Today’s New Reason To Believe

Posted by Fazale ‘Fuz’ Rana, Ph.D.

Three New Studies Support Biblical Account of Humanity’s Creation

What’s the first thing that comes to mind when you think of the state of Kentucky? Horse racing? Wildcat basketball? The Louisville Slugger? Bluegrass music? What about burgoo?

Though most people probably haven’t heard about this spicy stew, it’s as much a part of the traditions of the Bluegrass State as the Kentucky Derby. Burgoo consists of a mixture of meats (beef, chicken, pork, mutton, and game animals, if available) and vegetables cooked (and re-cooked) in a large kettle over an open flame until all the flavors meld together. No two Burgoo recipes are the same. The preparation and consumption of Burgoo serves as a center piece for social gatherings. At times the entire community contributes the ingredients to make a large pot of stew.

Molecular anthropologists have recently concocted a burgoo of their own consisting of discoveries that turn the heat up on the support for the Out-of-Africa hypothesis of human origins, and with it, the biblical account of humanity’s beginnings.*

Out of Africa Hypothesis

In a nutshell, this model (also called the replacement model) maintains that modern humans evolved recently (about 100,000 years ago) in East Africa from a small hominid population and then migrated around the world to replace pre-existing hominids. Proponents believe that Homo neanderthalensis and Homo erectus are evolutionary side branches and dead ends.

Relative Proportion of Harmful Mutations in European and African Populations

One recent study, carried out by an international team, examined genetic variation in fifteen African American and twenty European Americans. These workers characterized genetic variability by examining single nucleotide polymorphisms (SNPs) and categorizing the DNA sequence differences as benign, possibly damaging, and probably damaging.

They noted that African Americans harbor a greater degree of SNP diversity than European Americans. Interestingly, European descendents have a greater proportion of harmful variations than people with an African ancestry.

These results find explanation if humanity arose in East Africa from a small population, and recently migrated into Europe through a genetic bottleneck. Bottlenecks result when a population drops to low levels and then recovers its numbers, or if a small subpopulation becomes separated from the main group and then later grows in size.

Genetic and Copy-Number Variation

Another study characterized the genetic variability of twenty-nine populations from around the world by monitoring 525,910 SNPs and 396 copy-number differences.

Again, the patterns of genetic variability noted in these two studies for people groups from around the world fit with the predictions of the Out-of-Africa hypothesis.

A third recently reported study focused on about 650,000 SNPs found in the genomes of 938 people representing 51 populations from around the world. The SNP data clustered into a number of groups displaying a geographical relationship that indicates an African origin of humanity and subsequent spread around the world.

Overwhelming Evidence for the Out-of-Africa Hypothesis

These three new research reports can be thrown into a large simmering kettle of studies that support the Out-of-Africa model. (For a detailed discussion of the myriad evidences in favor of the Out-of-Africa Hypothesis see the book Who Was Adam? Collectively, the consensus that emerges from this work indicates that humanity originated recently (about 100,000 years ago) from East Africa (near the location theologians ascribed to the Garden of Eden) from a small population. Amazingly, studies using mitochondrial and Y chromosomal DNA markers trace humanity’s origin back to a single man and woman. These studies also indicate that humanity’s migration around the world began at or near the Middle East.

Though often presented and discussed within the context of the evolutionary paradigm, this model has profound biblical implications. In some respects, the Out-of-Africa hypothesis appears to be the biblical model awkwardly forced into the evolutionary framework, like an incorrect puzzle piece. If humanity’s genesis happened in the way described in Scripture, the genetic diversity patterns observed among people groups around the world would be very similar to those discovered by anthropologists. It looks as if Adam and Eve really existed, giving rise to all humanity.

Next week I will describe another study using DNA extracted from ancient head lice that also lends credence to the biblical account of humanity’s origin. I decided it would be best not to describe this work for now. I didn’t want to ruin anybody’s appetite.

