Tuesday, November 25, 2014

Bird Brains

A local news report informed me earlier this evening that there are 23,000 wild turkeys in NJ according to the state DEP. They mean the fowl, not the whiskey. It is not entirely clear to me who counted or how, but I’ll take the DEP’s word for it. At least a few of the birds live in the woods around my house. They don’t walk through my yard very often, but when they do they do so nonchalantly without apparent concern about ending up on the menu.

For anyone accustomed only to domestic turkeys the wild ones, though not technically a separate species, hold some surprises beyond the color of their feathers. For one thing they fly. They don’t fly particularly well, and most of the time they prefer not to, but they can. They sometimes swoop over the lawn or get up into the trees. For another thing they are fearless. Domestic turkeys are too in a way, but one gets the sense that domestic ones just don’t know any better. Wild turkeys are fearless out of confidence rather than ignorance. On occasion one can be aggressive. An aggressive turkey is annoying rather than truly dangerous, of course, except maybe to a toddler. Finally, they are smarter than their farm-bred kinfolk.

Domestic turkeys are stupid. There is no kinder way to say it and still deliver the facts. My grandfather, a farmer, lost some of the birds because they looked up in the sky with their beaks open when it was raining and drowned themselves. In their scholarly article Some Remarks on Bird's Brain and Behavior under the Constraints of Domestication, Julia Mehlhorn and Gerd Rehkämper remark, "domestic turkeys show the highest degree of brain reduction measured in any of the domesticated birds so far.” No surprise there. So, while these birds face bad odds at Thanksgiving time, if that Zombie Apocalypse depicted in so many movies ever happens, they’ll be safe. Unless it rains.

It long has been known that domestication reduces the brain size of animals. From the same Mehlhorn and Rehkämper article: “Empirical data on brain sizes which show smaller brains in dogs than in wolves or in domestic ducks in comparison to mallards seem to support this point of view.” Before we admire too much the skills of our ancestors who successfully dumbed down animals to make them more manageable, it’s worth noting that they did the same to themselves. To us.

Brain size peaked in humans 20,000 years ago and since then has dropped substantially, both as a percentage of body mass and in absolute terms – from an average 1500 cc to 1350 cc. (Homo Erectus was 1100 cc – we’re getting there.) David Geary, a cognitive scientist at the University of Missouri, speculates, “I think the best explanation for the decline in our brain size is the Idiocracy theory.” He and his colleague Drew Bailey were able to show a correlation in the archaeological record between population density and brain size decline, whether in early farming regions such as the Middle East or hunter-gatherer regions such as aboriginal Australia. “We saw that trend in Europe, China, Africa, Malaysia—everywhere we looked.” The hypothesis is that when societies grow large enough to carry the dim bulbs who would not be clever enough to survive without a social safety net, there is no particular advantage to large brains or high intelligence. The dim bulbs live to reproduce. There is, on the other hand, an advantage to characteristics that suit living peacefully among others. In other words, there is an advantage to being tame and domesticated. Domestication, once again, shrinks the noggin. Hence the reference to the Idiocracy movie.

So long as the turkey is on our menu and not we on its, we’re probably not in too much trouble. But if a Cro-Magnon shows up for dinner, don’t try to beat him at chess afterward.


  1. Bird Brains, and I thought this was going to be about politicians. Some fowl can be aggressive. There used to be a duck pond where I lived and occasional a duck would be in a bad mood and try and chase or peck at someone. It could have been some sort of protective thing, wild animals and even domestic are unpredictable at times. I used to walk around that duck pond, which was pretty beautiful and peaceful, particularly at sunset, and noticed a couple of ducks following me one day. They stayed up with me pretty good too, but I finally ditched them.

    My grandparents used to raise chickens and for whatever reason as a kid they used to frighten me. The other day I wondered why chickens lost their ability to fly or it seems that they have. I guess body mass has something to do with it.

    I was thinking of the domestic angle of humans as I read your article. That Idiocracy theory is interesting in that the larger society supports the dim blubs who wouldn't survive without a safety net--brings home the idea of the Darwin Awards, and that even then, some don't survive. It also reminds me of those video shows where some teenager is riding his bike off the rooftop of his house or someone trying to start a barbecue pit with gasoline--not ending well.

    I guess it also diminishes those old science fiction stories where humans evolve with this larger brain and the size of our heads gets bigger. Perhaps our heads have gotten bigger, just not physically. Ha.

    I used to go to a comic shop where the owner would joke about the missing link saying that there isn't any--meaning, they still walk among us. Ha.

    1. There is an episode of the Outer Limits called “The Sixth Finger” which is a prime example of that SF trope: David McCallum goes into a handy-dandy evolution machine and emerges with a big head. It seems there is one more reason (not that there needs to be another) that the plot premise is flawed.

      Red Junglefowl (wild chickens) can fly, but pretty badly. Like domestic turkeys, domestic chickens have too high a ratio of body mass to wing area to fly. Birds do try to bully people sometimes. My grandfather had a pet goose that was more effective than any watchdog. He’d attack anyone who came to the front door.