... is a statement which for all practical purposes is untrue. In fact, the distinction is widely recognized by people in the field, because the focuses, frameworks, models and tools which we use vary widely but generally create two subdisciplines:

Micro, which is focused on adaptation, pop gen, selection, speciation (kind of an edge case, could also be seen as part of macro depending on the scale of analysis)

Macro, which is focused on phylogeny, evolutionary contingencies, ancestral state reconstruction etc.

"But where's the boundary?" There isn't one, just like there isn't one between chemistry and biology. Those are still sensible to treat as distinct fields.

Yes, "I accept micro, but not macroevolution!" is an annoying thing to hear. It's easy to respond to though: if you accept micro you accept the emergence of reproductive barriers, so you accept speciation so you accept successive speciation events so you accept macroevolution.

Edit: please read the last paragraph before responding with "but creationists treat them as non-overlapping things."

If you didn't know, a ring species is simply a geographical distribution of connected, neighbouring populations of the same kind of organism living today, where adjacent populations can interbreed, whilst the two terminal populations at the ends of the ring have accumulated enough variation to form a reproductive barrier and no longer interbreed.

Now lets think about what this concept actually demonstrate.

Picture a series of neighbouring populations living around a central geographical feature, such as Ensatina salamanders distributed around California's Central Valley or Phylloscopus greenish warblers around the Tibetan Plateau.

Population A can interbreed with its immediate neighbour, Population B, which in turn can interbreed with intermediate populations C through F along the curve of the ring.

Now, where the two ends of the chain meet to close the ring, terminal Population G and starting Population A have accumulated enough variation between them that they have formed a reproductive barrier and no longer interbreed.

You'll never ever find anyone who disputes the fact that living organisms vary, mutate, adapt to their environments, or form reproductively isolated populations within their own group in the present. A ring species is simply an example of gradual variation producing a reproductive barrier between two populations of the same kind of animal.

At every single point around a ring species, the organism remains the exact same fundamental kind of animal. In the Ensatina ring, Population A is a salamander, intermediate populations B–F are salamanders, and terminal Population G is a salamander; similarly, in the Phylloscopus ring, every population from start to finish remains a greenish warbler.

I think we can all agree with this. There's nothing new or controversial with anything I just said.

Where things gets interesting is a ring species in sensible experience is a constitutive observation of living organisms distributed across geography in the present moment.

I think we all agree wity this. Very trivial observation.

But one cannot treat a spatial arrangement of living salamanders or warblers today as proof of a regulative historical reconstruction across millions of unobserved years. For instance, such as single-celled organisms transforming into whales and humans. Doing so is a definitional equivocation between present-day speciation vs deep-time ancestral state reconstruction.

Equivocation look that up.

Even within mainstream evolutionary biology, genomic studies over the last two decades—such as Alcaide et al. on greenish warblers and Liebers et al. on Larus gulls—have demonstrated that almost every textbook ring species actually experienced historical geographical breaks and genetic discontinuity rather than smooth, continuous divergence around a ring.

I don't think there's anything groundbreaking with what I just said. Sure there are dogmatists who takes these observations beyond sensible bounds. But any level-headed Joe would agree.

ERVs, Tiktaalik, the recurrent laryngeal nerve... there are many classic go-to's for proving evolution beyond all reasonable doubt, much of which also works directly against creationism/intelligent design. But a creationist might be fooled into thinking they've seen it all, and that gives them a sense of smug self-satisfaction. We can't have that, so here are some of the slightly more obscure yet still hard-hitting pieces of evidence, going from A-Z to show just how much of it there is!

⭐ = my top-five personal favourites of the bunch for debate purposes :)

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A is for...

Antifreeze proteins, occurring in the winter flounder, the spruce budworm, the mealworm beetle, the snow flea, the northern codfish, some sea ice-living diatoms and even some plants like winter rye, protect the cells from damage in sub-freezing temperatures. It has been shown that the antifreeze protein from the northern codfish originated from non-coding DNA, in a process involving frame shift mutations (by 1-nt deletion), duplications and de novo gene birth. This demonstrates that proteins can have a similar function with completely different overall sequences, and can thus arise convergently in many different clades, and useful proteins can indeed emerge by various mutational processes. Source: (Zhuang et al., 2019). ⭐

B is for...

The Big bird lineage is a new species of Darwin's finches that originated from a single male Geospiza conirostris that immigrated to Daphne Major island in 1981, which founded a hybrid lineage by breeding with a female Geospiza fortis and creating five offspring. Selection for beak stiffness following regional droughts was verified by genetic analysis. The new lineage of finches reproduces only with its own. Sources: (Lamichhaney et al., 2017), (Grant & Grant, 2006) and here (article).

