With the advent of September, children all across the country are gearing up for another year of backpacks, books, and peanut butter and jelly sandwiches. That’s right, it’s time for school. In school, children develop new skills, learn new information, and establish patterns of thinking and behavior that will serve them their entire lives. And their teachers - people whose jobs it is to teach others what they do not already know – are one of the driving forces behind the process.
Teaching sounds so simple that you might be surprised to learn that it has always been believed to be exclusively human. You might think that there are many examples in nature of animals teaching each other. After all, don’t mother cats bring live mice to their kittens to show them how to kill and eat live prey, and don’t baby birds learn how to fly from their mothers? True – but that’s not the kind of teaching behavioral scientists like to study. There are, in fact, two kinds of teaching – social teaching and active teaching.
In social teaching, a youngster learns by watching and copying adults performing a task. In active teaching, an individual is a teacher if it changes its behavior in the presence of an uninformed observer at some initial cost to itself. This change in behavior sets an example so that the uninformed individual learns more quickly than it would on its own. In social teaching, knowledge is passed on passively, without deliberate initiation by the knowledgeable individual. In active teaching, the teacher initiates the instruction solely to pass knowledge along. Thus a young duck learning to migrate by flocking south with other ducks was not “taught” the process, since the experienced ducks would have flown south regardless.
Here is classic example of social learning. Dr. Michael Noonan is a professor of animal behavior at Canisius College. He has reported how orcas in a Canadian marine preserve set “water traps” to catch and eat seagulls. In one case, one orca (Alpha) set the trap with apparent success; some weeks later, the killer whale’s brother (Beta) began setting the same trap. After study, Dr. Noonan concluded that this was the result of Beta watching Alpha and then mimicking the technique, not due to an active teaching role of Alpha. Alpha was not a teacher. He was merely an example.
While there are many examples of social teaching in nature, scientists have only recently proved that active teaching takes place in non-humans. The results come from two surprising animal species – a tiny British ant (Temnothorax albipennis) and the plains-dwelling meerkat (Suricata suricatta).
In one study, Drs. Nigel Franks and Tom Richardson from Bristol University showed that ants use a technique called “tandem running” to teach each other about a source of food. This technique involves an ignorant ant (the student) closely following an experienced ant (the teacher). The student uses its antennae to periodically stop the teacher to determine its location relative to local landmarks. This process results in a slow initial journey to the food of interest (in fact, at least 4 times slower than the teacher would take on its own); however, the student learns the location of the food so well that it subsequently takes any number of paths to and from the food without the need for random foraging. The scientists concluded that all the requirements for active teaching are in place, thus proving this ant species as the first non-human species to teach each other.
Shortly thereafter, Drs. Alex Thornton and Katherine McAuliffe from the University of Cambridge demonstrated teaching in wild meerkats. Meerkats live in social groups of a dominant male and female (who produce the pups), a variable number of adult helpers (who rear the pups), and the pups themselves. The meerkat diet consists of insect and animal prey, some of which can be quite dangerous to an untrained pup. A scorpion sting, for example, can be crippling or even lethal for an animal the size of a meerkat. Thornton and McAuliffe showed how the helper meerkats teach pups to disable and then eat scorpions without being stung. This teaching takes more time and effort for the helpers than would merely providing the pups with a diet of dead scorpions. However, it results in a decreased scorpion sting rate and faster development of the hunting skills for the pups. Again, the data was clear. Meerkats, like humans and British ants, actively teach their young.
So this marks the first non-human species to be proved as engaging in active teaching. (Of course, I suspect they probably do not wait until September to start their lessons as humans do.) Admittedly, ants, being insects, do not have nearly the same appeal that meerkats do. So while ants are able to teach each other, I suspect it’ll be a while before we see any television shows featuring “The Ant Food Finding School.” But for all of you who enjoy watching “Meerkat Manor” on Animal Planet, I’d like to propose a possible sequel on the Learning Channel. It’s called “Meerkat Elementary School.”
Monday, August 27, 2007
Friday, August 24, 2007
What is it about tickling?
