Our Understanding of Giraffes Does Not Measure Up | Hacker News Reader

Our Understanding of Giraffes Does Not Measure Up

nytimes.com

117 pointsdnetesn40 comments

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

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

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.

Warning: don't watch if you're squeamish or a pet owner.

Why not? You don't see anything except a cat walking.

"Decerebrated" means the cat has had it's brain removed.

Zombie cat. On a treadmill.

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.)

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

Interesting - thanks.

>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.

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.

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.

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.

"June 21 is World Giraffe Day — the longest day for the tallest animal" :D What animal should be celebrate on Dec 21 then?

pony

The largest nocturnal animal, though i can't seem to find which that is, possibly the snow leopard: the largest night for the largest night animal.

Which would be a tiger, I believe.

Peculiar. Don't most wild giraffes live south of the equator?

but everyone that worries about those silly dates are north of the equator.

Maybe something flat, like a flounder or a manta ray.

June 21 is the longest day only for the northern hemisphere. The southern hemisphere would therefore celebrate giraffes on the (or about) the 21st Dec.

Also, from a cursory search, giraffes occur both north and south of the equator in Africa. So neither northern or southern hemisphere could lay sole claim to picking a day.

But around the equator, the length of the day barely varies, so the entire idea behind it is lost.

I nominate the shrimp. Not the shortest animal, but it sure sounds like it ought to be.

Those Voronoi things are fascinating indeed.

Giraffes are heartless creatures

Perhaps your comment is a reference to something that I don't know about, or a sarcastic quip. However, it is in direct conflict with the substance of the article:

"Female giraffes, for example, have been found to form close friendships with one another that can last for years, while mother giraffes have displayed signs of persistent grief after losing their calves to lions."

In fact, the emotional behavior of giraffes is a focal point of the article.

its a reference to this image, btw: http://viciulgandirii.files.wordpress.com/2012/03/giraffes-a...

I thought geraffes were dumb.

Why are there so many random NY Times articles ending up on the front page lately? Back 6 months ago I never remember seeing these articles and now there seems to be one hitting the front page every day. I could understand if they were relevant technical articles but one about giraffes?

The worst part is they create very poor discussions where most of the comments get down voted because what can one really say about a story about giraffe evolution?

Because someone submitted them and others up voted them. Don't compain just flag it or ignore it.

So if a group of people wants to change the fundamental focus of this site from technology to animal evolution we're not allowed to say anything about it? Flagging doesn't do anything because too many people take your approach of just ignoring it (or worse down voting any concern as complaining).

There definitely seems to be a growing group of users who are looking to greatly expand the scope of this site and to me that dilutes the quality of the site.

1. I don't down vote comments like yours because I try not to down vote (I once down voted in anger and felt bad, ever since I've reserved them for the most ignorant comments I come across and rarely even bother then).

2. If I ignore it, I'm not up voting it. I'm up voting posts that I think have some value.

3. This site is about whatever people on this site find interesting. If evolution (an interesting subject) happens to come up, it'll likely get up voted and discussed.

4. We get some slow days when it's mostly fluff here. And then we get days when it's nothing but academic math papers. It comes and goes, deal with it.

> "Flagging doesn't do anything"

It most certainly does. A few days back I watched an article with hundreds of votes drop like a rock as the flags rolled in (it was fairly political, and I suspect it gathered a bunch of flags as soon as the flamewar started.) It went from near the top of the front page to approximately the fourth page in a matter of perhaps ten minutes.

One flag won't do much. But if enough other people agree with you that something doesn't belong, it'll disappear.

> "change the fundamental focus of this site from technology to animal evolution"

One reason you're not getting as much agreement as you might expect: the fundamental focus of this site is not technology. It's anything that gratifies intellectual curiosity. Technology and animal evolution both fall into that category, as do history, chemistry, mathematics, and occasionally even religion (not samey-samey stuff, but genuinely new discoveries or interesting topics -- like when the Vatican decided to create a giant digital archive, or when a guy did a Show HN about software he made for his church.)

HN is for stories of intellectual interest. The community tends to be focused on programming and startups—with many exceptions, of course—but that doesn't mean the topics are. PG explained this when he changed the site name back in 2007: https://news.ycombinator.com/hackernews.html, and it has been at the top of HN's guidelines for years: https://news.ycombinator.com/newsguidelines.html.

> because what can one really say about a story about giraffe evolution?

One can always say nothing.

NYTimes doesn't let you highlight text?

I'm able to highlight text using a mouse.

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