A user's guide to animal welfare science
Contents
1. fee ee ELSEVIER TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 Full text provided by www sciencedirect com science Q DIRECT A user s guide to animal welfare science Marian Stamp Dawkins Department of Zoology South Parks Road Oxford OX1 3PS UK Here provide a guide for those new to the burgeoning field of animal welfare science as to what this compre hensive relatively young discipline is all about Drawing on all branches of biology including behavioural ecology and neuroscience the science of animal welfare asks three big questions Are animals conscious How can we assess good and bad welfare in animals How can we use science to improve animal welfare in practice also provide guidelines for an evidence based approach to welfare issues for policy makers and other users of animal welfare research Introduction Animal welfare issues increasingly force themselves onto everyone s agenda scientists have to provide environmental enrichment for their animals for welfare reasons 1 zoos are under pressure for confining wild animals in cages 2 farming practices are criticized and debated 3 and people are urged to buy free range eggs and meat on the grounds that the welfare of the animals is better Many welfare issues are so vast that people avoid thinking about them For example 2 10 broiler chickens are killed for meat worldwide each year 4 and uncounted millions of rodents are2. issues what improves animal health and what the animals themselves want will help to bring about genuine improvements to animal welfare in practice and ensure that legislators can make evidence based decisions Although the most controversial issues in animal welfare concern the way humans treat captive and domestic animals the ways those animals respond are rooted in their evolutionary past and in how their wild ancestors responded to threats to their fitness Beha vioural ecologists thus have a major contribution to make to animal welfare science by connecting this evolutionary legacy to what now matters to the animals themselves Acknowledgements I thank Roland Bonney Tracey Jones Ruth Layton and Edmund Rolls for their comments References 1 Benefiel A C et al 2005 Mandatory enriched housing of laboratory animals the need for evidence based evaluation ILAR J 46 95 105 2 Hosey G R 2005 How does the zoo environment affect the behaviour of captive primates Appl Anim Behav Sci 90 107 129 Weaver S A and Morris M C 2004 Science pigs and politics a New Zealand perspective on the phase out of sow stalls J Agric Environ Ethics 17 51 66 4 Scientific Committee on Animal Health and Animal Welfare 2000 The Welfare of Chickens Kept for Meat Production Broilers European Commission http europa eu int comm food fs sc scah out39_eupdf Mason G J and Littin K E 2003 The humaneness of rodent pes
3. make the link www sciencedirect com of investigation might be the honesty or otherwise of signals 53 the dynamics of weaning conflicts the way animals balance anti predator strategies with their other needs and the role of social facilitation decision making Just understanding how the time budgets of captive or domestic animals differ from those of their wild or feral counterparts provides a baseline or jumping off point for f s a bs zi on a 4 gt iyo Mo ASS Hee CA Taa PRANAN NATAN ASINA S A mae Wy vrs Se mre Figure I Pig rearing system inspired by a study of feral pig behaviour 59 Photograph reproduced with permission from FAI http www faifarms co uk assessing welfare between the complexity of behaviour and conscious experience For example chimpanzees can recognize themselves in mirrors in the sense that they use mirrors to respond to or examine parts of their bodies that they cannot usually see 22 Although this might indicate self awareness and a conscious knowledge of self 23 24 there is no necessary conscious component at all 25 The complexity of social life has been suggested as the driving force for the evolution of consciousness on the grounds that deception cheating and trying to outwit cheaters require a particularly complex type of forward planning and perspective taking 26 However apparently complex outcomes can result from simple rule following 27
4. org articles groups conservation bes_ieem_conf 18 22 July 2006 International Fish Biology St Johns Canada http www heb pac dfo mpo gc ca congress 23 29 July 2006 11th International Behavioral Ecology Congress Tours France http Awww isbe2006 com 6 10 August 2006 Animal Behaviour Society Salt Lake City USA http www animalbehavior org ABS Program Snowbird05 www sciencedirect com
