next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects
Index of Subjects John: fascinating, didn't know about the English robins being part of the action, though some of the info in your 1999 source does sound a bit suspect. Did they really supply milk in open, completely uncovered containers in the early 1900s? (Antibiotics hadn't been discovered but communicable 'germs' and moulds were known to exist then). Did the BTs' digestive systems really evolve substantially in a few short years, and how is this actually known -- did someone show that lactase enzyme activity increased substantially over a few years? (possible to do now but improbable to do back then -- hard to believe. I recall a conversation with a Finn a while back that lactose intolerance had dissipated quickly during human agricultural evolution in Europe, but 'quickly' meant of the order of 1000 years in that case. Perhaps someone else can update this). Another difficult-to-believe quote was that about ..."the social propagation process: the way blue tits spread their skill from one individual to members of the species as a whole". This implies a now mostly disbelieved view of evolution called group selection -- individuals communicating with non-related others for the 'benefit of the species' (a problem here being that the BT cream specialists would be gifting away an advantage to other, unrelated naive BTs that are their actual competitors but are not genetically related, to their own obvious disadvantage). A good read but perhaps take with a few pinches of salt? Steve Quoting john belbin <jbelbin@ns.sympatico.ca>: > I thank Steve Shaw for reminding me about an old bird story from Britain > that I had quite forgotten. The Blue Tit (Titmouse) and the milk bottle is > now one of the commonest animal lore stories in Britain. > I was brought up in the southern English county of Hampshire (Hants), right > opposite the Isle of Wight and I remember this behaviour from about 1948 or > thereabouts. It was highly frustrating for a young boy because the Blue Tits > were stealing the heavy cream off the top of the milk which I had always > considered my own special treat - we didn't have many in those days right > after the second world war had just finished. Steve is also right about the > clanking milk delivery. Our milk came directly from Tom Parkers farms and > was delivered by a horse drawn wagon that was so fancied up that Tom won > several awards. They are probably now in the local museum. > > For those who would like more information:- > > Extract from: The Living Company by Arie de Geus, Nicholas Brealey, 1999 > The United Kingdom has a long standing system of delivering milk in bottles > to the door. At the beginning of the 20th century these milk bottles had no > top. Birds had easy access to the cream which settled in the top of the > bottle. Two different species of British garden birds, the blue tits and red > robins, learned to siphon up cream from the bottles and tap this new, rich > food source. > > This innovation, in itself, was already quite an achievement. But it also > had an evolutionary effect. The cream was much richer than the usual food > sources of these birds, and the two species underwent some adaptation of > their digestive systems to cope with the unusual nutrients. This internal > adaptation almost certainly took place through Darwinian selection. > > Then, between the two world wars, the UK dairy distributors closed access to > the food source by placing aluminium seals on their bottles. > > By the early 1950's the entire blue tit population of the UK, about a > million birds, had learned how to pierce the aluminium seals. Regaining > access to this rich food source provided an important victory for the blue > tit family as a whole; it gave them an advantage in the battle for survival. > Conversely, the robins, as a family, never regained access to the cream. > Occasionally, an individual robin learns how to pierce the seals of the milk > bottle. But the knowledge never passes to the rest of the species. > > In short, the blue tits went through an extraordinarily successful > institutional learning process. The robins failed, even though individual > robins had been as innovative as individual blue tits. Moreover, the > difference could not be attributed to their ability to communicate. As > songbirds, both the blue tits and the robins had the same wide range of > means of communication: colour, behaviour, movements, and song. The > explanation could be found only in the social propagation process: the way > blue tits spread their skill from one individual to members of the species > as a whole. > > John Belbin - Kingston > > > -- Stephen R. Shaw Ph.D. Dept of Psychology & Neuroscience Dalhousie University 1355 Oxford Street Halifax, Nova Scotia, Canada B3H 4J1 e-mail: srshaw@dal.ca phone: 1-902-494-2886 fax: 1-902-494-6585
next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects