How our shrinking brains are turning us into Homo Domesticus

This is the first contribution, I hope of many, by T.J. His background is as varied as entrepreneurship, medicine, game development and politics.

I must admit, at the outset, that when I first vocalised the thoughts herein, I did it as a form of humour and out of frustration regarding my fellow man. However, the more I thought about it, the more I reckon there might be some validity in it. This is not necessarily in the sense that a new human subspecies has actually developed, but that process may have indeed started.

You probably learned in school that a species is a group in which two individuals can reproduce. If they can’t, they aren’t the same species. Things are a bit more complex than that, and there are many arguments regarding that definition. For example, what if A and C can’t mate, but B can mate with both?

what is homo domesticus

A subspecies is even harder to define. As a rule of thumb, if it looks a lot different but can theoretically breed, its a subspecies*. This generally involves some sort of “block” on breeding: how else would the populations look different? In fact, a definition regarding the propensity to breed can also be used. A great example is the tiger. In that case, the different subspecies are separated geographically so mating is difficult (tigers don’t do long distance relationships). Physical differences can reinforce the problem in a feedback loop. A female Chihuahua can conceive offspring with an Irish Wolfhound, but I’m not too sure how well things will workout in the long run (Wolfhounds always leave the seat up, you see).  Eventually, things get so bad, they just become two different species, and they don’t even require lawyers to do so. For our purposes we will be super pragmatic: if Wikipedia says it’s a subspecies, it is.

homo domesticus tame human being

“But T.J., Wikipedia doesn’t say there is a new human subspecies!” I hear you say. Well yes, I’m getting to that. First, let’s discuss a subspecies that is on Wikipedia, Canis Familiaris, but you might know him as Spot, or Fido, or something – the domestic dog. Of course, our oldest friend is also basically a wolf and can successfully breed with one. (In fact, different wolf species can even breed occasionally, as I said, it’s complicated). The point is, we consider the domestic dog a separate subspecies. The fact that we don’t consider each breed of dog a subspecies is basically down to taxonomical snobbery and a fear of having to come up with a bunch of Latin names.

Why is the dog important here? Well one way to make a new subspecies is domestication. This is the manner in which I think we have formed a new subspecies of human. Let’s call him Homo Domesticus.

In 1959, a Soviet scientist called Dmitri Belyaev conducted an experiment.

He hypothesised that domestication was the result of selecting for “tameability”, not other traits like fertility or strength.

Had the Soviets not starved all the farmers in the country to death beforehand, they could have just asked them about it instead of conducting a 50 year experiment. But then again, that was the result of policy created by Soviet academics, so maybe there was some conflict of interest. Anyway, the experiment involved selectively breeding foxes to domesticate them. Belyaev was right. By the tenth generation of foxes, 18% were so tame that he had to come up with a new category of tameness for them. It is theorised that this is linked to lower adrenaline production by the “domestic” foxes.

homo domesticus explained

What is very interesting is that domestic rats also have smaller adrenal glands than their wild counterparts. I am conflating an atrophied adrenal gland with lesser adrenal production, but it is not an unsound assumption. They also have smaller brains, hearts and other organs. So could it be that domestication is simply the result of lesser adrenal production? Let’s park this idea for a minute and move on to a more popular species (for reasons I will never know).

Humans have had a decreasing brain size for the last 28,000 years, Wikipedia reliably informs me. Upon discovering this, I immediately thought, could we be domesticating ourselves?! It turns out I’m not the first to think this. A study by Bailey and Geary used population density as a proxy for advanced societies and found that there was a correlation between this and brain size reduction in history. The conclusion was that “life got easier”, basically.

Since individuals had more security from those around them, they could scrape by with less intelligence.

Now I am tempted to leave things here with a note that a reliance on our fellow man will therefore lead to humans becoming stupid – brain size does map to intelligence on a large scale such as human evolution, but that would be intellectually dishonest. There is a large body of academics that think that the reliance on others may have nothing to do with intelligence. It could be down to heat loss, or that our brains became more efficient at doing what they do and needed less volume. I am tempted to discuss why I think those ideas have merit but are untrue, but do not have the space here. Furthermore, I want to keep this light and cutting rather than scientific and thorough (too late, say you).

homo domesticus smaller brain

Personally, I have a much darker theory. Brain size did correlate to intelligence and to societal complexity. But not because we are all happy bunnies living in wonderland. Let me take the case of one our “best” moments as a species: agriculture!

Agriculture is great, apparently. Yet human health suffered immensely as a result. The fossil record shows (is it a fossil record if the bones have not petrified?) that human height dropped four inches and there is a myriad of pathologies that developed upon the adoption of agriculture. This later changed but only after about 8,000 years. So why did we do it? Or a better question would be, why did we keep doing it? Perhaps it was because societal elites were able to domesticate others. Whether they are slaves or peasants, the result is the same.

One group forces the other to farm, and if they don’t, they are killed. Almost as if they are selecting for tameness…

Of course, that wasn’t 28,000 years ago. It isn’t hard to imagine the same process earlier in history? In fact, for the farming peasants to be tame enough to stay, they would likely have already been tamed in prior generations. Remember the foxes? 18% in only ten generations. I should also have mentioned that domestic rats do not run away after losing a fight like wild rats, they stay and lie submissively. By the twentieth generation, 35% of foxes were of the super tame variety. How many human generations in 28,000 years? About 1,000, actually.

But hold on! How is that a subspecies? Well, for most of human history there has been a tendency to mate with those of a similar social standing. This functions as a block to mating and could result in certain traits becoming concentrated, forming two subspecies. Maybe it’s not so far fetched.