5. 05 Two neural correlates of consciousness Trends Cogn Sci 9 46 52 Ramirez J M and Cabanac M 2003 Pleasure the common currency of emotions Ann N Y Acad Sci 1000 293 295 Sherwin C M and Olsson A S 2004 Housing conditions affect self administration of anxiolytic by laboratory mice Anim Welf 13 33 38 Danbury T C et al 2000 Self selection of the analgesic drug carprofen by lame broiler chickens Vet Rec 146 307 311 Bermond B 2001 A neuropsychological and evolutionary approach to animal consciousness and animal suffering Anim Welf 10 S47 S62 Rutherford K M D 2002 Assessing pain in animals Anim Welf 11 31 54 Moloney V et al 2002 Validation of a method for assessment of acute pain in lambs Appl Anim Behav Sci 76 215 238 Gentle M J 1992 Pain in birds Anim Welf 1 235 247 Sneddon L U et al 2003 Do fish have nocioceptors Evidence for the evolution of a vertebrate sensory system Proc R Soc Lond B Biol Sci 270 1115 1121 Rose J D 2002 The neurobehavioral nature of fishes and the question of awareness and pain Rev Fish Sci 10 1 38 Chandroo K P et al 2004 Can fish suffer Perspectives on sentience pain fear and stress Appl Anim Behav Sci 86 225 250 Sherwin C M 2001 Can invertebrates suffer Or how robust is the argument from analogy Anim Welf 10 S103 S118 Chapman C R and Nakamura Y 1999 A passion for the soul an introduction to
6. 1993 Affect cognition and awareness affective priming with optimal and suboptimal stimulus exposures J Pers Soc Psychol 64 123 739 21 Griffin D R and Speck G B 2004 New evidence for animal consciousness Anim Cogn 7 5 18 Go On www sciencedirect com 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 Gallup G G Jr 1970 Chimpanzees self recognition Science 167 86 87 Platek S M et al 2004 Where am I The neurobiological correlates of self and other Cogn Brain Res 19 114 122 Bekoff M and Sherman P W 2003 Reflections on animal selves Trends Ecol Evol 19 176 180 Heyes C M 1998 Theory of Mind in non human primates Behav Brain Sci 21 101 114 Byrne R W and Corp N 2004 Neocortex size predicts deception rate in primates Proc R Soc Lond B Biol Sci 271 1693 1699 Sachs J L 2004 The evolution of cooperation Q Rev Biol 79 135 160 Chen M K and Hauser M 2005 Modelling reciprocation and cooperation in primates evidence for a punishing strategy J Theor Biol 235 5 12 Bshary R and Schaffer D 2002 Choosy reef fish select cleaner fish that provide high quality service Anim Behav 63 557 564 Hampton R R 2001 Rhesus monkeys know when they remember Proc Natl Acad Sci U S A 98 5359 5362 Block N 20
7. 2004 Using behaviour to assess welfare Anim Welf 13 S38 S7 Patterson Kane E H et al 2002 Rats demand social contact Anim Welf 11 327 332 Mason G J et al 2001 Frustrations of fur farmed mink Nature 410 35 36 Whay H R et al 2003 Animal based measures for the assessment of welfare state of dairy cattle pigs and laying hens consensus of expert opinion Anim Welf 12 205 217 Farm Animal Welfare Council 1993 Second Report on Priorities for Research and Development in Farm Animal Welfare Ministry of Agriculture Fisheries and Food Stolba A and Wood Gush D G M 1989 The behaviour of pigs in a semi natural environment Anim Prod 48 287 298 Mason G J and Latham N R 2004 Can t stop won t stop is stereotypy a reliable animal welfare indicator Anim Welf 13 S57 S69 Nicol C J et al 2002 Study of crib biting and gastric inflammation and ulceration in young horses Vet Rec 151 658 660 Millman S T et al 2004 The impact of applied ethologists and the International Society of Applied Ethologists in improving animal welfare Appl Anim Behav Sci 86 299 311 Mellor D J 2003 Guidelines for the humane slaughter of the fetuses of pregnant ruminants Surveillance 30 26 28 64 65 66 67 68 69 70 71 72 Grandin T 2003 Transferring results of behavioural research to industry to improve animal welfare on the farm ranch and the slaughter plant Appl Anim Be
8. For example cheats do not have to be detected by an elaborate working out of what would I do in his place but lose out to simple strategies such as tit for tat and its variants 28 in which animals remember what happened in past encounters and act accordingly Even simpler win stay lost shift strategies result in animals moving away from places where social rewards are not forthcoming 29 so that non cooperators automatically lose out on long term benefits with no consciousness on either side Recently particular attention has been focused on the possibility that animals monitor the state of their own memories Monkeys perform better on some tasks when allowed to choose for themselves whether to take the test or an easier but less rewarding option than when the experimenter decides for them suggesting that the monkeys knew how much they knew 380 Although we should not forget that computers can be programmed to TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 79 behave differently depending on how uncertain they are about an outcome experiments of this sort have opened up new possibilities for asking animals about what they think they know even though we cannot use words to ask them 9 11 Studies of animal cognition continue to amaze us with what animals can do and deliver a major assault if not a complete solution to the problem of animal consciousness Pleasure and suffering The second category of
