Recent scientific studies have concluded that all living humans appear to be descended from a single set of parents who lived much more recently than would have been expected by those who hold to the theory of evolution. The most recent of these studies, by M.Y. Stoeckle and D.S. Thaler, found that the same applies to virtually every species on the planet. Decision asked professor David DeWitt, chair of the department of biology and chemistry at Liberty University, to evaluate the findings from a Biblical perspective.
Although more than 7 billion people are living today on earth, genetically, we are all remarkably similar. Regardless of nationality, ethnic group or skin tone, all humans share nearly all of their DNA in common.
For a scientist like me who holds a high view of the Bible and its origin claims, it is very significant that recent studies have found that each species, including humans, seems to have had a unique set of parents, all about 100,000 years ago.
But before we go further, let’s look at the science behind these studies.
The earth contains a vast array of amazing creatures, from the octopus in the ocean depths to the eagle that soars through the air. Animals range in size from the towering giraffe to the lowly ant, and they thrive in habitats from the swamp to the arctic. And they come in a variety of sizes, shapes, colors and behaviors. One of the goals of biology is to catalog and understand this diversity of life. With so many different organisms, this is no small task!
The current classification system for animals (naming by genus and species) was developed by Carl Linnaeus in the 1700s, but people were studying the living world long before that. King Solomon learned much from the study of creation, as 1 Kings 4:33 says: “He spoke of trees, from the cedar that is in Lebanon to the hyssop that grows out of the wall. He spoke also of beasts, and of birds, and of reptiles, and of fish.” The first person to classify and name creatures was Adam, the first human. The Book of Genesis tells how God brought all of the animals to Adam to see what he would name them. This first job is ongoing, as biologists are still classifying and naming organisms.
Recently, some scientists have been using DNA “barcodes” to identify species. Just like the familiar black and white bars on items at a store are used at the checkout to identify an item, a DNA barcode would indicate to which species an individual organism belonged. But unlike the UPC codes on packaging, these DNA barcodes are actually just a specific string of DNA nucleotides. The use of DNA barcodes as a means of species identification was first suggested in 2003.
Now, stay with me. Although the human genome—the complete genetic makeup of humans—contains some 3 billion of what are called “DNA bases” and some 20,000 genes, the DNA barcode is derived from a subset of the DNA bases in just one gene: Cytochrome Oxidase subunit I (COX I). This gene is found in mitochondria, which are bacterial-sized structures inside many of the cells in our body. While most of our DNA is found in the nuclei of our cells, a small amount of DNA is also contained in our mitochondria.
And because mitochondria are essentially only passed from mother to offspring, mitochondrial genes are not combined and shuffled like genes found in the nucleus, which come from both mother and father. This makes mitochondrial genes better for use as a DNA barcode to identify species.
Stoeckle and Thaler analyzed the DNA barcodes from 5 million individual organisms, representing some 100,000 different species, with an eye toward evaluating whether this barcode can indeed function as a species identifier.
The results were striking: Barcode variation within each species was tightly clustered within the species, with wide gaps between them. In other words, variation of the barcode within the species represents individual “islands” with nothing connecting them. This result parallels the fossil record, which is characterized by clusters of variation with gaps between the clusters.
Because of this tightly constrained variation in the barcodes, it appears that virtually all species of animals—regardless of population size or similarity to fossils—descend from unique ancestors, at roughly the same time.
This would suggest that at some point, humans and all species of animals went through a severe population bottleneck, followed by a population expansion from roughly the same time frame. This tells us that the entire population of each species was restarted by a single mother for that species. Otherwise, we would expect to find a much wider range of mitochondrial gene variation among different organisms. Given the various habitats and types of species, it is difficult to imagine the circumstances that would induce a universal bottleneck. However, the Bible describes one such bottleneck that would be capable of a global reset of animal diversity—the flood at the time of Noah.
Importantly, while studies suggest that all living humans have descended from a single woman who existed 100,000 years ago, the actual age could be much less—as little as 10,000 years or less. In order to arrive at 100,000 years, scientists make several unprovable assumptions regarding the mutation rate and starting size of the population. Slight changes in these variables could result in an age more consistent with young earth creation. Indeed, a previous study that used an empirically measured mutation rate for mitochondria resulted in far younger ancestors. If the same held for other species, it would be strong evidence in support of young earth creation.
The bottom line is that the Bible tells us the evidence for a Creator God can be clearly seen and understood from what has been made (see Romans 1:19-20). The Creator filled the earth with all species of animals, and He also created humans. But humans sinned, and sin separates us from God and condemns us to an eternity apart from Him. So God sent His Son to save us by dying on the cross and rising from the dead so that all who believe in Him can inherit eternal life. ©2018 David A. DeWitt
The Scripture quotation is taken from The Holy Bible, English Standard Version.
David A. DeWitt, Ph.D., is chair of the department of biology and chemistry at Liberty University. He is the author of the book “Unraveling the Origins Controversy” as well as numerous scientific articles.