Rosa Rubicondior: Refuting Creationism - Observed Evolution Over 125 Years!

Monday, 30 June 2025

Refuting Creationism - Observed Evolution Over 125 Years!

Authors Stephanie Smith and Anderson Feijó examining chipmunk specimens in the Field Museum’s collections.

Chicago’s rodents are evolving to handle city living - Field Museum

The knee-jerk response from any creationist worth his or her salt, when shown evidence of observed instances of evolution, is to demand a redefinition of the term *evolution*—away from its scientific meaning of a change in allele frequency in a population over time, and towards the creationist’s caricature: a species instantaneously transforming into an entirely unrelated taxon. This is, of course, something evolutionary biologists have never claimed, and which—if it ever occurred—would actually refute the Theory of Evolution.

This is the all-too-familiar, disingenuous tactic of setting the bar impossibly high for one’s opponent, while keeping it at ground level for one’s own evidence-free superstition.

So, for those creationists more interested in finding workarounds to ease the cognitive dissonance between what they would like the facts to be and what science actually shows, than learning the truth about the world around us, the news that researchers at Chicago’s Field Museum have demonstrated evolutionary change in the city’s rodent populations over the last 125 years will likely present little difficulty. They can always chant, “But it’s still a chipmunk/vole/etc., so not evolution!”

However, for those with the intellectual integrity and humility to base their opinions on observable evidence, rather than dismissing any evidence that doesn't conform to their preconceived alternative reality, this finding is a compelling vindication of a basic principle of the Theory of Evolution: that species change over time in response to environmental pressures.

The researchers have recently published their findings in the journal Integrative & Comparative Biology.

Examples of professional creationists using that disingenuous tactic: The tactic of redefining evolution to an absurd or caricatured version — typically insisting that unless one “kind” instantly transforms into a completely different “kind” (e.g., a dog giving birth to a cat), then it’s not “real” evolution — is a common rhetorical strategy among professional creationists. Here are several well-documented examples of this tactic in action:

Ken Ham (Answers in Genesis)

Ken Ham routinely contrasts “observational science” (which he accepts) with “historical science” (which he rejects), claiming that evolution falls into the latter and is therefore mere speculation. He frequently demands that evolution be demonstrated by showing one “kind” turning into another, using language like:

“There is no observable evidence for molecules-to-man evolution. Dogs produce dogs; cats produce cats.”
— Ken Ham, Creation Museum and public debates

This is a classic case of moving the goalposts: dismissing well-documented changes in allele frequencies and speciation events because the new species is still “a dog” or “a cat” by some undefined creationist taxonomy.

Ray Comfort (Living Waters)

Ray Comfort is notorious for asking people to “name one instance of a species evolving into another,” and then rejecting any examples that don’t match his demand for an animal turning into something radically different (e.g., a cow becoming a whale).

“There is no evidence of one animal kind turning into another. Give me one—a dog becoming a non-dog, for example.”
— Ray Comfort, in numerous YouTube videos and publications

He uses the phrase “microevolution is not macroevolution” while refusing to acknowledge that macroevolution is simply the cumulative result of microevolution over longer timescales.

Duane Gish (Institute for Creation Research)

The late Duane Gish was famous for the “Gish Gallop,” a debating style overwhelming opponents with fast-talking nonsense. But central to his anti-evolution argument was this same redefinition. He often claimed:

“No one has ever observed a fish turning into an amphibian, or a reptile into a bird. These are fairy tales.”
— Duane Gish, ICR lectures and books

He dismissed actual fossil transitions (like Tiktaalik or Archaeopteryx) as merely “fully fish” or “fully bird,” ignoring their intermediate features.

Kent Hovind (Creation Today)

Kent Hovind often mocks evolution by demanding examples of “a dog turning into a non-dog,” insisting that all observed change is “just variation within a kind.” He famously said:

“If you put a dog on an island, and it evolves longer hair, it’s still a dog!”
— Kent Hovind, seminar debates and videos

This sets an impossibly high bar for evolutionary change, requiring instantaneous, taxonomic transformation, while ignoring what actual evolutionary theory proposes.

Harun Yahya (Adnan Oktar)

This Turkish creationist author, now serving a lengthy prison sentence for various criminal offences, repeatedly insists that no transitional forms exist and that every species appeared fully formed. His writings suggest that unless we observe a fish literally turning into a land animal in real time, evolution is invalid:

“Fossils show that living beings never underwent evolution, but appeared suddenly with all their characteristics.”
— Harun Yahya, various publications

This relies on the false assumption that evolution should be visible on human timescales as dramatic leaps rather than gradual shifts over generations.

