The cycling infrastructure in the Netherlands is fantastic, and cyclists in my hometown of Utrecht would be the happiest in the world if it weren’t for one thing: pigeons.
One moment you’re cycling in the sun with a cool breeze in your face, the next moment you’re braking and swerving. A pigeon casually crossed your path, seemingly unaware of the danger it was putting itself in. Growing up, I often wondered how stupid they must be to walk blindly into traffic. Many years later I found myself puzzling over the intellect of pigeons again, but this time in a new article in the journal PLOS Biology on collective intelligence and flight paths.
While this research overall suggested that my biases might be correct, some details in my new research results suggested that pigeons might actually be more intelligent than I gave them credit for.
Several years ago, when I was still unimpressed by pigeon intellect, I came across a 2017 research paper by biologists Takao Sasaki and Dora Biro. Their research outlined how pigeons fly back home when released from a specific location. At first the birds find a somewhat circuitous route. They then seemed to remember and reproduce exactly the same path with each successive release.
But Sasaki and Biro showed that when naive pigeons were paired with more experienced pigeons, their new route was slightly more efficient. Over several generations, the researchers replaced the most experienced bird in a pair with a naive bird. As stable pairs continued to fly the same (more circuitous) routes over and over again, generational turnover meant that each generation got a little closer to the most direct route from A to B.
Some scientists have taken this as an example of cumulative culture. This is new behavior that is passed on to others through social learning, which improves performance and is repeated over time to generate successive improvements. This last concept is also known in psychology as a ratchet.
Whether the cumulative pigeon culture is the same as ours remains a hotly debated topic among scientists. However, these pigeons and their cumulative route improvements interested me, and I wanted to know how they did it. Sasaki and Biro suggested that the birds could pool information and evaluate their performance.
On the other hand, I wondered if there could be a path to cumulative route improvements that didn’t require intellect. I turned to computer simulation and developed a simplified model for bird navigation. I wanted to create robot pigeons that could show route improvements without communication or complicated thinking.
The robot pigeon model consisted of four components. Pigeons know roughly where they live thanks to the sun and the Earth’s magnetic field (we know this because people have stuck magnets to the heads of pigeons, disrupting their navigation). They also seem to enjoy flying together, and the coordination of their direction of travel is a crucial part of crowd behavior. The third element was the route memory. When released from the same spot, the pigeons fly home in the same manner, apparently using landmarks along the route. Finally, their flight paths usually have continuity. This reduces the chance of abrupt sharp turns, avoiding erratic patterns.
Just as Sasaki and Biro did with real pigeons, I let my robot pigeons “fly” solo, in pairs and with generational progression. In each generation, the most experienced robot was replaced by a naive robot. Despite being highly simplified versions of pigeons (without communication or thought), the robots successfully flew from A to B, remembered peculiar paths and showed cumulative improvements.
The nice thing about computer models is that you can break them to see how they work. By adjusting the robots’ settings, I was able to demonstrate conditions in which pairs with generational change generally performed better than pairs in a control condition (without generations). I was also able to eliminate each of the components to demonstrate that goal direction, social proximity, and route memory were necessary for cumulative route improvements to occur.
The final question was why the piegons in Sasaki and Biro’s research found increasingly efficient routes. Some of this is obvious. Each new naive robot pigeon could learn a set path from its more experienced colleague. However, this does not explain why the routes improved. It turns out that naive pigeons actually helped experienced pigeons here.
They had no predetermined path to follow, but they knew approximately where the goal was. This made them slightly more likely to deviate from the route towards the goal, subtly making the new pair’s route slightly more efficient.
The research showed that cumulative route improvements can occur across generations in the absence of communication or complex thinking. It depends on pigeons’ rough idea of where the goal is, their memory for past paths and their tendency to stick together.
Does this mean that pigeons are really stupid?
My model produced similar paths to Sasaki and Biro’s pigeon data and showed that birds could operate in a stupid way. That said, the model’s parameter estimates were quite varied. They were also subtly different when pigeons flew alone, in stable flocks or with generational change.
This means that pigeons are not automatons: individual birds behaved in different ways, and may even have adapted to the circumstances. Although pigeons’ behavior generally matches the model, they can also do smart things that the model does not reflect.
An example of this can be found in a 2021 study by engineering scientist Gabriele Valentini and colleagues, using data from Sasaki and Biro. It was analyzed who takes the “leadership” in pairs of naive and experienced pigeons. They found that paired navigation is surprisingly democratic, with both naive and experienced pigeons initiating explorations for route improvements.
That certainly sounds like it could be some form of intelligence – even if those new routes sometimes accidentally cross a cycle path.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Edwin Dalmaijer does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant relationships beyond his academic appointment.