In a recent entry (“Let’s talk about feet”), I discussed some of the amazing features of human feet, including the fact that feet are ticklish. That sparked a question in my mind – what makes us ticklish? Why are some parts of our bodies more ticklish than others? Why are some people extremely ticklish, while others can stand seemingly hours of feathers-on-the-toes temptation without even cracking a smile? And is it really true that you can’t tickle yourself?
Ticklishness is neurologically hardwired into our brains. The sensation of tickling is controlled by a highly developed part of the brain called the cerebral cortex. The cerebral cortex is one of the largest parts of the brain; it contains all of the centers that receive and interpret sensory information, initiate movement, analyze information, reason and experience emotions. Neurologically, a ticklish response is similar to a developed defense response against dangerous creepy-crawly critters like poisonous spiders and bugs. This explains why we tend to be ticklish on exposed or vulnerable parts of our bodies – like our feet, armpits and stomachs. Make sense, right? The sensation of tiny little legs crawling across my toes would easily make me jump, brush the area vigorously, and remove whatever’s causing the feeling. Sounds a lot like what happens when someone tries to tickle my feet!
Ticklishness might be more than simply a neurological phenomenon, though – scientists also believe that it is a learned response. Two essential factors must be in place for tickling to occur. First, there must some form of a mock attack. Someone else must be coming at you in such a way that your brain interprets as potentially hostile. But second, and equally importantly, there must be a perceived lack of real threat. In other words, I must believe both that you can make me laugh uncontrollably and that you won’t actually hurt me in the process. If a good friend suddenly tickles you from behind, both of those criteria are met – it’s startling, surprising, and maybe initially scary, but there’s also no real threat. As the Encyclopedia Britannica says to describe when a child will find tickling enjoyable, “The child will laugh only – and this is the crux of the matter – when it perceives tickling as a mock attack, a caress in mildly aggressive disguise.”
Tickling also has a relational aspect. Robert Provine, professor of neuroscience at the University of Maryland, Baltimore County and author of "Quest for Laughter", believes that tickling is an important form of non-verbal communication. For children, tickling is most often done during a time of playing, either with their parents, siblings, or playmates. Above the age of puberty, tickling usually is a form of flirtation, and is often done in the context of a sexual relationship. All in all, Dr. Provine points out that tickling is always done between people who have a good relationship – parents and children, siblings, good friends or spouses. Strangers or coworkers don’t usually try to launch a tickle attack!
So what about the idea that you can’t tickle yourself? Once again, our brains provide the answer. The human brain knows what feelings to expect whenever the body performs a certain motion. The region of the brain that controls this is called the cerebellum. The cerebellum is a relatively primitive region at the base of the brain that monitors movement and sensation. We don’t pay attention to most of these things – for example, our brain ignores the feeling of clothes on our skin. If we had to pay attention to every sensation our bodies experienced, we’d be overwhelmed! Instead, our brains are wired to pay attention to startling, surprising or unexpected sensations. This is the neurological reason why we can’t tickle ourselves. When you move your hands towards your feet, your brain expects the associated sensations, realizing “Oh, it’s just me. No problem.” Without the surprise, unease, or feeling of mock attack, it simply doesn’t tickle. That’s not to say that you can’t stimulate the nerves in your feet to feel funny when you try – but you’re probably not going to break out laughing in the same way as if someone else was doing it to you.
And just in case you were wondering, humans are not the only ones who are ticklish. Chimpanzees have been observed tickling each other when playing. (Does that qualify as monkeying around?) And even other animals can get in on the fun. In 1999, two neurobiologists at Bowling Green State University published results from a tickling study on rats. When the rats were tickled at the napes of their necks, they chirped and kicked their feet. I guess that’s what it sounds like when a rat giggles!
Ticklishness is neurologically hardwired into our brains. The sensation of tickling is controlled by a highly developed part of the brain called the cerebral cortex. The cerebral cortex is one of the largest parts of the brain; it contains all of the centers that receive and interpret sensory information, initiate movement, analyze information, reason and experience emotions. Neurologically, a ticklish response is similar to a developed defense response against dangerous creepy-crawly critters like poisonous spiders and bugs. This explains why we tend to be ticklish on exposed or vulnerable parts of our bodies – like our feet, armpits and stomachs. Make sense, right? The sensation of tiny little legs crawling across my toes would easily make me jump, brush the area vigorously, and remove whatever’s causing the feeling. Sounds a lot like what happens when someone tries to tickle my feet!