9. It would not have to be conscious The gap between doing and feeling is still there however small it might seem Anatomy and brain function The most direct way of deciding whether animals are conscious would be to compare their physiological equip ment and brain functions with our own 85 Pain in mammals 36 37 and toa lesser extent birds 38 has been well studied and more recently the discovery of nociocep tors in fish 39 has led to the view that they also feel pain and can suffer 40 41 On the basis of physiological and behavioural responsiveness even invertebrates cannot be dismissed 42 But definite answers to the questions of whether they consciously experience pain as we do does their pain hurt and suffering does it matter to them remain frustratingly elusive 10 43 particularly as our own pain can be modulated by input from different brain pathways 44 Far from resolving the question of animal consciousness comparative brain anatomy has lead McPhail 16 to conclude that only humans are conscious and Baars 45 to come to the different conclusion that at least all vertebrates are Even the promise of being able to use non invasive brain imaging techniques such as PET and fMRI to www sciencedirect com compare human and animal brains 23 will be a long time bearing fruit It has been more difficult than anticipated to find the neural basis of consciousness in humans 12 31 Consciousness as an evolved fe
10. ature is properly part of biology but it is difficult to study How can good and bad welfare be recognized The second major question that animal welfare science deals with is how to measure and assess animal welfare 7 46 Poor physical health caused by disease injury or deformity is relatively straightforward to recognize and can often be quantified for example by scoring how well an animal is walking or the size of lesions on its body Other less obvious measures of decreased health such as depressed immune function 47 resource dependent changes in the sex ratio of offspring and reduced food intake 48 have recently been imported from other disciplines These can often give an indication that all is not well with the animal before clinical symptoms become obvious To go further and investigate the mental health state of an animal wecan use both physiology and behaviour The physiological measures of welfare that have been used so far have been autonomic responses such as increased heart rate and raised levels of hormones such as corticosteroids stress hormones 7 49 Although these are objective measures they can be difficult to interpret in welfare terms because many of these changes are part of the adaptive way in which the animal responds to its environment and because apparently pleasurable activi ties such as sex and hunting prey can lead to similar changes to those that are apparently unpleasant such as e
11. ced welfare 7 and those that are positively beneficial for the animal 60 can equally be established using the two question approach Some stereotypies actually seem to benefit the health of the animal Repeated biting of wooden doors or food troughs shown by some stabled horses 61 for example is associated with reduced gastric ulcers possibly because the abnormal behaviour stimulates the production and swallowing of salive which in turn protects the stomach from excess acid Others such as bar biting in restricted sows where the animal rubs its mouth until it bleeds indicate poor welfare on the most basic health grounds 7 As emphasized earlier there is no one single measure of welfare How can science be used to improve animal welfare in practice Having measured good and bad welfare it is then necessary to translate what has been found into Box 2 Improving animal welfare in practice Genuine improvements in the welfare of animals are most likely to occur if legislators and other users of animal welfare science follow certain key guidelines i Suggested improvements in animal welfare such as environ mental enrichments giving animals more space should be based on answers to two questions will they genuinely improve animal health Will it give the animals something they want ii Many different sorts of measurements health behaviour and physiology might have to be made to answer these as there is n
12. cial farms in cooperation with farmers and other end users will greatly increase the applica bility of the results of welfare research compared to relying on smaller scale studies carried out in a laboratory This involvement can take the form of epidemiological studies of what is currently happening on farms 65 and even participation in farm level experiments For example 11 major broiler chicken producers in the UK and Denmark recently agreed to manipulate the stocking density crowding as measured by kgm of whole chicken houses in a coordinated experiment that involved gt 2 7 million birds 66 This gave policy makers a better preview of the probable effect of enacting legislation to change stocking density than any small scale laboratory could have done and indicated that limiting stocking density would have much less effect on chicken welfare than previously supposed Working directly with farmers has the further advantage that other factors such as food safety can be studied simultaneously so that policy decisions can be based not only on what is best for animal welfare but also in the wider context of human health effects on the environment and what the public wants to see happening 67 Second critically evaluating already published data through the evidence based approach that has revolutio nized clinical medicine 68 and is beginning to be used in veterinary medicine 69 and conservation 70 71 greatly inc
