Forensic Science: Bringing Justice by Investigating the Past

A few years ago, while I was working at the American Association for the Advancement of Science, a man with a DNA-bedecked necktie stood before a crowd in the organization’s DC headquarters. “The double helix is my thing,” he said. “I believe in science.” The speaker, a bearded former marine and commercial fisherman, may have seemed an odd spokesman for this message—but only until you heard his story. As the first death-row inmate to be exonerated based on DNA evidence, Kirk Bloodsworth owes his very life to the power of science to peer into the past, which definitively showed  he was innocent of the rape and murder of a nine-year-old girl nearly a decade earlier.

Stories like Bloodsworth’s are compelling examples of the power of science to reconstruct the past, a power seen not only in forensics but in the science of origins as well. The connection between forensic science and evolution is hardly new; I first encountered it a number of years ago in developmental biologist Sean B. Carroll’s wonderful book The Making of the Fittest, subtitled “DNA and the Ultimate Forensic Record of Evolution.” Both evolutionary and forensic sciences attempt to reconstruct past events without the aid of eyewitness testimony, by collecting surviving clues, generating hypotheses, and testing hypotheses against the collected data.¹ For Bloodsworth, DNA testing on a long-forgotten piece of evidence matched not Bloodsworth, but another man who was then convicted of the crime after Bloodsworth’s release.

Yet you don’t have to listen in to Christianity’s ongoing origins conversation long to hear that many Christians are deeply ambivalent about the reliability of science when it investigates the past. In their zeal to counter evolutionary science, groups like Answers in Genesis (AiG) draw a hard line between what they call “observational science” (“which deals directly with the present…that builds airplanes and cell phones, and put a rover on Mars”) and “historical sciences”—those sciences, like evolution or forensics, that study contemporary clues to reconstruct past events.²

The young-earth creationist (YEC) argument here is not that historical sciences are necessarily invalid, but rather that they require interpretation and are uniquely prone to misinterpretation based on the interpreter’s pre-existing ideas. So a scientist under the spell of “man’s word” will inevitably see evidence for evolution in the fossil record, while a believer in “God’s Word” will clearly see evidence for special creation. Seeing scientific data as so interpreter-driven as to support such divergent views as evolutionary biology and young-earth creationism seems an oddly postmodernist stance for an apologetics ministry to take, but this tack has nonetheless become a cornerstone of much AiG material.³

But if historical sciences are indeed to be considered suspect, then what are we to make of the kind of forensic sciences that in 1993 cleared Bloodsworth of a murder committed nearly a decade earlier? Articles on AiG’s website describe both evolution and forensics as historical sciences. In both cases, “the facts don’t speak for themselves” but “must be interpreted,” and these interpretations can be fatally flawed. Perhaps the data was misinterpreted and did not truly support the conclusion, or perhaps the evidence was deliberately planted or tampered with to mislead investigators. Let’s consider these two possibilities as they relate to forensics and evolution.

On the first point, it certainly is true that many forensic techniques fall far short of the standards expected of rigorous science. The National Academy of Sciences and the American Association for the Advancement of Science have both in recent years published summative scientific critiques of forensic methods. Many forensic techniques are admirably rigorous (DNA matching, for one), while others turn out to be questionable if not downright shoddy (such as analysis of fingerprints, hair, or bite marks). But the NAS and AAAS reports also show that these various techniques stand or fall based on their own varying scientific merits; they are not all equally tainted simply by virtue of being “historical” sciences. And while it’s certainly true that forensic evidence can be planted or tampered with, it’s hard to see how that would translate to the origins conversation. If all the evidence for evolution and the great antiquity of the earth were deliberately planted or tampered with, that would amount to either the most extravagant of all conspiracy theories (if scientists worldwide had coordinated a two-century-long coverup), or to insurmountable theological problems (if God or even Satan were the one who planted or tweaked evidence to suggest evolution or an old earth).

Ironically, it is perhaps examples from observational sciences that most strongly illustrate the fallibility that YECs see as a feature of historical science. A prime example would be the notorious unreliability of many one-off medical research publications.⁴ Just consider the meandering conversation over the past several decades about “good fats” and “bad fats,” or whether eggs have a harmful effect on cholesterol levels. Not only is the observational science behind such research incredibly difficult, but it’s particularly susceptible to food industry pressure and bias to an extent that should certainly make us question the simplistic claims often made about the relative merits of observational and historical science.

Nor is it entirely clear that YECs themselves follow their distinction absolutely; in another article, AiG uses historical science (scientific reconstructions of past climatic trends going back to the last Ice Age) to cast doubt on consensus science on anthropogenic climate change—a heavily observational science.⁵ I don’t doubt that YECs are honestly convinced of their sharp historical/observational science distinction; but we should certainly be skeptical if the distinction seems to be selectively deployed simply to avoid consensus science that makes one uncomfortable.

The question is not whether evolutionary biology—or climate science, forensics, or nutritional science—is “historical science” or “observational/experimental science.” If we stick with these terms, evolutionary biology is really all of the above. It uncovers historical processes and causes, as well as present biological relatedness, based on repeated observation and experimentation. The real question, then, is whether or not it is good, rigorous science. And the evidence for evolution that is extraordinarily robust, convincing a worldwide “jury” of scientists, including not a few Christians, that the case has been proven beyond reasonable doubt.

Kirk Bloodsworth read about DNA testing in his cell, and what he learned compelled him to push for his case’s evidence to be reexamined using new forensic techniques that were not available at the time of his conviction. But DNA wasn’t all that he was reading about in his cell. His mother, who died while he was imprisoned, sent him a Bible which he began to read, and eventually he became a Christian while in jail. For those exploring the science-faith dialogue, there’s a kind of beauty in that, as both science and the Bible showed Bloodsworth the truths that would give him life.