In his book, The World in Six Songs, Daniel Levitin posutlates the ability to make or participate in music may have conferred an evolutionary advantage to early humans. It’s a reasonable hypothesis based on both archeological and anthropological evidence. And some paleontological finds, too.
We know from remains of bone flutes and other instruments, that humans made music at least 40,000 years ago. What that music was like, what role it played in primitive culture and society, what ceremonial or bonding purposes it had, will always be speculation (although we do know they likely used the pentatonic scale). We can only infer music’s roles from its uses in historic – i.e. since the invention of writing – civilizations, but we can never be sure what happened – and why – before the historical record.
When humans started singing, drumming, or making instruments to accompany themselves is simply something we will never know. Anything to suggest when is mere speculation. And even suggesting why is, too. We’re using post hoc analysis to infer purpose and reason.
We do know that group singing and dancing involves the release of certain neurochemicals like oxytocin, that can have powerful social-bonding effects on individuals, but we don’t know whether the particular chemistry is recent, ancient or even had the same effect on earlier cultures. However, given the relatively common and similar effects observed today, it’s another reasonable speculation that they occurred earlier within our evolution and helped humans bond, cooperate and accomplish group tasks.
And we do know that non-literate or non-technological societies – what few remain, such as those rare Amazonian tribes – use music and singing in social and cultural activities and rituals. Music and singing are as powerful in their cultures, in their daily lives, as sex and magic.*
(The co-development of music and civilization is fascinating, but apparently fragile. Music was mostly a communal activity, much more participatory, before the post-WWI development of communication technology. Today, thanks to the internet, digitalization and newer technologies, music is less a shared, bonding activity than it is a passive experience. Musicians – the people who create the experience – still create and shape public opinion and taste, but like alchemists and shamans, they are on the fringe of society.
There is a glimmer of hope that music may be returning to its communal, social roots with the recent growth in popularity of the ukulele and the resurgence of communal ukulele groups…)
Levitin – as brilliant as he is about neuroscience and music – seems confused about evolution and natural selection. And a few other sciences, as I’ll explain below.
Levitin offers a scenario to explain how natural selection works. Problem is: it doesn’t. It’s more Lamarckian than Darwinian.**
And he confuses several other science, too. Here’s what Levitin writes:
Suppose there are some people who, by virtue of random mutation, enjoy eating dirt. An epidemic of fatal virus sweeps the world, attacking hundreds of millions of people. It turns out that a particular compound, found only in dirt, kills the virus. Those people who eat dirt would survive and nearly everyone else could be wiped out within only one or two generations. (p.55)
Where to start? With dirt perhaps. What is “dirt?” Soil, sand, organic material, clay, bacteria, fungi and other living creatures, minerals, metals, compost – humus – water, debris, worms, litter, old cigarette butts, animal feces… there is no constant compound in soil (“dirt”) that we can expect is the same everywhere. The dirt in Mongolia, in the rain forest and in my garden are all wildly different. The many creatures living in my garden soil are different from those living in an African soil, an Australian soil and an Arctic soil.
What’s in soil that could affect viruses at all? Not much; take out the local flora and fauna, and t’s generally a benign mix of nutrients and inert material. It feeds a lot of life, and if it were toxic, the life would die.
Typical soil mineral materials are:
- Quartz: SiO2
- Calcite: CaCO3
- Feldspar: KAlSi3O8
- Mica (biotite): K(Mg,Fe)3AlSi3O10(OH)200
So what in dirt would kill a virus? Viruses are not like other life forms. They don’t eat. They don’t metabolize material like bacteria or protozoans, or in fact the rest of the tree of life. Viruses don’t ingest chemical compounds. Or anything else. You can’t poison them.
But even if it proved lethal to viruses, what’s to say that compound is found in dirt everywhere? Eating my garden soil may not kill any virus or save me simply because the lethal compound may be unique to Transylvania or Nepal. Would it be organic?
