Passing over Scientific Problems with Evolution – Discovery Institute

Photo: Skull fragment, Homo erectus, by Commie cretan (Own work) [CC BY-SA 3.0], via Wikimedia Commons.

Editors note: In a multipart series, Casey Luskin is reviewing a new book by philosopher William Lane Craig.Look here for the full review so far.

In his bookIn Quest of the Historical Adam, William Lane Craigs rhetorical strategy is essentially to accept whatever mainstream evolutionary paleoanthropology says, and see if Adam and Eve can still stand. As heput itin an interview withChristianity Today, his hope [is] that, by showing there is no incompatibility between contemporary evolutionary science and the affirmation of a single human pair at the headwaters of the human race, we can prevent that obstacle to faith. Even a review of the book in the journal Science observes that Craig takes evolution as a given. In locating Adam and Eve within the speciesHomo heidelbergensis, Craigs goal is to present a position of reasonable faith, and his tactical approach could indeed be useful for those who want to claim that the Bible is not in contradiction with mainstream evolutionary science. Thats fine as far as it goes. But this strategy means that sometimes Craig assents to evolutionary assumptions and arguments that are highly dubious, and he misses opportunities to point out severe weaknesses in evolutionary models.

Craig focuses on various crucial genetic mutation[s] which occurred in the human lineage since our last common ancestor with chimpanzees. These could explain the extraordinary expansion of the brain unique to human beings. His primary examples involve a single base pair substitution in the geneARHGAP11Band three human-specificNOTCh2NLgenes (pp. 277, 278). He acknowledges that we do not know if these mutations had any direct effect on language ability. Yet he later cites human-specific features of two other genes that may be necessary for speech. These genes areAUTS2(which Craig admits has an unknown function), andFOXP2(which Craig argues seems to be necessary for human speech) (p. 325). In 2018 theFOXP2 story was discredited because the genetic signal that was thought to exist in the gene turned out to be a false statistical artifact,1 making it surprising that Craig continues to cite it.

Thus, aside from FOXP2 (which has been discredited), its not entirely clear what import these genetic traits have for human language and cognition. But lets assume for the sake of argument that all of these mutations are necessary though surely not sufficient to explain humanitys advanced cognitive and linguistic abilities. Craig never makes it exactly clear whether he views these mutations as arising and spreading via standard evolutionary mechanisms, or as having been guided by Gods intervention in the natural world. At one point he suggests the mutations could be divinely caused (p. 307), but his general framing lacks such qualifications, suggesting they are ordinary mutations that arose via standard evolutionary mechanisms. Writing in First Things, Craig proposes that God selected two [hominids] and furnished them with intellects by renovating their brains and endowing them with rational souls which sounds like divinely caused mutations. In his book he is open to divine causation in the creation of Adam and Eve, but does not seem strongly committed to it:

The radical transition effected in the founding pair that lifted them to the human level plausibly involved both biological and spiritual renovation, perhaps divinely caused. (p. 376, emphasis added)

In First Things Craig then proposes that Adam and Eve were not as cognitively advanced as modern humans, and postulates that humanity experienced standard evolutionary changes after Adam and Eve including some that would emerge slowly through environmental niche construction and gene-cultural coevolution to evolve the more advanced brains we have today.2What this suggests is that not only does Craig seem to propose or allow that many (if not all) of humanitys intellectual abilities evolved via natural mechanisms, but he effectively believes we evolved upward after Adam and Eve a model which contrasts sharply with the traditional Christian view that humanity has fallen from Adam and Eves initial state.

In his book its never quite clear if Craig thinks that the specific mutations he discusses occurred via standard evolutionary mechanisms, Gods direct intervention, or some kind of hybrid of the two. To give one of multiple examples, he says, The most plausible scenario is that in a common ancestor of humans, Neanderthals, and Denisovans, the ancestral PDE4DIP-NOTCH2NL pseudogene was repaired by an ectopic gene conversion from NOTCH2. This event may have been crucial to human evolution (p. 279) To give another example, when discussing ARHGAP11B, he writes that Neanderthals, Denisovans, and humans:

share in this crucial genetic mutation that helps to explain the extraordinary expansion of the brain unique to human beings. Indeed, since the mutation occurred in the species ancestral to Neanderthals, Denisovans, andHomo sapiens, these findings are consistent with the humanity of someone belonging to a large-brained ancestral species likeHomo heidelbergensis, in which the mutation occurred. (p. 278)

Perhaps these mutations were divinely caused. Yet in this retelling, whatever divine causation might mean (in Craigs view), it appears indistinguishable from standard evolutionary explanations. Lets set aside Craigs ambiguity about what he means and just ask: What is the raw data here and does it demand assent to an evolutionary view?

