Back in 2001, a study was done that found a gene that was linked to language and speech called the FoxP2 gene, which stands for Forkhead bOX P2 (Marcus and Fisher, 2003). This link between the two purposed the idea that a person’s urge to chat and murmur is inherent and that some aspects of a person’s linguistic capacities are from this gene (Trivedi, 2001). This gene is thought to be involved with a person’s ability to acquire spoken language (Marcus, Fisher, 2003). Before the discovery of the FoxP2 gene from a family known as “KE”, there was no information on whether a gene and language were connected.  The “KE” family members that had the mutated FoxP2 gene, suffered from both verbal and orofacial dyspraxia (Marcus and Fisher, 2003). Verbal and orofacial dyspraxia is linked to the reduced movements around the mouth for controlling speech (Marcus, and Fisher, 2003). The discovery of the “KE” family is the only known documented case of inheritance of a language disorder (Marcus, and Fisher, 2003). It is a very challenging task to find exact genes that affect language but with finding the “KE” family, it was possible to link the FoxP2 gene with language disorders.

Function

The FoxP2 gene functions by giving instructions to make proteins, known as a transcription factor, which are able to connect to other areas of DNA (Trivedi, 2001). It belongs to a collection of other genes that all make proteins that contain the forkehead-box domains (Marcus and Fisher, 2003). Being a transcription factor, the FoxP2 gene, is able to control the activity of the other genes within the DNA. This gene is active in many tissues, most importantly before you are born and throughout your life (Weiguo, et al, 2017).  It has a huge role in the formation and function of brain circuits that are closely connected to language (Heston and White, 2015).  Many studies have suggested that the FoxP2 gene plays a large role in how the brain develops, both in the growth of neurons and how the signals are transmitted between the neurons (Weiguo, et al, 2017).  When a person does have problems with their FoxP2 gene, they struggle with the orofacial movements that are necessary in making the correct forms of speech, like members of the “KE” family showed (Heston and White, 2015).

“KE” Family

The FoxP2 gene, was found through research conducted looking at speech and language disorders, from a family classified as “KE”. Within this family many of them had disorders that prohibited them from selecting and constructing “the fine movements with the tongue and lips that are necessary to speak clearly” (Trivedi, 2001). The KE family consists of three generations of about fifteen members that suffer from language and speech problems (Marcus and Fisher, 2003).  By testing the “KE” family members that had the disorders, researchers were able to learn more about the FoxP2 gene. It was found that the FoxP2 gene, was most likely located in the region of chromosome seven that includes about seventy genes (Trivedi, 2001). Researchers were lucky enough that multiple members of the “KE” family had this disorder, because they were able focus on the exact gene that was damaged, where they were able to find the mutated FoxP2 gene (Trivedi, 2001). Researchers were then able to connect the language disorders the family members were having with the mutated FoxP2 gene (Marcus and Fisher, 2003).

Members of the “KE” family that have the mutated FoxP2 gene showed verbal dyspraxia meaning impaired abilities in coordinated movements that are needed through speech. They also showed impairment in both speech and verbal comprehension along with issues in language production (Shu, et. al., 2005). The family members were unable to produce certain aspects of language, which prohibits them from communicating without error. Orofacial dyspraxia is the most prominent aspect of the disorder and is the core feature (Marcus and Fisher, 2003). The FoxP2 gene disorder also affects the “KE” member’s non-speech movements including, written language such as verbal fluency (Marcus and Fisher, 2003). This disorders are not that recognizable to others who are not around them consistently. It is not that extreme of a disorder where it is noticeable as soon as you start talking to them. It may take a couple minutes until you are able to pick up some of the differences the members have with the disorder (Marcus and Fisher, 2003).

Zebra Finches

There are many similarities between human speech and finches’ songs that make songbirds very valuable to researchers when investigating the FoxP2 gene. Finches, which are songbirds, carry the FoxP2 gene, where it plays a large role in their language ability (Heston and White, 2015). The FoxP2 gene is very important to songbirds because they learn how to sing largely through mimicking (Heston and White, 2015). With the Zebra finches, the young males learn to communicate by watching the older males and then learn through mimicking the sounds and songs the older males sing. This method of learning how to sing, relies on a set of brain nuclei that is called the song control circuit (Heston and White, 2015).

In the finches the FoxP2 gene is located in Area X, where the song control circuit is and where mutations in the FoxP2 gene would be found (Weston and White, 2015). Speech impairment for the finches with mutated FoxP2 genes, would consist of inaccurate song learning and not being able to make the correct sounds (Heston and White, 2015). The mutated FoxP2 gene would lead to overexpression making the young finches unable of copying the older finches’ songs (Heston and White, 2015). If there were to be no errors in the FoxP2 gene in finches, the relationship between the singing neural activity and Area X would be uninterrupted (Heston and White, 2015).

These errors in the finches are similar to humans who also show signs of a mutated FoxP2 gene (Heston and White, 2015. In the finches the errors occur during the style and formation of individual syllables, meaning that the finches have problems with selecting the right song and executing what they are actually going to sing (Heston and White,2015). Humans also show high errors in vocal motor patterns, which connects the idea that the FoxP2 gene is closely connected to language (Heston and White, 2015).

