[Paleopsych] Fwd: Universal Footprint: Power Laws

HowlBloom at aol.com HowlBloom at aol.com
Tue Oct 11 05:52:20 UTC 2005


 
Fascinating.  But you have me hooked.  What in the world could  the answer be 
to the following question: "Our  brains expanded at he same rate in (exponent 
about 1.5) evolution as did the  antlers of giant deer and horns of giant 
sheep! ... Why?"
 
And why are periglacial environments,  environments poor to the naked eye, 
richer than tropical environments, which  seem very, very rich?
 
How does the PERCEPTION of what's trash and  what's treasure, of what's a 
resource and what's not, feed into the  equation?  Seemingly the bigger the 
brain, the more likely its owner is to  see resources where smaller brained 
creatures obstacles and emptiness.  But  is this true?
 
Deer presumably inherit the strategies that  tell them what is trash and what 
is treasure--what is food and what is  not.  They don't make discoveries that 
turn yesterday's waste into  tomorrow's resource, the way human inventors do. 
 And deer don't have the  repository of solutions inventors draw from, then 
add their discoveries  to--culture.
 
So why do the same formulae apply in the case  of deer and of humans?  Why do 
deer find the north, with its eight months  of scarcity, richer than the 
south, with its twelve months of  lushness?
 
Where does the technology that produces  clothing,  shelter, and tools for 
hunting and harvesting  fit?  What analog of this technology is available to the 
deer?
 
Are deer antlers useful for anything--for  scraping lichen and moss off of 
rocks, for example?  Or are they simply  what most of us have always 
thought--gaudy displays of excess evolved to  appeal to the females of the species?
 
And why does the gaudy display of excess show  up so often in a cosmos that 
we think obeys strict laws of  frugality?
 
How does this extravagance fit into the  notions of economy that underlie 
Paul Werbos' Laplaceian math?  And how  does this excess production of new form 
fit into a universe that many think is  ruled by the form-destroying processes 
of entropy?
 
A lot of questions, Val, but you've provided  food for a lot of thought.  
Howard
 
In a message dated 10/10/2005 7:31:47 PM Eastern Standard Time,  
kendulf at shaw.ca writes:

Dear Howard, 
The essay on power functions struck a cord within for a number of  reasons. 
(a) Biologists are – finally – waking up to utility of power  functions, 
which, since the 1920’s have been one of the major tools of the  agricultural 
discipline of Animal Science. These scientists – totally innocent  of biology – 
developed great mastery in the study of body growth and  production in 
agricultural animals. Their goals were strictly utilitarian (how  to produce bigger 
haunches in cattle and sheep, or longer bodies in pigs so as  to get longer slabs 
of beacon etc. because that’s where the money led),  however, when I took 
Animal Science in the late 1950’s I became quickly aware  of the applicability of 
both, their insights and methods, in the study of  evolution and ecology of 
large mammals. That included anthropology, us, as I  shall illustrate for the 
fun of it, below. And then there is the Bible of  Animal Science, the genial 
summary work of Samuel Brody (1945) Bioenergetics and Growth, (mine is a  Hafner 
reprint). An utterly timeless, brilliant work if there ever was  one!  So, 
that’s my first source  of happiness! (b) Might I raise the hope that, finally, 
after decades of  working with power functions - in splendid isolation - I 
just might be able to  discuss insights about human biology and evolution using 
power functions? The  closest I ever got was explaining to colleagues how to 
use their hand  calculator to pull logs and anti-logs! So, the essay raised my 
hopes - and  there is nothing like hope! And that’s my second source of 
happiness. (c)  In over 40 years of reading and  reviewing papers I have caught only 
one out and out fraud! And this gentleman  had the gift of creatively misusing 
power functions. The paper I got was based  on the second half of a PhD 
Thesis for which Harvard had awarded him a  doctorate. He had bamboozled four 
eminent scientists into signing off that  piece of fraud. By one of those co 
incidents I was just working on something  very similar to him and became suspicious 
because his theoretical predictions  fitted his data too well, and the raw 
data in that are never looked that good.  I managed to recreate all his 
calculations and discovered that he had misused  his own data, had falsely attributed 
data to existing authors (whom I called  on the phone), that he had invented 
not only data – his own and under the  names of reputable scholars, but that he 
had created fictitious references as  well. Then a buddy in mathematics 
looked at some of his mathematical  discussions and declared them as invalid on 
multiple counts. I returned with  my friend a stinging review promising we would 
expose him next time. The  fellow had a most undistinguished career in several 
degree mills subsequently  and the only other paper of his I subsequently 
refereed was OK, but mediocre.  I refused to read the published first half of his 
thesis, but some buddies who  did shook their head and wondered out loud that 
there is something eerie about  that paper! Yes indeed! However, I kept my 
mouth shut and a fraud was able to  acquire a university position. So much for 
happiness! 
Power functions are absolutely basic to understanding life processes,  and 
they do a sterling job of relieving the theory of evolution of unnecessary  ad 
hoc explanations. If you have it handy,  please see “Primary rules of 
reproductive fitness”  pp.2-13 of my 1978 “Life  Strategies…” book. Some of the 
insights in the essay presented as new are  actually discussed in D’Arcy Thompsons 
(1917) On Growth and Form. To my  embarrassment I discovered that his book by 
a zoologist is known better in  Architecture and the Design disciplines than 
among current zoologists.  Thompson  uses real mathematics, where as current 
life scientists focus on statistics.  It is he who discusses that globular cells 
merely take advantage of the fee  shape-forming energy of surface tension and 
that it costs real energy for a  cell to deviate from this shape. In 
principle life scavenges free energy from  physics and chemistry to function as 
cheaply as possible, for power functions  drive home mercilessly just how costly it 
is to live and how supremely  important to life is the law of least effort, or 
Zipf’s (1949) Law. 

