The remarkable endurance of the Y chromosome ‘master of maleness’
Context:
- The Y chromosome, popularly known as the “master of maleness,” has fascinated scientists and history for a very long time.
Y chromosome:
- In addition to the 22 pairs of chromosomes in each pair, humans also have a pair of sex chromosomes called X and Y.
- The definition of sex is governed by these sex chromosomes. They carry sex-determining genes.
- All biological men have two X chromosomes, while all biological females have two X chromosomes.
- The Y chromosome’s “sex-determining region Y” controls the biological male sex.
A “juvenile offender”:
- It is estimated that between 200 and 300 million years ago, a common ancestor of all mammals contained the Y chromosome. Its DNA tells a remarkable tale of evolution and it has had a unique genetic adventure.
- Researchers published the complete genomic sequence of the Y chromosome in 2003. This sequence provided an overview for 23 million of the approximately 60 million nucleotides that make up the Y chromosome.
- Only 55 genes total were encoded by the chromosome, or around 2% of the genetic content in a cell.
- Many scientists jokingly refer to the Y chromosome as the “juvenile delinquent” among chromosomes because of its high frequency of repetitive sequences, poor functional utility (due to the small number of genes), resistance to socialisation (i.e., recombination with other chromosomes), and high propensity to degenerate over the course of evolution.
- In fact, the little Y chromosome’s restricted capacity for recombination has allowed it to pass the heritage of generations from father to son.
Essential genes:
- Approximately 0.5% of all men worldwide receive a Y chromosome from Genghis Khan or one of his descendants, according to a ground-breaking genetic study that was published in March 2003 in the American Journal of Human Genetics.
- Genes necessary for biological processes, such as those controlling longevity and ageing, are found on the Y chromosome.
- In the animal kingdom, including mammals, scientists have noticed major differences in lifespan between the sexes: females often live longer than males.
- Males’ lack of a second Y chromosome, which exposes the damaging X chromosomal changes, is the primary cause for this phenomenon.
- As men get older, they lose their Y chromosome, which is known to be associated with a greater risk of cancer, Alzheimer’s disease, and a shorter life expectancy.
Removing the Y:
- Heart failure has been noted in rodents with LoY, as well as weak heart muscles (cardiomyopathy), stretched or thickened heart tissue (fibrosis), and heart failure. According to studies, LoY develops in people as they age and is linked to a number of disabling medical conditions.
- The degenerative effects of LoY in mice’s hearts may also be reversed by transforming growth factor beta 1-neutralizing antibodies, providing a potential treatment approach for this condition.
- The Y chromosome takes up roughly one-third of the size of the human X chromosome. As a result, the loss of the Y chromosome is a genuine problem for many animal species, including humans.
Conclusion:
- The Neanderthal genome sequences, a distant relative of modern humans, contain apparent proof that the Y chromosome was replaced beginning with modern humans. Because this demonstrates that such replacement is not new to the human lineage, the Y chromosome may someday have to relinquish its prized position as “master of maleness” to another chromosome.
