Placental Development Triggered by Genomic Parasites

Prefabricated package of genes prompts placental development.

Placental mammals and marsupial mammals are believed by evolutionists to have diverged from a common ancestor more than 100 million years ago. Now a Yale research team has unveiled the essential genetic difference that enables placental mammals to nurture their young in utero.

They discovered a 1532 gene unit1 regulated by a transposon. Transposons are bits of so-called “junk DNA” which can appear at various places in the genome and sometimes function in a regulatory capacity. Transposons have been likened to prefabricated cut-and-paste genetic parts. Because they resemble viruses, some evolutionists assume they entered the genome of some ancestor as a parasite and contributed either positively or negatively to the evolution of the organism.

“In the last two decades there have been dramatic changes in our understanding of how evolution works,” said Gunter Wagner, the senior author of the paper published in Nature Genetics. “We used to believe that changes only took place through small mutations in our DNA that accumulated over time. But in this case we found a huge cut-and-paste operation that altered wide areas of the genome to create large-scale morphological change.”

By comparing the genomes of marsupial opossums to the genomes of armadillos and humans—two placental mammals—the Yale team discovered the placental mammals each possessed a large block of genes that are only expressed in the uterine lining of placentals. About 13% of those genes are part of the non-coding transposon that regulates their expression.

“Transposons grow like parasites that have invaded the body, multiplying and taking up space in the genome,” said lead author Vincent J. Lynch, but this transposon activates the genes that enable the uterus to respond to hormonal signals and develop a placenta.

“These transposons are not genes that underwent small changes over long periods of time and eventually grew into their new role during pregnancy,” Lynch added. “They are more like prefabricated regulatory units that install themselves into a host genome, which then recycles them to carry out entirely new functions like facilitating maternal-fetal communication.” Thus, the researchers contend that “the evolution of pregnancy was associated with a large-scale rewiring of the gene regulatory network.”2

Evolutionists debate the origin of transposons. Such a transposon—if it were the evolutionary marvel so claimed—would be the agent of giant evolutionary leaps. Microorganisms are designed to horizontally transfer genomic islands of information, but such a process is not seen in mammals. Furthermore, when evolutionists make such a claim, they leave open a new question: namely, where did the information in the transposon come from?

What the research team has in fact uncovered is not the genomic parasite that gave placental mammals the ability to branch off on the phylogenetic tree but a genetic package designed by God to equip creatures He designed to be placental mammals to form placentas. And the presence of a similar chunk of 1532 genes in both humans and armadillos does not imply we share an evolutionary ancestor. It instead supports the biblical truth that we share a Common Designer who used the same package of gene regulators to enable those placental functions needed in both.

Read more about how “junk DNA” can be God’s tool at “‘Junk’ DNA: Evolutionary Discards or God’s Tools?.”

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  1. Vincent J. Lynch et al., “Transposon-mediated Rewiring of Gene Regulatory Networks Contributed to the Evolution of Pregnancy in Mammals,” Nature Genetics 43 (2011): 1154–1159, doi:10.1038/ng.917.
  2. Ibid.


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