The Daily Science Update for Tuesday was Skin Sample Is Two Million Years Old? In it we have a return to the topic of soft tissues which were so popular back in July.
Back in July, along with a number of DpSUs on the subject, Mr Thomas created a list of “Published Reports of Original Soft Tissue Fossils.” At the time I went over this list, commenting on each entry in what was admittedly a rather typo-riddled post. I said I would make summary of the contents – considering I didn’t at the time, now is a good a time as any to do so.
To briefly go over the DpSU for today, we have those two million year old A. sediba fossils which apparently also have what might be preserved skin. To take a quote from an article on the subject:
“It looks like skin; it’s in the right position to be skin – but extraordinary claims require extraordinary evidence.”
Brian Thomas argues that the fossil, then, could not possibly be two million years old if it contains soft tissue. The article also lobs around the odd accusation of persecution and conspiracy against researchers in the feild of discovering soft tissue finds.
There are a few problems with the ‘it can’t be two million years old’ claim. For one, at this stage they a) don’t know for sure that it’s skin and b) there are processes that could preserve it. To quote the FAQ for the project:
If it is soft tissue, we need to know how it may have been changed as it was preserved, whether through drying, soaking in anoxic conditions, mineralization, or some combination of processes.
The stand out here is mineralisation. If soft tissue is mineralised then there is no reason why it can’t last as long as the bones do. If they don’t know that the observed thing is skin, and they can’t tell, if it is skin, whether or not it has been mineralised, then Mr Thomas has no case at this stage. As we shall see, even for finds that genuinely are cases of the original soft tissue surviving for exceedingly long periods of time, the most you can conclude from them is that our ideas about how long organic material can last before it decays are incorrect – it seems that they can last a little longer.
I’ve written to Dr John Hawks, a person involved, seeking comment from him – the FAQ and other information I’ve seen on his site may possibly be out of date, being some months old – and if I get a response you will see more about this. In the mean time, on to the summary.
Quite a number of the examples in the list, including the first one, have the same problem as the above. “Soft tissues” are still called that once they have been fossilised/mineralised, and they can still be called ‘exceptionally preserved’ even when we’re still talking about mineralisation having occurred. My inability to read past the abstract on a good number of papers is also a problem here.
The entries on the list fall into several categories of different finds.
Many of the entries are to do with finds in Amber. Normally, when something like an insect is preserved in amber the internal portion rots away, just leaving the shape of the organism. However, it seems that amber may be capable of preserving traces of things that were inside of it. The list is arranged in chronological order of publication. We start with DNA and move on to real live bacteria and yeast (an also a mammalian hair, although that just seems to be a preserved shape, albeit in stunning detail, and so is irrelevant). While it seems likely that many of the earlier DNA finds were contamination, the later bacteria ones seem to have been reproducible.
This tells us that amber is good for preserving things, but the fact that this kind of thing is actually hard to do is an important sign pointing towards a date for these finds at much more than the 6000 years of the YECs.
The bacteria finds can be subdivided into spore and non-spore finds. When bacteria are in spore form they are much more hardy than otherwise, and there are two other places on the list where they are recovered from salt crystals rather than amber. There was another entry about a non-spore forming bacteria found in amber, but it was of a kind that was just generally good at suriving. Adittionally, the bacteria was able to utilise many things present in the amber for survival, rather than just waiting around for 120 million years.
The presence of a large number of papers on this list where the soft tissue has been mineralised suggest the Mr Thomas could not recognise the kind of preservation we’re looking for if it fell on him. This includes the ‘Ichthyosaur skin’ in number 10, and a good number of papers about fossilised melanosomes.
These seem to be the most promising. However, they mostly seem to be a case of particularly hardy proteins and/or circumstances that increase the ability for them to survive.
Summary of the summary
Again, B.T. wouldn’t know soft tissue if it fell on him. Additionally, it’s very clear from the finds that not only is it much harder to find legitimate cases of ‘soft tissues’ that have survived intact for millions of years than you would expect if they were really only a few thousand years old, but it is also harder to find them in older rocks, as you would expect if there were significant age differences between the earlier and later finds.
However, at ages of only a few million years there do seem to be a few traces and residues of soft tissues, suggesting that they may be able to survive that long. And in many cases, for example the bacteria in the Permian evaporitic deposit, it seems that it would be harder for creationism to explain the observations than a system that involved the finds being very old.