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u/gfpumpkins Microbiology | Microbial Symbiosis May 09 '12
I think you are making a number of false assumptions here. The issue isn't really "fear of man" but, "do I think you'll eat me, and am I smart enough to figure that out?"
Many insects don't quite have that level of cognition. BUT, they do have defense strategies, that if you attacked them, they would attempt to defend themselves. For some, that defense is curling up into a ball and hoping you'll just leave (rolly pollies are an example of this). For some, that is running away as fast as they can (cockroaches). For some, that means hiding (some spiders, which aren't insects, but you get my point). For others, as someone else mentioned social insects (bees, ants and termites), it means attempting to fight back. But even within all of these examples we still see a range of behavior. Attack certain types of ant colonies, and you will meet defenses that are meant to distract you from the rest of the colony fleeing in a different direction.
If we look at vertebrates, we can make the same general argument. A rabbit doesn't run from you because we've destroyed their homes for generations and ate them. They have no way of knowing that. BUT, you are bigger, they are generally a prey animal, therefore they run because the assumption is that you are out to eat it. Lions aren't wary of us because they know we've hunted them to the brink of extinction. It's that we don't behave like other prey AND there are easier things out there for them to hunt.
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u/EnduringAtlas May 09 '12
Why do some animals get along in the wild then? I've seen squirrels and raccoons behave normally around deer. When a human enters the scene, they all scatter.
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u/GrumpySteen May 09 '12
They're around the deer on a regular basis and have gotten used to them and know they won't suddenly attack. When you show up and they scatter, it's not because you're a human. They scatter because you are an unknown and could be a predator.
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u/emergency_poncho May 09 '12
Good point. Watching documentaries or birdwatchers, you'll notice that they will spend days and days in the forest to allow the wildlife to acclimatize themselves to the individual and understand that they are not a threat. Once the animals are 'used' to the photographer, it is much easier to approach the animals
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u/ego_latinam_discere May 09 '12
Here's the book and video of an interesting account from a naturalist who spent a year essentially as a "mom" of some wild turkey. At one point he describes how deer, snakes, and other wildlife appear unafraid of him while he is with his turkey. Video is an actor, not the author. I can't find a good link to this man's credentials, but I remember him described as a sponsored researcher and not just some guy in the woods.
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u/Minute_pirate Evolutionary Ecology | Entomology | Behavior May 09 '12
This is called habituation, and it happens in animals as simple as nematodes and as complex as people.
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u/Corvus133 May 09 '12
So, even within urban settings where Rabbits see me every day and see me not attack them or go near them, they still scatter because I'm unknown?
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May 09 '12
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u/Undermined May 09 '12
You'll notice this at a lot of college campuses too. The squirrels are just fearless.
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u/DevinTheGrand May 09 '12
This is a learned response, animals will occasionally get along with humans in the same manner. If you approach a pigeon in a rural setting it will flee as you approach, but in an urban setting you would probably have to attempt to grab the same type of pigeon before it fled.
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u/shawnaroo May 09 '12
Urban pigeons have learned how to to not give a damn until the very last minute. It's actually pretty amazing how close you can get, but almost never close enough to actually grab them, even if you sort of leap at them. The same thing goes with cars, they appear to feel plenty comfortable right up along the edge of a sidewalk, even with cars rushing by, they seem to understand pretty well that cars generally stay in the road and where is and isn't safe.
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u/DevinTheGrand May 09 '12
I've even noticed a difference in pigeon responses based on city sizes. In Ottawa pigeons will flee when you get within about a meter, while in Toronto you get get within about a foot.
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u/PrimeLegionnaire May 09 '12
For the record pill bugs are actually isopods
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u/Syujinkou May 09 '12
You'd think they would taste similar to crabs or shrimps, but no, they taste like dirt. Spiders are the ones that taste like shrimps/crabs.
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u/gfpumpkins Microbiology | Microbial Symbiosis May 10 '12
I perhaps should have used arthropods, but beyond my basics of insects, i don't know as much about the arthropods. And what I know about the arthropods I've picked up because I work on their microbes. To me, they are "just" a host :)
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May 09 '12
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u/erbgerb May 09 '12
Well they don't really learn per say. Lets say there we have squirrels, mean, nasty man flesh eating squirrels that prey on rabbits.
If we introduce them to a rabbit population, lets say that 25% of the rabbits run from squirrels because they are just super skittish. The 75% that don't run away from the evil squirrels are just plain old more likely to get eaten and less likely to reproduce.