13. e hardest problem in biology 12 13 We have no idea how the populations of nerve cells that comprise our brains give rise to conscious thoughts and emotions or even the most basic feelings of pain and hunger sentience in ourselves This ignorance of how our own consciousness is caused makes it difficult to know what to look for as evidence for it in other species particularly those such as birds whose brains are anatomically different from ours 14 The situation is further complicated by recent dis coveries from psychology that many complex actions in humans e g driving a car or playing a musical instru ment can be carried out quite unconsciously 11 12 15 www sciencedirect com 0169 5347 see front matter 2005 Elsevier Ltd All rights reserved doi 10 1016 j tree 2005 10 017 78 TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 Box 1 The behavioural ecology of animal welfare a personal view Adopting an evolutionary approach could help us to understand what might improve animal welfare for the following reasons i The domesticated and captive species whose welfare concerns so many people carry with them an evolutionary legacy of responses that in the wild helped them to survive and reproduce e g fleeing from predators seeking water or shelter Figure l ii These mechanisms are of two types direct threats to fitness which can be assessed as reduced health and loss of reproductive success and ant
14. evidence for animal consciousness centres more explicitly on basic sensations of pain pleasure and suffering also called sentience or phenomenal consciousness 31 One approach is to ask humans about their conscious experiences of pain or pleasure and then to use the similarity of behaviour of humans and other animals such as rats when both are say deprived of water to infer that the thirsty rat similar the thirsty human has the same conscious experience of pleasure in the taste of water 32 Impressive in this context is the phenomenon of self medication i e animals learning to give themselves drugs that are known to give relief from pain or anxiety in humans 33 Broiler chickens given the choice between two coloured foods one of which contained Carprofen a non steroidal anti inflammatory drug that relieves pain in humans will learn to choose the colour with the analgesic but only if they themselves are lame and have obvious leg weaknesses Healthy birds have no such preference 34 For many people this is enough to show that birds with bad legs experience pain in the same way that we do but strictly speaking a non conscious explanation is possible A vehicle could be designed to fill itself with one of several kinds of lubricant based on which one had in the past been shown to result in the lowest fuel consumption It could be said to find one lubricant more rewarding more likely to be ingested in future
15. g that access to water to swim in is something that is important to them Faced with a diversity of different welfare measures some of which seem to contradict each other animals do 80 TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 not always choose what is best for their long term health for example animal welfare scientists have taken one of two complementary approaches One strategy is to take the sum of as many measures as possible behavioural health physiological and to use a check list of different ones 57 and to triangulate on what is good welfare The other is to focus on just the two questions are the animals healthy and do they have what they want 54 For example the fifth of the Five Freedoms that the Farm Animal Welfare Council 58 argued were essential to good welfare is the Freedom to perform most natural patterns of behaviour But is natural behaviour essential for welfare After all being chased by a predator is natural for most wild animals but it is not obviously good for welfare By asking whether the health of an animal is improved by being allowed to behave naturally and whether the animal shows evidence of wanting to do the behaviour we can distinguish between natural behaviour that does improve welfare and that which might not 59 Similarly the distinction between stereotypies repeated fixed behaviours with no apparent function that might indicate redu
