4 ms·

I was hoping the article would mention something about their neuroscience, too. From a control systems perspective, it's rather remarkable that they're able to

by 3JPLW 12y ago

I was hoping the article would mention something about their neuroscience, too. From a control systems perspective, it's rather remarkable that they're able to stand upright. They have similar nerve conduction velocities as we do… but have much longer latencies[1]! It'd be interesting to do further studies and simulations of the control system requirements with such a long delay. 1. http://jeb.biologists.org/content/216/6/1003.full http://jeb.biologists.org/content/216/6/1003.full

icegreentea 12y ago
Remember that a lot of 'standard' movements aren't fully controlled from the brain. Instead, the brain generators modulating signals to structures/systems lower in the spinal - ie increasing or decreasing your rate of walking. There's lots of evidence of these 'Central Pattern Generators' being located below the brain - which would reduce signal lag. For a somewhat disturbing example of this, here's a 'decerberated' cat on a treadmill. https://www.youtube.com/watch?v=wPiLLplofYw https://www.youtube.com/watch?v=wPiLLplofYw That said, the fact that any vertebrae (even our selves) are able to move and react so well is pretty amazing, given that our own neural lag is in the ~100ms range. It's really a testament to the robustment of the multi-tier control that we (animals in general.. but especially large animals) have evolved.
- chiph 12y ago
  Warning: don't watch if you're squeamish or a pet owner.
  - ars 12y ago
    Why not? You don't see anything except a cat walking.
    - chiph 12y ago
      "Decerebrated" means the cat has had it's brain removed. Zombie cat. On a treadmill.
- scrumper 12y ago
  Fascinating (if a little hard to stomach) video. This seems to imply that bipedal locomotion is learned, while quadrupeds have the skill hardwired into lower-level structures. (Certainly, having watched my eldest figure it out, it doesn't seem to be an innate ability in humans.)
  - icegreentea 12y ago
    Just because the structure resides below the brain, doesn't mean that it's simply 'innate'. For example, while deer fawn are famously able to start walking right away, a kitten is actually pretty terrible at walking for many weeks - they still have to learn. Perhaps part of the difference between the 'apparent' skill of quadrapedal and bipedal learning is that a) quadrupedal is inherently easier (its more stable, more forgiving of small deficiencies), b) bipedal 'failure' is a lot more drastic (especially when you have the proportions of a child.. you don't have a lot of leg to catch yourself), and c) we're simply more familiar with bipedal motion, and therefore more critical of flaws on observation. In addition, there is suggestive evidence that human bipedal motion is CPG driven [1]. I think a reasonable analogy to draw is that at birth a CPG is kind of a lower level controller, all hooked up, but not yet programmed. It takes time and practice to tune and program the controller to generate useful output. [1] http://brain.oxfordjournals.org/content/117/5/1143.abstract http://brain.oxfordjournals.org/content/117/5/1143.abstract
    - scrumper 12y ago
      Interesting - thanks.
jotux 12y ago
>I was hoping the article would mention something about their neuroscience, too. The article specifically mentions this and cites the study you linked. >Or maybe the giraffes are worried about tripping over their own feet. Heather More and Shawn O’Connor of Simon Fraser University in British Columbia and their colleagues measured so-called sensorimotor responsiveness in the giraffe: how long it takes a nerve signal to travel from a muscle in the ankle up to the brain and back again. Reporting in the Journal of Experimental Biology, the researchers found that the nerve conduction rate in the giraffe is pretty much the same as it is in a shrew, rat or any other mammal. >Given the comparatively greater distance a nerve signal has to travel in the giraffe, Dr. More said, it’s possible the giraffe faces real challenges in reacting quickly to events down under — a rock beneath its hoof, or a bite to its ankle.
- pedrocr 12y ago
  >Given the comparatively greater distance a nerve signal has to travel in the giraffe, Dr. More said, it’s possible the giraffe faces real challenges in reacting quickly to events down under — a rock beneath its hoof, or a bite to its ankle. Why would this be any different in a giraffe vs an elephant? A quick googling tells me a giraffe is 5.5m tall whereas an elephant is 4m tall. Since an elephant is also longer than a giraffe the brain to rear hoof distance shouldn't really be all that different. A blue whale on the other hand is 30m long, so it seems like giraffes are well inside the normal design spec for large mammals.
  - judk 12y ago
    Whales probably aren't very nimble. They don't have to balance on little feet. And elephants have very wide feet, probably easier to balance on.
- TheCraiggers 12y ago
  I forget the scientific term, but I remember that humans (and I would suppose other mammals as well, at least) have bundles of nerves located in the spine that can force muscles to react immediately based on certain stimuli, like pain. If I accidentally grab a hot object, my brain doesn't even come into the equation until I've already dropped it. The knee-taps that we all got as kids that make your leg jerk are a form of this reflex, and I remember it being really important for keeping your balance without even having to think about it. I would presume it's the same for giraffes. If something bites an ankle, the signal probably doesn't have to go all the way to the brain and back. If one leg senses a loss of balance, it should reflexively act to maintain balance. I'm sure the researchers are all well aware of this, but I'm surprised that the article makes it out to be that we can't understand how giraffes can even walk. If anybody knows why reflexes wouldn't apply to giraffes, I'm curious to know it.

