Carnivorous Plants
A The naturalist and author of Origin of Species, Charles Darwin, was fascinated by carnivorous plants. In 1860, soon after he came across his first carnivorous plant—the sundew, Drosera—he wrote, 'I care more about Drosera than the origin of all the species in the world.' He spent months running experiments on the plants. He dropped flies and bits of meat on their leaves and watched them slowly fold their sticky tentacles over their prey. He thought it incredible that brushing a leaf with a single strand of human hair was enough to bring about a response. Yet sundews, he observed, ignored raindrops. To react to such a false alarm, he reasoned, would obviously be a great evil to the plant. This was no accident. This was adaptation.
B Darwin expanded his studies from sundews to other species in his book Insectivorous Plants. He was amazed at the quickness and power of the Venus flytrap. He showed that when one of its leaves snapped shut, it formed itself into a temporary 'stomach', secreting enzymes that could dissolve the prey. He noted that a leaf took more than a week to reopen after closing, and reasoned that the interlocking spines along the margin of the leaf allowed tiny insects to escape, saving the plant the expense of digesting an insufficient meal.
C Today, biologists using 21st-century tools to study cells and DNA are beginning to understand how these plants hunt, eat, and digest—and how these strange adaptations came about in the first place. Alexander Volkov, a plant physiologist at Oakwood University in Alabama, believes he has figured out the Venus flytrap's secret. 'This,' Volkov declares, 'is an electrical plant.' When an insect brushes against a hair on the leaf of a Venus flytrap, the movement sets off an electric charge. The charge builds up inside the tissue of the leaf but is not enough to stimulate the snap, which keeps the Venus flytrap from reacting to false alarms, such as raindrops. An insect, however, is likely to brush a second hair, adding enough electric charge for the leaf to close. Volkov's experiments reveal that the electric charge travels down fluid-filled tunnels in a leaf, which opens up pores in cell membranes. Water rushes from the cells on the inside of the leaf to those on the outside, causing the leaf to rapidly flip in shape from convex to concave, like a soft contact lens. As the leaves flip, they snap together, trapping an insect inside.
D The bladderwort plant has an equally sophisticated way of setting its underwater trap. It pumps water out of tiny air sacs or bladders, lowering the pressure inside. When a water flea or some other small creature swims past, it bends hairs on the bladder, causing a flap to spring apart. The low pressure sucks water in, carrying the creature along with it. In one five-hundredth of a second, the flap swings shut again. The cells in the bladder then begin to pump water out again, creating a new vacuum.
E Many other species of carnivorous plants act like living flypaper, catching animals on sticky tentacles. Pitcher plants use yet another strategy, growing long tube-shaped leaves into which insects fall. Some of the largest have pitchers up to 30cm deep and can consume whole frogs unlucky enough to fall into them. Sophisticated chemistry helps make the pitcher a death trap.
F Nicholas Gotelli, of the University of Vermont, is trying to figure out what evolutionary forces pushed these plants towards meat. Carnivorous plants clearly benefit from eating animals; when scientists feed pitcher plants extra bugs, the plants get bigger. But the benefits of eating flesh are not the ones you might expect. Carnivorous animals, like ourselves, use the carbon in protein and the fat in meat to build muscles and store energy. Carnivorous plants, however, take nitrogen and phosphorus from the flesh in order to build light-harvesting enzymes. Eating animals, in other words, lets carnivorous plants do what all plants do: grow by taking energy directly from the sun.
G Unfortunately, they do a really bad job of it. That's because they have to use a lot of energy to make the equipment they need to catch animals—the enzymes, the pumps, the sticky tentacles, and so on. A pitcher or a flytrap is not very good at photosynthesis because, unlike plants with ordinary leaves, they do not have flat solar panels that can absorb lots of sunlight. Gotelli suspects that only under special conditions are the benefits of being carnivorous greater than the costs. The poor soil of bogs and swamps, where many carnivorous plants grow, offers little nitrogen and phosphorus, so carnivorous plants enjoy an advantage there over 'conventional' plants. Also, bogs are often flooded with sunshine, so even an inefficient carnivorous plant can carry out enough photosynthesis to survive. 'They're stuck, and they're making the best of it,' says Aaron Ellison of Harvard University.
