The Progression of Animal Testing Across Species

             Animal testing is frequently used across the sciences—including neuroscience—as human analogs, often when using human subjects is either unfeasible or unethical. The most common animals in scientific testing are rats and mice due to the ease of testing and genetic similarities to humans, alongside primates which are more sparingly used due to their ancestral relationship to humans and increased ethical guidelines. However, researchers have also been studying different species to explore novel connections and interactions that may apply to humans. By using these animals, neuroscientists and neurobiologists can explore various aspects of the field, including embryonic development, neural mapping, and cognition.

              In the article Why Birds Are Smart, Güntürkün et al. (2024) discuss the recent focus on avians in exploring human cognition and neural development. While being smaller, avian cortices match mammalian cognition through increased neuronal density.  Like human counterparts, many avians present cognitive mechanisms comparable to other mammals like apes, including stimuli discrimination, object permanence, limited word comprehension, and strong working memory. Separate from cognition are shared physical structures, including the cerebral cortex and hyperpallium which have high topology and similar row/column-like patterns to humans. By understanding similarities that may be present between humans and avians, researchers are better able to understand what makes a “smart” or cognitively advanced creature. Even with differences between neural structures (e.g. avians lack of motor areas in the isocortex), researchers can use their findings to better understand how cognition may be represented in different forms, as well as the ancestral and derived traits that are shared and discriminated between species.

              This article led me to inquire what other animals have been used to further understand neurological traits and processes among humans. In the article Xenopus leads the way: Frogs as a pioneering model to understand the human brain, Exner & Willsey (2021) discuss the role of the Xenopus genus (i.e. frogs) in various forms of testing including genetic research and embryonic development. This genus has shown similarities in embryonic development to humans, as well as row/column-like neural organization that is customary with mammals. Through the similarities, researchers have used this animal model to explore the prediction of genetic disorders and whether they can be altered through CRISPR targeting or other drug treatments. Because of Xenopus’ quick and external embryonic development, researchers have also focused this alongside genetic alterations to explore potential treatments and applications to human genetic diseases. Through the vast array of research that can be performed among the Xenopus genus, Exner & Willsey argue for further recognition of other animal models like frogs as important and necessary bases of future neurological understanding.

              Both articles present the importance of animal research beyond conventional models as a way of better understanding not only the animals themselves, but the underlying neural mechanisms that may be applied to other species, including humans. These animals can better expand upon the knowledge and treatment surrounding various genetic and developmental disorders. In exploring other animals in neurological research, scientists can also form a better, more well-established knowledge surrounding evolutionary connections across species that expand upon our self-understanding. The further exploration of animal species allows scientists to process our understanding of not only human processes, but the relation and connection between humans and other species.

References:

Exner, C. R. T., & Willsey, H. R. (2021). Xenopus leads the way: Frogs as a pioneering model to understand the human brain. Genesis, 59(1–2). https://doi.org/10.1002/dvg.23405

Güntürkün, O., Pusch, R., & Rose, J. (2024). Why birds are smart. Trends in Cognitive Sciences, 28(3), 197–209. https://doi.org/10.1016/j.tics.2023.11.002