Evolution Gone Wrong

From The Wall Street Journal:

In Voltaire’s “Candide,” the protagonist’s servant asks his master to explain the meaning of optimism. To which his master replies: “It is the mania for insisting that all is well when all is by no means well.” There is perhaps no more perfect description of the human condition, as all is manifestly not well. How could it be? From the moment of our inception, a silent biological clock begins the countdown to the end of our existence. Our genome contrives to mutate itself into a smorgasbord of potential pathologies, each capable of corrupting and unraveling us. We respond with attempts to medicate and therapize ourselves, to correct the built-in flaws and shining imperfections that make us so irresistibly human.

In Alex Bezzerides’s entertaining “Evolution Gone Wrong: The Curious Reasons Why Our Bodies Work (or Don’t),” the author’s quest is to determine the origins of the “aches and pains of the masses and why they happen”—not the mechanical causes of our maladies but the evolutionary ones. The explanation, Mr. Bezzerides concludes, may be found in our anatomical shortcomings—“trade-offs” made during our continuing evolutionary history. The result is that even healthy bodies operate at the edge of acceptable performance, while also being prone to fail in predictable ways.

The catalog of human fallibilities that Mr. Bezzerides assembles begins with an account of our suboptimal dentition. For many individuals, the textbook display of 32 neatly arrayed teeth, systematically configured to produce a perfect Hollywood smile, is at best hopeful and more frequently fictional. Reality more typically involves a procession of braces, extractions and eccentric protrusions. So why don’t our teeth fit into our mouths?

The answer, according to Mr. Bezzerides, is that four million years ago our ancestors transitioned from a fruit- and leaves-based diet to one of grasses and sedges. Their molars ballooned out to gargantuan proportions, which was not at first problematic, since their substantive jaws readily accommodated the newly enlarged teeth. But as humans controlled fire, learned to cook, became cooperative, and developed hunting techniques and an accompanying armamentarium of cutting implements, the requirement for robust dentition diminished. We were nevertheless stuck with the legacy of “a mouth full of large teeth.” Jaw and tooth size subsequently began to decrease, yet the distinct genetic programs controlling each led to a disconnect between their relative rates of reduction. While the human jaw enthusiastically embraced its “great shrink,” tooth-size reduction struggled to keep up. Hence the modern tooth-jaw mismatch.

Our imperfectly functioning eyes suffer similarly from constraints imposed by our distant evolutionary history. More than half of European adults have visual defects, while a quarter of U.S. children require visual correction. The problem, according to Mr. Bezzerides, is that the eyes of our vertebrate ancestors evolved to function underwater. When vertebrates first moved onto land 375 million years ago, their eyes had already existed for more than 100 million years. The reconfiguration of such established biological hardware was not trivial, leaving us with short-sightedness and a range of oddities, including the need to blink up to 14,000 times a day while deploying a Coke can full of lubricating tears.

Our evolutionary history may also have impacted our ability to perceive color. The nocturnal nature of the species predating the evolution of mammals may have led to a reduction in the number of photoreceptor types enabling human color perception. While many fish, reptiles and birds perceive color using four types of photoreceptors, we make do with three. As a result, the humble gecko perceives the world in up to a magnificent 100 million shades of technicolor, while we are limited to no more than one million.

Other aspects of visual performance also appear to have been affected by our evolutionary history. Unlike the eyes of the honeybee, the human eye filters out ultraviolet light—most likely to prevent DNA damage—making the bees’ nectar-guides invisible to us. Intriguingly, Mr. Bezzerides speculates that the late works of Claude Monet may have been influenced by the artist’s likely newfound ability to perceive ultraviolet light following cataract surgery at the age of 82.

Link to the rest at The Wall Street Journal (PG apologizes for the paywall, but hasn’t figured out a way around it.)

While not an expert in evolutionary biology, PG suggests that evolution develops various capabilities of living things to a “good enough” standard.

While a perfect set of teeth by 21st century aesthetic standards in some cultures may require braces, etc., a less-aligned set of teeth that we receive at birth may do a perfectly fine job of their principal purpose in our lives, masticating our food so our bodies can properly digest it. In PG’s understanding, evolution tends to work to a “good enough” standard rather than some subjective standard established by groups of humans.

If future humans are unable to find mates due to a lack of cosmetically-preferred dentation, perhaps evolution will then step in and, over several centuries, put orthodontists out of business.

Likewise, if three types of photoreceptors allow humans to find where they need to go and avoid danger, they’re good enough to permit humans to survive and thrive. While being able to perceive 100 million shades of technicolor might be fun, is such perception necessary for human life to continue?