H Unfortunately, the adaptations that enable carnivorous plants to survive in harsh habitats also make them extremely sensitive to environmental changes. Chemical fertilizers used in agriculture and pollution from power plants are adding extra nitrogen to many bogs in North America. Carnivorous plants are so finely adapted to low levels of nitrogen that this extra fertilizer is overloading their systems. Humans also threaten carnivorous plants in other ways. The black market trade in exotic carnivorous plants is strong, but even if this can be prevented, carnivorous plants will continue to suffer from other dangers. Their habitat is disappearing, to be replaced by shopping centers and houses. The suppression of wildfires by government agencies allows other plants to grow quickly and outcompete the Venus flytraps. Good news, perhaps, for flies. But a loss for all who delight in the inventiveness of evolution.
STRESS LESS
A How busy is too busy? For some it means sometimes having to have a short lunch; for others it may mean missing lunch altogether. For a few, it is not being able to take a day off once a month. Then there is a group of people for whom working every evening and weekend is normal, and feeling stressed is taken for granted. For most senior executives, workloads swing between extremely busy and frenzied. Neil Plumridge, vice-president of a management consultancy company, says that his weeks vary from a 'manageable' 45 hours to 80 hours, but average 60 hours.
B Three signs warn Plumridge about his workload: sleep, scheduling and family. He knows he is doing too much when he gets less than six hours' sleep for three consecutive nights, when he is constantly having to reschedule appointments, and when he misses a family birthday or anniversary. 'Then,' he says, 'I know things are out of control.' Plumridge states that stress is often caused by his having unrealistic expectations of himself. 'I'll promise a client that I'll do something tomorrow, and then I'll promise another client that I'll do the same thing, when I know it's not going to happen. I could have said: “Why don't I give that to you in 48 hours?” The client wouldn't care.'
C Over-committing is something people experience as an individual problem. However, new research indicates that people may be designed to over-commit. A study in the Journal of Experimental Psychology shows that people always believe that they will be less busy in the future. This is a misapprehension according to the authors of the report, Gal Zauberman of the University of North Carolina and John Lynch of Duke University. 'On average, an individual will be just as busy two weeks or a month from now as he or she is today. But that is not how it appears in everyday life,' they say. 'People make commitments long in advance that they would never make if the same commitments required immediate action. They discount future time investments relatively steeply.'
D Being 'too busy' is highly subjective, but for any individual there are some concrete signs of stress: disturbed sleep and declining mental and physical health are the most common examples. Figures for National Workers' Compensation (insurance against injury caused by work) show that stress causes the most lost time of any workplace injury: employees suffering stress are absent from work for an average of 16.6 weeks. The effects of stress are also expensive. The Australian Government insurer reports that in 2003–2004, claims for stress-related psychological injury accounted for 7% of insurance claims, but almost 27% of the amount paid out in claim payments.
E Experts say the key to dealing with stress is not to focus on relief—a game of golf or a massage—but to reassess workloads. Neil Plumridge says he makes it a priority to work out what has to change: that might mean allocating extra staff to a job, allowing more time, or changing expectations. He also relies on the advice of colleagues, saying that his peers coach each other on business problems: 'Just a fresh pair of eyes over an issue can help,' he states.
F Executive stress is not confined to big organisations. Vanessa Stoykov has been running her own advertising agency and public relations business for seven years. Her company has grown so fast that it appeared on the Business Review Weekly 'Fast 100' list of fastest-growing small enterprises in 2004, just after Stoykov had her first child. In 2005, revenue was projected to double to $2.4 million. She had just had her second child. With a fast-growing business and two small children, Stoykov says she has mastered the art of caring for children, typing, and talking on the phone at the same time. But, unlike many others, she appears to thrive on the mental stimulation of running her own business, despite the stress.
G Jan Elsner, a psychologist who specialises in executive coaching, says that doing well on a demanding workload is typical of senior executives. Some people work best with high-adrenaline periods followed by quieter times, while others thrive under sustained pressure. Elsner's practice is based on a movement known as positive psychology, a school of thought that argues that positive experiences—feeling engaged and challenged, for example—do not balance out negative experiences such as stress; instead they help people increase their resilience over time. Elsner says that many of the senior business people she coaches are increasingly relying more on regulating stress through methods such as meditation. She points to research showing that meditation can alter the biochemistry of the brain and the way that brains and bodies react to stress.
