Your First Breath Was Irreducibly Complex
Multiple changes had to take place on cue when you came out of the womb.
Baby’s first breath: it’s an unforgettable moment every parent cherishes. We each went through that transition from inside the womb to enter the outside world. When you think about it, though, it’s a radical change, far more than just emerging out of a birth canal. It requires going from a non-breathing creature in a fluid environment to an air-breathing creature in an oxygen atmosphere – in an instant, using lungs for the first time that had grown in a fluid-nourished world. Randy Guliuzza, MD, dazzled readers a few years ago in an ICR article about all the changes that must take place at that moment:
For a baby in the womb, almost everything about those vital functions is just the opposite for one important reason: the baby develops fully functional lungs that are yet inactive for oxygen exchange. Consequently, in order for a baby to survive, three major structural differences must exist that enable life in his temporary home.
First, the baby must have a substitute lung–a pretty tall order for even brilliant biomedical engineers. The placenta, a remarkable organ, has a brief existence, but it fulfills a myriad of vital functions–especially as the fetal lung and kidney. Second, the circuit to the lungs must be bypassed, so vessels must change to allow this temporary detour. (A new route that detours around a circuit is called a shunt.) Third, blood vessels must not only connect placenta to baby, but also inside from the point of attachment to normal vessels that lead to and from the heart. The umbilical cord meets the need for a placental-fetal connection, with one large-diameter vein and two smaller arteries. Inside the baby, these continue as the umbilical vein and umbilical arteries. (Italics in original)
Guliuzza goes on to describe how these structures and functions get rearranged at birth. “Less than a minute after birth, signals from baby’s nervous system cause strong sphincter muscles to close off the umbilical vein where it attaches near the liver and also close off the temporary pulmonary artery-aorta shunt,” he says. “(That large vessel permanently closes over the next one to two days.)”
A new paper in PNAS adds to the wonder of this dramatic switch. A team primarily of researchers in France discovered the role of two proteins in the signaling pathway that closes this shunt of blood from the umbilical cord to the baby’s own pulmonary system:
The transition to pulmonary respiration after birth requires rapid alterations in the structure of the mammalian cardiovascular system. One dramatic change that occurs is the closure of the ductus arteriosus (DA), an arterial connection in the fetus that directs blood flow away from the pulmonary circulation. Two members of the TGFβ family, bone morphogenetic protein 9 (BMP9) and BMP10, have been recently involved in postnatal angiogenesis, both being necessary for remodeling of newly formed microvascular beds.
If missing or mutated, they found by experimenting with mice, those proteins (BMP9 and BMP10), fail to close the DA duct, leading to physiological crisis or death. These proteins, furthermore, are regulated by eight genes on chromosome 2. Although not apparently involved in the initial functional closure of the DA, they are important for the anatomical closure that completes within 24 hours. Failure of that step is a leading cause of death in premature births, but is rare in normal births, they indicate. It involves a “profound remodeling of cells within the former DA lumen” as the signaling cascade recruits epithelial cells, new blood vessels and other tissues in a high speed reconstruction program that must hold for the newborn’s lifetime, potentially 100 years or more.
The authors make no attempt to explain how this system evolved. Indeed, how could they? Since natural selection depends on reproduction, a failure in any component of this complex transition would prevent the newborn from passing on any beneficial mutations (if it received any by luck) to the next generation. The system appears irreducibly complex, since all of the parts are required at the moment of birth and could not have been accumulated gradually.
Need evidence for creation? Look in the mirror. At birth, your tiny body underwent a rapid reconstruction program without you having to think about it, and without your parents having to think about it. Then you grew up to be an order of magnitude larger, and that reconstructed circulatory system grew with you without a breakdown. This is one of thousands of wonders in your own body that defy evolution. Read Guliuzza’s article with the new PNAS finding in mind, and then do the right thing: glorify God, and be thankful (Romans 1:18-21).