Ticklishness might be more than simply a neurological phenomenon, though – scientists also believe that it is a learned response. Two essential factors must be in place for tickling to occur. First, there must some form of a mock attack. Someone else must be coming at you in such a way that your brain interprets as potentially hostile. But second, and equally importantly, there must be a perceived lack of real threat. In other words, I must believe both that you can make me laugh uncontrollably and that you won’t actually hurt me in the process. If a good friend suddenly tickles you from behind, both of those criteria are met – it’s startling, surprising, and maybe initially scary, but there’s also no real threat. As the Encyclopedia Britannica says to describe when a child will find tickling enjoyable, “The child will laugh only – and this is the crux of the matter – when it perceives tickling as a mock attack, a caress in mildly aggressive disguise.”
Tickling also has a relational aspect. Robert Provine, professor of neuroscience at the University of Maryland, Baltimore County and author of "Quest for Laughter", believes that tickling is an important form of non-verbal communication. For children, tickling is most often done during a time of playing, either with their parents, siblings, or playmates. Above the age of puberty, tickling usually is a form of flirtation, and is often done in the context of a sexual relationship. All in all, Dr. Provine points out that tickling is always done between people who have a good relationship – parents and children, siblings, good friends or spouses. Strangers or coworkers don’t usually try to launch a tickle attack!
So what about the idea that you can’t tickle yourself? Once again, our brains provide the answer. The human brain knows what feelings to expect whenever the body performs a certain motion. The region of the brain that controls this is called the cerebellum. The cerebellum is a relatively primitive region at the base of the brain that monitors movement and sensation. We don’t pay attention to most of these things – for example, our brain ignores the feeling of clothes on our skin. If we had to pay attention to every sensation our bodies experienced, we’d be overwhelmed! Instead, our brains are wired to pay attention to startling, surprising or unexpected sensations. This is the neurological reason why we can’t tickle ourselves. When you move your hands towards your feet, your brain expects the associated sensations, realizing “Oh, it’s just me. No problem.” Without the surprise, unease, or feeling of mock attack, it simply doesn’t tickle. That’s not to say that you can’t stimulate the nerves in your feet to feel funny when you try – but you’re probably not going to break out laughing in the same way as if someone else was doing it to you.
And just in case you were wondering, humans are not the only ones who are ticklish. Chimpanzees have been observed tickling each other when playing. (Does that qualify as monkeying around?) And even other animals can get in on the fun. In 1999, two neurobiologists at Bowling Green State University published results from a tickling study on rats. When the rats were tickled at the napes of their necks, they chirped and kicked their feet. I guess that’s what it sounds like when a rat giggles!
Monday, August 20, 2007
The "small animal, short life" phenomenon
The question of why we get old is a very hot topic in life science research right now. (Of course, it’s been a hot topic of human interest for hundreds of years! Consider the story of Ponce de Leon and the quest for the fountain of youth.) But only relatively recently has science delved deeply into what makes us age. There have been lots of theories put forth over the years to try and explain aging. Many years ago, scientists studying aging discovered something interesting, which is this: the predicted life span of a mammal generally correlates with its body size. To explain this, let’s take a look at some examples, and I’ll show you how it works.
Your standard pet gerbil, weighing in at around 0.3 pounds, will live somewhere between 2 and 4 years. Holland Lop rabbits, a bit heftier at 5 pounds, can be expected to last 7 to 12 years. Golden retrievers, around an average of 70 pounds, usually survive 12 to 17 years. Let’s move away from domesticated pets and head on up mammal size chart. How about camels? Weighing in at 1,500 pounds, they hang around an average of 40 years. Going even larger still, elephants, which weigh anywhere from 6,000 to 16,000 pounds, typically live somewhere around 70 years. And what about the largest mammal of all, the blue whale, being a hefty 100 tons? Since whales don’t have teeth, which are typically used to determine age, it’s a little difficult to say exactly. But some scientists believe that blue whales can survive upwards of a hundred years. In fact, if you were to pick a mammal at random from the entirety of the natural world, you’d be pretty safe betting how long it could be expected to live based on its average body mass.
