Geneticists continue to research an issue of great interest to creationists. As this article at PhysOrg tells us: Common genetic ancestors lived during roughly same time period. They say:
Mitochondrial Eve and Y-chromosomal Adam — two individuals who passed down a portion of their genomes to the vast expanse of humanity — are known as our most recent common ancestors, or MRCAs. But many aspects of their existence, including when they lived, are shrouded in mystery.
Now, a study led by the Stanford University School of Medicine indicates the two roughly overlapped during evolutionary time: from between 120,000 to 156,000 years ago for the man, and between 99,000 and 148,000 years ago for the woman.
Even with a possible overlap, that’s not a result creationists want to hear. They also don’t want to hear this:
Despite the Adam and Eve monikers, which evoke a single couple whose children peopled the world, it is extremely unlikely that the male and female MRCAs were exact contemporaries. And they weren’t the only man and woman alive at the time, or the only people to have present-day descendants. These two individuals simply had the good fortune of successfully passing on specific portions of their DNA, called the Y chromosome and the mitochondrial genome, through the millennia to most of us, while the corresponding sequences of others have largely died out due to natural selection or a random process called genetic drift.
We’ll let you read that article by yourself. Also, here’s a link to the paper in Science: Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females. You need a subscription to read more than the abstract. We mention it because we have a great creationist reaction to that research.
This comes from the creation scientists at the Institute for Creation Research (ICR). They’re described in the Cast of Characters section of our Intro page. ICR’s article is Does ‘Y-Chromosome Adam’ Refute Genesis?
ICR’s article was written by Nathaniel T. Jeanson, described at the end as: “Deputy Director for Life Sciences Research [presumably at ICR] and received his Ph.D. in cell and developmental biology from Harvard University.”
We’ll skip ICR’s description of what the scientists found, and take you right to their interpretation. Here are some excerpts, with bold font added by us:
Secular geneticists believe that modern humans can trace their male genetic ancestry back to one man and their female genetic ancestry back to one woman. Two new studies suggest that female “mitochondrial Eve” and male “Y-chromosome Adam” lived a couple hundred thousand years ago. However, the assumptions researchers used to reach this dating concordance demonstrate the circular reasoning that is common in evolutionary age calculations.
Circular reasoning? That’s horrible! But ICR often slings that accusation around. As we’ve pointed out before, creationists actually endorse circular reasoning (see AIG’s Logic: Prepare To Lose Your Mind).
By the way, ICR mentions a few recent studies. We’ve only linked to one. They have the same objections to all of them. Let’s read on:
For example, rather than directly measuring mutation rates in various ethnicities, the authors assumed a constant rate across ethnicities. Previously published research undermines this assumption.
We haven’t looked into that. It wouldn’t matter for our purposes, because we’re certain that no reading of the mutational clock would be favorable to ICR, so that’s a trivial objection. They continue:
The authors also assumed a constant rate of change through time. Yet, the environmental changes associated with the Flood of Noah (e.g., possible accelerated radiometric decay) may have affected the rates of DNA change. Furthermore, in the approximately 4,000 years that have elapsed since the Flood, why should we assume that the human genetic mutation rate has been uniform?
That’s a powerful objection. They’re probably correct in assuming that the scientists didn’t consider that the Flood may have changed the laws of nuclear physics (we didn’t realize water could have that effect), but they also ignored the possibility that rate at which mutations occur may have significantly changed. Actually, the mutation rate had to be super-fast after the Flood, in order that the few “kinds” Noah took aboard the Ark could generate all the millions of species we see today. Here’s more:
Finally, the authors calibrated their molecular data to archaeological “dates.” These age assignments depend on notoriously unreliable radiometric dating techniques and thus are not independent validations for the molecular data.
Yet another flaw in the scientists’ work. This is really devastating! Here’s ICR’s conclusion:
All molecular-clock calculations require the observer to speculate about the past, and the Science study authors selected assumptions based on their model of evolutionary deep time, resulting in circular reasoning. Clearly, the hundred-thousand-year dates for “Y-chromosome Adam” and “mitochondrial Eve” do not bear up under careful scrutiny.
Those guys at ICR are fantastic. Creation science triumphs again!
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