Reading — 2026 Jan–Apr Recall Set 21

A The cane toad was introduced into Australia in 1935 to control sugar cane pests in Queensland. One hundred and one cane toads arrived at Edmonton in June in 1935. Breeding occurred almost immediately. The cane toad is tough and adaptable, as well as being poisonous throughout its life cycle, and has few predators in Australia. B Cane toads are large heavily-built amphibians with dry, warty skin. They have a bony head and over their eyes are bony ridges that meet above the nose. They sit upright and move in short rapid hops. Their hind feet have leathery webbing between the toes and their front feet are unwebbed. Adult cane toads have large swellings - the parotoid glands - on each shoulder behind the eardrum. Cane toads may be grey, yellowish, olive-brown or reddish-brown, and their bellies are pale with dark mottling. Average-sized adults are ten to fifteen centimetres long. The largest female measured in Queensland was twenty-four centimetres long and weighed one point three kilograms. Male cane toads are smaller and wartier than females. During the breeding season males develop dark lumps (nuptial pads) on their first two fingers; these help them cling to a female while mating. Their mating call is a long loud purring trill. Cane toad spawn is exclusive in Australia. It is laid in long strings of transparent jelly enclosing double rows of black eggs. The spawn tangles in dense dark masses around water plants, and hangs in ropy strands if picked up. C The natural range of cane toads extends from the southern United States to tropical South America. In 2002, cane toads occurred throughout the eastern and northern half of Queensland and have extended their range to the river catchments surrounding Kakadu National Park in the Northern Territory. In New South Wales, they occur as far south as Yamba and Port Macquarie. D Cane toads tolerate a broad range of environmental and climatic conditions and appear to be able to adjust and survive in almost any environment system, including sea water for short periods of time. This to a large extent explains their success in their spreading in Australia. Cane toads are found in environments ranging from sand dunes and coastal heath to the margins of rainforest and mangroves. They are most abundant in open clearings in urban areas, and in grassland and woodland. E Cane toads eat almost anything they can swallow, including pet food, carrion and household scraps, but most of their food consists of living insects. Beetles, honey bees, ants, winged termites, crickets and bugs are eaten in abundance. Marine snails, smaller toads and native frogs, small snakes, and small mammals are occasionally eaten by cane toads. The tadpoles of cane toads eat algae and other aquatic plants which they rasp off with five rows of tiny peg-like teeth. They also filter organic matter from the water. Large tadpoles sometimes eat cane toad eggs. F Cane toads were introduced to Australia to eat French's Cane Beetle and the Greyback Cane Beetle. The whitegrub larvae of these beetles eat the roots of sugar cane and kill or stunt the plants. The Australian Bureau of Sugar Experimental Stations imported about a hundred toads from Hawaii to the Meringa Experimental Station near Cairns. The toads bred quickly and more than three thousand were released in the sugar cane plantations of north Queensland in July 1935. At that time, some naturalists and scientists warned of the dangers of liberating cane toads in Australia. Their protests resulted in a brief moratorium on the release of toads, but releases resumed in 1936. The protestors were right. Firstly, cane toads compete for the resources of native animals, like food, which affects native populations. Secondly, cane toads don't have as many established predators as native animals and so their population grows quickly. Finally, some native animals who would normally feed on frogs try to eat toads and get poisoned. G All stages of the cane toad's life-cycle are poisonous. No humans have died in Australia from cane toad poison, but overseas, people have died after eating toads and even soup made from boiled toad eggs. Cane toads are also poisonous to pets. In Hawaii, up to fifty dogs a year have died after having cane toads in their mouths. Signs of dogs being poisoned through ingestion include profuse salivation, twitching, vomiting, shallow breathing, and collapse of the hind limbs. Death may occur by cardiac arrest within fifteen minutes. A cane toad responds to threat by turning side-on so its parotoid glands are directed towards the attacker. The poison usually oozes out of the glands, but toads can squirt a fine spray for a short distance if they want. The poison is absorbed through mucous membranes such as eyes, mouth and nose, and in humans may cause intense pain, temporary blindness and inflammation.

