A few weeks ago yet another sensational fossil was unveiled. It wasn’t a dinosaur or a hominid but rather several tiny mosquitoes. Fossils of mosquitoes are known from amber (fossilized tree sap) but are extremely rare in sedimentary rock. However, it isn’t the rarity of the fossil itself that made headlines. It was what researches discovered in the mosquito’s remains.
Here are some common headlines from this discovery. See if you can tell from the headlines what they found.
Blood Cells Found in Fossilized Mosquito (OneSquareLight blog)
Mosquito fossil with blood-filled belly discovered (Japan Times)
Unprecedented Blood-Filled Mosquito Fossil Raises Questions Over Evolutionary Dating Methods (Christian New Network)
Bloody Mosquito Fossil Supports Recent Creation (Institute for Creation Research)
Rare, blood-engorged mosquito fossil found (Fox News)
You would not be wrong if you got the impression from these headlines that what was found was a mosquito with a bellyful of blood including the cells contained in that blood. Many of the article conjured up images of Jurassic Park where DNA was extracted from the dino-blood that the mosquitoes drank. But these headlines are far too sensational.
Here are two additional headlines from popular science sources:
Fossil Mosquito Found with Bellyful (Scientific American) in the first line of the article they state that the fossil was found to contain iron in the fossilized belly of a mosquito indicative of its likely last meal of blood.
The Scientists: Fossilized Mosquito Blood Meal (The Scientist) The article begins: “Researchers have discovered a 46-million-year-old female mosquito containing the remnants of the insect’s final blood meal.”
Lastly, how about the title of the actual research article on which all of these other reports are based: Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito. (Proceedings of the National Academy of Science)
Oh, yeah, that last title really grabs you does’t it!?
So what is it about this little mosquito that created so much buzz? These latter headlines are a bit more accurate even if they sound far less exciting. What scientists found was a high abundance of iron and iron containing compounds in the fossilized abdomen of a female mosquito and a lack of similar iron compounds in the male fossil abdomens. Did they find blood cells? Definitely not! They found only evidence of porphyrin molecules which they reasonably deduced are the degraded remnants of former hemoglobin molecules which are found in red blood cells of vertebrates. Using some very precise instruments that allow them to examine tiny portions of the fossil they were able to show that these iron-beading organic molecules were found in the abdomens but not in the surrounding rock matrix. So not only are the scientists involved NOT claiming to have found red blood cells in the fossil they aren’t even saying they have found hemoglobin but rather only the very very stable remains (porphyrin) of a portion of hemoglobin.
You can probably tell from the headlines above that the details of this fossil find haven’t stopped creationists from claiming this fossil as further proof that the world must be young because this kind of preservation of blood is shocking given we are told the fossil is 46 million years old. Quite the contrary, I think it is quite interesting and it is great that we now have the technology to finally be able to analyze fossils like this. But what they found is not at all shocking. As the figure below shows they found porphyrin molecules which were already known to be able to survive millions of years under the right conditions. Crude oil and shale oil and even coal often contain measurable porphyrin even after the rest of the organic molecules of an organism have been chemically transformed into long hydrocarbon chains. So the thing they found preserved is not new to science at all. However it is still cool to find it in a specific fossil thus allowing us to confirm blood-sucking behavior on a long dead insect.
Preservation context is a problem for young earth creationism:
I attended a conference a week ago in which a young earth advocate referred to this blood-filled mosquito as further evidence against millions of years. As I just said what was actually found is really no challenge to an ancient earth. Rather, the question for young earth advocates is why are the biomolecules of this fossil so incredibly degraded if this fossil is only 4000 years old? A 4000 year old fossil should very well have intact DNA or at least detectable DNA nucleotides. No evidence of such preservation is found. The biomolecules that remain are extremely modified as expected if they had been preserved for millions of years.
Furthermore the geological context for preservation is not supported by any young earth model of earth’s history. Why? The authors note that the chance of this mosquito being preserved in the fossil record is vanishingly small because blood-engorged mosquitoes are “like a balloon ready to burst” and so easily disintegrate. The only scenario they can conceive this mosquito getting preserved in is a placid lake in which the mosquito falls and sinks down to the anoxic (oxygen-lacking) bottom where if gets covered by a rain of very fine particles over time. The layers of shale rock that these mosquitoes are found in thought by young earth creationist to have been laid down near the end of the global flood. If this conjecture is right, how could such a fragile insect be preserved in such a setting? Could a mosquito have been flying around for 6 months above a world covered in water and then fall into the global ocean and get preserved in very fine sediments that look like the bottom of a fresh-water lake? If the mosquitoes died early on in the flood year how did their bodies survive months of sloshing around the world while the 10,000 feet of layers of sediments below where they were deposited? These fossils attest very clearly to a calm and slow series of events rather than global catastrophe.
As some of these headlines suggest, many creationist commentators are quick to interpret these fossil finds probably without having read the original papers (see references below) and certainly without considering the context of their preservation. When the details of the find and the context of how this mosquito was preserved are considered there is no reason for any creationist to be gleeful. Unfortunately, as a soundbite, showing a fossil mosquito and then announcing that blood was found in it makes a compelling soundbite that is hard to refute in 40 words or less. I am at a word count of 1252 right now and I feel I’ve barely done this topic justice.
A mosquito’s last supper reminds us not to underestimate the fossil record. D. G. Briggs. This is a commentary on the main article in PNAS. 2013. PNAS 2013 ; published ahead of print November 1, 2013, doi:10.1073/pnas.1319306110
Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito. 2013. D. Greenwalt, Y. Goreva, S. Siljestrom, T. Rose, and R. Harbach. Published online before print October 14, 2013, doi:10.1073/pnas.1310885110
PNAS October 14, 2013