- The intelligence of reptiles has long been considered lower than that of birds and mammals. But recent research on reptile cognition shows that reptiles have a deep understanding of their environment.
- Reptiles’ understanding of their environment and the evolution of their learning may play a role in the conservation of biodiversity and the provision of ecosystem services, especially in farmlands.
- This post is a comment. The views expressed are those of the author and not necessarily those of Mongabay.
“Deep inside the skull of each of us, there is something like the brain of a crocodile” – Carl Sagan, Cosmos.
In science, reptiles are considered to have a lower intelligence compared to birds and mammals. Dumb, even. But over the past decade, significant research has been done in the field of knowledge of reptiles, and the results have been truly encouraging.
Mammals and birds are generally considered to be a sentient class of animals. However, the basic brain structure in both of these classes is similar to that of the reptilian brain, which diversified 280 million years ago. Reptiles and mammals are the only vertebrates in which the cerebral cortex has a distinct, albeit simple, three-layered structure, similar to the mammalian allocortex. The reptilian ventral pallium gives rise to the dorsal ventricular crest, which contributes to the complex cognitive abilities of birds. Although the cortex of reptiles contains fewer subdivisions than that of mammals, the basic parts remain the same. It is subdivided into the medial cortex, better known as the hippocampus; a lateral cortex, equivalent to the pear-shaped cortex of mammals; and the dorsal cortex, which receives multimodal input (eg, visual input in turtles).
Perhaps there is no reason not to recognize cognitive abilities in reptiles since enough time has passed since their evolution for the further evolution of cognitive mechanisms. In addition, the basic structure of the reptile brain should also have behavioural and morphological similarities to those of mammals and birds.
Charles Darwin, in his second book The Descent of Man and Selection in Respect to Sex, mentions that other animals are cognitively different from humans only in degree, not in type. In the reptilian brain, being a primitive, ancestral form, the structural and functional complexity may not be as complex as in birds or mammals. Therefore, cognitive processes are quite simple compared to higher taxa.
Reptiles are made up of three main orders – Chelonia, Crocodilia and Squamata – and they all have a deep understanding of their environment. For decades, scientists have been working to understand how they do what they do, and the results have often been unexpected. Reptiles have excelled at learning the cosmos and their environment, as well as colour and taste. The researchers also observed social learning, eavesdropping on warning sounds from other species, reverse learning, problem-solving, and evidence of good memory.
Why should we care about the intelligence of reptiles?
Although there is a lot of information about reptile cognition, we have not yet considered reptile cognition as having any practical significance for solving real-life problems. One of these effects can be seen in conservation. For example, Goans and blue-tongued skinks in Australia are at risk of death from eating cane toads due to their intolerance to the Bufonidae toxin secreted by the toads. Teaching Goannas and blue-tongued skinks with cane toad sausages laced with nausea-inducing chemicals was an aversion to learning. Trained reptiles released into the wild have learned to avoid cane toads. This learning and memory improved their survival.
Another possible value lies in the preservation of their ecological functioning. Most likely, due to our ignorance, we have not yet considered the ecosystem functions that they perform. For example, reptiles are a harbinger of agricultural community biodiversity and are somewhat resistant to pesticides. In addition, many of these farm-dwelling reptiles are also insectivorous, making them an important choice as bioregulators.
With our ever-growing population, it is almost impossible to prevent the growth of land claims from agriculture, nor to limit the amount of agricultural production – the use of agricultural land can only increase in the coming years. The concern is what will be left of biodiversity. However, the consequences are not limited to the loss of a few species. One of the main problems associated with increasing crop production is the increase in crop losses due to pest infestations. Several mitigating measures have been proposed over the past few decades, ranging from chemical to cultural practices. Given the detrimental effects of pesticides on the ecosystem, crop health, human health, and biodiversity, the only option left is to use natural resources, such as natural enemies, to control crop pests. The question here is, can cognitive biology help advance the science of pest control?
A brief overview of the cognitive abilities of reptiles shows that they can distinguish between colour, smell, shape, and quantity. They can remember, decide, and even follow social cues. Turtles, for example, distinguish between yellow versus blue or white, a skill that has evolved to select food rich in carotenoids. Fruit and flower colour recognition has been extensively studied in herbivorous reptiles such as iguanas, turtles, and tortoises. Thus, the ability of reptiles to learn may provide an opportunity to improve the provision of their ecosystem services.
Similarly, learning and remembering refuge, i.e. “spatial cognition”, can also benefit bioregulation. Reptiles remember feeding areas. In addition, lizards that are capable of picking up social cues have been observed to observe the movement of birds to randomly find fig trees, which are a rich source of insects. Turtles can follow social cues to learn how to avoid obstacles and forage for food. Reptiles displaying such behavioural flexibility allow us to explore such abilities through the lens of bioregulation. However, more precise experiments are needed that are relevant not only to pest control but also to the animals themselves in the wild.
Our understanding of the cognitive abilities of reptiles is still incomplete and requires more research. Our notion of these animals as “sedentary, dispassionate creatures acting like instinctive machines” must be quickly replaced to better understand the functional role they play in maintaining our ecosystem. It’s time to realize the importance of having these animals around us for their services to the ecosystem, many of which go unnoticed by us.
Banner image: Chameleon on a branch. Image by Hasmik Kazarian Olson via Unsplash (Public Domain).
List of 100 most unique and endangered reptiles published
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