Dr. Erich Jarvis and his research team report the results of their investigation on the effect of the gene Fork-head box protein #2 (FOXP2) with a genetic mutation on the vocalization patterns of adult male mice. In humans, FOXP2 regulates speech production and people with deficiencies of this protein have trouble forming complex syllables and speech construction. Mice communicate not through speech like humans , but they do use other vocalizations as a means for communicating with each other. Dr. Jarvis' study investigated wether the FOXP2 deficiencies in humans have the same consequences in mice.
Dr. Jarvis' results concluded that they do! He suggests that his results support the "continuum hypothesis", meaning that the FOXP2 affects vocalization patterns in humans as well as all other mammals.
The study used 26 male mice which were bread to have the FOXP2 mutation (just like it is found in humans with speech deficits). As well as 24 wild type male mice (normal amount of FOXP2). Both the heterozygous (FOXP2 deficient) and wild type mice were housed certain circumstances such as an active wild type female mouse, close to only the urine of a wild type female mouse, or with a sleeping mouse of either gender. These circumstances were duplicated from the research published by Chabout and colleagues in 2015.
The study discovered that in any of the social circumstances, wild type male mice expressed more duration and sequence differences in ultrasonic vocalizations (USV). USVs are high-pitched sounds mice make that cannot be heard by humans. The investigators still have to find out if the mice with FOXP2 deficiency had an effect on their communication patterns.
The results were that wild type mice can create complex vocalization patterns with no trouble. However, the FOXP2 heterozygotes had difficulty producing the same sounds as the wild type mice. The teams findings held true after an intricate statistical analysis was done by Dr. Jarvis.
The research team conducted another study using transsynaptic tracing to compare the vocal brain regions of of wild type and heterozygote FOXP2 mice. It was discovered that the vocal motor neurons of the heterozygote were more widely spread across the cortex in comparison to the wild type mice.
It still shocks me every time I read an article that proves how close animals are to humans. I always thought humans and other animals such as mice were completely different and that humans are superior to any other animals. Studies like this one proves that humans are not as different as I originally thought. Humans and mice are both mammals after all.