Scholars have measured the ‘fitness cost’ by extricating information from about 22,000 couples in the 19th century. It is the value that the parents pay in their own health and longevity for the privilege of their genes to live on in future generations.
The investigation revealed that:
1. aged women in comparison to men were more prone to die after having a child
2. women who had many children died prior than women who had few
Study showed that fathering too, affected the ‘fitness cost’. Since, fathering many children would be directly proportional to their longevity, which corresponds fathering more children, meant more risk of dying before their time.
Even children had to pay the price of ‘fitness cost’. It stated that youngest child in a family had lesser chances of surviving into adulthood and themselves becoming parents than their elder siblings. In addition, losing a mother raised every child’s risk of dying at a younger age.
The researchers collected the data from Church of Jesus Christ of Latter-day Saints in Salt Lake City. They analyzed the reproductive history and survival of more than 20,000 couples married between 1860 and 1895.
The data obtained were:
1. approximately, the duos bore 175,000 children
2. women’s average age at the birth of last child was 39 years
3. about 1,400 of them died within a year of delivering their last baby, and 2,400 within five years
4. for men, the corresponding numbers were about 600 and 1,700
5. nearly 18% of the children died by age 18
Thus, scholars concluded that longevity of parents would be less if the number of progeny were large. And that woman would suffer more than their partners would.
They also concluded that if a child loses either his mother or father at a very young age, then his life span too decreases and thus, he faces an early death.
