Fascinating physics talk on biology

[KimB]

Just got back from our colloquium at the Davis physics department, and I thought some people might find it a bit interesting

Here is a publication of what should be the same basic talk (I haven't watched or listened to this one, but it uses the same slides):
http://online.itp.ucsb.edu/online/pattern_i03/west/

I just found it to be incredible that he and his collaborators were able to look at the way certain numbers scale with mass of organisms (such as the metabolic rate), and use that to develop a biological theory. From what he has presented, it sounds pretty robust, too.

For example, it has been found that metabolic rate, of all organisms, from the single-celled to the whale, scales as M^(-3/4), and this metabolic rate scaling can in turn be derived from simply looking at the growth of the network that is required to get oxygen to the cells (or to the mitochondria within the cells), which would be the cardiovascular system in mammals.

 

[nelg]

Looking at slide 9 makes me wish I would have kept count.

 

[KimB]

Looking at slide 9 makes me wish I would have kept count.

Haha, yeah, he actually claimed to have used slide 9 as a case for himself to stop exercising

 

[_xxx_]

That ominous slide 9 is kinda creepy. If that's true, I'll stop excercising and look for ways to slow down my heartbeat and breathing...

 

[KimB]

Haha, well, it may be true if you also correspondingly change your diet so that you don't end up with other health problems that would artificially shorten your life. I think that typically exercise helps because while it may shorten how long you can possibly live, it gets your actual life expectancy closer to how long you can possibly live.

Anyway, age was the point that Dr. West made that was the least strong, by far. Basically, it's nearly impossible to do controlled experiments on life expectancy for most animals, and the experimental data that we do have is all over the place. He didn't even show the slides at our talk because of this.

He believes in his ideas as to life expectancy, certainly, but I don't think that his models are the largest factor for most people (i.e. things like diet, exercise, and lifestyle are all going to be more significant).

 

[_xxx_]

Now you're "enlightened", too! See, it works!

 

[nelg]

I was surprised that lost in all this talk of efficiency, was any mention of available work per calorie. IIRC, "big" follows a inverse rule wrt the percentage of calories required for work once metabolic support is factored in.

 

[nelg]

PS. Lance Armstrong is going to live forever.

 

[Bigus Dickus]

I don't have time to look at the slides at the moment, but hasn't a link between metabolic rate, life expectancy, and body mass been proposed numerous times over the past couple of decades? Or is this guy saying something else?

 

[_xxx_]

PS. Lance Armstrong is going to live forever.

Hardly, after the cancer he had and all the dope he consumed over the course of his career...

Bigus:

http://online.itp.ucsb.edu/online/pattern_i03/west/oh/09.gif

 

[mondoterrifico]

That ominous slide 9 is kinda creepy. If that's true, I'll stop excercising and look for ways to slow down my heartbeat and breathing...

I wouldn't worry, if that slide held for humans, we would all die from heart failure by age ~30.

 

[_xxx_]

Well, the first thing I got from that slide as I looked at it was "size doesn't matter". I'll print out a copy and go show it to all women I know!



Now seriously: you're correct, that 1.5 x 10^9 gives some ~35 years. Hmm...

 

[KimB]

I don't have time to look at the slides at the moment, but hasn't a link between metabolic rate, life expectancy, and body mass been proposed numerous times over the past couple of decades? Or is this guy saying something else?

Right. Some of the data that he quotes is from decades ago. What he's saying is that he thinks he's found the reason for it: that life is driven by the development of networks. For mammals, this is the circulatory system. By analyzing the circulatory system in detail, he was able to predict these scaling laws.

 

[Bigus Dickus]

Hmm... sounds interesting. I'll take a closer look when I get time.