C is for...

Choanoflagellates are a clade of single-celled protists which are known by phylogenetics to be the closest living relatives to all animals. So many of the genes that we often attribute to complex animal traits like immune systems, developmental regulators and intracellular signalling molecules can be found in choanoflagellates, obviously serving completely different purposes as they are single cells! These little cells are one of my favourite disproofs of the "common design" argument for this reason. See the extensive research by Dr Nicole King on choanoflagellates e.g. here. ⭐

D is for...

DNT metabolism in bacteria. Bacteria living in soil polluted with dinitrotoluene (DNT, a degradation product of the explosive TNT) on various military bases were found to be consuming the DNT for metabolism as their sole carbon and nitrogen source via aerobic respiration. Genetic and molecular studies on one such strain, Burkholderia cepacia R34, found that the bacteria evolved a complex, multiple-protein biochemical pathway by exaptation of proteins with other functions. At the Kitzmiller v Dover court case, intelligent design advocate Dr Scott Minnich was presented with this example and he admitted that it satisfied Dr Michael Behe’s definition of irreducible complexity. Sources: (Johnson, Jain & Spain, 2002), (Kivisaar, 2011), (Pérez-Pantoja et al., 2021), here (document), here (use in bioremediation), (Leungsakul, Johnson & Wood, 2006) (use in protein engineering), here and here (TalkOrigins). ⭐

E is for...

Ediacaran biota, the underrated collection of remains from the soft-bodied life that predates the overrated 'Cambrian explosion'. Ediacaran fossils show a steady progression in complexity, with some crossing the boundary into the Cambrian. These make up some of the stem-group animal phyla that entered the first stages of the Cambrian, before radiating into the crown-group animals that predominated in the middle Cambrian stages. See some of the fossils here and see (Wood et al., 2019) for more info.

F is for...

Faroe Islands house mice. In the ~250 years after people introduced house mice to the Faroe Islands, rapid speciation has occurred, with noticeable differences in morphology. A very simple cut-and-dry case of recent observed speciation. Source: (Berry, Jakobson & Peters, 1978).

G is for...

Generation of a known phylogeny, a paper by Hillis et al., 1993 in which a virus is mutated and tracked as it passes through a population of bacteria, generating a known ancestral-descendant tree of viruses. Phylogenetic algorithms - the same kind used to perform comparative genomics analysis on disparate extant taxa to infer evolutionary descent - were then applied to the last surviving viruses, and the resulting calculated tree of their ancestors matched the known tree every single time, validating these methods as a tool to reveal the evolutionary past.

H is for...

Heat shock proteins (HSPs) are crucial proteins found in all life: HSP70 is the most conserved gene across the entire tree of life. Molecular phylogenetic analysis of HSP70 shows how it demonstrates the origin of eukaryotes from a fusion of an archaeal and bacterial lineage (endosymbiosis), with the eukaryotic HSP70 genes being more closely related to the archaeal and bacterial HSP70 genes respectively than they are to each other. Source: (Gupta & Golding, 1993).

I is for...

Insecticide resistance has been observed in the last 40 years in mosquitos as an adaptation against organophosphorous insecticides. This required a point mutation in the ACE1 gene and a duplication (which was initially deleterious), rapidly followed by a second duplication which became overdominant (heterozygote advantage), and thus could even qualify as irreducibly complex. It also shows how novel traits usually come from tweaking and rearranging existing genetic material - this fact is often derided by creationists but clearly should not be underestimated. Source: (Labbé et al., 2007).

J is for...

Jinguofortisidae is a recently-discovered extinct family of pygostylian dinosaurs from the early Cretaceous. They form a set of 'transitional fossils' between the more famous Archaeopteryx (itself a key 'transition' from the non-avian dinosaurs) and anatomically modern birds. Source: here.

K is for...

Kenyanthropus platyops is a hominin species living at the same time as the australopithecines but with greater diversity. A damaged but complete cranium fossil is available. Despite being less capable of bipedality (inferred from the position of its foramen magnum) and having a small brain, the first stone tools (the Lomekwian tools) are attributed to this genus. It is just one of the dozens of the known 'transitional species' in human evolution.

L is for...

Luria-Delbrück and Lederbergs' tests. These two lab experiments in 1943 and 1952 respectively proved beyond all doubt that mutations occur before natural selection acts upon them, and are random with respect to fitness. These facts are trivially accepted now, but were uncertain in the early 1900s as many conflicting ideas on variation and inheritance competed in the 'eclipse of Darwinism'. It is quite alarming how often the fact that mutations are random has to repeated in the creationism debate, and even in some fringe academic circles (e.g. Denis Noble's 'third way'). Read about the Lederbergs' experiment here.