H Some experts believe there is too much emphasis on treating job stress as an individual problem. Tony LaMontagne, of the University of Melbourne, says that while personality traits do have some effect on stress, it is systemic stressors—qualities of job roles and organisations themselves—that have a far greater effect. His recent research shows that the major predictor of stress is the level of job control a person has. The best type of job combines challenging work with high autonomy. The worst jobs combine challenging work and low control. People with demanding jobs but little autonomy have up to four times the probability of depression and more than double the risk of heart attack.
When people are deaf to music
A Music has long been considered a uniquely human concept. In fact, most psychologists agree that music is a universal human instinct. Like any ability, however, there is great variation in people's musical competence. For every brilliant pianist in the world, there are several people we refer to as 'tone deaf'. It is not simply that people with tone deafness (or 'amusia') are unable to sing in tune; they are also unable to discriminate between tones or recognize familiar melodies. Such a 'disorder' can occur after some sort of brain damage, but recently research has been undertaken in an attempt to discover the cause of congenital amusia (when people are born with the condition), which is not associated with any brain damage, hearing problems, or lack of exposure to music.
B According to the research of Dr. Isabelle Peretz of the University of Montreal, amusia is more complicated than the inability to distinguish pitches. An amusic (a person who has the condition of amusia) can distinguish between two pitches that are far apart, but cannot tell the difference between intervals smaller than a half step on the Western diatonic scale, while most people can easily distinguish differences smaller than that. When listening to melodies which have had a single note altered so that it is out of key with the rest of the melody, they do not notice a problem. As would be expected, amusics perform significantly worse at singing and tapping a rhythm along with a melody than do non-amusics.
C The most fascinating aspect of amusia is how specific to music it is. Because of music's close ties to language, it might be expected that a musical impairment may be caused by a language impairment. Studies suggest, however, that language and music ability are independent of one another. People with brain damage in areas critical to language are often still able to sing, despite being unable to communicate through speech. Moreover, while amusics show deficiencies in their recognition of pitch differences in melodies, they show no problems with tonal languages, such as Chinese, and do not report having any difficulty discriminating between words that differ only in their intonation. The linguistic cues inherent in speech make discrimination of meaning much easier for amusics. Amusics are also successful most of the time at detecting the mood of a melody, can identify a speaker based on his or her voice and can discriminate and identify environmental sounds.
D Recent work has been focused on locating the part of the brain that is responsible for amusia. The temporal lobes of the brain, the location of the primary auditory cortex, have been considered. It has long been believed that the temporal lobes, especially the right temporal lobe, are most active when processing music, so any musical disability should logically stem from here as well. Because it has been shown that there is no hearing deficit in amusia, researchers moved on to the temporal neocortex, which is where more sophisticated processing of musical cues was thought to take place. New studies, however, have suggested that the deficits in amusics are located outside the auditory cortex. Brain scans of amusics do not show any reaction at all to differences smaller than a half step. When changes in tones are large, their brains overreact, showing twice as much activity on the right side of the brain as a normal brain hearing the same thing. These differences do not occur in the auditory cortex, indicating again that the deficits of amusia lie not in hearing impairment, but in higher processing of melodies.
E So what does this all mean? Looking only at the research of Peretz in the field of neuropsychology of music, it would appear that amusia is some sort of disorder. As a student of neurobiology, however, I am skeptical. Certainly the studies by Peretz that have found significant differences between the brains of so-called amusics and normal brains are legitimate. The more important question now becomes one of normality. Every trait from skin color to intelligence to mood exists on a continuum—there is a great deal of variation from one extreme to the other. Just because we recognize that basic musical ability is something that the vast majority of people have, this doesn't mean that the lack of it is abnormal.
F What makes an amusic worse off than a musical prodigy? Musical ability is culturally valued, and may have been a factor in survival at one point in human history, but it does not seem likely that it is being selected for on an evolutionary scale any longer. Darwin believed that music was adaptive as a way of finding a mate, but who needs to be able to sing to find a partner in an age when it is possible to express your emotions through a song on your iPod?
G While the idea of amusia is interesting, it seems to be just one end of the continuum of innate musical ability. Comparing this 'disorder' to learning disorders like a specific language impairment seems to be going too far. Before amusia can be declared a disability, further research must be done to determine whether lack of musical ability is actually detrimental in any way. If no disadvantages can be found of having amusia, then it is no more a disability than having poor fashion sense or bad handwriting.