At most, the data he cites simply shows that humans, Neanderthals, and Denisovans share certain similar genes and genetic traits which are involved in our brain development and linguistic abilities genes and genetic traits not found in living apes. This is not at all surprising since Neanderthals and Denisovans were highly similar to us, are thought to have had advanced cognitive abilities, and may even belong within our own speciesHomo sapiens. The evidence he recounts is not evidence of evolution. Rather, it simply identifies human-specific genetic features that probably help endow us with our advanced cognitive abilities. Merely identifying important genetic traits does not necessarily tell us that they arose by blind evolutionary mechanisms. After all, these traits could have been intelligently designed or even specially created by God in the creation of Adam and Eve.

But Craigs arguments typically seem to treat these mutations no differently from blind evolutionary events, which suddenly produced humanlike intelligence in some early hominid. Those of us who have been around the debate over evolution for a while have heard these kinds of miracle mutation stories before, and we have multiple reasons to be skeptical.

First, miracle mutation accounts of the origin of human cognition imply a teleology and design to evolution that contradict an unguided evolutionary story. If our cognitive abilities suddenly evolved by just one or two single mutational events, that implies that our profound human intelligence was sitting on a precipice, just waiting for certain specific mutations to occur before modern human minds could arise. But how did our minds get to that evolutionary precipice, where just one or two mutations could produce everything from Lao Tzu to Beethoven to Einstein? The idea implies a teleological, directed, and designed course to the origin of our cognition. Craig seems open to this option, but he never says it is his preference.

Second, miracle mutation accounts of the origin of human cognition lack credibility and often go belly-up upon closer scrutiny. InThe Language of God, Francis Collins asserted that a few specific changes inFOXP2somehow created our major linguistic abilities.3An article inTimeMagazine that same year similarly asserted that two mutations inFOXP2could have caused the emergence of all aspects of human speech, from a babys first words to a Robin Williams monologue.4More recently Yuval Noah Harari argued in his bookSapiensthat humans experienced some kind of a Tree of Knowledge mutation that occurred due to pure chance and caused a cognitive revolution.5

Such arguments that one or a few random mutations magically created humanitys advanced intellectual abilities strain credulity. The origin of human cognition and speech would have required many changes that represent a suite of complex interdependent traits. Two leading evolutionists writing in a prominent text on primate origins explain that human language could not evolve in an abrupt manner, genetically speaking, because many genetic changes would be necessary:

Bickertons proposal of a single-gene mutation is, I think, too simplistic. Too many factors are involved in language learning production, perception, comprehension, syntax, usage, symbols, cognition for language to be the result of a single mutation event.6

Humans are quite different because they possess language, which underlies every major intellectual achievement of humanity. This discontinuity theory is implausible because evolution cannot proceed by inspired jumps, only by accretion of beneficial variants of what went before.7

These authors are correct to reject such single mutation event hypotheses and would be justified in doing the same for two or three mutation events because human cognition is vastly too complex to arise in such a fashion.

Third, Darwinian evolution claims that these traits must arise and spread via random mutation acted upon by natural selection (and other standard evolutionary mechanisms such as genetic drift) blind processes that operate without any intelligent oversight. Such a blind trial-and-error mechanism is highly inefficient at producing new features that require multiple mutations in order to provide an advantage. This is especially true when it comes to an advanced biological feature such as human intelligence, which probably requires numerous complex genetic traits. This suggests a potential challenge to the neo-Darwinian evolution of human intelligence.

To understand this challenge, lets consider a seemingly simple example. In 2004 a study inNatureproposed that a single mutation that inactivated a protein could cause marked size reductions in individual muscle fibres and entire masticatory muscles leading to loss of masticatory strength,8which could have loosened jaw muscles, allowing our brains to grow larger. A news story widely circulated, titled Missing link found in gene mutation, framed the finding this way: an ancient genetic mutation for weaker jaws helped increase brain size, a twist that first separated the earliest humans from their apelike ancestors.9The story sounds plausible, but theres more to it. Leading paleoanthropologist Bernard Wood noted that this mutation alone could never have provided a selectable advantage, and would have required additional changes:

The mutation would have reduced the Darwinian fitness of those individuals. It only wouldve become fixed if it coincided with mutations that reduced tooth size, jaw size and increased brain size. What are the chances of that?

We thus have a situation where multiple coordinated mutations would be necessary to provide the advantage. Yet a 2008 population genetics study inGeneticsfound that to obtain only two specific mutations via Darwinian evolution, for humans with a much smaller effective population size, this type of change would take > 100 million years. The authors admitted this was very unlikely to occur on a reasonable timescale.10In other words, when a trait requires multiple mutations before an advantage is gained, it would require more than 100 million years within a species such as ours.