16. hav Sci 81 215 228 Nicol C J et al 2003 Matched concurrent case control study of risk factors for feather pecking in hens on free range commercial farms in the UK Br Poult Sci 44 515 523 Dawkins M S et al 2004 Chicken welfare is influenced more by housing conditions than by stocking density Nature 427 342 344 Glass C A et al 2005 Measuring the value to the public of pig welfare imporovements a contingent valuation approach Anim Welf 14 61 69 Abalos E 2005 The tools and techniques of evidence based medicine Best Pract Res Clin Obstet Gynaecol 19 15 26 Aragon C L and Budsberg S C 2005 Applications of evidence based medicine Cranial cruciate ligament injury repair in the dog Vet Surg 34 93 98 Sutherland W J et al 2004 The need for evidence based conservation Trends Ecol Evol 19 305 308 Cote I M et al 2005 Measuring coral reef decline through meta analysis Philos Trans R Soc Lond B Biol Sci 360 385 395 Bashaw M J et al 2001 A survey assessment of variables relating to stereotypy in captive giraffe and okapi Appl Anim Behav Sci 73 235 247 Forthcoming Conferences Are you organizing a conference workshop or meeting that would be of interest to TREE readers If so please e mail the details to us at TREE elsevier com and we will feature it in our Forthcoming Conference filler 6 11 August 2006 91st ESA Annual Meeting Memphis USA http www esa org
17. icipated threats to fitness where the animal behaves as if trying to avoid some future danger 6 7 For example a perfectly healthy animal with no predator in sight might be highly motivated to seek cover because natural selection has favoured those of its ancestors that had an emotional state of fear in open spaces and immediately sought cover iii Good welfare consists of good physical health no direct threats to fitness and the animal having what it wants no anticipated threats to fitness that are stimulating the animal to escape or seek something it needs iv The ethical issues in animal welfare arise from the fact that the direct and indirect threats to animal fitness are caused by human beings v Paradoxically it is the evolved mechanisms for coping with anticipated threats to fitness such as the fear that leads an animal to avoid a dangerous place that causes more concern about welfare than the direct threats themselves Humane death for example is regarded as less of a welfare problem than causing pain fear or frustration to a healthy animal 6 vi Behavioural ecologists have a major role to play in under standing the mechanisms by which different species respond to threats to their fitness and thus in defining what constitutes welfare health and what the animal wants for different species Fruitful lines Some human patients with certain sorts of brain damage can successfully reach out and touch object
18. killed most commonly with anticoagulant poisons because they are pests 5 Here I provide a guide to the burgeoning science of animal welfare now one of the most comprehensive of all the biological sciences a discipline that embraces behavioural ecology evolution neuroscience animal behaviour genetics cognitive science and even conscious ness studies The guide is intended for users of animal welfare science not so much those already working in the field but the many other people for whom the results of welfare research increasingly matter such as philoso phers interested in animal emotions politicians and legislators confronted with public demands for improve ments in the treatment of animals and behavioural ecologists interested in the ways animals make decisions and respond to real and perceived threats to their fitness 6 Indeed I hope to encourage more readers of TREE to take up some of the challenges raised by studying the welfare of animals Box 1 The views expressed are my own Corresponding author Dawkins M S marian dawkins zoo ox ac uk Available online 10 November 2005 What is animal welfare science Animal welfare is no more and no less difficult to define than is human welfare 6 7 When we talk about good welfare for humans we mean that someone is in good health and that their emotions are generally positive that they are fit and feeling good 8 Poor human welfare comes not on
19. ly from ill health injury and disease but also from states such as stress frustration boredom lone liness or grief Many of these mental symptoms also appear as physical symptoms but not always so that for humans we make a distinction between physical well being and mental well being So it is with animals 6 8 Good animal welfare also starts with physical health which is why animal welfare sciences has its roots in veterinary medicine although it does not stop there Good welfare implies that animals also have positive emotions such as pleasure and contentment rather than negative ones such as fear or frustration which we humans label suffering 7 8 Animal welfare science has met this challenge by asking three big questions i Are animals conscious ii How can we assess good and bad welfare in animals iii How can science be used to improve animal welfare in practice Are animals conscious Although many people believe without the need for science that other animals consciously experience pain and suffering in ways that are similar to the ways in which humans do an exciting development in animal welfare science is that it is now beginning to embrace advances in other disciplines that tackle the issues of consciousness itself 9 11 and so can potentially appeal to those more sceptical people for whom the issue of animal conscious ness is not obvious From a scientific point of view human consciousness is th
