X Chromosome's Role In Male Biology

It has long been assumed that the X chromosome is the "female" chromosome and the Y "male", but new research is beginning to challenge that idea. It was theorized that the shutdown of one of the X chromosomes in females slowed the evolution of the X chromosome and that these genes would be very similar across most mammals. Through research into this it was discovered that there are 144 human genes with no counterparts on the mouse and 197 mice genes with no counterpart on the human chromosome. In most cases these unshared genes, although being present on the "female" chromosome, are only expressed in males. Although this is relatively new research it would be interesting to see how this information pertains to human evolution and if it is in some way related to the "shrinking" Y chromosome.

http://www.wired.com/wiredscience/2013/07/x-chromosome-maleness/

http://www.hhmi.org/biointeractive/evolution-y-chromosome

Short genes?

In recent studies conducted by researchers at the University Children's Hospital of Boston, 12,000 children were surveyed and the test concluded that there is a correlation between a person's height and the number of deletions on certain chromosomes in the human genome. Up until today's genetic research, geneticists are only aware of approximately ten percent of the genetic makeup responsible for determining a person's height later in development. Recently, researchers have spent more and more time trying to find a link between a person's height and their genetic makeup. After careful research such as the studies completed at the University Children's Hospital of Boston, genetic abnormalities, coined copy number variants, are responsible for too little or too much DNA on certain chromosomes in the body. In shorter people, it was found that there was too little or even missing copies of height-determining DNA that could definitely contribute to the patient's height. For example, in his article Collins states, "While everyone has at least some of these deletions in their genome, covering thousands of individual components of DNA, others have several million."

Although this is a remarkable and reasonable accusation between a person's lack of DNA and thus shorter stature, the conductor of the research at the University Children's Hospital of Boston, Dr. Joel Hirschhorn, stated, "it showed a small but firm link between the amount of genetic material missing and a decrease in height." Therefore, no definite link has been established, but it is definitely an interesting step in the direction towards explaining a person's height.