This brings up an interesting question - why do big mammals live longer than little ones? Perhaps it’s because bigger mammals are harder to eat than smaller ones, and are less likely to turn into someone else’s dinner! I’m just kidding. The average life spans I’ve listed above are the length of time until a “natural” death, not death from predation or disease. Actually, scientists really don’t know why small animals live short lives. It might have something to do with metabolism and metabolic rate, or it might be related to the fact that small mammals produce babies extremely rapidly. The question is still up for debate.
But now that I’ve said all that, here’s what I find really the most interesting. There are some very notable exceptions to this “small mammal, short life; large mammal, long life” phenomenon. And just as scientists don’t know why small body size usually means short life span, they also don’t know why some animals are completely off the charts.
One animal I find particularly intriguing is the bat. Even though many people don’t like them, bats have a ton of interesting features that I might discuss in a future entry. For today’s purposes, suffice it to say that bats live much, much longer than you would expect for their size. On average, though they have a high infant mortality, once they reach adulthood, they live between 10 and 30 years. The oldest bat ever recorded was a wild caught banded little brown bat, 34 years old. Amazing, considering the average banded little brown bat weighs in at 8 grams – or 0.01 pounds. Comparing different animals, in fact, bats live longer per ounce of body weight than any other mammal on earth. The only mammal capable of true flight, with the ability to echolocate and an amazing anatomy, is also the longest-lived per ounce. Who would have thought that?
Your standard pet gerbil, weighing in at around 0.3 pounds, will live somewhere between 2 and 4 years. Holland Lop rabbits, a bit heftier at 5 pounds, can be expected to last 7 to 12 years. Golden retrievers, around an average of 70 pounds, usually survive 12 to 17 years. Let’s move away from domesticated pets and head on up mammal size chart. How about camels? Weighing in at 1,500 pounds, they hang around an average of 40 years. Going even larger still, elephants, which weigh anywhere from 6,000 to 16,000 pounds, typically live somewhere around 70 years. And what about the largest mammal of all, the blue whale, being a hefty 100 tons? Since whales don’t have teeth, which are typically used to determine age, it’s a little difficult to say exactly. But some scientists believe that blue whales can survive upwards of a hundred years. In fact, if you were to pick a mammal at random from the entirety of the natural world, you’d be pretty safe betting how long it could be expected to live based on its average body mass.
This brings up an interesting question - why do big mammals live longer than little ones? Perhaps it’s because bigger mammals are harder to eat than smaller ones, and are less likely to turn into someone else’s dinner! I’m just kidding. The average life spans I’ve listed above are the length of time until a “natural” death, not death from predation or disease. Actually, scientists really don’t know why small animals live short lives. It might have something to do with metabolism and metabolic rate, or it might be related to the fact that small mammals produce babies extremely rapidly. The question is still up for debate.
But now that I’ve said all that, here’s what I find really the most interesting. There are some very notable exceptions to this “small mammal, short life; large mammal, long life” phenomenon. And just as scientists don’t know why small body size usually means short life span, they also don’t know why some animals are completely off the charts.
One animal I find particularly intriguing is the bat. Even though many people don’t like them, bats have a ton of interesting features that I might discuss in a future entry. For today’s purposes, suffice it to say that bats live much, much longer than you would expect for their size. On average, though they have a high infant mortality, once they reach adulthood, they live between 10 and 30 years. The oldest bat ever recorded was a wild caught banded little brown bat, 34 years old. Amazing, considering the average banded little brown bat weighs in at 8 grams – or 0.01 pounds. Comparing different animals, in fact, bats live longer per ounce of body weight than any other mammal on earth. The only mammal capable of true flight, with the ability to echolocate and an amazing anatomy, is also the longest-lived per ounce. Who would have thought that?