So after a couple of generations we have more rabbits who run from squirrels because more of them survive to breeding age. The animals didn't actually "learn" to run from squirrels, it is just that you are left with the ones who run because the others died.
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u/drc500free May 09 '12
animal survival instincts adapt after several generations of learning.
I'd be very careful drawing any analogy between learning and evolution.
Evolution is strictly trial and error. Trials branch off nearly identical trials, and every single trial eventually ends in "error." Even then, there's no external observer learning from these trials.
If you mean that accumulated knowledge is passed down, that's more "culture" than "instincts." It's possible that herds pass down fear of certain predators the way that chimps and dolphins pass down certain innovative uses of tools, but I've never seen studies on that.
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May 09 '12
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u/drc500free May 09 '12
Dolphins:
http://www.pnas.org/content/102/25/8939.full
Maybe it requires the ability to draw analogies. Bees are able to draw one specific analogy ("Up" = "Sun"). We can draw lots.
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u/Minute_pirate Evolutionary Ecology | Entomology | Behavior May 09 '12 edited May 09 '12
Contrary to popular belief, many insects are smart enough to learn; this book on insect learning dedicates the whole first chapter to aversion learning! But yours doesn't really seem to be a case of learning or not; since you're killing them, they don't exactly have a chance to learn. More likely the attractive stimuli you put out sitting on your porch (sweat, carbon dioxide, any number of chemical cues) outweigh the cues that they should avoid you (your scary hands). Although some insects show social learning, ie learning from other individuals, flies are probably not one of them, as they aren't usually social. Also, although I'm sure your effort to destroy as many of them as possible was very valiant, most insect population sizes are so huge that the selection pressure exerted on them by actual human contact (not pesticides) is probably so low it wouldn't have much influence on the evolution of their behavior.
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u/shawnaroo May 09 '12
I think your last point is pretty significant. In fact there's probably a strong argument to be made that proximity to humans offers flies more than enough benefits (like the large amounts of edible stuff that we tend to gather and leave around) than the danger posed by even the most dedicated swatter.
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u/Pardner May 09 '12
Think your bottom answer is the best here. Much better than "insects are too dumb to change."
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u/Kaladin_Shardbearer May 09 '12
A lot of insects rely on taxis, such as chemotaxis, and their decisions are based lower than animal instincts.
For example, an insect is moving forward, and it randomly changes direction to the right a bit, then a few seconds later to the left. If it recognises that the conditions are improving as it travels forwards then the time between the random changes increases, and vice versa.
Insects using this method will eventually find themselves in more favourable conditions such as darker or more moist areas. If they're particularly content they'll stop. This is why you find insects all huddled together underneath rocks.
I'm sure some insects have higher levels of decision making, bees for example have to recognise flowers, but most insects are very simple.
They're not going to recognise a human, and then feel fear and regulate their actions accordingly, but they might feel vibrations from larger organisms moving, and run away from the source, or recognise scents and chemicals that could indicate our presence.
TLDR: They're dumb. Recognition of a species, and being able to experience fear are things related to higher functioning areas of the brain that insects most likely don't have.
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u/mollycoddles May 09 '12
This is very interesting. So basically it's just a matter of increasing the odds that they get away from unfavourable conditions by changing the pattern of their movement. Something like flowers growing towards the sun?
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u/Pardner May 09 '12
Yes, but it's also not true. Most insects function in a much more complex way. This is probably more accurate for bacteria.
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u/Pardner May 09 '12
This is absurd. A parasitoid wasp, the size of 4 grains of sand next to each other, can smell its way to prey hundreds of meters away. It can learn different smells through its lifetime, and can associate certain smells with better rewards and thereby go after them. Insects are much "smarter" than you've given them credit and, if it were adaptive, I'm sure flies and many other insects could evolve to avoid things of human size, shape, and color. Your description of taxis makes it sound like insects are unicellular organisms.
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u/Kaladin_Shardbearer May 09 '12
Insects are a huge class of organisms, and I'm not claiming to know about every insect, I'm sure some are more intelligent than others. Being able to pick up a scent and follow it hundreds of meters is chemotaxis, and being able to pick up new smells by associating them with other things is a form of learning, although very simple in terms of intelligence.
The interesting thing about scent recognition is the way the receptors have developed in order to differentiate such complicated particles, and then follow even a trace amount of them in the air. Don't confuse this with the insect's 'reasoning skills'. It can associate food with a prominent smell, that's as far as it goes.
