The violence around us….
I don’t think many of us would consider the world as less violent today than compared to the past.
Perhaps i’m being too sensitive. I am continuously shocked at our ability to employ brutality towards our fellow beings and the depths of callousness some are comfortable with given a varying moral stance. Sometimes I feel if no one was watching or we could get away with it, plenty of us would sink to depraved depths.
Many years ago I went to a lecture by Stephen Pinker (a science writer) whose research seemed to indicate that in the human kingdom violence has been in decline over a long period. Analysing data covering war, genocide, homicide and other categories he argues that forces such as commerce (hence co-operation), literacy, reasoning and the rise of the modern state have curbed violent motives — which he doesn’t think we are naturally programmed to have anyway. His thesis invited significant controversy with many academics, theologians and statisticians disagreeing — finding no change in levels of violence over history. I’m not sure what to think as it requires research well beyond my capability. However it caused me to ponder if evolution had lessened violence in the animal kingdom (or even if there was any logic to have done so) as the factors Pinker credits appear man made.
But if research on human violence is hard to draw conclusions on — the animal, bird and insect kingdoms are even more tricky to analyse. Peculiarly (or not as you’ve discovered I like to meander), search on the internet took me on a strange path; delving into how insects cope with violence from predators around them. It reminded me that nature is beautiful, terrifying, bizarre and ingenious concurrently. It also prompted me to think of videos I have seen where giant centipedes have fought scorpions or hornets….honestly I’m really not that kind of person! So this is random granted, but I thought it interesting enough to relate some of these astonishing idiosyncrasies so you too can be as bemused as I am! Here we go.
Bats use a system called echo location to find their prey which in practice means the sound that a bat emits is returned to it as an echo when it hits something. Synthesising these echo’s they can configure a picture of their surroundings to discover food. However there are moths that can hide from the bats hunting them. They do this by absorbing the ultrasound frequencies emitted by bats through the arrangement of scales attached to their wings. This reduces or eliminates the sound that is returned to the bat and so the moth can seem to disappear and live another day.
A cockroach has ‘mechanoreceptive hairs’ (called setae) that are able to detect a change in air pressure that precedes something that is moving fast through the air. This enables the cockroach to react extremely quickly and move away to avoid becoming someone’s lunch.
Some insects such as swallowtail caterpillars when attacked release a potent concentrate into the air which is quite offensive to other animals and causes them to turn away. Bombardier beetles go further by spraying a burning chemical mix from their abdomens at predators. How do they do that? Hydroquinone and Hydrogen peroxide are kept separately in cavities of their body. When an attack is imminent, the beetle is able to bring these liquids together which causes a reaction. The combination achieves a close to boiling temperature turning the mix into a gas which escapes the body of the beetle and is lethal to the predator.
Certain caterpillars have hairs that carry a toxin. When something brushes against these hairs, the toxin is released and creates pain as it seeps into the skin of whatever touched it.
The insect world has learnt to use mimicry where they fool predators into thinking they are dangerous insects and so be avoided. The Spinx moth for example looks like a large bumblebee; Drone flies and Hoverflies try to look like bees or wasps.
The Japanese honey bees have to gang up together to take on intruding hornets which are much larger than they are. When a hornet enters a bee hive, these bees band together and hold the hornet in a tight ball. They then vibrate vigorously generating heat and expiring C02 which raises the temperature of the ball of insects to 46 degree C. As the honey bees can survive up to 50 degree C, they do not die but the hornet which is held tightly within this ball is suffocated and burnt alive. As a sign of how culture will always win out, the Vietnamese honey bee employ a different tactic. They instead smear animal faeces around their hives which seems to deter hornets from entering.
Flies seem to have a reaction time that is quite incredible. For them time lasts longer than for us because they are able to rapidly blend images from the eye. We can process approximately 60 images per second in our brain. A fly 250 images a second, which means as they view our arm coming in to swat them it is as if we are doing it in slow motion. We have no chance of connecting unless we are sneaky. Some how husband seems to have figured out how to be and is our champion fly swatter…. a family always needs one….
Scientists have discovered species of sea slug that decapitate themselves after their bodies are infected with parasites. Within 3 weeks these sea slugs are able to re-grow their bodies from their head — parasite free. (More on Nature.com)
But these two are my favourite if slightly macabre defensive systems. An Assassin bug carries the dead bodies of ants around on its back. Strange but it seems to discourage spiders from attacking. And a clearly more psychotic caterpillar called a Gumleaf skeletonizer (brilliant name) after it has sheds skin carries its former heads in a stack on its body which acts as a deterrent to predators!
On a totally flimsy basis, given evolution has enabled these insect attributes to flourish, it seems unlikely that violence in the insect world has lessened over time but intuitively there seems a possibility that man made factors may have reduced violence in our society. I’m just glad I don’t have to walk around with three heads hoarded on top of mine to prove that….