Thje beauty of power functions is that they state rules with precision  and 
that such are essential to comparisons. Let’s look at an amusing example  that 
suddenly becomes relevant to understanding humans. As I detailed in my  1998 
Deer of the World (next most  important magnum opus) the deer family is 
marvelously rich in examples  essential to the understanding of evolutionary 
processes in large mammals,  humans included. They show several times a pattern of 
speciation from the  Tropics to the Arctic, that among primates only the  human 
lineage followed. In several deer lineages there is a progressive  increase in 
antler – those spectacular organs beloved by trophy hunters. There  is a 
steady, but step-wise, increase in size and complexity from equator to  pole!  The 
further north, the  larger the antlers! 
However, antlers do not increase in proportion to body mass (weight in  Kg 
raised to the power of 1), nor to metabolic mass (weight in Kg raised to  the 
power of  0.75), rather,  antler growth follows a positive power function, 
which, between species is  1.35. So, to compare the relative antler mass of small 
and large deer one  generates for each species y(antler mass in grams) = f 
(weight in  kg)1.35 . First of I can readily compare the amount of antler mass  
produced by species despite differences in body size. The largest antler mass  
is found in cursors (high speed runners) the smallest in forest hiders.  
However, in high speed runners, antler mass grows with body mass - within a  lineage 
- even faster than suggested above. The huge antlers of the Irish elk,  14 
feet of spread turn out to be of exactly the same relative mass as those of  his 
last living relative the fallow deer. A small fallow deer, scaled up to  the 
size of an irish elk would have 14 foot of antler spread! Are antlers  
incresing in size passively with body size? Yes, but only under luxury conditions. 
Note luxury! I a moment you will  see why! Antler mass is determined in above 
deer from small to large by  y(antler mass in grams) = 2.6 (wtKg) 1.50. Horn 
mass in  wild sheep happens to be y=2.32 (wtKg)1.49. And increase in  relative 
brain volume from Australopithecus gracilis to Homo sapiens is y(cm3 of  brain) 
= 1.56 (wtkg)1.575. Cute, isn’t it? The human brain is (a)  disassociated from 
body growth following positive allometry. (b) Provided the  environment 
allows individuals a significant vacation from shortages and want,  that is, body 
growth under luxury conditions, human brains expand with (lean!)  body mass – 
period! If humans fall below the expected value, then you have  some explaining 
to do! Smaller than expected brain size will therefore be a  function of poor 
nutritional environments. (c) Natural luxury environments are  periglacial 
and North Temperate ones – up to about 60oN, above and below that  conditions 
deteriorate. That is, up to about 60oN the annual productivity  pulse has a 
length and height to facilitates maximum growth. Therefore,  periglacial Ice Age 
giants are brainy, tropical ones are not! That certainly  applies to the huge 
brains of Neanderthal and Cro-magnids. As we invaded the  cold, but rich 
periglacial environments, getting a large brain to deal with  the increased 
diversity of demands (initially due to ever sharper seasonality)  was filling out an 
already available growth function! Our brains expanded at  he same rate in 
(exponent about 1.5) evolution as did the antlers of giant  deer and horns of 
giant sheep! Awesome organs all! Why? There is no ready  explanation. One would 
need to compare the growth exponents of other organs.   
I have written enough! Cheers, Val  Geist 