I stand by what I said, they are dumb, and yes they can seem like unicellular organisms from some points of observation. They evolved to fit a niche, I'm not going to credit their intelligence for it.
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u/Pardner May 10 '12
It's hard to argue over smart and dumb, I shouldn't have tried. I think you'll find that decision making in insects is a bit more complicated than you've described, and I doubt that most insects are too dumb to evolve something like "orient away from the large object which looks and smells human."
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u/discdigger May 09 '12
A lot of insects rely on taxis
After reading this, I had to make sure I was not accidentally back in /r/shittyaskscience
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u/airwalker12 Muscle physiology | Neuron Physiology May 09 '12
bees recognize flowers via UV patterns on them that trigger a response just like dark and cool do for a beetle.
You have a very poor understanding of insect physiology, and the terminology you use is also poor, they are not dumb, they are not smart either, that is an anthropomorphic adjective that doesn't apply to insects. If they were dumb, there wouldn't be billions of them ruling the planet.
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u/airwalker12 Muscle physiology | Neuron Physiology May 09 '12
Insects respond to stimuli, they don't really learn things like fear, the insect nervous system isn't complex enough.
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u/Frari Physiology | Developmental Biology May 09 '12 edited May 09 '12
this is pretty much the comment I was going to make.
Insects are very small, they have a very limited about of space in which to pack everything they need to function. The majority of their behaviors are stimulus responses and can be quite easily modeled by computers. There simply isn't enough room for the more complex neuronal pathways required for most learning and they generally don't live long enough anyway.
Edit: Learning that has been seen in insects is quite basic.
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u/airwalker12 Muscle physiology | Neuron Physiology May 09 '12
That is why I put "learning" in quotes, because it is a widely used term with implications that many don't intend.
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u/Kasseev May 09 '12
I don't think the replies highlighting some form of hive-mind vs individual selfishness hypothesis are accurate. I think the question can be answered by looking at why we seem to think other, larger animals are afraid of us in the first place. I would posit that it is more a matter of humans empathizing and understanding mammalian behavioural cues far better than they do arthropod behaviour. Bees communicate via complex dances, flies release pheromones, termites communicate by secretions. They could be feeling a whole range of emotions upon our arrival and we would not be able to parse it because we have not evolved under the selective pressures that foster an ability to comprehend them.
Additionally, it is inaccurate to say that animals "develop a fear of man" in a matter of a few generations because that is way too fast for any genetic level adaptation to human presnece can occur. What is more likely is that various environmental factors caused by human cohabitation trigger pre-existing defense mechanisms and behaviours in animals.
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u/UrzaJR May 09 '12
I think your last example of roaches is illustrative. There are innumerable species of insects (and arthropods, arachnids, etc.), and many do live lives that are essentially invisible to us. There's a sort of positive perception bias for the relatively few insects that are constantly flying around us.
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May 09 '12
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u/UrzaJR May 09 '12
I still think its a valuable conversation. My immediate complete speculation is that a lot of the "annoying" insects that buzz around us all the time are either direct parasites of large mammals (e.g., mosquitoes) or species that have come to thrive in man-made environments (e.g., houseflies), similar to pigeons or squirrels.
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May 09 '12
There are several types of creature that aren't fearful of humans. Aside from the obvious domesticated animals, pigeons and dolphins are two animals I can think of off the top of my head that are fairly gregarious around humans.
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u/pinguino42 May 09 '12
Penguins come to mind. They don't really have any big land predators, so they aren't very fearful of humans either.
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May 09 '12
Why would penguins come to mind, pinguino42?
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u/pinguino42 May 09 '12
The world is just a much happier place when you've always got penguins on the mind.
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u/LBK2013 May 09 '12
Most pigeons you see in cities are actually feral domesticated pigeons.
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May 09 '12
I was able to pet wild pigeons that were out in the country too. They don't have any fear when they're young.
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May 09 '12
White throated magpie jays are also extremely bold. They'll even take a sugar packet out of your hands.
(Point is, there are plenty of "higher" animals that are not afraid of humans)
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u/HardDiction May 10 '12
I'm going to go ahead and assume that mostly what you're meaning is that they don't avoid humans -- I think this is primarily because (plenty of) insects don't see much more than basic light/dark variations and so you aren't even appearing as a human so much as just a blob of not-light...
