A CLAIM THERE is no fossil evidence of “transitional” links, as predicted by Darwin, has recently been shared by Irish social media users, echoing long-debunked claims by creationists — people who believe that the variety of living species on Earth is explained by an immediate act of creation by God, rather than by evolutionary forces.
Transitional fossils are sometimes called “missing links”, particularly when referring to evidence that humans evolved from ancient apes, though modern scientists often consider this term misleading.
“There are literally zero transitional fossils!” proclaims one Irish social media post that has garnered hundreds of likes on Facebook.
The post goes on to list bullet points such as “The archeopteryx was a bird, not a transitional fossil between reptile and bird” and “no credible ape-to-human fossil identified”.
Similar arguments about the fossil record have been raging for about as long as the theory of evolution has been discussed.
It is well outside the scope of this factcheck to debunk or prove evolution or creationism — many books have been written on the subject.
However, the far narrower claim made on social media can be answered. Are there “literally zero transitional fossils”, as a popular social media post claims?
The British Geological Survey, a semi-public geoscience group, describes fossils as “the preserved remains of plants and animals whose bodies were buried in sediments, such as sand and mud, under ancient seas, lakes and rivers. Fossils also include any preserved trace of life that is typically more than 10;000 years old.”
It goes on to explain “Soft body parts decay soon after death, but the hard parts, such as bones, shells and teeth can be replaced by minerals that harden into rock. In very exceptional cases, soft parts like feathers, plant ferns or other evidence of life, such as footprints or dung, may also be preserved.”
However, what fossils count as “transitional” is contested, though there is a consistent general consensus that their existence would count as evidence in favour of evolution, while their absence would be a blow against the theory.
Depending on who you ask, transitional fossils can be assumed to mean: a trait or limb developing (such as primitive eyes, or body part that is between a hand and a fin); a creature which appears to be between orders or species (such as if an animal were part-lizard, part-fish); evidence of portion of a limb that appears in a later species (like tiny legs); an animal that contains all the characteristics of an earlier ancestor as well as a more recent evolution; or a series of animals representing a direct, linear transition from a primitive lifeform into a complex animal.
These are wildly different characteristics. Luckily, the origin of the concept of “transitional fossils” is generally agreed upon, and we can return to that concept’s source to see what exactly it refers to.
Oddly, it is often Darwin himself who is often quoted by creationists in support of their views.
“The number of intermediate varieties, which have formerly existed on the earth [must] be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links?” Darwin asked in his groundbreaking thesis on evolution, The Origin of Species, published in 1859.
“Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection which can be urged against my theory,” he wrote. “The explanation lies, as I believe, in the extreme imperfection of the geological record.”
Darwin’s explanation as to why there were so few “intermediate link” fossils is now redundant to our conversation — a major transitional fossil was believed to have been found in 1861, shortly after his book was published. Many more have been found since.
“As long as most of the links between any two species are unknown, if any one link or intermediate variety be discovered, it will simply be classed as another and distinct species,” Darwin also wrote.
While this seems flippant, it actually gives us a working definition of what to look for — a fossil that would appear to show a distinct species, but when taken in combination with two other species, actually shows that they are linked through an evolutionary lineage.
In this use, terms like “transitional fossil” do not designate a specific type of creature, but an artefact that establishes a link between species. If the theory of evolution is correct, almost any fossil is potentially a transitional fossil, depending on what information is already available.
Modern definitions are even looser: “a fossil that exhibits characteristics of both ancestral and derived forms,” reads the Merriam-Webster Dictionary’s entry for transitional fossils.
So, given Darwin’s meaning of the term, have any transitional fossils been found?
“Fossils with transitional morphology are not rare,” writes The National Center for Science Education, an American non-profit organisation. “Fossils illustrating the gradual origin of humans, horses, rhinos, whales, seacows, mammals, birds, tetrapods, and various major Cambrian “phyla” have been discovered and are well-known to scientists.”
Long lists of discovered transitional fossils are available, including ones that show the transition of animals from water to land and dinosaur to bird, as well as numerous hominid species that show increasing mutations toward humanlike physiology.
Evidence even exists in Ireland: Valentia Island off County Kerry boasts fossilised Tetrapod tracks, marking the transition of creatures from the ocean onto the land (though strictly speaking, these are fossils of an animal’s tracks, rather than the animal itself, so may not fit Darwin’s description).
Given this apparent abundance of examples, how is it that some creationists continue to claim that transitional fossils do not exist?
“Although some creationists do say that ‘there are no transitional fossils,’ it would be more accurate to state that there are no undisputed transitional forms,” reads an article published by the Institute for Creation Research, an American group that espouses creationism, saying that there is no “universally accepted transitional form”.
However, to claim that there are no transitional fossils and no “undisputed” transitional fossils are very different things — it would be like denying that certain crimes occurred purely on the basis that the accused put up a defence.
As it stands, there are currently long lists of fossils that are considered to show transitional forms between already known species, including ones that show the evolution of fish to amphibians, lizard to bird, and even ape to man.
A very detailed outline of the evolution of humanity, as well as the fossil evidence for each link, can be found here.
Claims that there remain “missing links” in the fossil record are true in a sense, but trivial, and aptly explained in a scene from the cartoon Futurama in which a talking ape challenges a professor asking “why has no one found the missing link between modern humans and ancient apes?”
“We did find it, it’s called Homo erectus,” the professor replies, to which the ape then asks why there is a missing link between apes and Homo erectus. The professor again answers that we have found it: Homo habilis. However, each time the professor replies with a known link, the ape points out that new gaps now exist between that link and the others.
The Institute for Creation Research article goes on to dispute numerous examples of transitional fossils, but in many cases does so on spurious grounds — largely saying that the transitional forms shown could also be explained by an creationism.
However for a fossil to be considered transitional, it does not need to disprove creationism, but merely to display “characteristics of both ancestral and derived forms” in a way that is consistent with evolutionary theories.
It is False to say there are ” literally zero transitional fossils!” Numerous “transitional fossils” that appear to illustrate changes between known species have been found since Darwin outlined their possibility.
Claims that none have been found often rely on criticising these fossils on the grounds that they do not meet certain irrelevant criteria. However, the claim that there are no transitional fossils — preserved remains which show evidence of both ancestral and later species — is false.
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