20. memphis 13 19 August 2006 24th International Ornithological Congress Hamburg Germany http www i o c org 22 26 August 2006 1st European Congress of Conservation Biology Eger Hungary http www eccb2006 org 4 6 September 2006 ECBB 3rd Joint European Conference on Behavioural Biology Belfast Northern Ireland http asab nottingham ac uk meetings asab php 5 7 September 2006 British Ecological Society Annual Meeting University of Oxford UK http www britishecologicalsociety org 10 14 September 2006 American Society for Fish Biology Lake Placid USA http www fisheries org html index shtml 3 7 October 2006 American Ornithologist Union Veracruz Mexico http www naoc2006 org 18 21 October 2006 Society of Vertebrate Palaeontology http www vertpaleo org 23 24 March 2006 Trade offs in conservation deciding what to save Zoological Society of London UK http www zoo cam ac uk ioz meetings htm 4 9 June 2006 ASLO Summer meeting Victoria Canada http aslo org meetings victoria2006 23 27June 2006 Annual meeting of the Society for the Study of Evolution State University of New York at Stony Brook USA http Isvl la asu edu evolution symp06 html 24 29 June 2006 Society for Conservation Biology San Jose USA http conbio org 2006 11 12 July 2006 BES IEEM Ecological Impact Assessments Science and Best Practice Bath Spa University College Bath UK http www britishecologicalsociety
21. o single measure of welfare iii Answers should as far as possible be derived in situ in the place where there is concern for animals such as on commercial farms and in zoos rather than from small scale studies which might not reflect the real world This means using large scale experiments an epidemiological approach or systematic meta analysis of published data iv Giving animals the benefit of the doubt and enacting legislation without such evidence might give short term satisfaction to campaigners but could make genuine improvements more difficult to achieve by distracting resources and attention v Improvements in animal welfare should be studied in the context of human health food safety and environmental protection www sciencedirect com improvements in the treatment of real animals those on commercial farms and in zoos for example Animal welfare science has already resulted in changes to the laws governing the treatment of animals 62 63 but there remains much research that does not get taken up in practice 64 Although there are many possible reasons for this including commercial pressures against change and a lack of funding to develop a research idea into a practical solution the way in which research is conceived and conducted might have also been partly responsible Two recent developments might help to change that Box 2 First it is increasingly recognized that carrying out research on commer
22. pain for consciousness researchers Conscious Cogn 8 391 422 Rainville P 2002 Brain mechanisms of pain affect and pain modulation Curr Opin Neurobiol 12 195 200 Baars B J 2001 There are no known differences in brain mechanisms of consciousness between humans and other mammals Anim Welf 10 S31 S40 Appleby M C and Hughes B O eds 1997 Animal Welfare CAB International Irwin M 1999 The immune correlates of depression Adv Exp Med Biol 461 1 24 Dallman M F 2001 Stress and sickness decrease food intake and body weight How does this happen When does this adaptive response progress to pain and suffering In Coping with Challenge Welfare in Animals including Humans Broom D M ed pp 301 316 Dahlem University Press Korte S M 2001 Corticosteroids in relation to fear anxiety and psychopathology Neurosci Biobehav Rev 25 117 142 Rushen J 1991 Problems associated with the interpretation of physiological data in the assessment of animal welfare Appl Anim Behav Sci 28 381 386 Toates F 1995 Stress Conceptual and Biological Aspects John Wiley amp Sons Oatley K and Jenkins J M 1996 Understanding Emotions Blackwells Weary D M and Fraser D 1995 Calling by domestic piglets reliable signals of need Anim Behav 50 1047 1055 54 55 56 57 58 59 60 61 62 63 TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 Dawkins M S
