there would be no point in courting a dad when no dads can stick around to invest in parental care. It also seems likely that whether those men are from this village or the one from a potential invader is not important once the stress conditions are in effect.
Continuing the speculations, perhaps old men and women would do what they can to support their kin, importantly they would also need to perpetuate the codes of religion and society that set all the surplus mouths to war. Social pressure should be used to push most unproven men into harm’s way. War is an opportunity to demonstrate survival from a variety of threats, but some young men are likely to feel a great reticence in pursuing their own doom. The social pressure, emerging from felt resource constraints, needs to be strong enough to combat the trepidation. We have plenty of examples in history, but none quite as dramatic as Sparta. In the hyper militarized state of Sparta, mothers were said to countenance their sons: “With it or on it” (in regard to their shields) and stories exist of mothers who went so far as to murder sons thought to have demonstrated cowardice5
References:
An Evolutionary and Ecological Analysis of Human Fertility, Mating Patterns, and Parental Investment
The Consequences of Sexual Selection and Uneven Sex Ratios in Humans
8,000 Years Ago, 17 Women Reproduced for Every One Man
A recent bottleneck of Y chromosome diversity coincides with a global change in culture
(They are pretty vague, but this coincides with cattle, horses, wheels and chariots )
Increase in Male Reproductive Success and Female Reproductive Investment in Invasive Populations of the Harlequin Ladybird Harmonia axyridis
“Males from invasive populations are more likely to mate first and gain a higher proportion of offspring with both invasive and native females.”
“and the increase in social inequality that occurred in Scandinavia during the Late Iron Age resulted in a male-biased operational sex ratio. This would have created a pool of unmarried men motivated to engage in risky behavior that had the potential to increase their wealth and status, and therefore the probability of entering the marriage market.”
Adrenergic and noradrenergic regulation of poultry behavior and production
INFLUENCING FACTORS LEADING TO DAMAGING BEHAVIOR - FEATHER PECKING AND CANNIBALISM IN GAME BIRDS
Ingestion of Lactobacillus rhamnosus modulates chronic stress-induced feather pecking in chickens
Serotonin is highly involved in both locust transformations and melanogenesis in humans
We will later need to take a look at the different types of metabolic increases. An increase from a stress hormone like noradrenaline is bound to have different behavioral consequences than from progesterone or thyroid.
In the recent evolutionary record, say 50k years or so, only 1 in 4 men were ever able to be fathers while practically all fertile women were able to find willing mates. The recent shift of agriculture included a period around 4,000 years ago when the ratio was as high as 1 in 17 and that pattern crossed most of the known globe.
In modern war this is probably not the case. For example, WWI significantly reduced the average male size in French society. Unfortunately, evolution will not yet have incorporated this environmental change in the nature of war.
Plutarch - On Sparta