Folding Heads

The human brain has been studied for hundreds of years, yet we know surprisingly little about it. For example, we still don’t understand how the human brain is put together during development so it can perform its many cognitive functions. One reason for this is that it is difficult to watch the human brain developing. However, new culture techniques have allowed us to get a rare window into how the human brain takes shape. Our work investigates these developmental processes, how they shape brain development and the impact the shape of the developing brain may have on its function

Ernst Haeckel was a German Zoologist who in 1866 coined the phrase “ontogeny recapitulates phylogeny” which means: the development of individual organisms (ontogeny) follows (recapitulates) the same phases of the evolution as its species' evolutionary development (phylogeny). For many decades this was accepted as natural law.

I will show that this does have merit but that it has been overplayed. I will discuss the development of the pharyngeal arches (structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures), which are a prominent feature of Haeckel’s pictures that were used to support his recapitulation theory. I will show that an evolutionary perspective is important in understanding these structures. Yet, I also wish to make the case that this has created confusion and that many of the textbook discussions of these structures are wrong.