A new study conducted by Chris Stringer and colleagues have led to a fascinating possibility that variation in the size and shape of the frontal sinuses can be linked to the development of the frontal lobe; the part of the brain accountable for emotion, planning, and speech. Frontal sinuses are “cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain” (Balzeau, 2022). Yet, despite knowing the job and role of the frontal sinuses, there is still very little knowledge on the evolutionary aspect of it.

Located right above the nose, the frontal sinus which has often been forgotten historically now offer possible insight to past relationships with ancient hominids.

As mentioned, Stringer and his team were able to undergo multiple studies to link the size of the frontal sinus among previous fossil hominids with the frontal lobe. First off, they conduced CT scans on 94 individuals, which were from more than 20 species of human fossil hominids. From this, they created 3D models of their frontal sinuses and compared them with one another. Their length and widths, as well as their shapes were recorded which led to further observations. For example, the team were able to determine that “species such as Homo erectus, Homo neanderthalensis and Homo sapiens have distinct ranges of sinus size, which researchers suggest could be linked to evolutionary constraints caused by the development of characteristics such as larger brains” (Bartek, 2022). This shows the evolutionary aspect of the human, emphasizing in the different amount of space the brain had to grow for each species. A common denominator that was found among the 3D models was the sinuses and the size of the frontal lobe starting from homo erectus and onwards. The size of the sinuses proved to be persistent and correlate with the development of one of the brain’s lobes (short extension) compared to the other. Studies suggest this part of the brain plays a role in determining humans dominant hand and is shared amongst most humans today.

However, as much discovery that was made, there were also many unanswered questions and confusion amongst the group. Homo rhodesiensis, for instance, display a very unusual large sinus size compared to their relatives. Although there is no clear explanation for their large sinus size, the team hypothesized that they are a specialized group. This means that their way of living and the environment they were exposed to was different from their relatives.

These species have extremely large brow ridges, which leads many to hypothesize their role in social signaling.

Although these new studies provided new insight and discoveries towards our human past and evolutionary progress, more studies will have to be done to answer questions like these. Sinuses should be evaluated and looked more upon for future studies conducted, as they will help us understand how todays human species came to be.

Further Readings: 

Clues to Apes and Human Evolution

To understand human evolution, follow the trail of sinuses

References: 

Saraceni, Jessica, 2022. “Frontal Sinuses in Hominin Skulls May Offer Clues to Evolution.” Archeology. https://www.archaeology.org/news

Balzeau, Antoine, 2022. “Frontal sinuses and human evolution.” Science. https://www.science.org/doi/10.1126/sciadv.abp9767

Tree-ring dating, often referred to as dendrochronology is one of two main methods of dating. A dendrochronologist is a scientist that specializes in tree rings in order to form conclusions about the natural world and human behavior. The technique was developed by A.E. Douglass, an American astronomer in the early decades of the last century (Renfrew and Bahn 2018, 108-140). Now used in modern archeology along with radiocarbon dating, Douglass pioneering technique cemented a ground foundation for dating artifacts found today.

In order to perform the process of tree-ring dating, dendrochronologists first measure and plot tree rings and produce a diagram that indicates the thickness of successive rings in an individual tree (Renfrew and Bahn 2018, 108-140). After this, it’s all about figuring out the age of each tree and organizing them by chronological order. This chronological sequence of timber can present a story of the past till now.

Figure 1. Dendrochronologists analyze sequences of tree timber in order to match its pattern rings to older timbers. This will give a chronological idea of the area/site.

The technique is now a crucial tool for archaeologists, who can use tree ring chronologies for more than 4,000 sites on six continents to trace up to 13,000 years of history. Although trees add a new ring every growing season, trees don’t develop their trunks consistently. Trunk growth is closely linked to climate conditions. Under ideal conditions, trees grow quickly, leaving wide annual rings behind. During droughts, unseasonable cold, and other unusual conditions, growth slows, leaving behind narrow rings (Blakemore 2019). With these findings, dendrochronologists are able to determine the age of the tree and the type of condition the tree lived under. Tree rings can tell us so much!

Figure 2. The conifer wood displays much variation in its rings. There is a contrast in color and width size due to the different variety of environmental conditions the tree was exposed to.

However, like previously mentioned, unfavorable conditions can leave the tree-ring method to be last in the pecking order. The big reason is being that the trees must be under ideal conditions. That being said, dendrochronology can’t be used as a worldwide technique given that climate is different and constantly changing. As a result, tree-ring dating “applies only to trees in regions outside the tropics where pronounced differences between the seasons produce clearly defined annual rings” (Renfrew and Bahn 2018, 108-140). Taking it a step further, the method can’t be used if the tree ring is from wood that’s been used by humans, have allowed a sequence that’s in the present, or if the sample is too complex to match with other samples. Nonetheless, dendrochronology will continue to be a pivotal tool for future generations, especially as warmer climates become more and more prevalent.

Further Readings: 

About Tree Rings

The History of the World is Written in Tree Rings 

References: 

Blakemore, Erin. 2019. “How are tree rings used to help date an archeological site?” National Geographic. https://www.nationalgeographic.com/culture/article/how-tree-rings-date-archaeological-site

Renfrew, Colin, and Paul Bahn. 2018. Archaeology Essentials: Theories, Methods, and Practice. Fourth edition. Thames & Hudson. 108-140.