The Pineal Gland; a Third Eye?
Ciana Dsouza
The Pineal gland is a small pea-shaped gland located in the centre of the brain, whose function has not yet been clearly understood. For centuries, it has been dubbed as a third eye: the link between our endocrine and nervous systems. But is this really the case? How important is this gland for our day-to-day lives?
The gland was first recognised by the ancient Greeks back in 210CE. Writings by Greek doctor and philosopher Galen elucidated that it owed its name to the resemblance in shape and size to pine nuts (Latin: pinus pinea). Although Galen was the supreme medical authority up until the late 1600s, scientists during his time usually modified or developed his ideas.
In the middle ages, the functions of this gland started to become clear. I state this, but chief anatomists (of the time) did liken it to a worm - it was depicted as a ‘worm-like obstacle’ between our thoughts and memories, essentially allowing us to look back at our past without disturbing our present thoughts. Subsequently, in 1637 when the whole idea of a third eye arose, Descartes described it as another eye within our brain that allowed us to better perceive what we visualise and allowed our organs to act upon this. In his book, about the pineal gland, Descartes talks about the gland as something that is “situated in the most suitable possible place for this purpose”, the gland is “in the middle of all the concavities; and it is supported and surrounded by the little branches of the carotid arteries which bring the spirits into the brain”. This is important as anatomically, it reinforces the fact that the gland allows us to perceive what we visualise although this viewpoint may be slightly too spiritual for modern day scientists. Later that year he wrote: “Since it is the only solid part in the whole brain, which is single, it must necessarily be the seat of the common sense.” Unfortunately, his views were almost universally rejected, and it was noticed that the gland is not actually in the middle of the ventricles, or indeed even vascularised. However, the idea of the gland being a link between our sight and organs remained – an idea that was developed upon by post-Cartesian modern scientists.
Modern-day scientific developments have summarised that the pineal gland is an endocrine gland secreting the “wonder drug” melatonin; a hormone that is secreted in the circadian rhythm (a cycle that follows physical, mental and behavioural changes). This is fascinating as it links to Descartes’ hypothesis of a vestigial third eye, and reinforces the idea that this gland may truly be the link between what we see and how our organs react to it. Melatonin is a hormone that controls the sleep-wake cycle and fitting with this, the pineal gland is seen as a photosensitive gland that can release hormones to interact with our organs to help us fall asleep or wake up.
So, can you live without one? Yes, this is possible – the fact being discerned from patients undergoing a pinealectomy surgery, or from having genetic mutations which lead to its absence from birth. Usually, a pinealectomy is performed due to cysts occurring in the region of the gland but can be due to other causes such as cancer or injury to the brain.
On an elementary level, living without a pineal gland makes it very difficult to wake up and fall asleep due to disruptions of the circadian rhythm. However, more severe effects have been reported in terms of regulating sexual development such as late changes in voice and general body growth due to inadequacies of the hormone gonadotropin.
So, is it really a third eye? I would say to some extent, yes, it is, due to its involvement in secretion of the key hormone melatonin – the release of which is dependent upon what our body sees. However, there is no extensive research that outlines its functions beyond this.
As aforementioned, the gland is the key link between our nervous and endocrine systems, and it is essential to help us maintain a circadian rhythm, regulating our sleep. While in the past it had an abundance of spiritual connotations, we now know that further research needs to be carried out in this area to broaden our understanding of the true purpose of this mysterious gland.
Reference list
Cox, M.A., Davis, M., Voin, V., Shoja, M., Oskouian, R.J., Loukas, M. and Tubbs, R.S. (2017). Pineal Gland Agenesis: Review and Case Illustration. Cureus, [online] 9(6). Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5498116/ [Accessed 9 Mar. 2021].
Lokhorst, G.-J. (2013). Descartes and the Pineal Gland (Stanford Encyclopedia of Philosophy). [online] Stanford.edu. Available at: https://plato.stanford.edu/entries/pineal-gland/.
Rosenfeld, J. (2016). 10 Mysterious Facts About the Pineal Gland. [online] www.mentalfloss.com. Available at: https://www.mentalfloss.com/article/89666/10-mysterious-facts-about-pineal-gland.