Bats

Bats rely heavily on using vocal signals for orientation and for capturing prey, making communication a critical aspect of their lives (Li, et al, 2007). In bats, the Foxp2 gene is very diverse and highly important for echolocating (Li, et al, 2007). There are bats that have the ability of echolocating and bats that are unable to do so, resulting from mutations in the Foxp2 gene (Li, et al, 2007). With echolocation in bats, they are able to emit pulses up to 200 sounds per second and understand echoes in milliseconds, making their spilt second decisions very crucial (Li, et al, 2007). These spilt second decisions revolve around making quick flight changes to avoid obstacles, predators and capturing prey.  The bat echolocation is very diverse and a necessity for the bats to survive (Li, et al, 2007). Over the year’s research has shown that the evolution of the Foxp2 gene in bats has excelled at a fast rate, making there be a higher Foxp2 variation (Li, et al, 2007). This can be from the bats capacity of vocal learning and just how much the rely on communication in their lives. Another reason for the accelerated Foxp2 gene in bats is because they are one of the few groups of vertebrates that have vocal learning, which is linked to the Foxp2 gene (Li, et al, 2007).

Other Animals

In general, there are other animals as well that have the FoxP2 gene. These animals include; Chimpanzees, Gorillas, and Rhesus macaque, where all of them have identical FoxP2 genes and a very similar Foxp2 gene to humans (Enard, et al, 2002). Evidence suggest that the FoxP2 gene has had a significant role in the development of a mousses’ brain for hundreds of years (Marcus and Fisher, 2003). Mice have a style of the gene that is 93.5 % identical to humans (Marcus and Fisher, 2003). Even though mice are not able to talk, they still communicate and the FoxP2 gene is involved in the communication for mice. When investigating the FoxP2 gene in mice, it was found that when the gene is mutated it can cause motor impairment, and an absence of ultrasonic vocalizations when the babies are removed from their moms (Shu, et al., 2005).

Conclusion

The Foxp2 gene is directly related to language in both humans and in some animals (White, et al, 2006). This evidence that the Foxp2 gene is linked to language originated from the “KE” family and the mutations they had within the FoxP2 gene (White, et al, 2006). The members that were affected show clear communication disorders that are from the mutations in the gene. As described animals such as mice, bats, and songbirds all have the FoxP2 gene as well. The language disorders that are involved with the mutated FoxP2 gene originate around the inability to make the proper movements needed for speech (Marcus, and Fisher, 2003). These problems with language are subtle, but they do exist and create problems for people who have mutated FoxP2 genes.  The FoxP2 gene in birds is very similar to both rodents and humans, by having the same cell types (White, et al, 2006). As it is in humans, the Foxp2 gene if mutated, can cause language problems in the animals as well. The songbirds and bats that have mutations in the Foxp2 gene have an increasingly difficult time communicating and rely heavily on communication (White, et al, 2006). By understanding that the Foxp2 gene is related to language, researchers are able to look at the evolution of the gene in both animals and humans.

References

Enard, W., Przeworkski, M., Fisher, S., Lal, C., Wiebe, V., Kitano, T., Monaco, A., and Paabo, S., (2002). Molecular evolution of FOXP2, a gene involved in speech and language. Retrieved from http://pubman.mpdl.mpg.de/pubman/item/escidoc:529489/component/escidoc:529488/Molecular_Evolution_Nature_2002.pdf

Heston, J., and White, S., (2015). Behavior-Linked FoxP2 Regulation Enables Zebra Finch Vocal Learning. Retrieved from http://www.jneurosci.org/content/35/7/2885

Li, G., Wang, J., Rossiter, S. J., Jones, G., & Zhang, S. (2007). Accelerated FoxP2 evolution in echolocating bats. Plos One, 2(9), e900.

Marcus, G., and Fisher, S., (2003). FOXP2 in focus: what can genes tell us about speech and language? Retrieved from file:///Users/mikesimes/Desktop/FOXP2%20in%20focus:%20what%20can%20genes%20tell%20us%20about%20speech%20and%20language%3F%20-%20ScienceDirect.webarchive

Weiguo Shu, a., Julie Y. Cho, a., Yuhui Jiang, a., Minhua Zhang, a., Donald Weisz, a., Gregory A. Elder, a., & … Peter Palese, a. (2005). Altered Ultrasonic Vocalization in Mice with a Disruption in the Foxp2 Gene. Proceedings Of The National Academy Of Sciences Of The United States Of America, (27), 9643.(2017). FOXP2 gene, forkhead box P2. Retrieved from https://ghr.nlm.nih.gov/gene/FOXP2#conditions

White, S. A., Fisher, S. E., Geschwind, D. H., Scharff, C., & Holy, T. E. (2006). Singing mice, songbirds, and more: models for FOXP2 function and dysfunction in human speech and language. The Journal Of Neuroscience: The Official Journal Of The Society For Neuroscience, 26(41), 10376-10379.