Thursday, August 16, 2007
Let's talk about feet
Today’s topic – the wonders of feet. That’s right, feet. I don’t know exactly why, but I find feet to be one of the more fascinating parts of human anatomy. They are an incredibly intricate and complex piece of the body, stand the heavy stress of bearing our full body weight every single day, take a lot of abuse by getting crammed into uncomfortable shoes, and are generally ignored. (Unless, of course, you’re talking about tickling – but more on that later.)
Here are a few of the more amazing facts about feet that I’ve come across:
-Human feet contain over a quarter of the bones found in the entire body – 26 bones per foot (or 28, depending on how you count).
-There are approximately 250,000 sweat glands in the average pair of feet – that’s enough to produce a pint of sweat every day.
-When you walk, you produce 2-3 times your body weight in pressure on your feet. When you exercise, the pressure gets even worse – they can cushion as much as a million pounds of pressure in 1 hour of strenuous activity!
-The average individual will walk over 115,000 miles over his lifetime – that’s enough to go around the world 4 times.
-The skin on the soles of your feet is 20 times thicker than the skin on the rest of your body.
Incredible, isn’t it? These amazing pieces of anatomy at the ends of our legs just keep on working, day in and day out, bearing enormous pressures, step after step. But do you want to know the thing that I find the most intriguing of all? For all the strength and resiliency of our feet, they are also one of the most sensitive areas on our bodies for being tickled. I know some people who can’t stand anyone else touching their feet, because it tickles too much. They can stand on them for hours, walk thousands of steps, balance on one or the other, and clothe them in socks, shoes and slippers of various materials, and yet a delicate touch by human fingers is unacceptable.
Personally, I find it fascinating how this part of our anatomy is put through such rigorous and grueling use – and yet is still sensitive enough to reduce us to helpless giggles.
Here are a few of the more amazing facts about feet that I’ve come across:
-Human feet contain over a quarter of the bones found in the entire body – 26 bones per foot (or 28, depending on how you count).
-There are approximately 250,000 sweat glands in the average pair of feet – that’s enough to produce a pint of sweat every day.
-When you walk, you produce 2-3 times your body weight in pressure on your feet. When you exercise, the pressure gets even worse – they can cushion as much as a million pounds of pressure in 1 hour of strenuous activity!
-The average individual will walk over 115,000 miles over his lifetime – that’s enough to go around the world 4 times.
-The skin on the soles of your feet is 20 times thicker than the skin on the rest of your body.
Incredible, isn’t it? These amazing pieces of anatomy at the ends of our legs just keep on working, day in and day out, bearing enormous pressures, step after step. But do you want to know the thing that I find the most intriguing of all? For all the strength and resiliency of our feet, they are also one of the most sensitive areas on our bodies for being tickled. I know some people who can’t stand anyone else touching their feet, because it tickles too much. They can stand on them for hours, walk thousands of steps, balance on one or the other, and clothe them in socks, shoes and slippers of various materials, and yet a delicate touch by human fingers is unacceptable.
Personally, I find it fascinating how this part of our anatomy is put through such rigorous and grueling use – and yet is still sensitive enough to reduce us to helpless giggles.
Wednesday, August 15, 2007
Science involves all the fun activities!
"Science involves all of the fun activities--sitting still, being quiet, paying attention, writing down numbers--yes, science has it all!"
--Principal Skinner, “The Simpsons”
I’m a scientist. Actually, I’m a post-doctoral fellow in the field of cellular and molecular biology, but that’s rather a mouthful, so I usually just say I’m a scientist. I work in a research lab, conducting experiments, collecting data, writing results. And if you were to follow me around on any given day, what you’d see is a lot of the following: looking through a microscope, typing numbers into my computer, reading papers about other people’s experiments, and sitting at my desk, thinking about what experiments I’m going to do to repeat the whole process the next day. Sounds like Principal Skinner was right – I do a lot of sitting still, being quiet, paying attention, and writing down numbers!
But I’m here to tell you, all this notwithstanding, that science is fun.
