“From Fossils to Mind” by de Sousa, Beaudet, et al.
Biography: Summarized by Jacob Davidson: Jacob is a student at Binghamton University currently working towards a bachelor of biological sciences. He enjoys playing guitar and piano, playing sports like baseball, basketball, and volleyball, and spending time either outdoors or with his pet cat, snake, and turtle.
What is the point of this paper? The point of this paper was to analyze the importance of endocasting techniques (i.e. creating casts of the inside of a fossilized skull’s cranial cavity; Figure 1), along with its limitations. This paper also emphasizes the importance of data sharing when trying to understand and compare extinct hominins’ (primates from which humans are very closely related to) brains to modern humans.
Methods: Prior to the application of endocasting techniques, studying ancient hominin neurology was very limited. The brain’s soft tissue rarely fossilizes, making it difficult to study. The brain does, however, leave imprints indicating its size, shape, and more on the cranial bone, revealing many different factors that can help interpret brain function. While relative brain size is believed to be loosely correlated with intelligence, many other factors that can be analyzed through endocasts reveal a lot about ancient hominins’ brains.
Results: One telling detail that can be analyzed in endocasts is the overall vasculature of the brain. This vascularity indicates cerebral blood flow, which demonstrates brain activity in both cognitive and functional processes. Blood flow can be estimated from small depressions that blood vessels made on the inner surface of the endocast. Another aspect of neurology that is revealed in endocasts is brain shape. Mammalian brains display a cerebrum (the upper part of the brain) that is positioned relatively higher, due to the development of the neocortex (the center of the brain). Modern human brains have a disproportionately large and superiorly positioned (i.e. higher) cerebrum. This leads to a key distinction between Homo sapiens and Neanderthals (our closest extinct relative): Homo sapiens has a “globular” endocranial shape. This distinction could be a key factor in modern human’s greater intelligence. In conjunction with modern day genetics testing, this shape could be linked to an important genotype expression, that also could play a role in interpreting differences in brain function and overall intelligence between Neanderthals and Homo sapiens.
While endocasts are revealing for the brain anatomy of extinct hominin species, they can only reveal so much information. In order to fully understand how extinct hominin species’ brains worked, many other things need to be accounted for. Everything from behavioral patterns to genetics need to be assessed when trying to paint a full picture of extinct hominin species. This is where the importance of scientific communication and data sharing is reflected. Most of the data on this topic is not currently shared, making research harder than necessary. Histological (i.e. tissue and cells) collections and databases contain a wide variety of data that can be used to help better understand many different extinct species’ brains. Through sharing this information, researchers can collaborate to learn even more, while also communicating their findings with museums, institutions, and other researchers.
Why is this important? Human history can be traced back millions of years. Modern humans (Homo sapiens) only appeared relatively recently in the fossil record, while the extinct evolutionary relatives of humans, such as the genera Paranthropus and Australopithecus, first appeared millions of years ago. Through analysis of fossil endocasts, along with comparisons to modern humans and other mammals, paleontologists can now better understand past hominin brain function, specialization, and plasticity (i.e. the ability to learn and create new pathways). This field of research is known as paleoneurology, and research in this field is key to understanding both ancient and modern hominin brain function and disease.
Broader implications: Biology helps us understand the world around us, but, arguably, it also serves a more important role. Biology has long helped us improve human life. From understanding human anatomy to sequencing the first human genome, biology and all of its subcategories have aided in the pursuit to improve human life. Paleoneurology serves a huge role in this pursuit. Through understanding hominin brains throughout time and comparing them to modern Homo sapiens brains, we can understand the evolutionary steps we took, along with the aspects of our brains particular to humans and how they may shine a light on subjects like mental health, disease, and neurodegeneration.
Citation: de Sousa, A. A., Beaudet, A., Calvey, T., Bardo, A., Benoit, J., Charvet, C. J., Dehay, C., Gómez-Robles, A., Gunz, P., Heuer, K., van den Heuvel, M. P., Hurst, S., Lauters, P., Reed, D., Salagnon, M., Sherwood, C. C., Ströckens, F., Tawane, M., Todorov, O. S., … Wei, Y. (2023, June 13). From fossils to mind. Nature News. https://www.nature.com/articles/s42003-023-04803-4