Large numbers of the public (more than 40% of Americans, according to a recent poll) firmly subscribe to a creationist worldview — the earth is only a few thousand years old; fossils are the remnants of creatures that perished in Noah’s flood; and species (including humans) have not evolved significantly since their individual creation. Many such people have never seriously investigated the scientific evidence, or feel that modern evolutionary theory can be dismissed because it is “only a theory.” But those who more seriously confront the scientific evidence, as well as the many authors (professional and amateur) who write books, articles, web columns and blogs defending the creationist worldview, have a daunting and unenviable task, a task that is made more problematic with every new fossil find, geochronological measurement or cross-species DNA study.
As a single example, serious creationists must confront the proliferation of hominin fossil finds in recent years, since such fossils pose a particularly acute challenge to the all-important notion that humans have been created apart from all other creatures (“special creation”). The following graphic shows the hominin family tree according to a recent compilation by Ian Tattersall: Graphic.
Creationists have typically dealt with these finds by classifying them as “human” or “ape.” However, various creationist authors have utterly failed to agree among themselves which specimens should be classified in which categories. For example, a table available at [Prehuman-fossils] shows six hominin fossils classified by several groups of creationist writers. The classifications range, quite literally, from all ape to all human, with five mixed versions in between. As biologist Ken Miller wryly notes of this disarray, “Ironically, validation of our common ancestry with other primates comes directly from those who are most critical of the idea.” [Miller2008, pg. 95].
Now creationists must face DNA evidence. The first complete human genome sequence was completed in 2000, after a ten-year effort that cost over $500 million U.S. dollars. But genome sequencing technology is advancing very rapidly — at least twice as fast as Moore’s Law (the observation that a wide range of computer hardware devices roughly double in capacity every 18 months to two years). Human genomes can already be sequenced for roughly $100,000, and several labs and private firms are racing to win the “X Prize” for demonstrating a technology with a cost of less than $10,000. And other teams are targeting $1,000 [Pollack2008]. Soon genome sequencing will be a standard part of modern biology and medicine.
Thus it was inevitable that genome sequencing and DNA analysis would make its mark in hominin research. In March 2010, scientists announced that as a result of analyzing mitochondrial DNA (mtDNA) found in a bone in Siberia, they have identified a new hominin species that co-existed with humans until as recently as 50,000 years ago, yet is roughly twice as distant (measured in terms of the time since a common ancestor) from modern humans as Neanderthal man. As explained in a Scientific American report [Wong2010],
Comparing the order of the genetic “letters”—or base-pairs, as they are termed—making up the Denisova [Siberian] mtDNA with the sequences of modern day humans and an early modern human, Krause and his collaborators found that the Denisova mtDNA differed from humans today in nearly twice as many letter positions as Neandertal mtDNAs do. Further analysis indicated that the most recent common mtDNA ancestor of the Denisova individual, Neandertals and modern humans dates to around a million years ago (making it twice as old as the most recent common mtDNA ancestor of Neandertals and moderns). This divergence date, the team says, indicates that the Denisova mtDNA is distinct from that of the H. erectus population that left Africa 1.9 million years ago, and also from that of the Neandertal ancestor H. heidelbergensis, which branched off from the lineage leading to modern humans around 466,000 years ago. As such, the researchers contend the Denisova mtDNA reveals a previously unrecognized migration out of Africa by a hitherto unknown group of hominins.
We are at the cusp of an explosion in DNA data, not only from ancient hominins but from many living species as well. Already, many inter-species studies have been done [SMR-DNA]. In addition, scientists are analyzing DNA sequences using employing advanced statistical methods (e.g., “maximum likelihood analysis”), running on powerful computer systems, to reconstruct the most likely family tree for a given set of organisms. Soon much of evolutionary history will be deducible purely from DNA analyses. Will this coming avalanche of scientific studies, not to mention numerous new hominin species already found, convince the die-hard creationists?
While those who defend creationism are entitled to their views, in my view it is most unfortunate that so many intelligent people have expended so much time and energy defending such a hopeless cause. I hope we will see the day that such people join thoughtful scientists in a meaningful dialogue as to the meaning of religion in an age of science. Both communities have much to gain.
- [Miller2008] Kenneth R. Miller, Only a Theory: Evolution and the Battle for America’s Soul, Viking, New York, 2008.
- [Pollack2008] Andrew Pollack, “The Race to Read Genomes on a Shoestring, Relatively Speaking,” New York Times, 9 Feb 2008, available at Online article.
- [SMR-DNA] “What do modern studies of biological proteins and DNA among different species tell us about evolution?”, available at Online article.
- [SMR-prehuman-fossils] “Are there missing links in the fossil record between ancient primates and modern humans?”, available at Online article.
- [Wong2010] Kate Wong, “No Bones about It: Ancient DNA from Siberia Hints at Previously Unknown Human Relative,” Scientific American, 24 Mar 2010, available at Online article.
