Relative Strength Decreases with Size

Often, I have wondered if the apparent strength of a human is skewed toward smaller people.  The people who can lift themselves up ropes with ease; do 100 pull-ups and push-ups; and those who are more agile are generally smaller in size, weighing far less than their Herculean neighbors at the gym, who can probably lift twice as much as they can. 

I’d put myself in the category of bigger men.  I’m pretty strong, but not Herculean.  As a man who can bench press 220 lbs- slightly more than my weight- I can’t even do a pull-up.  I can barely do 20 push-ups.  And I certainly can’t climb up a rope.  A man weighing 100 pounds less and can bench his weight can probably do at least 10 pull-ups, twice as many push-ups, etc. 

What finally explained this for me was the concept of surface area in relation to size, also called the square-cube law.  Think of a bodybuilder.  As their muscles get bigger, their strength only increases by the cross-section, whereas their mass increases by the entire volume.  Increasing the size of muscles while maintaining its proportions renders the bodybuilder weaker relative to his/her overall mass.             

The same can be said of many other animals.  Bigger animals have more surface area.  They therefore need a wider muscle-and-bone relationship to support their weight.  That’s why elephants can’t jump and ants can lift 50 times their weight.   

Preventing Spillover: How Eliminating Poverty and Deforestation Lessens the Transmission of Disease

Disease is a hot topic these days.  While it’s true that many of the deadliest diseases transmitted to humans came from bats, it's unfair to blame them and call for them to be culled.  Social policies have more to do with solving the threat of a pandemic than the obliteration of more species.  As if we haven’t already done that enough! 

The two hot spots where disease has risen the most are southern China and sub-Saharan Africa.  The Chinese can deal with their problem in whatever way they see fit, hopefully by outlawing wet markets, where rare animals are seen as delicacies that bring good luck (ah yes, the good fortune of a pandemic). 

Africa however has a different problem, relating to poverty.  There is currently no scientific consensus on the origin of AIDS, or how it was first transmitted to humans.  But there is a consensus that it originated from chimps in the Congo Basin of southeast Cameroon, circa 1908.  The AIDS pandemic may have resulted from Cameroonians living in extreme poverty, who had no choice but to eat chimp meat to survive.  In the book Spillover, David Quammen imagines such a scenario happening, in a memorable passage about the origin of AIDS transmission to humans. 

If we can fix extreme poverty in places like Africa, we may effectively prevent the next major pandemic from spreading.  Marburg and Ebola are far deadlier diseases than covid-19.  Granted they aren’t airborne, and therefore don’t transmit as easily; but imagine if an airborne variant were transmitted to humans.  With the ever-increasing population of Africa, it would be transmitted among humans easily.  By eliminating the need for consumption of rare animals, we limit the spread of disease, possibly preventing their extinction as a bonus.    

Another variable is our encroachment on the environment.  By "cutting down" on deforestation and the slaughter of defenseless animals, whose organs are often used as resources (in addition to being food), we better protect ourselves as a species from spillover happening.  Deforestation results in decreased habitat for many animals, forcing them into closer living quarters, allowing the probability of zoonotic transmission of disease to rise.  If we respect the environment by not putting so much pressure on animals to co-exist, we decrease the likelihood of another disease like covid-19 from spreading. 

Lifetime Limit on Heartbeats Across the Mammalian Kingdom

In the introduction to Scale by Geoffrey West, a graph is shown presenting a general limit on heartbeats in a lifetime for any species of mammal.  Regardless of size and metabolic rate, most species of mammal aren't able to pump more than 1.5 billion heartbeats in any given life, discounting the life expectancy of species that are endangered or die quickly due to outside influences.    

I find it remarkable that there is such a limit.  It explains why people with lower resting rates are generally in better shape, and tend to live longer.  If your resting rate is 60 or below, you have a better chance of living longer than people with rates above 60, because you will have taken longer to reach this mystical limit on heartbeats.  Let this be further proof that exercise and healthy eating helps you live longer. 

The South Pole Wall

     Astronomers have discovered a huge wall of galaxies hiding behind the Milky Way.  What they call the “South Pole Wall” extends 1.4 billion light years, wrapping like an arm around the backside of our local supercluster.  It rivals other large walls in size, such as the Sloan Great Wall, which is more than twice as far.  What makes this one so special is its proximity to us; it's the closest wall of such size that we’ve discovered so far.  It took so long to discover because of all the dust in the center of our galaxy blocking it from view.  Thanks to the mathematical modeling of galactic redshift, astronomers were finally able to detect its mass.