Learning outcomes By the end of this unit you should be able to: discuss processes upon and within, and internal structure of, differentiated icy bodies (primarily large satellites) in comparison with the terrestrial planets; describe the conditions that may be required to originate and foster life in an icy body and discuss the likelihood of their having occurred; recognise the moral and ethical issues of landing spacecraft on potential life-bearing worlds and appre
3.4 Stereoscopic vision DA explains that ancestral monkeys had to ‘decide whether a branch was within reach of a stretch or a jump – or beyond either’ [p.248]. Individuals that were able to judge distances between themselves and branches more accurately had a competitive edge over other individuals, which led to the development in primates of stereoscopic vision. Stereoscopic vision evolved convergently in carnivores that judge distances to capture fast-moving prey. The field of view of a single eye is t
3.3 Seeing red Watch the TV programme from 20.37–24.06 and reread LoM pp. 247–248 and 255. Write a paragraph of about 120 words explaining why the inability to detect the colour red would disadvantage anthropoid primates. Try also to in 3.2 Colour vision DA stresses that colour vision is very important in primates, not only because colour is used ‘in sexual displays’ such as advertising a female's receptiveness to mating [p. 275], but also to identify ripe fruit [p.247] and to select nutritious leaves [p. 255]. This section discusses these points in more detail and explains how the visual system in primates is able to detect colour. White light is composed of light of different wavelengths, from 300–800 nanometres (nm); 1 nm is on References 2.3 ‘Go Say’ science promotion events An increasing number of science museums and science centres hold regular organised events that stand apart from their exhibitions. The Dana Centre, which now has a permanent venue in the Wellcome Wolfson Building at the Science Museum, holds 10–20 events each month. They are designed to provoke discussion through a blend of debate, art, multimedia and performance, covering issues such as the ethics of prolonging the life of foetuses, the role of science in alleviating poverty, and what is, 2.2 ‘Go See’ science promotion events Every year, the BA (British Association for the Advancement of Science) runs a week-long Festival of Science in a different town or city, claiming it to be the largest public celebration of science in the country. The events are diverse in topic and character. The 2004 Festival in Exeter, for example, included a Presidential lecture on the responsibility of scientists, an exhibition on climate change, and an excursion to a nearby car park to test geometry by chalking lines on the ground. Fest 2.1 Institutional science promotion events Nowadays, engaging with science through an institutional science promotion event can be quite straightforward. You can find out about such events by, for example, reading posters in your local library, watching a science documentary on TV or browsing the internet. The range of such outreach events is remarkable – from long-standing mainstream programmes such as the Royal Society Christmas lectures on TV and the annual BA (British Association for the Advancement of Science) Science Week, to Introduction For many years, the view that dominated the science–public realm was that if only ‘the public’ were educated more, they would better appreciate the intrinsic value of science in their lives. Moreover, under this approach, people were too often seen as ‘empty vessels’ waiting to be filled with scientific knowledge that was transmitted one-way from experts to citizens – an idea that you will recognise as the ‘deficit model’ of how ‘the public’ understands science. With a few 5 Summary Domesticated organisms evolve in artificial environments under artificial selection, and opportunistic or enforced hybridisation often occurs between species that would not normally interbreed. Natural selection cannot be eliminated and continues to operate. At least two different forms of dwarfism are common in domesticated livestock and humans, but only the rarer midget type of dwarfism occurs in wild lineages. Domesticated mammals and birds have distinctive patterns of skin pigmentation th 4.3 Phenotypic changes that appeared without being selected As well as these behavioural changes, many of the selected foxes had unusual white markings (Figures 13c and d). The first colour change that the Russian investigators noted in their foxes was a white ‘star’ on the forehead similar to that of other domesticated mammals (Author(s): 4.2 Experimental domestication of foxes In 1959, the Russian geneticist Dmitri K. Belyaev (1917–1985) launched a long-term experiment to tame captive-bred red foxes by selecting for a single behavioural trait: lack of fear and aggression towards humans. Over 40 years, more than 45 000 foxes were bred in captivity at a remote farm near Novosibirsk, Siberia. Various behavioural, physiological and morphological characters were studied in each fox. Selection for tameness was strict: each animal was assessed once a month for seven mon 4.1 Introduction Domestication of dogs and of most other livestock took place so long ago that reconstructing the course of events is extremely difficult. Written records and illustrations describing the origins of many modern breeds are also sparse until the 19th century. We can only guess at what the domesticators were aiming to produce and how and when domesticated traits appeared in the species subjected to artificial selection. However, a little-known experiment on the domestication of red foxes (Vulp 2.2 Size and shape The shape of the head is determined mainly by the relative sizes of the jaws and the nose and the back of the skull containing the brain, eyes, ears and, in artiodactyls, the horns or antlers. All these structures may differ greatly between otherwise similar species. 1.2 Artificial selection Selection acts on phenotypic characters whatever their origin, and can retain or eliminate the characters' genetic basis. Artificial selection is any selective breeding intentionally practiced by humans leading to the evolution of domesticated organisms. Artificial selection may oppose or amplify or be neutral in relation to natural selection. Most livestock, including dogs, cats, goats, pigs, cattle, sheep, guinea pigs, horses, geese and poultry and scores of crop plants were d Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: Figure 1 Dr J Durst, Schonenberg, Switzerland; Figure 7 Courtesy of SOHO. SOHO is aproject of international cooperation between ESA and NASA; Figure 8 US National Oceanic and Atmospheric Administration; Figure 13 © The Royal Astronomical Society; Figu 2 Inside the Sun To account for its brightness and activity, the Sun must contain a power source. However, the nature of that power source was a great puzzle in the nineteenth and early twentieth centuries. Fossil records and ideas about evolution were beginning to provide firm evidence that the Earth must be at least hundreds of millions of years old, rather than thousands of years as was previously thought, and the Sun must be at least as old as the Earth. The only fuels known at the time were coal, wood, o 1.4 The invisible Sun
Figure 7 shows an image of the Sun, taken when a huge prominence was visible (bottom left). The image was recorded using instruments that are sensitive to ultraviolet radiation rather than visible light, so the colours that you see are ‘false’. They simply indicate different levels of intensity of ultraviolet radiation. The u 2.5 Tree squirrels Coevolution also underpins the relationship between many tree squirrels and the trees that house them. The creation of food caches as a ‘winter-larder’ is mutually beneficial, partly because squirrels are sufficiently profligate in their habits to ensure that many stores are overlooked. Stealing by neighbours is so common that such over-provision may be essential – it's not through forgetfulness or lack of skill; grey squirrels appear able to detect nuts buried as deep as 30 cm below th 8.1 Introduction You know by now that plants can synthesise all the complex molecules that make up their tissues and seeds from very simple molecules – water, carbon dioxide and minerals from the soil. Mammals, on the other hand, need to take in many complex molecules ready-made, and some foods do not contain the right amounts or the right mix of nutrients. They have evolved various strategies to overcome the shortfalls, some of which are described in this section.
Activity 3
SAQ 7