Besides, if this were really the case, scientists would likely be able to identify the compound, isolate and replicate it for everyone.
Even in a pandemic, viruses have to spread from person to person and that takes time. Usually there are two vectors: airborne and direct contact. Since we can isolate ourselves in hermetically sealed rooms, and avoid touching one another or sharing fluids, the transmission could be at least delayed long enough to work out a solution.
Viruses are simply a protein shell (sometimes with a lipid membrane) around genetic material (RNA or DNA). They are tiny on a scale that’s hard to conceive. A typical rhinovirus – the source of the common cold – is in size to a human red blood cell what a golf ball is to a modest detached family home: tiny. A single grain of sand would be to a virus what a mountain is to that golf ball. A big mountain, at that.
Viruses can be managed (somewhat) by inactivating or removing them. Viruses do not have the chemicals or machinery to reproduce or metabolize, or internal structures like mitochondria and nuclei, so they can’t be killed like bacteria or protozoans. They spread by injecting their own genetic material into a host cell, hijacking its genetic-protein engine, and using the host’s mechanism to reproduce and assemble more viruses, usually killing the cell in the process.
Since virus removal is a mechanical process, usually done outside the body, it’s not something eating dirt can achieve. (Viruses also have the annoying ability to go dormant within a host, and reactive often years later.)
Inactivating a virus might occur through chemical alteration. That requires the surface chemistry of the virus to be altered so it can no longer recognize a host cell, attach to it, and inject itself into it. Altering that surface chemistry is tricky, difficult and has only been managed with a handful of expensive and complex drugs. Would a simple compound found in dirt do so? Unlikely. If it existed, viruses likely have encountered it and adapted.
Viruses are adept at evolving to counter challenges, and we would expect them to become resistant to any such compound very quickly. Viruses have proven remarkably difficult to control, much less kill. Consider the many variations of common flu virus.
And liking does not mean anyone will actually eat dirt. Just think of the social stigma we share about eating dirt. Liking anything is usually not a genetic disposition, but a chemical/neurological and subjective state: personal taste. In fact it can be learned or trained: people teach themselves to eat or not eat a wide variety of foods all the time. Many cultures eat things other cultures find repulsive: insects for example (it’s ironic that anyone who eats lobster or crab would find eating insects disgusting… but that’s another post…)
One of the key points in natural selection is inheritability. If you can’t pass along the mutation in a stable, reproducible form, then it’s an evolutionary dead end.
I am disposed to like ginger marmalade. I doubt if my children or grandchildren share that, and even if they did it won’t be because of a marker on my genes. When I first began drinking, I liked sweet wines and though dry wines were bitter. Today I like dry red wine and cannot stand sweet wine. Tastes can change because they are individual and personal, and tempered by age, peer pressure and experience.
Liking something isn’t usually inheritable (however, obsessive craving may be for entirely different reasons).
What eating dirt would be – if it was effective in killing viruses – in effect, is a merely temporary result: not an evolutionary step. More like taking an Aspirin for a headache than a real cure. You’d have to keep eating dirt for it to be effective because the virus would keep re-infecting you.
Only some of what we eat stays within us. Most of it is returned to the source through excrement and urination. The body is fairly strict – although sometimes fooled – about what compounds it allows into the blood stream or past the blood-brain barrier. Dirt would get broken down in the gastric juices and at the bacterial buffet in our digestive system. The point of digestion is to reduce what we eat to two categories: nutrient and waste. Complex molecules get broken down into simple forms. Minerals get dissolved for transport in our blood. A lot of compounds don’t survive the process intact.
It’s more likely any useful compound in dirt would have to be eaten constantly and regularly for the infected to stay alive. It’s not even like immunization where the vaccine teaches the body to develop resistance. Dirt – or its active compound – could be distributed in capsules, like daily medicine. But it wouldn’t be evolutionary.