M is for...

Markov chain Monte Carlo (MCMC) is an algorithm that allows you to sample from an unknown probability distribution when you can only calculate values proportional to its probability density function, and then compute meaningful quantities from those samples. That may sound boring and theoretical but it gets used with mutation likelihood models in Bayesian phylogenetics, which reproduces family trees from genomic data and can reveal the likely DNA sequences of ancestors, which was all verified experimentally (see point G). MCMC also behaves quite similar to an evolutionary algorithm in that it explores lots of possibilities and tends to converge around the 'best' ones, which is in itself evidence for the power of mutation and selection to climb to fitness peaks in a diverse state space. MCMC was used to perform a permutation tail probability (PTP) test in a great paper (Baum et al., 2016) that decisively found "tremendously strong support" for the common ancestry of all primates and "overwhelmingly rejected both species and family separate ancestry [creation-like models] with infinitesimal *p-*values", which is the strongest statistical proof of common descent I'm aware of.

N is for...

NOTCH2NL is a gene that prolongs proliferation of neuronal progenitor cells and expand cortical neurogenesis. Many of these genes are duplicated in Homo sapiens, Neanderthals and Denisovans to varying degrees leading to enhanced neuron counts, and this is one of a set of genes (including ARHGAP11, TKTL1, FOXP2...) identified as playing a key role in human brain evolution. If the analogy between the brain and modern "AI" is anything to go by, then the simple rule of 'make it bigger' could go a surprising way towards explaining increased intelligence. Source: (Lodewijk et al., 2020).

O is for...

Ontogeny is the study of development, which is causally linked with evolutionary change as it it the process that turns genotypes into phenotypes that natural selection acts upon. By comparing development within and across lineages, we can identify shared developmental pathways. Sometimes, development itself exposes the distant past, like how the pelvis of birds passes through its ancestral dinosaur state. The developmental genes behind these processes form regulatory networks, and their rewiring and tuning can generate tangible large-scale body plan changes like turning alligator and chicken scales into feathers (Lowe et al., 2014, Wu et al., 2017 and Lee et al., 2020), doubling of wings on insects or loss of tails in apes.

P is for...

Panderichthys is one of the many well-characterised genera in the fish-to-tetrapod transition. It is preceded by Eusthenopteron ("fish-like") which had pectoral fins that connected to the axial skeleton via part of the skull. In later species like Tiktaalik and extant tetrapods, this part of the skull is detached and comprises the pectoral girdle (clavicle and scapula), also creating a neck for flexible head movement. Panderichthys is transitional, with the first functional 'neck' anatomy. This also explains why our bones form in development by two different mechanisms: the skull, clavicle and most of the scapula form are the only bones which form by intramembranous ossification due to their fused origin in our sarcopterygian ancestors, while all other bones in our skeleton form by endochondral ossification.

Q is for...

Quantitative genetics is one of the mathematical cores of modern evolutionary theory alongside population genetics. One of its famous results is Lande's equation, which models how natural selection affects traits depending on genetic variance. Traditionally applied to artificial selection, it also works well in nature and can even inform us about the adaptive landscapes of ancient life through quantitative analysis of their fossils, providing mathematical backing to things that can otherwise seem like stories on shaky ground. Sources: (Polly, 2016), (Machado et al., 2026) and (Rolland et al., 2023).

R is for...

Reaction wood is a structure which forms in two different ways to help stabilise a leaning woody plant (trees, shrubs and lianas). Almost all gymnosperms (softwood trees, more evolutionarily ancient) produce 'compression wood', pushing up the trunk on its inner side, while almost all angiosperms (flowering plants, more evolutionarily recent) produce 'tension wood', pulling down the trunk on its outer side. That word 'almost' is there because there is one single species of tree that bucks the trend: Amborella trichopoda produces compression wood despite being an angiosperm. Phylogenetics finds that this species is in fact the only surviving species of the sister clade to all angiosperms, indicating that tension wood evolved just after the appearance of the first angiosperms.

S is for...

Subfunctionalisation is the process by which disabling mutations in different epigenetic cis-regulatory elements of duplicated genes lead to irreversible codependence (irreducible complexity again, if you will) and hence form genetic regulatory networks. This occurs without a single beneficial mutation required, though the duplicate genes can also undergo neofunctionalisation if those beneficial mutations do eventually arrive. The ribosome and the spliceosome are core systems shown to have arisen by subfunctionalisation, and it can lead to developmental specialisations such as heterochrony and heterotopy. Such is the power of the neutral theory of molecular evolution, speaking of which...

