Senior Freshman Animal Behaviour Lecture 5 :

Transcription

1 Senior Freshman Animal Behaviour Lecture 5 : Cultural Transmission Part 2: Imitation How do animals do cultural transmission? We do it through imitation, but that s actually quite difficult. Imagine a dog wanting to open a gate by imitating owner s actions Dog needs to: Know that the same actions would get the same result Know the owner s moves made the gate open Picture himself in the owner s position Imagine the action from a different viewing angle Understand the mechanics of the latch at least a bit. 1

2 Four mechanisms mistaken for true imitation: 1) Stimulus enhancement 2) Social faciitation 3) Contagion (or observational learning) 4) Emulation 1) Stimulus enhancement = learning by watching others that a particular object or area is of interest, leading to investigation of that object or area. Early 70 s milk delivered to the door in bottles with foil caps. Blue and great tits started to peck open the lids and drink the cream on top of the milk. This behaviour spread all across the UK surprisingly quickly. It was assumed the birds watched each other and learned the behaviour. Held up as a good case of imitation in the wild. 2

3 Sherry and Galef 1984 investigated bottle opening by blue tits. 3 groups of birds 1) Watch demonstrator bird open bottle 2) Just get bottle, opened previously by bird 3) Given closed bottle Result: groups 1 and 2 equally fast to learn to open the bottle, group 3 slower Conclusion: Not imitation but Stimulus enhancement = attention of observer drawn to an object or area by demonstrator. Bird s attention drawn to importance of the bottle; method to open it trial and error. Imo the Japanese Macaque, studied by Kawamura 1959 Scientists put out rice and potatoes for macaques, onto sand. One day Imo took potato and put it into the water and the sand fell off. Later discovered could sort rice from sand in same way. Both behaviours spread through the group quickly, so researchers thought it good evidence of imitation. But to study Imo s behaviour the researchers put out more food whenever the behaviour was seen. Effectively rewarding the behaviour. Others learned through stimulus enhancement (the sea is important) and instrumental learning (carry food to the sea and you get more food). 3

4 Rewards are a common problem with almost all anecdotal evidence. Must avoid rewarding behaviour or you are simply training the animal to do the behaviour, it s not learning through cultural transmission. Reward may be subtle: e.g. Baby dolphin in a zoo imitated sealion in same enclosure in postures for sleep, swimming style and grooming. BUT there are interpretations other than imitation. Also saw a man smoking, went to mum and took a mouthful of milk then spat out the milk to make same effect. Interpretation of dolphin s behaviour 1) It was indeed imitating what it saw, OR 2) It did random moves, some of which were seen by the public as being imitation. When they saw this, the public responded by clapping. Dolphins like an audience, so he learned to do those particular moves more often. So possible that dolphin was trained through instrumental learning to do particular movements which look to us like imitation of others in its environment. 4

5 2) Social Facilitation = carrying out an already known behaviour when others in the social group are doing it too. Advantageous because safer and need less vigilance. If it s safe for someone to do an activity, chances are it s safe for you to do it too. Just timing of behaviours, not acquisition of new ones. 3) Contagion or Observational Conditioning = the observer catches the mood of the demonstrator, and copies its general attitude to the novel object. e.g. learning to mob a predator by observing the response of a demonstrator. Humans are very prone to this, particularly when young. 5

6 Bandura et al did Bobo Doll Experiment to demonstrate contagion: 3 stages to expt 1) Preschool children did art project while: For Group 1 adult calm playing with quiet toy; ignored nearby Bobo doll For Group 2 adult attacked Bobo doll with physical attack while making violent comments 2) Each child alone had their aggression raised by being shown some toys, then told the other kids can play with these but not you. 3) Each child was taken into a new room where the bobo doll was, and given choice of Non-aggressive toys : Tea set, crayons, teddies, farm animals Aggressive toys: Mallet and peg board, dart gun, Results: Children who had seen a calm adult chose mainly nonaggressive toys and were nice to the bobo doll. Children who had seen an aggressive adult chose aggressive toys and attacked the doll violently. Conclusion: Children pick up the attitude of adults by contagion. (Seeing aggression does NOT give it a safe outlet, it breeds it!) 6

7 4) Emulation= when an animal understands the goal of a behavioural sequence, but gets to that goal by its own means, discovered by trial and error, not by imitating the exact moves of the demonstrator. Need a task that can be done two ways. e.g. mechanical fruit Fruit opened by 1) twisting and pulling or 2) poking out the fastening rods. If emulation, we expect no correlation between demonstrator s choice of opening technique and observer s. If true imitation, expect good correlation; observer should do what demonstrator did. Whiten 1996 used mechanical fruit to investigate emulation vs imitation in chimps and human children aged 2, 3 and 4 years. Demonstrator was adult, familiar to each group. Results: Both chimps and children were influenced by the demonstrator, so some degree of imitation present. Chimps much more likely to use own method - emulation. As kids got older, they imitated more and emulated less. In fact older kids copied all movements, even irrelevant ones. Good imitation, but intelligent? 7

