Context: 

Many animal species have a genuine fear of losing the Y chromosome in the distant future. This has happened in some species that have naturally lost this chromosome.

About Chromosome:

• It is a part of a cell in living things that decides the sex, character, shape, etc. that a person, an animal or a plant will have.

Sex Chromosome:

• In humans, in addition to the 22 pairs of chromosomes in each, we have a pair of sex chromosomes called X and Y. 
• Sex as a specification is determined by these sex chromosomes. They carry sex­-determining genes. 
• All biological males have X and Y chromosomes and all biological females have two X chromosomes. 
  • The ‘sex­-determining region Y’ on the Y chromosome determines the biological male sex.

Y Chromosome:

• It is estimated to have emerged around 200­-300 million years ago in a common ancestor of all mammals.
• The Y chromosome, is often referred to as the master of maleness.
• Scientists published the complete genetic sequence of the Y chromosome in 2003. 
• This sequence provided an outline of 23 million bases of the 60 million or so bases that together make up the Y chromosome. 
• In total, the chromosome encoded for only 55 genes and accounted for around 2% of the genetic material inside a cell.

Loss of the Y Chromosome in Humans: 

• Men lose the Y chromosome (LoY) with age and this is associated with a higher frequency of cancers, Alzheimer’s disease, and a shorter lifespan. This has been corroborated by studies on mice models.
• The human Y chromosome is about one-­third as big as the X chromosome. So, many animal species, including humans, have a genuine fear of losing the Y chromosome in the distant future.
• Species such as rodents have naturally lost their Y chromosome.

News Source: The Hindu