----- Original Message ----- 
From:  _HowlBloom at aol.com_ (mailto:HowlBloom at aol.com)  
To: _paleopsych at paleopsych.org_ (mailto:paleopsych at paleopsych.org)  
Sent: Friday, October 07, 2005 12:26  PM
Subject: [Paleopsych] Fwd: Universal  Footprint: Power Laws



 
In a message dated 10/7/2005 3:13:06 PM Eastern Standard Time, Howl  Bloom 
writes:

 
 
All thanks, Jim.  I just gave a presentation related to this  subject to an 
international quantum physics conference in Moscow--Quantum  Informatics 2005.  
I wish I'd seen the article before giving the  talk.  It would have come in 
handy.
 
Meanwhile I tracked down a copy of the full article.  It's  downloadable for 
free at 
_http://www.pasteur.fr/recherche/unites/neubiomol/ARTICLES/Gisiger2001.pdf_ 
(http://www.pasteur.fr/recherche/unites/neubiomol/ARTICLES/Gisiger2001.pdf) 
 
Better yet, enclosed is a file with the full article and with another  
article that relates.  I may not have the time to read these, so if  you digest 
anything interesting from them and get the time, please jot me  an email and give 
me your summary of what these articles are getting  at.
 
Since Eshel Ben-Jacob has been trying to point out for years why such  
concepts as scale-free power laws and fractals fail to get at the creative  twists 
evolution comes up with as it moves from one level of emergence to  another, 
anything in these pieces that indicates how newness enters the  repetition of 
the old would be of particular interest.
 
Again, all thanks.  Onward--Howard
 
In a message dated 10/5/2005 5:12:27 PM Eastern Standard Time,  
JBJbrody at cs.com writes:

_Biological  Reviews_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#)  (2001), 76: 161-209 Cambridge University Press  
doi:10.1017/S1464793101005607 Published Online 17May2001 *This article  is 
available in a PDF that may contain more than one articles. Therefore  the PDF 
file's first page may not match this article's first page.  
_Login_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#)   
_Subscribe  to journal_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#)  
_Email  abstract_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#)  
_Save  citation_ (http://journals.cam
bridge.org/action/displayAbstract?fromPage=online&aid=74595#)  
_Content  alerts_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#)  

Review Article

Scale invariance in  biology: coincidence or footprint of a universal 
mechanism?

T.  GISIGER a1 _p1_ 
(http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74595#p1)   
a1 Groupe de Physique des Particules, Université de Montréal, C.P.  6128, 
succ. centre-ville, Montréal, Québec, Canada, H3C 3J7 (e-mail: 
_gisiger at pasteur.fr_ (mailto:gisiger at pasteur.fr) )

Abstract

In  this article, we present a self-contained review of recent work on  
complex biological systems which exhibit no characteristic scale. This  property 
can manifest itself with fractals (spatial scale invariance),  flicker noise or 
1/f-noise where f denotes the frequency of a signal  (temporal scale 
invariance) and power laws (scale invariance in the size  and duration of events in the 
dynamics of the system). A hypothesis  recently put forward to explain these 
scale-free phenomomena is  criticality, a notion introduced by physicists 
while studying phase  transitions in materials, where systems spontaneously 
arrange themselves  in an unstable manner similar, for instance, to a row of 
dominoes. Here,  we review in a critical manner work which investigates to what 
extent  this idea can be generalized to biology. More precisely, we start with a  
brief introduction to the concepts of absence of characteristic scale  
(power-law distributions, fractals and 1/f- noise) and of critical  phenomena. We then 
review typical mathematical models exhibiting such  properties: edge of 
chaos, cellular automata and self-organized critical  models. These notions are 
then brought together to see to what extent  they can account for the scale 
invariance observed in ecology, evolution  of species, type III epidemics and some 
aspects of the central nervous  system. This article also discusses how the 
notion of scale invariance  can give important insights into the workings of 
biological  systems.