Summary of the Tactic

Across these examples, the disingenuous tactic usually follows this pattern:

Reject the scientific definition of evolution as change in allele frequency over time.
Invent a strawman in which evolution requires a drastic, instantaneous change in “kind.”
Dismiss real-world examples of evolution as mere “variation” or “adaptation,” not “true” evolution.
Demand impossible evidence (e.g., direct observation of a land mammal giving birth to a whale).

This tactic isn’t just wrong—it’s rhetorically dishonest, as it misrepresents evolutionary biology while failing to apply any similar standards of evidence to their own supernatural claims.

They also explain their research in a Field Museum press release.

Chicago’s rodents are evolving to handle city living
Chipmunk and vole skulls from over 125 years reflecting changes in diet and noise exposure
In general, evolution is a long, slow process of tiny changes passed down over generations, resulting in new adaptations and even new species over thousands or millions of years. But when living things are faced with dramatic shifts in the world around them, they sometimes rapidly adapt to better survive. Scientists recently found an example of evolution in real time, tucked away in the collection drawers of the Field Museum in Chicago. By comparing the skulls of chipmunks and voles from the Chicagoland area collected over the past 125 years, the researchers found evidence that these rodents have been adapting to life in an increasingly urban environment.

Museum collections allow you to time travel. Instead of being limited to studying specimens collected over the course of one project, or one person’s lifetime, natural history collections allow you to look at things over a more evolutionarily relevant time scale.

Stephanie M Smith, co-corresponding author
Negaunee Integrative Research Center
Field Museum of Natural History
Chicago, IL, USA.

. The Field Museum’s mammal collections are made up of more than 245,000 specimens from all over the world, but there’s especially good representation of animals from Chicago, where the museum is located. What’s more, these collections represent different moments in time throughout the past century.

We’ve got things that are over 100 years old, and they're in just as good of shape as things that were collected literally this year. We thought, this is a great resource to exploit.

Stephanie M Smith.

The researchers picked two rodents commonly found in Chicago: eastern chipmunks and eastern meadow voles.

We chose these two species because they have different biology, and we thought they might be responding differently to the stresses of urbanization.

Anderson Feijó, co-corresponding author.
Field Museum of Natural History
Chicago, IL, USA.

Chipmunks are in the same family as squirrels, and spend most of their time aboveground, where they eat a wide variety of foods, including nuts, seeds, fruits, insects, and even frogs. Voles are more closely related to hamsters. They mostly eat plants, and they spend a lot of time in underground burrows.

Two of the study’s co-authors, Field Museum Women in Science interns Alyssa Stringer and Luna Bian, measured the skulls of 132 chipmunks and 193 voles. The team focused on skulls because skulls contain information about the animals’ sensory systems and diet, and they tend to be correlated with overall body size.

From the skulls, we can tell a little bit about how animals are changing in a lot of different, evolutionary relevant ways—how they're dealing with their environment and how they're taking in information.

Stephanie M Smith.

Stringer and Bian took measurements of different parts of the skulls, noting things like the overall skull length and the length of the rows of teeth. They also created 3D scans of the skulls of 82 of the chipmunks and 54 of the voles. This part of the analysis, called geometric morphometrics, entailed digitally stacking the skull scans on top of each other and comparing the distances between different points on them.

These analyses revealed small but significant changes in the rodents’ skulls over the past century. The chipmunks’ skulls became larger over time, but the row of teeth along the sides of their mouths became shorter. Bony bumps in the voles’ skulls that house the inner ear shrank over time. But it wasn’t clear why they were changing.

To find an explanation for these changes, the scientists turned to historical records of temperature and levels of urbanization.
We tried very hard to come up with a way to quantify the spread of urbanization. We took advantage of satellite images showing the amount of area covered by buildings, dating back to 1940.

Anderson Feijó

(Specimens older than 1940 were either from areas that were still wild in 1940, and thus could safely be assumed to be wild before that, or from highly urbanized areas like downtown Chicago.)

The researchers found that the changes in climate didn’t explain the changes in the rodents’ skulls, but the degree of urbanization did. The different ways the animals’ skulls changed may be related to the different ways that an increasingly urban habitat affected them.