Craig did not cite the above example in his book, but it is highly analogous to the examples he does raise. He cites at least three mutational events (some of which might themselves have required multiple point mutations) as necessary for the advent of human intelligence. Undoubtedly, numerous complex mutational events would be required to transition from the apelike australopithecine intellect of our supposed ancestors to modern human cognition. If theGeneticspaper cited above is correct, then if among these events, just two point mutations were ever required to yield an advantage, they would be extremely unlikely to arise via blind evolution in a population of hominids on the timescale allowed by the fossil record (i.e., ~750,000 years since the appearance ofHomo heidelbergensis, or ~2.5 million years since our genusHomosupposedly evolved from australopithecines).

This represents a potent challenge to the neo-Darwinian evolution of human cognition that flows directly out of the mathematics of population genetics. Unfortunately, because Craig never directly disputes mainstream evolutionary theory, his readers miss out on an opportunity to hear about this powerful challenge to neo-Darwinism.

Craig doesnt spend much time discussing the origin of the genusHomo, although he does cite anthropologist Ian Tattersall, arguing for the futility of trying to divide what is now a very extensive hominid record between australopiths andHomo (p. 256). In his quest to fit Adam and Eve within mainstream evolutionary science, he misses another major opportunity to point out a serious deficiency in the evidence for human evolution: the lack of fossil evidence documenting a transition from the ape-like australopithecines to the human-likeHomo. This gap in the fossil record is well attested in the literature.

OneNaturepaper noted that earlyHomo erectusshows such a radical departure from previous forms ofHomo(such asH. habilis) in its height, reduced sexual dimorphism, long limbs and modern body proportions that it is hard at present to identify its immediate ancestry in east Africa11 or anywhere else for that matter. Another review similarly notes, it is this seemingly abrupt appearance ofH. erectusthat has led to suggestions of a possible origin outside Africa.12Likewise, a paper in theJournal of Molecular Biology and Evolutionfound thatHomoandAustralopithecusdiffer significantly in brain size, dental function, increased cranial buttressing, expanded body height, visual, and respiratory changes, stating:

We, like many others, interpret the anatomical evidence to show that earlyH. sapienswas significantly and dramatically different from australopithecines in virtually every element of its skeleton and every remnant of its behavior.

Noting these many differences, the study called the origin of humans, a real acceleration of evolutionary change from the more slowly changing pace of australopithecine evolution. It stated that such a transformation would have required radical changes: The anatomy of the earliestH. sapienssample indicates significant modifications of the ancestral genome and is not simply an extension of evolutionary trends in an earlier australopithecine lineage throughout the Pliocene. In fact, its combination of features never appears earlier. These rapid and unique changes are termed a genetic revolution where no australopithecine species is obviously transitional.13

For those unconstrained by an evolutionary paradigm, its not obvious that this transition took place at all. The stark lack of fossil evidence for this hypothesized transition is confirmed by three Harvard paleoanthropologists:

Of the various transitions that occurred during human evolution, the transition fromAustralopithecustoHomowas undoubtedly one of the most critical in its magnitude and consequences. As with many key evolutionary events, there is both good and bad news. First, the bad news is that many details of this transition are obscure because of the paucity of the fossil and archaeological records.

As for the good news, they admit: [A]lthough we lack many details about exactly how, when, and where the transition occurred fromAustralopithecustoHomo, we have sufficient data from before and after the transition to make some inferences about the overall nature of key changes that did occur.14In other words, the fossil record shows ape-like australopithecines (before), and human-likeHomo(after), but not fossils documenting a transition between them. In the absence of intermediates, we are left with inferences of a transition based strictly upon the assumption of evolution that an undocumented transition must have occurred somehow, sometime, and someplace. Evolutionists assume this transition happened, even though we do not have fossils documenting it.

Similarly, the great evolutionary biologist Ernst Mayr recognized the abrupt appearance of our genus:

The earliest fossils ofHomo,Homo rudolfensisandHomo erectus, are separated fromAustralopithecusby a large, unbridged gap. How can we explain this seeming saltation? Not having any fossils that can serve as missing links, we have to fall back on the time-honored method of historical science, the construction of a historical narrative.15

Another has commentator proposed that the evidence implies a big bang theory of the appearance ofHomo.16

This large, unbridged gap between the apelike australopithecines and the abruptly appearing humanlike members of genusHomochallenges evolutionary accounts of human origins. Unfortunately Craig mentions none of this problematic evidence in his book. While he convincingly shows that Adam and Eve could be located within an evolutionary scenario, his readers are deprived of opportunities to learn why an evolutionary scenario might not be the right answer, after all.

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Passing over Scientific Problems with Evolution - Discovery Institute