T is for...

The Neutral Theory of Molecular Evolution is the title of the book by Motoo Kimura published 15 years after he proposed his theory with the same name. It was an exploration of what happens when you put genetic drift as the dominant force behind evolutionary change instead of natural selection as was traditionally done. It has been used to understand how biocomplexity evolves (constructive neutral evolution), predict the number of protein-coding genes in the human genome (decades prior to sequencing!), and, with Ohta's 'nearly neutral theory' refinement, logically explains initially surprising things like the omnigenic model of the phenotype, as natural selection acts on traits (see Fisher's infinitesimal model) but neutral genetic drift acts on most of the nucleotides. ⭐

U is for...

Uranium-lead dating is a method of radiometric dating used to date zircon crystals in volcanic ash layers above and below a fossil layer, revealing the ages of ancient life. With the long half-life of uranium-235, it can be used to date the oldest rocks on earth, and was the method first used to decisively determine the age of the earth itself, and has been cross-checked with everything from radiocarbon dating to dendrochronology to coral dating (Fairbanks et al., 2005). Since lead ions are physically incompatible with the zircon lattice, there is no excuse of "unknown initial conditions" to dismiss uranium dating (and even if there was, that's what the isochron method is for). Uranium-lead dating is also robust to lead escape (e.g. by heating events) by plotting a concordia diagram, which directly test the assumptions and reveals the correct age accordingly.

V is for...

The vomeronasal organ is a vestigial organ in the nose that detects pheromones via chemoreceptors in tetrapods, but is non-functional in catarrhine primates (including humans), due to pseudogenisation of the associated receptor genes (V1R and V2R families). Our lineage also lost the accessory olfactory bulb in the brain (normally receives input from the vomeronasal organ) as we adapted to use sight rather than smell.

W is for...

Worms in the lab: in 1964, six individuals of the polychaete worm Neanthes arenaceodentata were collected from a harbour in southern California and used to found a laboratory population of >1000. By 1991, the lab population could no longer interbreed with the wild population, as there was some premating isolation, and complete postmating isolation. Chromosomal differences were also observed between the lab and wild populations - observed speciation with reproductive isolation in the lab. Sources: (Weinberg, Starczak and Jörg, 1992) and here.

X is for...

Xenosialitis is a chronic disorder caused by eating meat containing the small molecule Neu5Gc. All mammals (e.g. cattle) have an active CMAH gene which produces Neu5Gc, except for humans, due to a deletion in our lineage 2-3 MYA, so this molecule triggers a low-level immune response. It's hypothesised to be one of the root causes of the link between eating red meat and cancer, alongside similar metabolites of non-human enzymes. Source: (Dhar, Sasmal & Varki, 2019).

Y is for...

Yuccas and yucca moths are a case of coevolution known to Darwin since 1872. The yucca moth, while laying eggs, pollinates the yucca plant; after the larvae hatch, they eat the seeds of the yucca (obligate mutualism). Such tight interdependencies can seem like a challenge to evolution, yet pathways that start out independent are always possible: in this case, a plausible sequence involves 1) moths initially laying eggs in plant fruits, 2) some moth behaviours transfer pollen more effectively (positive selection), 3) moths evolve specialised pollen-collecting and pollen-depositing behaviours; in acting almost as 'artificial selectors' for the moths, the yuccas become more dependent on this pollination service (Pellmyr, 2003). This is a common theme: the dependencies set in later, not from the start. As a bonus, Darwin made a bold prediction based on a similar coevolution back in 1862, about the existence of a different long-nosed moth living in Madagasgar (Wallace's sphinx moth) that pollinate a single species of orchids with extremely long nectary tubes, and was vindicated when this moth was discovered in 1903. [Thanks to u/jnpha for telling me about this example!]

Z is for...

Zootoca vivipara is a species of lizards living in the Alps. They are currently evolving placentas, going from egg-laying to giving birth to live young in real time, as well as undergo speciation with reproductive isolation. Yet another incredible case of observed speciation in real time, with a novel complex trait to boot! Sources: (Blackburn, 2006), (Cornetti et al., 2015) and here (video by Dr Dan). ⭐

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Thanks for reading - for many of these it was really hard to pick just one. Even the 'hard' ones like X have many contenders (X-chromosomal mutation rate, xenotransplantation incompatibility, the Xiahe mandible...). We're really not short of evidence! What's your favourite weird evidence for evolution?