Introduction: The natural lifespan of humans is determined by the rate of aging, which is determined by the length of chromosomal telomeres, which are associated with the lifespan of the father, and we have many unknown factors about lifespan! Before understanding the rate of aging depends on what? This question is preceded by a concept that needs to be understood: chromosomal telomeres Chromosomal telomeres (Telomere): are repetitive sequences of DNA at the ends of linear chromosomes. Telomeres are a special structure at the end of linear chromosomes that, in normal human cells, can gradually shorten as the cell divides. The length of telomeres reflects the cell’s replication history and replication potential, and is called the “mitotic clock” of cell life. Human cells, for example, can divide for up to 50 generations. And the closer we get to old age, the fewer generations a cell can divide. This decrease in the reproductive capacity of cells is reflected in aging at the organ and individual level. To better understand the aging process, researchers at Lund University have turned to small birds for help. A new study investigates whether small birds are born with long or short chromosome ends, called telomeres. Our genome is made up of genes arranged on chromosomes. The ends of chromosomes are called telomeres, and they protect the chromosomes from sticking to other chromosomes. The longer the telomeres the longer the chromosomes will be active. Conversely, the shorter the telomeres, the shorter the activity time of the chromosomes and the shorter the activity time of the cell. The more we know about telomeres, the better we can understand the aging process in humans and other animals. In the current study, researchers from Lund University are trying to find the reason for the large variation in telomere length in newborn individuals. This raises the question of whether longer telomeres at the beginning of life should be more favorable than shorter ones. Asghar Muhammad, who participated in the study, said, “It is notable that there are already differences between individuals in such early life, both for humans and animals.” The researchers used 30 years of data from identifiable individuals of the great reed warbler from Lake Kvismaren in south-central Sweden. The aim of the study was to find out which genetic factors affect the length of chromosomal telomeres in small birds. Fortunately, with long-term measurements, it was possible to compare the telomere lengths of these newborn chicks with those of their parents. The results of the study found that the telomere length of these young birds was uniformly influenced by both genetic and non-genetic factors. The older the female gave birth, the longer the telomere length of the newborn birds. The non-genetic factors are more related to females than to males. For example, females can affect hormone and antibody levels in the early stages of egg formation. These factors affect the rate at which chromosomal telomeres become shorter during the first 10 days of growth. Asghar Muhammad noted that, unlike humans, previous studies have shown that non-genetic factors are important and that the length of telomeres in human offspring is related to the father rather than the mother. For humans, the age of the father determines the length of the child’s chromosomal telomeres. The older the father, the longer the telomeres.