Genetically engineered mice with altered FOXP2 gene have been found to produce lower decibel squeaks than unaltered mice. Since the mouse FOXP2 gene has not altered as much as the human version during evolutionary time, the changes observed may indicate how human language development took place.
Studying evolution with genetically engineered mice
Scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have been carrying out research to understand the impact of genetic changes in humans over the course of evolution.
A major focus of their efforts is the FOXP2 gene and researchers have created genetically engineered mice with a human-like version of this gene. Essentially this involved two amino acid substitutions to the murine FOXP2 so that it produced proteins similar to those created by human FOXP2. By studying the changes this wrought in the mice, it is possible to understand how genetic changes may have affected our hominid ancestors.
The FOXP2 Gene
FOXP2 stands for Forkhead box P2. This gene is one of many belonging to a family of transcription factors that produce Forkhead box proteins. The gene contains around 100 amino acids set in a particular sequence and the name 'Forkhead box' describes this amino acid structure. There are 17 families that contain this DNA-binding structure and these are designated from FOXA to FOXQ. The FOXP2 gene is a second subtype of the 16th member of these families.
Researchers believe that the FOXP2 gene is linked to language development in humans. It is also a very crucial gene in the development of various brain, lung, and stomach tissues. It is found mainly in the basal ganglia region of the brain.
FOXP2 occurs in all animals, but the human version of the gene shows some definite changes that might explain why humans have the capacity for complex communication levels that other mammals lack.
Genetically Engineered Mice
The researchers observed the following changes in the genetically engineered mice -
- Mice pups, when they are removed from their mother, produce high decibel squeaks. In the case of the genetically engineered mice, squeaks of lower frequency were observed.
- The mice were observed to have modified exploratory behavior. They showed less inclination to explore their surroundings than normal mice.
- The mice showed reduced levels of the neurotransmitter dopamine. Dopamine, which is produced in the basal ganglia region, is responsible for body control and learning abilities.
- The basal ganglia region showed a more complex growth of nerve cells with increased dendritic length. This indicates that changes to the basal ganglia region were relevant in speech evolution in humans.
FOXP2 gene, of course, is not the sole gene responsible for language abilities; it works in tandem with a cascade of other genes. So, in short, altering the mice FOXP2 genes to resemble human ones is not going to produce talking mice, but it will give us a clearer picture of how we managed to do it ourselves.