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June 8 - June 19, 2021
Like the layers of an onion, the cells and molecules that make up the human body have seemingly infinite levels of complexity.
Everyone knows that it is impossible to understand current events in a specific country without understanding the history of that country and how the modern state came to be.
(We even carry around thousands of dead viruses tucked in the DNA of every one of our cells, and we spend our lifetimes dutifully replicating these carcasses.)
Presbyopia, which literally translates as “old-man sight,” begins to set in around age forty. By the age of sixty, virtually everyone has difficulty making out close objects. I’m thirty-nine, and I have noticed that I hold books and newspapers farther and farther from my face each year. The time for bifocals is nigh.
Had I been born before, say, the 1600s, I would probably have gone through life unable to do anything that required me to see farther than arm’s length.
Compare ours with cats’, whose night vision is legendary. So sensitive are cats’ eyes that they can detect a single photon of light in a completely dark environment. (For reference, in a small, brightly lit room, there are about one hundred billion photons bouncing around at any given moment.)
To date, there are no workable hypotheses that explain why the vertebrate retina is wired backward. It seems to have been a random development that stuck because correcting it would be very difficult to pull off with sporadic mutations—the only tool evolution has in its toolkit.
Nature “invented” the camera-like eye at least twice, once in vertebrates and once in cephalopods. (Insects, arachnids, and crustaceans have an entirely different type of eye.)
Nowhere are there more differences between humans and nonhuman primates than in the facial bones and skull.
The human neck is just a glaring vulnerability.
The throat conveys both food and air—what could possibly go wrong?
when we are swallowing, we have to stop breathing momentarily.
The anatomical adaptation to upright walking never quite finished in humans.
It is not possible to isolate the ACL and strengthen it with exercise. It is what it is. Repeated strain doesn’t make it stronger; it makes it weaker.
Nature is replete with animals that have bones they don’t need, joints that don’t flex, structures that aren’t attached to anything, and appendages that cause more problems than they’re worth.
The flexibility of the wrist joint is restricted by the many bones in there, not facilitated by them.
No robot arm will ever be designed to imitate our nonsensical bone structure.
Humans have more dietary requirements than almost any other animal in the world.
The domestication of animals for meat and eggs (roughly five thousand years ago in the Middle East and at different points elsewhere) mostly solved the problem of rickets.
there are more individual bacterial cells in your colon than there are human cells in your entire body.
So the wonderful bacteria of the human gut are nice enough to provide B12 for us, but the gut is so poorly designed that we send all of that B12 to the toilet.
Beriberi was a tradeoff our ancestors made unknowingly, because they didn’t realize that their bodies could not produce a simple molecule required for the most basic chemical function: converting dietary calories into usable energy.
nine of the twenty amino acids are called essential because we have lost the ability to manufacture them.
plants are even more self-reliant than most microorganisms because they can synthesize the energy source themselves, too, using energy from the sun.
garbanzo beans, contain large quantities of all nine essential amino acids all by themselves, as do quinoa and a few other so-called superfoods.
During a famine, it’s not the lack of calories that is the ultimate cause of death; it’s the lack of proteins and the essential amino acids they provide.
Our intestines are so bad at extracting calcium from food that our bodies are forced to extract it from our bones instead—a strategy with devastating consequences.
The majority of the creatures on earth are mostly or completely vegetarian, yet their intestines do just fine in processing iron.
It’s not enough to eat the right foods to meet our exacting dietary needs; we must eat those foods in the correct combinations. It’s no wonder so many of us opt for a multivitamin instead.
we are hardwired for obesity. Yet most popular explanations of how and why things have gone wrong miss the evolutionary lesson at the heart of this growing problem.
People don’t eat too much just because they can. They eat too much because they were designed to.
So why don’t we find obese animals in the wild? The answer—a rather disturbing one—is that most wild animals are teetering on the edge of starvation pretty much all the time.
The hard truth is that humans in the developed world are surrounded with high-calorie foods that they are ill equipped to resist.
It is quite remarkable that, even though humans have been evolving separately from some mammals for over a quarter of a billion years, we all have a similar number of functional genes.
In fact, every day, you experience millions of mutations throughout your body.
Our GULO gene is more than 85 percent identical to the DNA sequence of the functional GULO gene found in carnivores such as dogs and cats.
Were it not for this broken gene, the AIDS crisis might never have happened, or at least it might not have been so widespread and so deadly.
Humans have a whole host of persistent genetic diseases that have been with our species for generations, millennia, even millions of years.
Compared to binary marriage, polygamy substantially intensifies the selective pressures of health and survival because of the direct competition of males with one another.
Nearly half of human DNA is made of autonomously replicating, highly repetitive, dangerously jumping, pure genetic nonsense that the body dutifully copies and maintains in each one of its billions of cells.
This is one reason why human males produce sperm in such large numbers. You need about two hundred million of them to start with in order to get just one to its destination.
between 10 and 25 percent of all recognized pregnancies end in spontaneous abortions (miscarriages) within the first trimester (thirteen weeks).
Embryologists estimate that, even with otherwise normal sperm and eggs, 30 to 40 percent of all conception events result in either failure of the embryo to attach to the uterine wall or spontaneous abortion shortly after it has.
when a human sperm and a human egg fuse, the resulting embryo ends up with the proper number of intact chromosomes only around two-thirds of the time.
As of 2014, all but one of the major developed countries had an infant mortality rate below 0.5 percent. The one exception is the United States,
In the United States in 1955, for instance, more than 3 percent of babies did not make it to their first birthday. That rate is six times higher than it is today.
In other words, ultrasounds, fetal monitoring, antibiotics, incubators, respirators, and, of course, expert physicians and midwives have all worked together to bring the human infant mortality rate down to what it is for most other species naturally.
We are basically all born premature. Premature, and completely helpless.
infants aren’t the only ones at risk during childbirth; mothers can and do die from it too.
Most people born during prehistory thus didn’t make it to reproductive age at all, but many of those who did enjoyed a fairly long life, even by today’s standards.