(Received October 4 1999)
(Revised July 14  2000)
(Accepted July 24 2000)

Key Words: Scale  invariance; complex systems; models; criticality; fractals; 
chaos;  ecology; evolution; epidemics; neurobiology.  

Correspondence:

p1 Present address: Unité de  Neurobiologie Moléculaire, Institut Pasteur, 25 
rue du Dr Roux, 75724  Paris, Cedex 15, France. 








Retrieved February 16, 2005,  from the World Wide Web   
http://www.sciencenews.org/articles/20050212/bob9.asp  Week of Feb. 12, 2005; Vol. 167, No.  7 , p. 
106 Life on the Scales Simple mathematical relationships underpin  much of 
biology and ecology   Erica Klarreich  A mouse  lives just a few years, while an 
elephant can make it to age 70. In a sense,  however, both animals fit in the 
same amount of life experience. In its  brief life, a mouse squeezes in, on 
average, as many heartbeats and breaths  as an elephant does. Compared with 
those of an elephant, many aspects of a  mouse's life—such as the rate at which 
its cells burn energy, the speed at  which its muscles twitch, its gestation 
time, and the age at which it  reaches maturity—are sped up by the same factor 
as its life span is. It's as  if in designing a mouse, someone had simply 
pressed the fast-forward button  on an elephant's life. This pattern relating 
life's speed to its length also  holds for a sparrow, a gazelle, and a person—
virtually any of the birds and  mammals, in fact. Small animals live fast and die 
young, while big animals  plod through much longer lives.   "It appears as if 
we've been gifted with just so much life," says  Brian Enquist, an ecologist at 
the  University of  Arizona in  Tucson. "You can spend it all at  once or 
slowly dribble it out over a long time."  a5850_1358.jpg Dean MacAdam  Scientists 
have long known that most  biological rates appear to bear a simple 
mathematical relationship to an  animal's size: They are proportional to the animal's 
mass raised to a  power that is a multiple of 1/4. These relationships are 
known as  quarter-power scaling laws. For instance, an animal's metabolic rate  
appears to be proportional to mass to the 3/4 power, and its heart rate is  
proportional to mass to the –1/4 power.  The reasons behind these laws were a  
mystery until 8 years ago, when Enquist, together with ecologist James Brown  of 
the University of  New Mexico in Albuquerque and  physicist Geoffrey West of 
Los Alamos (N.M.) National  Laboratory proposed a model to explain 
quarter-power scaling in mammals (SN:  10/16/99, p. 249). They and their collaborators 
have since extended the  model to encompass plants, birds, fish and other 
creatures. In 2001, Brown,  West, and several of their colleagues distilled their 
model to a single  formula, which they call the master equation, that predicts a 
species'  metabolic rate in terms of its body size and temperature.  "They 
have identified the basic rate  at which life proceeds," says Michael Kaspari, an 
ecologist at the  University of  Oklahoma in  Norman.  In the July 2004 
Ecology, Brown,  West, and their colleagues proposed that their equation can shed 
light not  just on individual animals' life processes but on every biological 
scale,  from subcellular molecules to global ecosystems. In recent months, the  
investigators have applied their equation to a host of phenomena, from the  
mutation rate in cellular DNA to Earth's carbon cycle.  Carlos Martinez del  
Rio, an ecologist at the  University of  Wyoming in  Laramie, hails the team's 
work  as a major step forward. "I think they have provided us with a unified  
theory for ecology," he says.   The biological clock  In  1883, German 
physiologist Max Rubner proposed that an animal's metabolic  rate is proportional to 
its mass raised to the 2/3 power. This idea was  rooted in simple geometry. If 
one animal is, say, twice as big as another  animal in each linear dimension, 
then its total volume, or mass, is 23 times  as large, but its skin surface is 
only 22 times as large. Since an animal  must dissipate metabolic heat 
through its skin, Rubner reasoned that its  metabolic rate should be proportional to 
its skin surface, which works out  to mass to the 2/3 power.   a5850_2473.jpg 
Dean MacAdam   In 1932, however, animal scientist Max Kleiber of the 
University of  California, Davis looked at a broad range of data and concluded that 
the  correct exponent is 3/4, not 2/3. In subsequent decades, biologists have  
found that the 3/4-power law appears to hold sway from microbes to whales,  