Another mistake Levitin makes is in how random mutations work. When they are inheritable, they are within a small group, usually within well-defined geographic and population boundaries (this is how species are created). And often it starts with a small core, or even a single animal. It’s unlikely that numerous people scattered around the globe would simultaneously but independently develop the same mutation. Any mutation that is the result of an outside force – chemicals, cosmic rays, radiation, etc. – would not be an evolutionary change.
Levitin also writes,
Consider house cats. cats kick dirt or sand or whatever is nearby over their excrement, But it is unlikely that they understand the germ theory of disease, and are covering their excrement to minimize contagion. Instead, some ancestral cats had a genetic mutation that triggered the release of a certain reinforcing neurochemical (let’s call them “happy juice) when they kicked after excreting. The cats with this mutation were less likely to get sick or to spread disease to their offspring, facilitating this mutation’s rapid spread through the genome. (p.55-56)
Wrong again. In fact, cats do not uniformly cover their feces. Doing so is a reaction to population and to socializing tendencies or stresses.
Feral cats leave their scat uncovered to mark their territory – as do many animals. Some feral cats frequently replenish their fecal markers along the border of their territory. And when another cat wants to challenge that boundary or its owner, it marks the same location with its own urine or feces. It doesn’t bury them. Burial only occurs when these solitary animals are pressed into social (pack) situations. Like when we have multiple, unrelated (by birth) cats in our homes.
In multiple-cat households, cats may cover their feces to reduce social pressure, or may leave them uncovered to state dominance or challenge. Cats may use their uncovered feces as markers to indicate stress or distress, too.
And the pattern of covering or leaving feces may change as the population dynamics change: when an alpha animal ages or becomes ill, it may cover its feces to avoid conflict; while a beta animal may stop doing so because it recognizes the opportunity to advance. House cats may also do so in deference to their human owners; often seen as the alpha animals (or as minions, depending on the cat…).
An evolutionary advantage would not simply be covering feces: it would be resistance or immunity to the bacteria that cause illness. Covering feces is more likely a learned behaviour (any pet owner who has trained a cat or dog, or watched animals interact in a household can tell you about shared/learned behaviour and anyone who has had kittens or puppies has seen how the mothers or parents taught the young…).
Dogs sometimes kick their feces with their back legs, which spreads them over a wider area, rather than covers them. That would seem counter-evolutionary by Levitin’s standard, since it spreads the potential germs.
I’ve never owned a dog that actively covered its own feces like a cat. If Levitin was correct about the process, this means dog populations would be more ill from feces-born disease and parasites than cats. I’ve never seen anything to support that idea.
Dogs will frequently urinate on a spot where another dog has urinated, mixing scents and sending messages we humans can’t decipher. And I have yet to own a dog that doesn’t sniff closely another dog’s feces. A real evolutionary development would be in the immunity or resistance to any feces-born contaminants or bacteria.
Most mammals and many other animals have developed an intuitive understanding that their own feces are not welcome in dens, nesting, eating and sleep areas – probably an evolutionary development in the manner Levitin suggests: to distance the animals from potential disease or threat. But, because they have generally better and keener senses of smell, animals use feces and urine as identifiers and markers; individually, for territory and for pack behaviour. Many animals investigate feces or urine spots, and sniff each other’s backsides (where anal scent glands are).
This isn’t meant to denigrate Levitin’s expertise in music or neuroscience, but I find some of his comments about other sciences need challenging.
* Most writers describe them as pre-literate or pre-technological, as if they were simply on the way to becoming like us; a necessary step to living in the suburbs, owning an Pod and spending your leisure hours staring at the TV set. I’m not convinced that we have the superior society or culture and am dubious about some of the social benefits claimed for technology.
** The theory of natural selection is simple and elegant. Berkeley University summarizes it thus:
- There is variation in traits. For example, some beetles are green and some are brown.
- There is differential reproduction. Since the environment can’t support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do.
- There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis.
- End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown. Eventually, the advantageous trait dominates.
Got that? Yes, it is that simple.