UNDERDEVELOPED FACE AND JAWS
The first published theoretical framework for evolutionary theory came from Jean-Baptiste Lamarck in 1800. Lamarckian theory was based on the “inheritance of acquired traits”. The physiological needs of organisms, created by their interactions with the environment, drove Lamarck’s theory of evolution. He noted that a change in the environment caused changes in the needs of organisms living in that environment which in turn caused changes in their behavior such as greater or lesser use of a structure or organ. Lamarck’s Second Law stated that such changes were inheritable. Scientists of his era ridiculed this theory and denigrated his character. Lamarck died in 1829 in poverty and disrepute because of his controversial beliefs.
Charles Darwin, in 1859, acknowledged the theory of Lamarck. Erasmus Darwin, Charles’ grandfather, was actually an avid supporter of Lamarckian Theory. When Charles was studying the finches on the Galapagos, he noted changes in their beaks in times of drought that were passed on to their offspring, and population changes were noted in a few years rather than thousands of years. Lamarackian Theory was little more than a footnote in science history until very recently.
In a 2005 experiment at Duke University, female and male fat yellow agouti mice were mated and the females divided into two groups. One group got vitamin supplements equivalent to a prenatal human formula. The control group got the same mice food but no vitamin supplements. The supplemental group produced skinny brown mice. The control groups produced fat yellow mice. Both groups had identical DNA but the agouti fat yellow gene was not expressed in the vitamin supplemented group. This process is called methylation. When a methyl group binds to a gene it changes its expression without actually changing the DNA.
This scientific discipline studying changes like methylation is called epigenetics. Epigenetics established that the same gene does not always produce identical results. A given set of genes is not an immutable blueprint. The exact same set of genes can produce different outcomes in different organisms depending on which genes have undergone methylation. Environmental factors play a big role in gene expression.
What is of even greater interest is that the skinny brown mice when mated with each other continue to reproduce skinny brown mice. Environmental factors in the life of the mother can affect the inheritance of traits in her offspring. Score one for Lamarck. Epigenetic changes have been demonstrated to occur post-natal as well as intra uterine. Epigenetic changes have been shown to involve fathers as well as mothers and occur throughout life. Epigenetics provides a plausible explanation by which adaptive changes can occur that cause mouth breathing. Doctors must now examine function, breathing and swallowing and treat early to prevent serious problems later in life. Environmental challenges can change gene expression so a simple look at the parents is not adequate.
There are two parts of the face that can be underdeveloped; the upper or maxilla and the lower or mandible. Either one or both can be underdeveloped depending on the interplay of genetics and environmental factors such as mouth breathing, lip posture, swallowing, and tongue posture. Breast feeding vs. bottle-feeding, presence of environmental pollutants, allergens, diet and nature vs. nurture have recently assumed a greater degree of importance in understanding kids mode of breathing and facial development.