creatures of sizes ranging over a mind-boggling 21 orders of magnitude.  For most 
of the past 70 years,  ecologists had no explanation for the 3/4 exponent. 
"One colleague told me  in the early '90s that he took 3/4-scaling as 'given by 
God,'" Brown  recalls.  The beginnings of an  explanation came in 1997, when 
Brown, West, and Enquist described metabolic  scaling in mammals and birds in 
terms of the geometry of their circulatory  systems. It turns out, West says, 
that Rubner was on the right track in  comparing surface area with volume, but 
that an animal's metabolic rate is  determined not by how efficiently it 
dissipates heat through its skin but by  how efficiently it delivers fuel to its 
cells.  Rubner should have considered an  animal's "effective surface area," 
which consists of all the inner surfaces  across which energy and nutrients pass 
from blood vessels to cells, says  West. These surfaces fill the animal's 
entire body, like linens stuffed into  a laundry machine.  The idea,  West says, 
is that a space-filling surface scales as if it were a volume,  not an area. If 
you double each of the dimensions of your laundry machine,  he observes, then 
the amount of linens you can fit into it scales up by 23,  not 22. Thus, an 
animal's effective surface area scales as if it were a  three-dimensional, not 
a two-dimensional, structure.  This creates a challenge for the  network of 
blood vessels that must supply all these surfaces. In general, a  network has 
one more dimension than the surfaces it supplies, since the  network's tubes add 
one linear dimension. But an animal's circulatory system  isn't four 
dimensional, so its supply can't keep up with the effective  surfaces' demands. 
Consequently, the animal has to compensate by scaling  back its metabolism according 
to a 3/4 exponent.  Though the original 1997 model  applied only to mammals 
and birds, researchers have refined it to encompass  plants, crustaceans, fish, 
and other organisms. The key to analyzing many of  these organisms was to add 
a new parameter: temperature.  Mammals and birds maintain body  temperatures 
between about 36°C and 40°C, regardless of their environment.  By contrast, 
creatures such as fish, which align their body temperatures  with those of their 
environments, are often considerably colder. Temperature  has a direct effect 
on metabolism—the hotter a cell, the faster its chemical  reactions run.  In 
2001, after  James Gillooly, a specialist in body temperature, joined Brown at 
the  University of New  Mexico, the researchers and their collaborators  
presented their master equation, which incorporates the effects of size and  
temperature. An organism's metabolism, they proposed, is proportional to its  mass 
to the 3/4 power times a function in which body temperature appears in  the 
exponent. The team found that its equation accurately predicted the  metabolic 
rates of more than 250 species of microbes, plants, and animals.  These species 
inhabit many different habitats, including marine, freshwater,  temperate, 
and tropical ecosystems.   The equation gave the researchers a way to compare 
organisms with  different body temperatures—a person and a crab, or a lizard and 
a sycamore  tree— and thereby enabled the team not just to confirm previously 
known  scaling laws but also to discover new ones. For instance, in 2002, 
Gillooly  and his colleagues found that hatching times for eggs in birds, fish,  
amphibians, and plankton follow a scaling law with a 1/4 exponent.  When the 
researchers filter out the  effects of body temperature, most species adhere 
closely to quarter-power  laws for a wide range of properties, including not 
only life span but also  population growth rates. The team is now applying its 
master equation to  more life processes—such as cancer growth rates and the 
amount of time  animals sleep.  "We've found  that despite the incredible 
diversity of life, from a tomato plant to an  amoeba to a salmon, once you correct for 
size and temperature, many of these  rates and times are remarkably similar," 
says Gillooly.  A single equation predicts so much,  the researchers contend, 
because metabolism sets the pace for myriad  biological processes. An animal 
with a high metabolic rate processes energy  quickly, so it can pump its heart 
quickly, grow quickly, and reach maturity  quickly.  Unfortunately, that  
animal also ages and dies quickly, since the biochemical reactions involved  in 
metabolism produce harmful by-products called free radicals, which  gradually 