8 True imitation = when an animal learns a new behaviour or sequence of movements which lead to a particular goal, by watching a demonstrator carry out that sequence of actions. Perhaps the chimps would have been better imitators if they had a chimp demonstrator. But maybe imitation is not so adaptive anyway! An experiment with budgies which used the same species as demonstrator does seem to show true imitation. Galef et al Budgies Imitation Experiment Birds were given new feeding dishes with lids, which could be opened with foot or beak by a demonstrator budgie. Observer birds had never seen these food dishes before. Treatments: Group 1 saw demonstrator use foot. Group 2 saw demonstrator use beak. Results: Almost all Group 1 observer birds used foot. Almost all Group 2 observer birds used beak. Conclusion : Budgies can learn a new action by observation, i.e. budgies can show true imitation. 8

9 Similar experiments with pigeons and quail show the same type of results. Quail study had the dish opened by stepping on a lever, or pecking the lever. BUT not strictly imitation as movements already known (stepping and pecking) so this is classed as emulation only. Moore 1992 studied Okichoro the parrot Attempted unanswerable demonstration of imitation between species. Put Okichoro in a room alone with a video camera. Every now and then a keeper went in and said ciao, nod or look at my tongue and made a suitable gesture. Absolutely no reward was given to Okichoro for any response he might make guarding against accidental instrumental learning. The researchers then watched the video 9

10 Okichoro, all on his own, practicing the moves with the appropriate words. True imitation as shows new moves, unrewarded and too complex to be hit upon by accident. So even if chimps can t do it, parrots can! Teaching = when the demonstrator modifies its behaviour only in the presence of appropriate naïve observers and at some cost to itself. The observer should also learn the information taught earlier or faster than they would have if they had not been taught. Caro and Hauser 1992 showed teaching in cheetah Mothers sometimes don t choke prey but bring back for cubs to learn how to kill. Older cubs allowed to overtake mother and make the kill. Cost: danger of losing prey 10

11 Similarly, in nut opening chimp troops, mother may leave implements and nuts near anvil for young to try with, and learn to open the nuts. Cost: Wasted nuts if juvenile doesn t find them Fewer nuts for mother. Just watching mother doesn t count as teaching, since mother not altering her behaviour or incurring any costs. Outcomes from Cultural Learning 1) New ideas spread very quickly. 2) Local dialects and traditions (culture!). e.g. primate local traditions such as termite fishing and nut cracking. 11

12 Huffman 1970s-80s discovered Stoneplay in Japanese macaques Invented by a young female called Glance in 1974 Collected a set of stones, stacked them up, knocked them down Became very protective of them if anyone approached. Huffman returned after 4 years and a few more of the troop were doing it. In 10 years it spread to almost half the troop; 27 males and 14 females. Cultural transmission was only ever to those younger than Glance Outcomes from Cultural Learning: 3) Speciation! Peter and Rosemary Grant 1994 studied two Galapagos Finches: Medium Ground finch and Large Cactus finch The two species are very similar indeed in appearance. Large Cactus finch has a more repetitive song than the medium ground finch. If the female is given a choice of the two songs, choose that of their own species 95% of time. So females can recognise species on song. Medium ground finch Large Cactus Finch 12

13 Large Cactus Finch Experiment to see what keeps the species separate. Taught cactus finch male to sing ground finch song (by cultural transmission) and offered them as mates to both species of female. Result: female cactus finches not interested in him, but ground finches mated with him; i.e. mated according to song not species. Repeated with male ground finches got same result. Offspring produced by these matings healthy and fertile. Medium ground finch Conclusion: this culturally learned song in the males, and culturally learned preference in the females is all that separates the species. Memes and the future Ideas spreading through cultural transmission were called memes by Richard Dawkins 1976 in The Selfish Gene. Cultural differences, passed on as memes, can be very long lasting (books, CDs, Data bases) And spread incredibly quickly worldwide (broadcasting, internet) Is this a good thing?? Old ideas may not be relevant / beneficial now. New ideas are untested for safety. Inability to forget isn t healthy but can we lose memes stored in databases? Or just lose all our time sifting through them! 13

14 Recommended reading: NB Same as last week! Alcock J. Animal Behaviour 8th Edition Chapter 2 Understanding the proximate and ultimate causes of bird song Dugatkin L.A Principles of Animal Behaviour pp cultural transmission of diet in rats pp Chapter on all aspects of cultural transmission pp Cultural transmission of mate choice Goodenough et al Perspectives on Animal Behaviour pp Cultural transmission in a variety of contexts Background reading: New Scientist 24th March 2001, Vol 169 p26 Culture Shock evidence for culture in humpback whales. New Scientist 3rd Aug 2002 Vol 175 p 41 The golden meme the evolution of ideas passed on by human culture. 14