Over the last century, chipmunks in Chicago have been getting bigger, but their teeth are getting smaller. We believe this is probably associated with the kind of food they're eating. They're probably eating more human-related food, which makes them bigger, but not necessarily healthier. Meanwhile, their teeth are smaller— we think it's because they're eating less hard food, like the nuts and seeds they would normally eat.

Anderson Feijó

Voles, on the other hand, had smaller auditory bullae, bone structures associated with hearing.
We think this may relate to the city being loud— having these bones be smaller might help dampen excess environmental noise.

Stephanie M Smith.

While these rodents have been able to evolve little changes to make it easier to live among humans, the take-home lesson isn’t that animals will just adapt to whatever we throw at them. Rather, these voles with smaller ear bones and chipmunks with smaller teeth are proof of how profoundly humans affect our environment and our capacity to make the world harder for our fellow animals to live in. This is a wake-up call.

These findings clearly show that interfering with the environment has a detectable effect on wildlife.

Anderson Feijó

>
Change is probably happening under your nose, and you don't see it happening unless you use resources like museum collections.

Stephanie M Smith.

Publication:

Anderson Feijó, Alyssa Stringer, Luna Bian, Stephanie M Smith,
Limited cranial shifts in city-dwelling rodents after a century of urbanization
Integrative and Comparative Biology, 2025;, icaf081, https://doi.org/10.1093/icb/icaf081.

Abstract
Urbanization and climate change can have unexpected effects on organisms that share space with humans. Examining these effects is important for understanding how wildlife have so far adapted to human modifications on the environment, and can aid in mitigating damage to the well-being of local populations going forward. Properly documenting these effects requires samples covering long, evolutionarily-relevant time spans. Most studies are not designed to span more than a few years, but natural history collections provide ready-made long-term samples, accumulated through the continuing efforts of field collectors. Here, we used museum specimens of two ecologically distinct rodent species collected over 100 years in the greater Chicago region to examine the effects of urbanization and climate change on cranial morphology. We quantified the shape of the skulls of eastern chipmunks (Tamias striatus) and eastern meadow voles (Microtus pensylvanicus) using linear and geometric morphometrics, and investigated the effects of urbanization and climate (represented by annual mean temperature) on skull variation through time. Spatiotemporal urbanization levels were incorporated in the analyses to account for uneven urbanization growth. Overall, we recovered a significant albeit limited effect of urbanization and, to a lesser degree, climate on driving skull shifts in both species. We attributed these limited shifts to a non-directional selective pressure caused by a heterogeneous urbanization growth and oscillating climate. We further recovered different responses between the two rodent species. Chipmunks showed a weak association of cranial changes with urbanization and climate, although their size increased throughout the study era. Interestingly, they also showed a decrease in toothrow length, indicating a possible dietary shift. On the other hand, vole cranial morphology was stronger associated with degree of urbanization and showed a more obvious shift in morphospace occupation between urbanization categories. Voles from highly urbanized sites displayed a reduction in shape diversity and flatter skulls. These different patterns between chipmunks and voles reveal species-specific responses to the same human-induced habitat changes and the need for nuanced conservation plans in the face of continuing change. Our study emphasizes the importance of analyzing long temporal series to assess urban selection on phenotypic traits.

Anderson Feijó, Alyssa Stringer, Luna Bian, Stephanie M Smith,
Limited cranial shifts in city-dwelling rodents after a century of urbanization
Integrative and Comparative Biology, 2025;, icaf081, https://doi.org/10.1093/icb/icaf081.

© [year] [publisher].
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

To summarise, this research delivers a double blow to creationist claims.

Firstly, the researchers conducted their work without the slightest suggestion that supernatural explanations were needed. Their observations fit squarely within the framework of the Theory of Evolution, as understood by mainstream science. This stands in stark contrast to the repeated assurances from creationist leaders that evolutionary biology is on the verge of collapse and that scientists are secretly harbouring doubts. For over half a century, these predictions have failed to materialise, yet the myth persists within creationist circles.

Secondly, the observed changes in the rodent populations were exactly what evolutionary theory would predict. The genetic and morphological shifts correlated closely with the transition from rural to urban environments—precisely the kind of environmental pressure that drives natural selection. Rather than undermining evolution, the findings offer a textbook example of it in action.

In short, this is not only evidence for evolution, but evidence that it continues to operate just as the theory describes — gradually, naturally, and in response to measurable changes in the environment. And when specimens are available across time, they reveal a clear, progressive trajectory of change — unlike the fossil record, which is inevitably patchy due to the rarity of fossilisation.

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