degrade cells.   "Metabolic rate is, in our view, the fundamental biological 
rate,"  Gillooly says. There is a universal biological clock, he says, "but it 
ticks  in units of energy, not units of time."  Scaling up  The researchers 
propose that their  framework can illuminate not just properties of individual 
species, such as  hours of sleep and hatching times, but also the structure of 
entire  communities and ecosystems. Enquist, West, and Karl Niklas of  Cornell  
University have been looking for  scaling relationships in plant communities, 
where they have uncovered  previously unnoticed patterns.   a5850_3175.jpg  
REGULAR  ON AVERAGE. Newly discovered scaling laws have revealed an unexpected  
relationship between the spacing of trees and their trunk diameters in a  
mature forest. PhotoDisc  The  researchers have found, for instance, that in a 
mature forest, the average  distance between trees of the same mass follows a 
quarter-power scaling law,  as does trunk diameter. These two scaling laws are 
proportional to each  other, so that on average, the distance between trees of 
the same mass is  simply proportional to the diameter of their trunks.  "When 
you walk in a forest, it looks  random, but it's actually quite regular on 
average," West says. "People have  been measuring size and density of trees for 
100 years, but no one had  noticed these simple relationships."   The 
researchers have also discovered that the number of trees of a  given mass in a forest 
follows the same scaling law governing the number of  branches of a given size 
on an individual tree. "The forest as a whole  behaves as if it is a very 
large tree," West says.  Gillooly, Brown, and their  New Mexico colleague Andrew  
Allen have now used these scaling laws to estimate the amount of carbon that  
is stored and released by different plant ecosystems.  Quantifying the role 
of plants in  the carbon cycle is critical to understanding global warming, 
which is  caused in large part by carbon dioxide released to the atmosphere when  
animals metabolize food or machines burn fossil fuels.  Plants, by contrast, 
pull carbon  dioxide out of the air for use in photosynthesis. Because of this 
trait,  some ecologists have proposed planting more forests as one strategy 
for  counteracting global warming.   In a paper in an upcoming Functional 
Ecology, the researchers  estimate carbon turnover and storage in ecosystems such 
as oceanic  phytoplankton, grasslands, and old-growth forests. To do this, they 
apply  their scaling laws to the mass distribution of plants and the 
metabolic rate  of individual plants. The model predicts, for example, how much stored 
 carbon is lost when a forest is cut down to make way for farmlands or  
development.  Martinez del  Rio cautions that ecologists making practical  
conservation decisions need more-detailed information than the scaling laws  generally 
give. "The scaling laws are useful, but they're a blunt tool, not  a 
scalpel," he says.  Scaling  down  The team's master equation  may resolve a 
longstanding controversy in evolutionary biology: Why do the  fossil record and genetic 
data often give different estimates of when  certain species diverged?   
Geneticists calculate when two species branched apart in the  phylogenetic tree by 
looking at how much their DNA differs and then  estimating how long it would 
have taken for that many mutations to occur.  For instance, genetic data put 
the divergence of rats and mice at 41 million  years ago. Fossils, however, put 
it at just 12.5 million years ago.  The problem is that there is no  
universal clock that determines the rate of genetic mutations in all  organisms, 
Gillooly and his colleagues say. They propose in the Jan. 4  Proceedings of the 
National Academy of Sciences that, instead, the mutation  clock—like so many 
other life processes—ticks in proportion to metabolic  rate rather than to time.  
The  DNA of small, hot organisms should mutate faster than that of large, cold 
 organisms, the researchers argue. An organism with a revved-up metabolism  
generates more mutation-causing free radicals, they observe, and it also  
produces offspring faster, so a mutation becomes lodged in the population  more 
quickly.  When the  researchers use their master equation to correct for the 
effects of size and  temperature, the genetic estimates of divergence times—
including those of  rats and mice—line up well with the fossil record, says Allen, 
one of the  paper's coauthors.  The team  plans to use its metabolic framework 