That’s right, science is fun. It’s exciting. It’s cool. It’s got a lot of gee-whiz-ness to it. There’s always something new, something unexpected, something that’s, quite frankly, downright unbelievable. Granted, the things I find fascinating do not all come directly from my lab bench – or my department, or even my institution. But it comes from scientists out there just like me. Let me give you a few examples of some of the latest science tidbits I’ve learned recently that make me sit up say “wow.” Did you know…
…that if the nerves in your skin were stretched out end-to-end, they would reach an average of 45 miles - almost the same distance as from the northern to southern edge of Rhode Island.
…that the average human cell contains enough DNA to wrap around the outside of the cell 15,000 times – yet it is packaged tightly enough to fit with no trouble.
…that bats have a ridiculously long life span for being such a small mammal. They can live up to 20 or 30 years– even though other mammals of comparable size, such as mice and rats, typically only live a few years.
…that there are places in the Atacama desert in Chile, sandwiched between the Andes mountains and the Pacific ocean, that do not see any rain for hundreds of years at a time. Some spots have been rainless for 400 years! Still, some plants, animals, and even humans live there – sustained by tiny pockets of fog that come in from the ocean.
…that the magnetic field of the earth wanders – and sometimes the poles even completely reverse themselves! This happens fairly infrequently, though – reversals happen sometime between every 5000 to 1 million years.
With this blog, I plan on discussing these and other wonders of the scientific world. I plan on writing about a variety of topics, including life sciences, medicine, astronomy and geology. Some of my topics will be brand new discoveries, and others will be long-known items that I find particularly intriguing. My hope is that you will come away from everything that I write knowing something that you didn’t know before. And I hope that it tickles your interest. Let the wonders begin!
--Principal Skinner, “The Simpsons”
I’m a scientist. Actually, I’m a post-doctoral fellow in the field of cellular and molecular biology, but that’s rather a mouthful, so I usually just say I’m a scientist. I work in a research lab, conducting experiments, collecting data, writing results. And if you were to follow me around on any given day, what you’d see is a lot of the following: looking through a microscope, typing numbers into my computer, reading papers about other people’s experiments, and sitting at my desk, thinking about what experiments I’m going to do to repeat the whole process the next day. Sounds like Principal Skinner was right – I do a lot of sitting still, being quiet, paying attention, and writing down numbers!
But I’m here to tell you, all this notwithstanding, that science is fun.
That’s right, science is fun. It’s exciting. It’s cool. It’s got a lot of gee-whiz-ness to it. There’s always something new, something unexpected, something that’s, quite frankly, downright unbelievable. Granted, the things I find fascinating do not all come directly from my lab bench – or my department, or even my institution. But it comes from scientists out there just like me. Let me give you a few examples of some of the latest science tidbits I’ve learned recently that make me sit up say “wow.” Did you know…
…that if the nerves in your skin were stretched out end-to-end, they would reach an average of 45 miles - almost the same distance as from the northern to southern edge of Rhode Island.
…that the average human cell contains enough DNA to wrap around the outside of the cell 15,000 times – yet it is packaged tightly enough to fit with no trouble.
…that bats have a ridiculously long life span for being such a small mammal. They can live up to 20 or 30 years– even though other mammals of comparable size, such as mice and rats, typically only live a few years.
…that there are places in the Atacama desert in Chile, sandwiched between the Andes mountains and the Pacific ocean, that do not see any rain for hundreds of years at a time. Some spots have been rainless for 400 years! Still, some plants, animals, and even humans live there – sustained by tiny pockets of fog that come in from the ocean.
…that the magnetic field of the earth wanders – and sometimes the poles even completely reverse themselves! This happens fairly infrequently, though – reversals happen sometime between every 5000 to 1 million years.
With this blog, I plan on discussing these and other wonders of the scientific world. I plan on writing about a variety of topics, including life sciences, medicine, astronomy and geology. Some of my topics will be brand new discoveries, and others will be long-known items that I find particularly intriguing. My hope is that you will come away from everything that I write knowing something that you didn’t know before. And I hope that it tickles your interest. Let the wonders begin!
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