So who are they then? In areas where there are wolves and dogs, wolf-dog hybrid occur. They might be a different subspecies, but that doesn’t mean that the big bad wolves aren’t utterly dashing to the refined domesticated ladies. Sort of like a canid James Dean, I guess. Furthermore, in humans, we know that while there was a tendency to mate in a certain social circles historically, it was by no means as rigid as portrayed today. William the Conqueror is a good case in point. (His mother was the daughter of a tanner.) Therefore, the process of domestication and subspeciation is likely incomplete in us. We all probably have both traits, to varying degrees. There are the wild men and the servile.

The significance of all this is that in the last few decades publicly traded corporations and the state encroached more into our everyday lives, filling the role of our trainers and being run by the most domesticated, institutionalised humans of all.

Due to the above, we risk completing the process of domestication. Don’t be under the illusion that we have more personal freedoms than in yesteryear, but that’s an argument for another day.

* To qualify as breeding in this context, the offspring must be “viable”, that is, fertile.

14 Comments Add yours

  1. Plectrumm says:

    I too have pondered that evolutionary path for our species, give what we know of breeding for traits. Then you have to consider the prolific interracial mixing taking place in a more globalized world. Then you have to consider the scary trajectory of overpopulation and the power of exponential growth (every 70 years the doubling effect) which suggests 30 million humans in 140 years…

    Liked by 1 person

    1. Dr T.J. McGrath-Daly says:

      I think we overestimate the effect of globalisation. I remember reading a study that suggested the point in our history with the most globalisation was the height of the Dutch tulip trade, not today. As for overpopulation, I would have to imagine that competition will have reduced our population growth by then

      Liked by 2 people

      1. Plectrumm says:

        There are more people breeding across races, cultures, and social barriers than any other time in human history! The globalization you are referring to is economic, and that too is at all time highs for volume and scope.


  2. Anony Mole says:

    Well that was a surprise. Shrinking brains — had to fact check that (grin).
    The start of the Holocene appears to be one of the triggers for this (warmer favors smaller bodies, smaller bodies = smaller pelvises, smaller pelvis = smaller heads).
    And the discovery of agriculture which produced surplus food and forced permanent villages seem to have augmented the theory of reduced aggression necessary for cooperation.
    Homo Domesticus? The wealthy of the world would certainly hope you’re right. Let the rabble squabble for the scraps while we live the high-life up here in our rarefied exclusive enclaves.
    How about Homo Virtutalis. We may soon be able to live much of our lives in virtual worlds where our brain size would be just large enough to support the cognition of virtual reality.
    I would have thought that the fact that Cesarean sections are now a common way to give birth that humanity might grow alien-large heads now.
    Thanks for the interesting post.

    Liked by 1 person

    1. Dr T.J. McGrath-Daly says:

      Yes, I’ve seen the warmer conditions theory. There is a lot of evidence based around latitude being a factor (and therefore temperature) so maybe it is the cause. However, it may also be wishful thinking on our part! I think agriculture would still need aggression to force people to farm though.
      Your point about Caesarean section is very interesting. It also opens up a whole new area: how modern medicine is affecting our physical evolution.

      Liked by 2 people

  3. Interesting idea, I have never given human evolution of the last tens of thousands of years that much thought.

    I wonder about your statement that intelligence correlates with brain size. Crows and ravens have small brains, but are very smart.

    Also, meditation increases grey matter in for instance the hippocampus, which is associated with learning and memory. It seems to me that that is pretty vital to intelligence. What do you think of brain density’s importance?

    Liked by 1 person

    1. Dr T.J. McGrath-Daly says:

      I think that it is definitely a plausible explanation for our decreasing brain size. However, I am always cautious about coming to conclusions that make me the pinnacle of evolution or culture. It’s very tempting to explain things using a reason that still lets us consider ourselves smarter or as smart as out ancestors. Applying Occam’s Razor, my guess is that we are just stupid now! But I could be guilty of overcompensating.

      Liked by 1 person

  4. Steve Ruis says:

    Of course we are “domesticating ourselves.” This is why per capita violence has been on the decline for centuries. Males are being feminized and females masculinized. This is the only path to the future that doesn’t result in us killing one another to destruction. And even it is not a secure path.

    Liked by 1 person

    1. Dr T.J. McGrath-Daly says:

      I always have doubts about violence statistics since governments have a motive to make them look like they are reducing. Also, I think it is very dangerous to assume masculinity and femininity are bad. They have gotten us this far in evolution, and while nature isn’t always morally superior, it does work. Furthermore, there is nothing to say a genderless society will be peaceful. An interesting though I have that I may write about in future: have nuclear weapons really changed anything? Did biological warfare in the middle ages (yes, it happened!) pose as much of a doomsday risk as nuclear weapons do today, since they didn’t have modern medicine?

      Liked by 1 person

  5. Great article. YES! We are being domesticated through almost every means…including religion. This is why even when it comes to religion and spirituality, one should not proverbially “swallow” the combination of dogma, tradition, and lack of deep philosophy as all there is regarding the transcendence of humankind. To think, rebel and reform is what keeps the human race free.

    Liked by 2 people

    1. The more I think about these things, the more I realise that my “conclusions” are nothing but a work in progress. It’s hard to maintain such an attitude when we naturally long for certainty. Thanks for the comment and sorry for delayed response, it got filtered automatically for no reason at all!

      Liked by 2 people

  6. Fascinating subject! I’m not too concerned about our species as long as there are a lot of specimens of Homo Ludens around …


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