---

___________________________________

*These studies made science news headlines when first published. I discussed the scientific and biblical implications of this research on the February 22, 2008 edition of our new podcast, RTB’s Science News Flash. This podcast offers a unique Christian perspective on headline-grabbing discoveries. A free subscription to this podcast is available through iTunes.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

Gene Splicing May Account for the Biological and Behavioral Distinctions of Humans

Chimpanzee exhibits top many people’s list of favorite zoo attractions. Watching these apes carry on delights human observers of all ages. The antics of chimps, often compared to human behavior, are not the only thing about these wonderful creatures that captivates the interest of humans. Genetic comparisons between chimps and humans generate their fair share of fascination.

The high degree of genetic similarity between humans and chimpanzees represents one of the most popular and seemingly convincing arguments for the evolutionary origin of man. Presumably, the 95-99% overlap of DNA sequences indicates that humans and chimpanzees arose from a common ancestor in the relatively recent past (about 6 million years ago).

Yet a number of other studies suggest that humans and chimpanzees may be much more genetically distinct than commonly believed. And these differences appear to show far more biological and behavioral significance than the overlap in DNA sequences. (See here and here for recent discussion on some of these genetic differences.)

New work has uncovered yet another genetic departure between humans and chimps: alternate gene splicing.

Alternate Splicing

DNA is the molecule that harbors genetic information within a cell. This information essentially consists of the instructions necessary to make and regulate the activity of all the proteins used by the cell. The region of the DNA molecule that specifies the production of a single protein chain is called a gene.

Proteins, the “workhorse” molecules of life, take part in virtually every cellular and extracellular structure and activity.

Protein production begins when the cell’s machinery makes a copy of the information housed in a gene by assembling a molecule known as messenger RNA. Once assembled, messenger RNA migrates from the nucleus of the cell into the cytoplasm. At the ribosome, messenger RNA directs the synthesis of the protein.

In humans and chimps, after messenger RNA is produced, it undergoes extensive modification before it heads to the ribosome. The final modifications to messenger RNA involve the so-called splicing reactions. In eukaryotes, the sequences that make up a gene consist of stretches that code for part of the protein (called exons) interrupted by sequences that don’t code for anything (called introns). After the gene is copied by assembling the messenger RNA, the intron sequences are excised from the messenger RNA and the exons spliced together. A RNA-protein complex called a spliceosome mediates this process.

Remarkably, the spliceosome can splice a single messenger RNA in different ways to produce a range of functional proteins. Known as alternate splicing, this variation is possible because the spliceosome does not necessarily use all the splice sites. Structuring genes to contain non-coding regions (introns) interspersed between coding regions (exons) serves as an elegant strategy that allows a single gene to simultaneously house the information to produce a range of proteins.

Chimps and Humans Differ in Alternate Splicing

For the first time, researchers have examined differences in alternate splicing between humans and chimpanzees. Even though no one had previously compared alternate splicing in humans and chimpanzees, researchers hoped to see differences, since about two-thirds of genes in humans and mice undergo alternate splicing and complex alternate splicing reactions are unique to tissues and organs.

The researchers discovered that a significant proportion of alternate splicing reactions in humans, chimps, and mice are highly similar. From an evolutionary perspective, this means that the splicing reactions haven’t evolved over the span of 80-90 million years. This makes sense. Splicing is an extremely precise process. Mistakes in splicing are responsible for some human diseases. Medical disorders, such as atherosclerosis, cardiomyopathy, and myotonic dystrophy, result because splicing errors fatally distort or destroy the information—temporarily stored in messenger RNA—needed to assemble protein chains at ribosomes. And improperly produced proteins cannot carry out their functional role in the cell.

In spite of what appears to be the resistance of alternate splicing patterns to evolve, the researchers also noted that six to eight percent of the genes examined in their study displayed differences in alternate splicing patterns in humans and chimps. And it appears that these differences evolved rapidly. The alternate splicing differences were observed for both brain and heart tissues and involve genes that take part in diverse functions. These results suggest that differences in alternate splicing patterns could account for some of the biological and behavioral differences between humans and chimps.

More and more, it appears that humans and chimps display key genetic differences where it counts. And these differences explain why humans visit the chimpanzee exhibit at the zoo, and not the other way around. For more information on these kinds of genetic comparisons between humans and chimps and how they fit into a biblical framework see an article I wrote for a recent issue of Connections or the book Who Was Adam?