to investigate why the tropics are so  much more diverse than temperate zones 
are and why there are so many more  small species than large ones.   Most 
evolutionary biologists have tended to approach biodiversity  questions in terms 
of historical events, such as landmasses separating,  Kaspari says. The idea 
that size and temperature are the driving forces  behind biodiversity is 
radical, he says.  "I think if it holds up, it's going  to rewrite our 
evolutionary-biology books," he says.  Enthusiasm and skepticism  While the 
metabolic-scaling theory  has roused much enthusiasm, it has its limitations. Researchers 
agree, for  instance, that while the theory produces good predictions when viewed 
on a  scale from microbes to whales, the theory is rife with exceptions when 
it's  applied to animals that are relatively close in temperature and size. For 
 example, large animals generally have longer life spans than small animals,  
but small dogs live longer than large ones.  a5850_4238.jpg Dean MacAdam  
Brown points out that the  metabolic-scaling law may be useful by calling 
attention to such exceptions.  "If you didn't have a general theory, you wouldn't 
know that big dogs are  something interesting to look at," he observes.  Many 
questions of particular  interest to ecologists concern organisms that are close 
in size. Metabolic  theory may not explain, for example, why certain species 
coexist or why  particular species invade a given ecosystem, says John Harte, 
an ecologist  at the University of  California,  Berkeley.  Some scientists 
question the very  underpinnings of the team's model. Raul Suarez, a comparative 
physiologist  at the University of  California,  Santa Barbara disputes the  
model's starting assumption that an animal's metabolic rate is determined by  
how efficiently it can transport resources from blood vessels to cells.  Suarez 
argues that other factors are equally important, or even more so. For  
instance, whether the animal is resting or active determines which organs  are using 
the most energy at a given time. 
"Metabolic scaling is a many-splendored thing," he says.  Suarez' concern is 
valid, agrees  Kaspari. However, he says, the master equation's accurate 
predictions about  a huge range of phenomena are strong evidence in its favor.  
Ecologists, physiologists, and other  biologists appear to be unanimous on one 
point: The team's model has sparked  a renaissance for biological-scaling 
theory.  "West and Brown deserve a great deal  of credit for rekindling the interest 
of the scientific community in this  phenomenon of metabolic scaling," Suarez 
says. "Their ideas have stimulated  a great deal of discussion and debate, 
and that's a good thing."  If you have a comment on this  article that you would 
like considered for publication in Science News, send  it to 
editors at sciencenews.org. Please include your name and location.  To subscribe to Science News  
(print), go to https://www.kable.com/pub/scnw/ subServices.asp.  To sign up 
for the free weekly  e-LETTER from Science News, go to  
http://www.sciencenews.org/pages/subscribe_form.asp.  References:  Brown, J.H., J.F. Gillooly, A.P.  
Allen, V.M. Savage, and G.B. West. 2004. Toward a metabolic theory of  
ecology. Ecology 85(July):1771-1789. Abstract.  Gillooly, J.F., A.P. Allen, G.B.  
West, and J.H. Brown. 2005. The rate of DNA evolution: Effects of body size  and 
temperature on the molecular clock. Proceedings of the  National  Academy of 
Sciences 102(Jan.  4):140-145. Abstract available at  
http://www.pnas.org/cgi/content/abstract/102/1/140.  Gillooly, J.F. . . . G.B. West . . .  and J.H. 
Brown. 2002. Effects of size and temperature on developmental time.  Nature 
417(May 2):70-73. Abstract available at  http://dx.doi.org/10.1038/417070a.   
Gillooly, J.F., J.H. Brown, G.B. West, et al. 2001. Effects of size  and 
temperature on metabolic rate. Science 293(Sept. 21):2248-2251.  Available at 
http://www.sciencemag.org/cgi/content/full/293/5538/2248.  Savage, V.M., J.F. Gillooly, 
J.H.  Brown, G.B. West, and E.L. Charnov. 2004. Effects of body size and  
temperature on population growth. American Naturalist 163(March):429-441.  
Available at http://www.journals.uchicago.edu/AN/  
journal/issues/v163n3/20308/20308.html.  Suarez, R.K., C.A. Darveau, and J.J.  Childress. 2004. Metabolic 
scaling: A many-splendoured thing. Comparative  Biochemistry and Physiology, Part B 
139(November):531-541. Abstract  available at 
http://dx.doi.org/10.1016/j.cbpc.2004.05.001.  West, G.B., J.H. Brown, and B.J.  Enquist. 1997. A general 