by 3JPLW 12y ago

icegreentea 12y ago

Remember that a lot of 'standard' movements aren't fully controlled from the brain. Instead, the brain generators modulating signals to structures/systems lower in the spinal - ie increasing or decreasing your rate of walking. There's lots of evidence of these 'Central Pattern Generators' being located below the brain - which would reduce signal lag. For a somewhat disturbing example of this, here's a 'decerberated' cat on a treadmill. https://www.youtube.com/watch?v=wPiLLplofYw https://www.youtube.com/watch?v=wPiLLplofYw That said, the fact that any vertebrae (even our selves) are able to move and react so well is pretty amazing, given that our own neural lag is in the ~100ms range. It's really a testament to the robustment of the multi-tier control that we (animals in general.. but especially large animals) have evolved.

chiph 12y ago
Warning: don't watch if you're squeamish or a pet owner.
- ars 12y ago
  Why not? You don't see anything except a cat walking.
  - chiph 12y ago
    "Decerebrated" means the cat has had it's brain removed. Zombie cat. On a treadmill.
scrumper 12y ago
Fascinating (if a little hard to stomach) video. This seems to imply that bipedal locomotion is learned, while quadrupeds have the skill hardwired into lower-level structures. (Certainly, having watched my eldest figure it out, it doesn't seem to be an innate ability in humans.)
- icegreentea 12y ago
  Just because the structure resides below the brain, doesn't mean that it's simply 'innate'. For example, while deer fawn are famously able to start walking right away, a kitten is actually pretty terrible at walking for many weeks - they still have to learn. Perhaps part of the difference between the 'apparent' skill of quadrapedal and bipedal learning is that a) quadrupedal is inherently easier (its more stable, more forgiving of small deficiencies), b) bipedal 'failure' is a lot more drastic (especially when you have the proportions of a child.. you don't have a lot of leg to catch yourself), and c) we're simply more familiar with bipedal motion, and therefore more critical of flaws on observation. In addition, there is suggestive evidence that human bipedal motion is CPG driven [1]. I think a reasonable analogy to draw is that at birth a CPG is kind of a lower level controller, all hooked up, but not yet programmed. It takes time and practice to tune and program the controller to generate useful output. [1] http://brain.oxfordjournals.org/content/117/5/1143.abstract http://brain.oxfordjournals.org/content/117/5/1143.abstract
  - scrumper 12y ago
    Interesting - thanks.

jotux 12y ago

>I was hoping the article would mention something about their neuroscience, too. The article specifically mentions this and cites the study you linked. >Or maybe the giraffes are worried about tripping over their own feet. Heather More and Shawn O’Connor of Simon Fraser University in British Columbia and their colleagues measured so-called sensorimotor responsiveness in the giraffe: how long it takes a nerve signal to travel from a muscle in the ankle up to the brain and back again. Reporting in the Journal of Experimental Biology, the researchers found that the nerve conduction rate in the giraffe is pretty much the same as it is in a shrew, rat or any other mammal. >Given the comparatively greater distance a nerve signal has to travel in the giraffe, Dr. More said, it’s possible the giraffe faces real challenges in reacting quickly to events down under — a rock beneath its hoof, or a bite to its ankle.

pedrocr 12y ago
>Given the comparatively greater distance a nerve signal has to travel in the giraffe, Dr. More said, it’s possible the giraffe faces real challenges in reacting quickly to events down under — a rock beneath its hoof, or a bite to its ankle. Why would this be any different in a giraffe vs an elephant? A quick googling tells me a giraffe is 5.5m tall whereas an elephant is 4m tall. Since an elephant is also longer than a giraffe the brain to rear hoof distance shouldn't really be all that different. A blue whale on the other hand is 30m long, so it seems like giraffes are well inside the normal design spec for large mammals.
- judk 12y ago
  Whales probably aren't very nimble. They don't have to balance on little feet. And elephants have very wide feet, probably easier to balance on.
TheCraiggers 12y ago
I forget the scientific term, but I remember that humans (and I would suppose other mammals as well, at least) have bundles of nerves located in the spine that can force muscles to react immediately based on certain stimuli, like pain. If I accidentally grab a hot object, my brain doesn't even come into the equation until I've already dropped it. The knee-taps that we all got as kids that make your leg jerk are a form of this reflex, and I remember it being really important for keeping your balance without even having to think about it. I would presume it's the same for giraffes. If something bites an ankle, the signal probably doesn't have to go all the way to the brain and back. If one leg senses a loss of balance, it should reflexively act to maintain balance. I'm sure the researchers are all well aware of this, but I'm surprised that the article makes it out to be that we can't understand how giraffes can even walk. If anybody knows why reflexes wouldn't apply to giraffes, I'm curious to know it.