re philosophy quest how boldly in article sti kinnoq gap caltech edu palmer cco caltech edu david m palmer writes gary ke zv uucp gary coffman writes lack of a skeleton means that muscles have to actively resist gravity at all times on land rather than supplying only balancing forces that means that much more energy would be required for the creature to function the bones also supply leverage points for pushing and lateral movement that s why you don t find large active boneless creatures on land hydraulics can make rigid tubes no energy required just for support hydraulics also allow a creature to produce large forces with weak muscles using the principle of a hydraulic jack rather than a lever this is one of those yes but things it s true that a hydraulically pressurized tube can be somewhat more rigid than an unpressurized tube but even at psi levels a hydraulic hose will bend rather easily though it s straight on compressive strength is high and it s torsional resistance increase is practically nil on the other grasping member there s no doubt that hydraulic leverage exists in nature tree roots are an example given time they can shatter concrete as osmotic pressure increases it s interesting to note that on land creatures are either two legged or legged with tiny insects having or legs but never legged though that would be a stable configuration it can be argued that legged creatures kangaroos are legged the specific number of limbs a creature has is an accident of evolution it is hard to make changes in some structures the panda has a thumb plus as many fingers as its ancestors five on each hand but the thumb is a modified wristbone rather than a modified finger and extra fingers are much more common than extra limbs especially fully functional ones kangaroos limbed i don t think so if you take the view that the tail is a limb then monkeys and kangaroos are limbed i think the tail is a different kind of structure grossly enlarged in the case of the kangaroo but primarily still an instrument of balance rather than locomotion i don t know much about panda thumbs so i ll ask is it opposable thermodynamic considerations of surface volume relationships would seem to dictate that active complex creatures stay in a size range similar to what we see about us inch tall intelligent aliens seem unlikely as do those much larger than the elephant why can t a lemur or a brontosaurus be intelligent yes i know that the brontosaurus is a mythical beast produced by putting the head of another dinosaur on an apatosaurus but so far space aliens are also mythical well i won t say flat out that they can t be intelligent but i ll bring a couple of lines of argument to bear to try to show why i don t think it s likely first let me say that when i say intelligent i mean complex behaviors in response to novel situations on a level with or greater than human tool use and tool building ie assuming suitable manipulators are present on the creature to allow it to alter it s enviroment in a planned way it will do so that s certainly not a universal or complete definition of intelligence but it will suffice for a putative technological alien now no one knows exactly what makes a brain capable of thought but it s generally accepted that one of the criteria is a certain level of complexity this is generally determined by the number of neuron cells and their interconnections so a creature the size of a lemur wouldn t have enough neurons to support complex thought this argument is considerably less clear in the case of the dinosaur there s room for a large brain though no indication that one ever developed one reason this may be true is neuronic speed the electrochemical messages that trigger neurons require time to propagate this makes it difficult for a highly complex central brain to coordinate the movements of very large creatures so there s little selection pressure for such brains instead a simpler distributed network evolves this doesn t rule out intelligent dinosaurs but it points in that direction then there are the thermodynamic arguments a tiny creature like the lemur needs to eat frequently because it s internal heat is rapidly lost due to it s high surface to volume ratio i contend that a creature that must spend most of it s time and energy feeding won t have the time to develop and exercise intelligence that argument may be somewhat weak the dinosaur s problem is the reverse it must moderate it s heat production because it s high volume to surface ratio makes it tend to retain waste heat i m assuming that a certain temperature range is optimal for chemical reactivity reasons for productive neuron function so creatures would tend to need to maintain a regulated temperature in a range near that of humans if they are carbon based that tends to rule out cold blooded creatures as potential homes of intelligence some people contend that some of the dinosaurs may have been warm blooded but for a creature the size of a brontosaur it s activity levels would have to be restrained or it would be prone to generate an internal steam explosion from the waste heat whales are similar size but they can reject heat to the ocean a much more efficient sink than air i suspect that for intelligence to manifest itself a certain degree of activity in interacting with the environment is necessary ie monkey curiousity i doubt a large dinosaur would be capable of that much activity gary gary coffman ke zv you make it gatech wa mei ke zv gary destructive testing systems we break it uunet rsiatl ke zv gary shannon way guaranteed emory kd nc ke zv gary lawrenceville ga