model for the origin of allometric scaling models  in biology. Science 276(April 
4):122-126. Available at  
http://www.sciencemag.org/cgi/content/full/276/5309/122.  Further Readings:  Savage, V.M., J.F. Gillooly, . . .  A.P. Allen . . . 
and J.H. Brown. 2004. The predominance of quarter-power  scaling in biology. 
Functional Ecology 18(April):257-282. Abstract available  at 
http://dx.doi.org/10.1111/j.0269-8463.2004.00856.x.  Weiss, P. 1999. Built to scale.  Science 
News 156(Oct. 16):249-251. References and sources available at  
http://www.sciencenews.org/pages/sn_arc99/10_16_99/bob1ref.htm.  Sources:  Anurag Agrawal 
Ecology and  Evolutionary Biology Cornell University Ithaca, NY 14853  Andrew Allen 
Biology Department  University of New Mexico Albuquerque, NM 87131  James H. 
Brown Biology Department  University of New Mexico Albuquerque, NM 87131  
Steven Buskirk Department of Zoology  and Physiology University of Wyoming 1000 E. 
University Avenue Laramie, WY  82071  Brian Enquist Department  of Ecology 
and Evolutionary Biology University of Arizona Tucson, AZ  85721  James Gillooly 
Biology  Department University of New Mexico Albuquerque, NM 87131  John 
Harte Energy and Resources  Group 310 Barrows Hall University of California, 
Berkeley Berkeley, CA  94720  Michael Kaspari  Department of Zoology University of 
Oklahoma Norman, OK 73019  Carlos Martínez del Rio Department  of Zoology and 
Physiology University of Wyoming Laramie, WY 82071  Karl Niklas Department of 
Plant  Biology Cornell University Ithaca, NY 14853  Raul Suarez Department of 
Ecology,  Evolution and Marine Biology University of California, Santa Barbara 
Santa  Barbara, CA 93016  Geoffrey B.  West Theoretical Physics Division Los 
Alamos National Laboratory MS B285 Los  Alamos, NM 87545  From Science  News, 
Vol. 167, No. 7, Feb. 12, 2005, p. 106.       Home | Table of Contents |  
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----------
Howard Bloom
Author of The Lucifer Principle: A  Scientific Expedition Into the Forces of 
History and Global Brain: The  Evolution of Mass Mind From The Big Bang to the 
21st Century
Recent  Visiting Scholar-Graduate Psychology Department, New York University; 
Core  Faculty Member, The Graduate  Institute
www.howardbloom.net
www.bigbangtango.net
Founder:  International Paleopsychology Project; founding board member: Epic 
of  Evolution Society; founding board member, The Darwin Project; founder: The 
 Big Bang Tango Media Lab; member: New York Academy of Sciences, American  
Association for the Advancement of Science, American Psychological Society,  A
cademy of Political Science, Human Behavior and Evolution Society,  
International Society for Human Ethology; advisory board member: Institute  for 
Accelerating Change ; executive editor -- New Paradigm book  series.
For information on The International Paleopsychology Project,  see: 
www.paleopsych.org
for two chapters from 
The Lucifer Principle:  A Scientific Expedition Into the Forces of History, 
see  www.howardbloom.net/lucifer
For information on Global Brain: The  Evolution of Mass Mind from the Big 
Bang to the 21st Century, see  www.howardbloom.net

 
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----------
Howard Bloom
Author of The Lucifer Principle: A  Scientific Expedition Into the Forces of 
History and Global Brain: The Evolution  of Mass Mind From The Big Bang to the 
21st Century
Recent Visiting  Scholar-Graduate Psychology Department, New York University; 
Core Faculty  Member, The Graduate  Institute
www.howardbloom.net
www.bigbangtango.net
Founder:  International Paleopsychology Project; founding board member: Epic 
of Evolution  Society; founding board member, The Darwin Project; founder: The 
Big Bang Tango  Media Lab; member: New York Academy of Sciences, American 
Association for the  Advancement of Science, American Psychological Society, 
Academy of Political  Science, Human Behavior and Evolution Society, International 
Society for Human  Ethology; advisory board member: Institute for 
Accelerating Change ; executive  editor -- New Paradigm book series.
For information on The International  Paleopsychology Project, see: 
www.paleopsych.org
for two chapters from  
The Lucifer Principle: A Scientific Expedition Into the Forces of History,  
see www.howardbloom.net/lucifer
For information on Global Brain: The  Evolution of Mass Mind from the Big 
Bang to the 21st Century, see  www.howardbloom.net

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