After two long years, I’m doing fieldwork again, this time studying spiders in South Africa! Being in the field, I am viscerally aware of the creatures around me in a way I cannot replicate when I’m at home. But I’ve learnt that spotting a creature, even watching its behaviour and interactions, is only the first step towards understanding it. The next step — a crucial one — is linking what we see in one or a few animals to the sum total of human scientific knowledge. Others before us may have spent time making observations and conducting experiments on similar creatures, collecting data that they went on to describe carefully in scientific papers. To me, much of the beauty of science derives from linking a private moment of discovery to others’ long-held knowledge — does your discovery match what others have found, does it complement previous work or build on what we know, or does it perhaps push against the ideas that others have held?

In the past two years, instead of engaging with plants and animals directly, I’ve been learning about the beast that is scientific literature. In a way, I’ve been trying to understand its evolution, to discern how a littler corner of the scientific literature got to be a certain way. I’ve been observing this corner closely, much as I would an ant or frog.

The particular focus of my work was the mating system of anolis lizards, a group of over 400 species found in many parts of the Americas. Until relatively recently, it’s been widely thought based on decades of behavioural research that most anolis lizards are territorial and polygynous. This means that each individual remains within a small area known as its territory, and that female territories are contained within a male’s. Moreover, males prevent other males from entering their territories, allowing them to maintain “exclusive mating access” to the females within their territories. This description is so prevalent, in both scientific and popular accounts of these lizards’ biology, that most people wouldn’t stop to think twice about it.

But genetic paternity tests have shown repeatedly that individual female anolis lizards mate with multiple males, which means that males aren’t maintaining exclusive mating access to females, and that the description of territoriality given above isn’t quite how these lizards behave. This led me to wonder how we came to believe that anolis are territorial in the first place, so I set about reviewing relevant scientific literature. Through this work, I realised that sometimes even things that we think are well-supported scientific facts — such as territoriality in anolis — may be based on insufficient evidence.

The path towards cementing the idea that anolis are territorial began with studies conducted in the 1930s, which concluded territoriality based on strange and limited data. Most subsequent studies ended up assuming territoriality implicitly or explicitly. This assumption affected how studies were designed, how data was analysed, and how observations were interpreted. It thus became unlikely that studies would consider important, or even be able to detect, behaviours that were not quite territorial but were still potentially important for these lizards’ mating system.

To illustrate this, imagine that you are a biologist setting out to map lizard territories. You need to go out into the field, catch a bunch of lizards, mark them individually, and then repeatedly survey the area around where you caught them to discern the boundaries of each individual’s territory. But how do you decide how big an area you’re going to survey? Here’s where your assumptions become crucial — if you go in assuming that these lizards have small territories, which they do, then you’re justified in surveying a relatively small area. But if you assume that lizards have small territories and in reality, they move over much bigger areas and don’t stick to a single spot, then surveying a small area will prevent you from discovering the full complexity of these animals’ movement behaviour, and learning how that complexity might have evolved. Indeed, you’ll be most likely to observe precisely those individuals that remain in a small area, even if these represent only a fraction of the population, and will likely conclude that these lizards are territorial based on those observations.

Surveying relatively small areas is just one way in which research on anolis social behaviour has depended, for decades, on territoriality. Consequently, the facts we have come to hold about these lizards’ biology look very different than they may have if biologists had started out with different assumptions, or had clarified what their assumptions were. The upshot is that, at this point, we simply don’t know if anoles are territorial or not.

In this world where the very concepts of knowledge, facts, and scientific expertise are under dispute, I fully recognise the danger of writing about how science can do an incomplete or even incorrect job of discovering truths about the natural world. But it won’t do science any good if we ignore how our processes of discovery can be blinkered by unwarranted assumptions. The future of science cannot depend on us pretending that we scientists are infallible.

Ambika kamath is a behavioural ecologist, currently based at the University of California, Santa Barbara; ambikamath@gmail.com

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