Science and Technology Daily News (Reporter Liu Xia) According to a recent report by the physicist organization network, a new international cooperation study conducted by researchers from Australia, the United Kingdom and the United States shows that as a result of the evolutionary response to the decline in embryo vigor, women in 30 When you are many years old, you are more likely to conceive fraternal twins.
Women are more likely to conceive twins in the middle of reproductive life, but the reason behind it has always been an unsolved mystery. Now, the researchers explain the evolutionary history behind this phenomenon in the journal Nature, Ecology and Evolution.
Joseph Tomkins, an associate professor at the University of Western Australia ’s School of Biological Sciences, said: “Double ovulation—that is, the frequency of ovulation of two eggs during a menstrual cycle continues to evolve to maintain female fertility. Our latest research shows that The evolutionary response to the decline in the viability of the related embryos, as the female age increases, the possibility of emitting two eggs also increases. "
Over the past few decades, the frequency of fraternal twins has increased in many countries due to improved assisted pregnancy techniques, improved nutrition, and delayed childbearing age.
To explain how twin birth rates rise and fall with the age of the mother, Tomkins and colleague Robert Black collaborated with researchers at the University of Diebold in the United States and the London School of Hygiene and Tropical Medicine in the United Kingdom to use mathematical methods for modeling. They found that most women may emit two eggs in each cycle of reproductive life, but only a small proportion of them conceive and give birth to twins.
Tomkins said: "This research we conducted proves that in the ancestral population, evolution tends to choose two eggs to be discharged, but only one child is born, which shows that fraternal twins are a byproduct of fertility choices, not an increase. A way to have a population. "
The researchers say that as more and more women postpone the age of childbearing, the proportion of fraternal twins is also increasing. This study provides important insights into how evolution affects modern life.