The recognition of the wealth and diversity of England’s coastal archaeology has been one of the most important developments of recent years. Some elements of this enormous resource have long been known. The so-called ‘submerged forests’ off the coasts of England, sometimes with clear evidence of human activity, had attracted the interest of antiquarians since at least the eighteenth century, but serious and systematic attention has been given to the archaeological potential of the coast only since the early 1980s. It is possible to trace a variety of causes for this concentration of effort and interest. In the 1980s and 1990s, scientific researches into climate change and its environmental impact spilled over into a much broader public debate as awareness of these issues grew; the prospect of rising sea levels over the next century, and their impact on our current coastal environments, have been a particular focus for concern. At the same time archaeologists were beginning to recognise that the destruction caused by natural processes of coastal erosion and by human activity was having an increasing impact on the archaeological resource of the coast. The dominant process affecting the physical form of England in the post-glacial period has been the rise in the altitude of sea level relative to the land, as the glaciers melted and the landmass readjusted. The encroachment of the sea, the loss of huge areas of land now under the North Sea and the English Channel, and especially the loss of the land bridge between England and France which finally made Britain an island, must have been immensely significant factors in the lives of our prehistoric ancestors. Yet the way in which prehistoric communities adjusted to these environmental changes has seldom been a major theme in discussions of the period. One factor contributing to this has been that, although the rise in relative sea level is comparatively well documented, we know little about the constant reconfiguration of the coastline. This was affected by many processes, mostly quite localised, which have not yet been adequately researched. The detailed reconstruction of coastline histories and the changing environments available for human use will be an important theme for future research. So great has been the rise in sea level and the consequent regression of the coast that much of the archaeological evidence now exposed in the coastal zone, whether being eroded or exposed as a buried land surface, is derived from what was originally terrestrial occupation. Its current location in the coastal zone is the product of later unrelated processes, and it can tell us little about past adaptation to the sea. Estimates of its significance will need to be made in the context of other related evidence from dry land sites. Nevertheless, its physical environment means that preservation is often excellent, for example in the case of the Neolithic structure excavated at the Stumble in Essex. In some cases these buried land surfaces do contain evidence for human exploitation of what was a coastal environment, and elsewhere along the modern coast there is similar evidence. Where the evidence does relate to past human exploitation of the resources and the opportunities offered by the sea and the coast, it is both diverse and as yet little understood. We are not yet in a position to make even preliminary estimates of answers to such fundamental questions as the extent to which the sea and the coast affected human life in the past, what percentage of the population at any time lived within reach of the sea, or whether human settlements in coastal environments showed a distinct character from those inland. The most striking evidence for use of the sea is in the form of boats, yet we still have much to learn about their production and use. Most of the known wrecks around our coast are not unexpectedly of post-medieval date, and offer an unparalleled opportunity for research which has as yet been little used. The prehistoric sewn-plank boats such as those from the Humber estuary and Dover all seem to belong to the second millennium BC; after this there is a gap in the record of a millennium, which cannot yet be explained, before boats reappeared, but built using a very different technology. Boatbuilding must have been an extremely important activity around much of our coast, yet we know almost nothing about it. Boats were some of the most complex artefacts produced by premodern societies, and further researches on their production and use make an important contribution to our understanding of past attitudes to technology and technological change. Boats needed landing places, yet here again our knowledge is very patchy. In many cases the natural shores and beaches would have sufficed, leaving little or no archaeological trace, but especially in later periods, many ports and harbours, as well as smaller facilities such as quays, wharves, and jetties, were built. Despite a growth of interest in the waterfront archaeology of some of our more important Roman and medieval towns, very little attention has been paid to the multitude of smaller landing places. Redevelopment of harbour sites and other development and natural pressures along the coast are subjecting these important locations to unprecedented threats, yet few surveys of such sites have been undertaken. One of the most important revelations of recent researches has been the extent of industrial activities along the coast. Fishing and salt production are among the better documented activities, but even here our knowledge is patchy. Many forms of fishing will leave little archaeological trace, and one of the surprises of recent surveys has been the extent of past investment in facilities for procuring fish and shellfish. Elaborate wooden fish weirs, often of considerable extent and responsive to aerial photography in shallow water, have been identified in areas such as Essex and the Severn estuary. The production of salt, especially in the late Iron Age and early Roman periods, has been recognised for some time, especially in the Thames estuary and around the Solent and Poole Harbour, but the reasons for the decline of that industry and the nature of later coastal salt working are much less well understood. Other industries were also located along the coast, either because the raw materials outcropped there or for ease of working and transport: mineral resources such as sand, gravel, stone, coal, ironstone, and alum were all exploited. These industries are poorly documented, but their remains are sometimes extensive and striking. Some appreciation of the variety and importance of the archaeological remains preserved in the coastal zone, albeit only in preliminary form, can thus be gained from recent work, but the complexity of the problem of managing that resource is also being realised. The problem arises not only from the scale and variety of the archaeological remains, but also from two other sources: the very varied natural and human threats to the resource, and the complex web of organisations with authority over, or interests in, the coastal zone. Human threats include the redevelopment of historic towns and old dockland areas, and the increased importance of the coast for the leisure and tourism industries, resulting in pressure for the increased provision of facilities such as marinas. The larger size of ferries has also caused an increase in the damage caused by their wash to fragile deposits in the intertidal zone. The most significant natural threat is the predicted rise in sea level over the next century, especially in the south and east of England. Its impact on archaeology is not easy to predict, and though it is likely to be highly localised, it will be at a scale much larger than that of most archaeological sites. Thus protecting one site may simply result in transposing the threat to a point further along the coast. The management of the archaeological remains will have to be considered in a much longer time scale and a much wider geographical scale than is common in the case of dry land sites, and this will pose a serious challenge for archaeologists.

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. 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. 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 such deficiencies in tonal languages. Amusics who speak tonal languages, such as Chinese, 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. 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 engaged in musical activity, 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. 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. 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? 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.