A common claim by creationists is that there are 'no transitional fossils', despite advice from their own people to stop using this argument. These claims are often made in a blog or forum comment section rather than on an official website, since it is clearly a ludicrous statement. They also crop up a lot in comments on YouTube videos alongside such gems as 'If we evolved from monkeys, why are there still monkeys?'. (The mindset of the claimant is usually clear enough due to the accompanying derogatory statements about Barack Obama and/or homosexuals.)
Anyway back to my point, transitional fossils. This is one of my favourite photos:
Skull A is that of a modern day chimpanzee, the closest living relative to humans, which are represented by Skull N (Edit: For those who claim there is no proof of the relationship between humans and chimps, see here - prepare to be pwned). Since evolutionary theory predicts that humans and chimps share a common ancestor, there necessarily must have been hominid-like organisms in the past with intermediate morphologies between the two modern day species. Now look at all the other skulls. Pretty convincing evidence if you ask me. Here is a list of the species for each skull and the given dates for their ages:
(A) Pan troglodytes, chimpanzee, modern
(B) Australopithecus africanus, STS 5, 2.6 My
(C) Australopithecus africanus, STS 71, 2.5 My
(D) Homo habilis, KNM-ER 1813, 1.9 My
(E) Homo habilis, OH24, 1.8 My
(F) Homo rudolfensis, KNM-ER 1470, 1.8 My
(G) Homo erectus, Dmanisi cranium D2700, 1.75 My
(H) Homo ergaster (early H. erectus), KNM-ER 3733, 1.75 My
(I) Homo heidelbergensis, "Rhodesia man," 300,000 - 125,000 y
(J) Homo sapiens neanderthalensis, La Ferrassie 1, 70,000 y
(K) Homo sapiens neanderthalensis, La Chappelle-aux-Saints, 60,000 y
(L) Homo sapiens neanderthalensis, Le Moustier, 45,000 y
(M) Homo sapiens sapiens, Cro-Magnon I, 30,000 y
(N) Homo sapiens sapiens, modern
Now the photo is slightly misleading in that it suggests a steady progression from chimps to humans. This is not how evolution happened. The chimp and human lineages split about 5-7 million years ago and so predate the above photo. The chimp skull is just there for reference. The comparisons should really be studied from B-N, that is from Australopithecus to humans. A similar diagram could be made tracking the evolution to the modern day chimp, but the differences may be less obvious. In fact, at a glance, the modern chimp skull is actually quite similar to Australopithecus (although there are many differences, look at the eye sockets).
Another thing to point out is that these particular skulls may not have belonged to individuals that were direct ancestors of modern humans, they may well have been on other branches on the hominid evolutionary tree (see picture below). This is not really a problem though, as it is simply like comparing similarities between aunts, uncles and cousins, instead of directly comparing parents and offspring. The point being that comparisons can still be informative and a range of transitional features from modern day chimps to modern day humans is evident, indicative of common ancestry. Of course, the fact still remains that many of the species above could have belonged to populations that were direct ancestors of modern day humans.
Hominid evolution (including Kent Hovind, proponent of the 'no transitional fossil' argument)
Tracking the changes in the skull between Australopithecus and humans, we can notice gradual changes which would be considered transitional. Notice how the palate (roof of the mouth) retracts over time, indicating that less strength was needed to chew food. Although not visible on the above photo, the lower jawlines of these early hominid skulls are even more pronounced and follow a similar pattern of change.
This is most likely a direct result of the use of fire, as cooked food is much easier to breakdown and chew than raw meat and plants. It is thought that Homo habilis invented the use of fire for cooking, and accordingly it is the Homo habilis skull (Skull E) which first shows a reduced size in the palate.
Also, notice how the brain size increases massively in a steady progression from Australopithecus to humans. One hypothesis actually links these two morphological changes. Is is thought that a mutation in a protein called MYH16, a chief component of the powerful jaw muscles, resulted in a reduction in the size of the chewing apparatus. This may have reduced the physical restraints on the rest of the skull, allowing it to grow and accommodate the increasing size of the brain.
All fascinating stuff!
Now how on earth can a creationist look at these skulls and claim that there are no transitional fossils? Well some claim that this is just evidence of 'variation within kinds' or that transitional fossils must be direct ancestors and not from other branches. These claims are weak. Firstly, if it only represents 'variation within kinds' then these creationists are still conceding that chimps and humans are the same 'kind', in direct contradiction to their faith. Secondly, no evolutionist claims that transitional fossils must be from direct ancestors, merely that they show transition between the morphology of a particular feature in two distinct specimens. These changes show that features have evolved in populations over time. It is not necessary to show the change in these features in a direct ancestral line.
Look at it like this...
Imagine you were trying to find and catalogue a photo of each of your direct male relatives, father, grandfather, great-grandfather, etc, in order to compare a particular feature, say nose size. You have photos that span 10 generations (unlikely, but humour me) but you are missing one photo, lets say the 7th generation. As luck would have it, you do have a photo of the brother of your missing direct male relative. Of course you would prefer to have the actual direct relative, but in the absence of this photo, the photo of the brother can still act as a good substitute. It is likely that the brother had similar features to your direct relative and so his nose size is still informative. In fact you could look at photos of siblings for a few of the generations and not really lose any informational power. This is why transitional fossils, or features, do not need to come from a direct ancestor.
Anyway, the demands of creationists in this respect are ludicrous. Even if there were fossils in a direct ancestral line in front of them, they would simply say that there still isn't enough evidence. They would ask for the fossils that show transition from each specimen to the next (i.e. imagine a photo with twice as many skulls). If you could provide them, they would ask for the next set of intermediate fossils, and again, and again...
More fossils to a creationist doesn't mean more evidence, it means more gaps! It seems like the only way to satisfy them would be to produce fossils from every organism that has ever lived on this planet.
Meh.
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Edit: Below is the chart showing that although creationists are adamant that none of these are transitional and all are either apes or humans, they are not able to agree on which are which.
Evolutionists also disagree on how fossils should be classified, which species they belong to, etc. True enough. But according to evolutionary thinking, these fossils come from a number of closely related species intermediate between apes and humans. If this is so, we would expect to find that some of them are hard to classify, and we do. Creationists, on the other hand, assert that apes and humans are separated by a wide gap. If this is true, deciding on which side of that gap individual fossils lie should be trivially easy. Clearly, that is not the case.
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