Hi, y’all! I am new to Nature Network blogs, and, in this quick post, will introduce myself and the topics . My name is Caio Maximino, a Brazilian graduate student, and I will be writing about the evolution of brain and behavior. This is a rather intricate topic; in its present state, evolutionary neuroscience conflates data from both the neurosciences and evolutionary developmental biology, in an attempt to make sense of the wide array of comparative data on the nervous system and behavior of many different species. Two major themes, as in evolutionary biology, are present in all current attempts to systematise the field: diversity and similarity.

The evolutionary biologist Theodosius Grygorovych Dobzhansky once said that nothing in biology makes sense except in the light of evolution ; this phrase is widely (perhaps overly) quoted by evolutionary biologists whenever they introduce their field, and it is possible that it constitutes a somewhat exaggerated reductionist approach to biology – but the fact remains that evolution is the most powerful organizing principle in all of biology. In the history of neuroscience, evolution has waxed and waned cyclically, in an almost Viconian fashion. For example, most nineteenth century neuroanatomists had an evolutionary and developmental perspective in mind in their preparations ; the influence of Darwin’s work was very much present (and recent) so that Victorian neuroanatomists would feel almost obliged to explain the diversity of brain morphologies (as well as their commonalities) through an evolutionary perspective.
As in the majority of the biological sciences, however, it was not until after the “evolutionary synthesis” (which happened in the years between 1936 and 1947) that the evolution of the brain began to be studied, en masse, per se. Of course, theories of brain evolution had already appeared before that (for example, Papez’s views on directional evolution of brain complexity, later expanded by MacLean’s triune brain theory), but critical mass was reached only after 1) the modern evolutionary synthesis reconciled genetics and evolutionary biology; 2) more powerful techniques (both from neuroscience and evolutionary biology) arose; and 3) developmental biology was reconciled with evolutionary biology.
In all its history, again, evolutionary neuroscience had two main problems to tackle. The first of these problems is the question of similarity. When one looks at vertebrate brains, many commonalities can be observed; for example, all vertebrates possess the same basic brain divisions. Evolutionary biology explains these similarities in terms of judgments of homology (similarity by commonality of origin) and homoplasy (similarity by evolutionary convergence). A structure is considered homologous to another structure in a different species if their “sameness” is due to a shared evolutionary history, while it is considered homoplaseous when this similarity is not due to a common evolutionary origin. With the rise of cladistics (that is, thinking about the evolution of any single trait in terms of its distribution in a phylogenetic tree, that depicts the relationships between species), judgments of homology and homoplasy are much more sofisticated, and hypotheses on the evolutionary history of any single trait can be tested with more accuracy.
A second observation that drove the development of evolutionary neuroscience is the presence, in specific vertebrate brains, of diversity – that is, of “novel” structures, reorganization of previous structures, enlargements of brain and structure size, and so on. This is the question that is more puzzling and explored in evolutionary neuroscience. Glenn Northcutt proposed that we can study brain evolution by asking four questions about changes in brains) What major changes have occurred in neural organization and function? 2) When did these changes occur? 3) By what mechanisms did these changes occur? and 4) Why did these changes occur?
In general, evolutionary neuroscientists have concentrated more on species differences than in species similarities when it comes to brains. This is understandable if we appreciate fully Northcutt’s proposal. As we can see, all the questions that he proposed are about changes in brains. In general, differences are more informative than similarities. This does not mean, of course, that they are more common than similarities, or even that they are more important from an evolutionary perspective; however, appreciation of those differences between species (and higher taxonomic levels) has an heuristic value – that is, a great potential to generate novel knowledge.
In this blog, we will delve into the fascinating field of evolutionary neuroscience. As you must have guessed by now, we will try to focus on those two major themes – novelty and conservation, similarity and difference – in commenting perspectives, history, and basic foundations of this research programme. We hope that you enjoy the ride, and learn a few things in the process – after all, that is what I will be doing, uh?