23. rease the value of research findings Although it might seem obvious to say that animal welfare decisions should be evidence based this is by no means always the case in practice For example a recent European Union report on the welfare of broiler chickens 4 based its conclusions for legislation on gt 500 publications but made no attempt to rank the publications on their research quality magnitude of effect sample size or whether the studies were conducted on commercial farms or in small groups By contrast controversial issues such as whether enrich ments really improve welfare 2 or what can be done to reduce stereotypies in zoo animals 59 72 are now being tackled more usefully by objective evaluation of large numbers of already published research papers Conclusions Animal welfare science thinks big It asks big questions about animal consciousness animal health and animal emotions and it tackles big issues that affect millions of people and billions of animals To do so it draws on a variety of new techniques and approaches so that it is now one of the most comprehensive of all the biological TRENDS in Ecology and Evolution Vol 21 No 2 February 2006 81 sciences Animal consciousness is central to the study of animal welfare but is still tantalizingly the hard problem and needs to be respected as such There is no single measure of animal welfare no convenient equivalent of a litmus test but focusing on two
24. s in front of them but then say that they are not conscious of seeing them at all 16 They are thus simultaneously blind consciously and sighted unconsciously guided reaching For much of what we do there appear to be multiple routes to the same behaviour only some of which involve consciousness 15 But if the same action e g breathing or stretching a limb can occur in humans through either a conscious or an unconscious pathway the argument that if the behaviour of another animal is similar to that of a human that animal too must be conscious 17 is weakened An animal could be doing the same behaviour but using its evolutionarily older unconscious circuits 18 Even human emotions can be unconscious 15 19 For example people can be subliminally influenced in how they interpret a stimulus by a brief 50 ms flash of a happy or sad face immediately beforehand even when they have no conscious awareness of having seen any faces 20 Greater understanding of the human brain has thus made deciding which non human animals are conscious more difficult than ever However new research findings have opened up some intriguing ways forward Animal cognition Griffin 21 argued that consciousness in humans evolved to enable adaptively flexible behaviour and that therefore the best way to find evidence for consciousness in animals would be to look for adaptively flexible behaviour in other species The problem as we have seen is to
25. scaping a predator 50 51 Even in humans it is difficult to judge whether someone is feeling angry fearful or just plain excited just from knowing what their autonomic responses are 52 We will never understand the physiology of animal emotions just by looking at autonomic responses We need to understand what is going on in their brains 23 Behaviour has the advantage that it can be studied non invasively and can give a direct insight into the view of the situation from the perspective of the animal For example the squeals of piglets give an honest indication of how hungry they are 53 The apparently simple question Does the animal have what it wants is the key both to whether it is being treated in ways it dislikes e g pain it wants to avoid and to whether it is deprived it wants something it does not have 54 We now have several different ways of asking animals what they want and whether they find the situations they are in pleasurable or distressing For example rats have been shown to press a bar more for the reward of being allowed access to a cage containing other rats than they will for an empty cage indicating that being with social companions is something they want 55 Caged mink will push doors to gain access to a water bath and will continue to do so even when the doors are loaded with weights but they will not make this effort for an empty cage or a cage full of novel objects 56 suggestin
26. t control Anim Welf 12 1 37 6 Dawkins M S 1998 Evolution and animal welfare Q Rev Biol 73 305 328 7 Broom D M ed 2001 Coping with Challenge Welfare in Animals including Humans Dahlem University Press 8 Webster A J F et al 2004 Welfare assessment indices from clinical observation Anim Welf 13 S93 S98 9 Mendl M and Paul E S 2004 Consciousness emotion and animal welfare insights from cognitive science Anim Welf 13 Suppl S17 S25 10 Bateson P 2004 Do animals suffer like us Vet J 168 110 111 11 Paul E S et al 2005 Measuring emotional responses in animals the utility of a cognitive approach Neuro Biobehav Rev 29 469 491 12 Blackmore S 2003 Consciousness An Introduction Hodder amp Stoughton 13 Koch C 2004 The Quest for Consciousness A Neuroscientific Approach Roberts amp Co 14 Burish M J et al 2004 Brain architecture and social complexity in modern and ancient birds Brain Behav Evol 63 107 124 15 Rolls E T 2005 Emotion Explained Oxford University Press 16 Weiskrantz L 2003 Roots of visual awareness Prog Brain Res 144 229 241 17 de Waal F 2005 Animals and us suspicious minds New Scientist 2502 48 18 McPhail E M 1998 The Evolution of Consciousness Oxford University Press 19 Berridge K C and Winkielman P 2003 What is an unconscious emotion The case for unconscious liking Cogn Emotion 17 181 211 20 Murphy S and Zajonc R
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