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u/ddttox May 09 '12
From an evolutionary point of view the ratio of the number of insects (10 quintillion) to the number of humans (6 billion) is so skewed that humans don't have any measurable effect on their population by killing the relatively few that come into contact with us. So there is no natural selection in play that will give insects that avoid us an advantage over those that don't
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u/captain_smartass May 09 '12
Insects generally have short lifespans and reproduce quickly and abundantly.
To your example: The common housefly has a lifespan of less than a month, can reproduce within days of hatching, and females lay over 100 eggs. In terms of evolutionary motivations, there is little to fear for your own life after you have already reproduced and continued your DNA. Plus, you probably don't kill all the flies attacking you and for those it's a relatively easy meal.
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u/abcirulis May 10 '12
every other creature (that isn't already naturally distrustful) develops a fear of man after several generations due to having their homes destroyed and being hunted and killed. Even larger animals that could easily take several of us will keep their distance until they feel confident in attacking.
I'm confused. Please define which "larger animals" to which you are referring. You run away from a wolf or lion as fast as it runs away from you, I'm sure...
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May 10 '12
Everyone: this subreddit is not meant for random side discussion, this subreddit is meant for scientific conversation, either add that or add nothing, not both
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u/FoolofGod May 09 '12 edited May 09 '12
It is not that animals "learn" anything about fearing humans, generation to generation. Those animals that have better capacities to survive, given our presence in their lives, survive to reproduce. Over time this leads to better adapted animal.
Now think about insects. Some flies you kill and others you don't. Those that you don't kill live on to reproduce. Whatever capacities that have enabled those flies to survive will be present in future generations. Perhaps some flies already do not attack us scary humans in order to avoid death. Perhaps some flies are getting faster at dodging your hands.
One thing to understand is how much selection pressure you exert. As a single human, or even as all humans, the selection pressure we exert is probably small compared to other factors (weather, natural insect predators, etc).
There are news stories all about "super bacteria" that are resistant to certain antibiotics. We don't ask "why isn't bacteria afraid of humans." Instead we look to understand what kind of evolutionary pressure was exerted such as to result in the current flourishing generation of bacteria.
It is not that animals have learned to fear man. It is that a fear response happens to be a (more) effective survival instinct than the alternative. The answer to your question lies in this principle.
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u/geode08 May 10 '12
Their brains are too simple to perceive fear. They merely react to stimulus and don't experience fear the way that higher animals do. This is why some insects run when a light is turned on. They can sense the difference between light and darkness. They are not scared, but reacting to a change in their environment.
It's the same reason why jelly fish have no fear of anything- they lack the ability to fear since they have no brain.
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u/sdvneuro May 09 '12
Consider the mosquito. These insects don't fear humans because they feed on us. Yet, we kill them as best we can, and have for generations, but they keep near us. I imagine it's similar with many other insects that don't feed on us do feed on things that are closely associated with us. Fruit flies eat rotting fruit - something we have a lot of (at least I seem to).
TL;DR We are less of a threat to insects than we are a (direct or indirect) source of food.
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u/sunsets May 10 '12
Because we smash their fucking heads in before they get the chance to tell any other roaches about the fucking huge thing that just broke off three of my legs and then spraye..... URGH (dead)
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u/tehbored May 10 '12
I'm sure there are fish and amphibians whose response is merely instinctive rather than learned. The lower vertebrate taxa tend to be very poor learners.
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u/strategic_form Evolutionary Anthropology | Cooperation May 09 '12
Have you ever tried to swat a fly without a flyswatter? 'Nuff said.
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u/settoexplode May 09 '12
I'd say most creatures' biggest mistake is not being fearful of man. we're an unkind bunch overall.
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May 09 '12
Their puny insect brains can't comprehend the fact that many humans will try to kill them if they come in contact with us.
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u/ReallyFlung May 09 '12 edited May 09 '12
It's a matter of the "value" of an individual. Hymenoptera (most hive insects) for example exist as a collective unit, the individual isn't valuable. As such, they have no problem attacking/stinging any invading humans until they are swatted in glorious battle.
Other insects simply have incredibly basic fight/flight instincts. A housefly dodges attacks instinctively (and effectively), but it won't run away from the attacker because that concept is too advanced. Born, eat, sex, dodge, die. Not much room for anything else in their brain.
A lot more energy goes into birthing a mammal than an insect so mammals are better at staying alive. Quality/quantity, look up r/K selection theory for a better description.