Additionally, what percentage of the gecko’s brain is devoted to processing these 99 million additional colors? Might that that be one reason why the Theory of Relativity was discovered by a human and not a lizard?

7 thoughts on “Evolution Gone Wrong”

  1. “While being able to perceive 100 million shades of technicolor might be fun, is such perception necessary for human life to continue?’

    Fun? Finding drapes that match the carpet would be a nightmare.

  2. PG is correct.
    Evolution literally works through survival bias and “survival of the fittest” only applies in times of stress (and in the business word, for companies and business models. 😉 )

    For organisms, as long as the genome doesn’t get the individual killed before it procreates it will endure more or less unchanged. Physical changes come (humans are in fact still evolving measurably within historical times, in ways that are not always “polite” to discuss.) but not fast enough to keep up with cultural demands. Without going too far, look at the ever-increasing need for vision correction. Eyes evolved for the open savanna suffer under modern environments.

    Likewise, we are genetically predisposed to prefer high calorie foods like sweets and fats because of the need to load up in the distant hit or miss days. Back issues. Childbirth dangers. The increasing “new” number of ways we die as we live longer and longer; the latest research says our “natural” upper limit looks to be 150 but the generic reality is 30 is all that is required of us. Anybody that lives to see grandchildren is ahead of the game. 🙂

    Key thing to remember is nature and generics don’t rule us anymore.
    Science (literally: knowledge) and technology (the uses of the knowledge we inherit) are mankind’s answer to both. Our motto might as well be “Buzz Off, Gaia.” 😀

  3. A simple evolutionary perspective leaves certain human species peculiarities less easily explained:

    1) The common persistence of females post-menopause (and often greater than males who are still fertile) — is it a spandrel or do they improve the survival chances for their grandchildren?

    2) Exclusive male homosexuality. Since (at least in principle) they don’t breed (and can’t be raped to force births), or likely at least breed less than non-homosexuals, how does the trait survive (presumably via nephews/nieces)? Spandrel or do they somehow improve the survivability of the primitive group and thus keep the trait alive via collateral relatives?

    There are lots of examples like these…

    (*Spandrel — an accidental result of using an arch. It serves no actual purpose in its own right, but if you have arches, you have spandrels. https://en.wikipedia.org/wiki/Spandrel )

    • Evolutionary biology/genetics has statistical evidence that suggests a common answer to both; as you pointed out, extended families survived better if they had grandparents and non-breeders as part of tbe communities. One of the few advantages ofso many humans infesting the planet is the statistic contibution to science studies, like GWAS.


      Note the past tense: the two cases have since diverged and will continue to do so even more moving forward. Grandparents are even more valuable today as repositories/distributors of knowledge and culture thanks to medical technology. The longer tbey hang around, the longer they contribute to the family. (Even economoically, if tbey don’t actively work to take all the fruits of tbeir labors with them.) It is one reason why death taxes are so despised. High achievers are almost always dynastic thinkers.

      The contribution of non-breeders, both by choice or other circumstances (sex selection, like in China) is declining, though. To whatever extent it is genetic, the trait distributes collaterally by relatives that do breed. If tgat extent is identified many societies will seek to depress it or (as in space colonies) minimize it because generic viability of small populatios relies on breeders.

      Gun stuff, no?

      • (sigh)
        Typo alert: it was meant to be “good stuff”.
        Not sure how autocorruption made “good” into “gun”.

  4. I’ve mentioned this before.

    In 2013, Dr. Eugene McCarthy announced that Humans were the result of pig and chimpanzee hybrid.

    When I saw the first announcement I thought of the great Spencer Tracy movie, _Inherit the Wind_, would now be called _Inherit the Swine_. I read all the information, watched the fun Jimmy Kimmel skit, then went to Sam’s Club to shop. Standing there, looking at the vast crowd standing in line, I thought, Yes, what a bunch of pigs, and wanted to start calling, sooey, sooey, pig, pig, pig, and see if people would come over to see me.

    The Hybrid Hypothesis

    The concept was even mentioned on Jimmy Kimmel.

    Humans evolved from male Pig and Chimpanzee

    This explains so much.

  5. Not even mentioned is the greatest one: the compromise necessary for the female of our species to save space for the duplicating machinery that is typically used fewer than a dozen times – leaving all kinds of damage in its wake. We survive as a species because the women generally live long enough to wean the young, almost as generally until the young are capable of independence.

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