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So that’s what chemistry is good for…

Stinky stuff! This fits perfectly with my biased preconceptions. So here are two examples of chemistry used to analyze things you’d normally run away from.

The oldest traces of human poop have been dug out of a cave in Spain — and it’s Neandertal poop. It’s about 50,000 years old, and it’s been reduced to a compressed, thin smear of organic compounds, so I guess it isn’t actually so stinky anymore, but there was enough of it to analyze chromatographically. In case you’ve wondered your whole life about what Neandertal poop would look like, here you go.

Microphotographs of a slightly burned coprolite of putative human origin identified in El Salt Stratigraphic Unit X (sample SALT-08-13). The images under plane polarized light show the pale brown color and massive structure of the coprolite, as well as the common presence of inclusions, which are possibly parasitic nematode eggs or spores.

Microphotographs of a slightly burned coprolite of putative human origin identified in El Salt Stratigraphic Unit X (sample SALT-08-13). The images under plane polarized light show the pale brown color and massive structure of the coprolite, as well as the common presence of inclusions, which are possibly parasitic nematode eggs or spores.

Dead for 50 millennia, and what we know about this dead person is that they took a massive dump that was full of parasites. TMI.

I thought the paper was preliminary and rather general — they don’t or can’t make very specific conclusions, but then, I imagine they were excited to be the first to get any discussion of Neandertal feces into the scientific literature. We do know a couple of things: Neandertals ate both their meat and their vegetables, and they had gut bacteria with similar physiological properties to our own.

Taken together, these data suggest that the Neanderthals from El Salt consumed both meat and vegetables, in agreement with recent hypotheses based on indirect evidence. Future studies in Middle Palaeolithic sites using the faecal biomarker approach will help clarify the nature, role and proportion of the plant component in the Neanderthal diet, and allow us to assess whether our results reflect occasional consumption or can be representative of their staple diet. Also, this data represents the oldest positive identification of human faecal matter, in a molecular level, using organic geochemical methods.

Besides having corroborated our method and obtained the first evidence of an omnivorous Neanderthal diet from faeces, our results also have implications regarding digestive systems and gut microbiota evolution. Approaching the evolution of the human digestive system is difficult because there is no fossil record indicating soft tissue preservation. Our results show that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol due to the presence of bacteria capable of doing so in their guts. Further research will allow us explore this issue in the context of human evolution.

I said I had two unpleasant examples of useful chemistry, and here’s the second: using the characteristic odors of different stages of decay to quantify the time of death.

An international research team used two-dimensional gas chromatography time-of-flight mass spectrometry to characterise the odours that create this smell of death:  volatile organic compounds (VOCs).  By measuring the VOCs released from pig carcasses the team identified a cocktail of several different families of molecules, including carboxylic acids, aromatics, sulfurs, alcohols, nitro compounds, as well as aldehydes and ketones. The combination and quantities of these VOCs change as a function of time as a cadaver goes through different stages of decomposition.

I think I’m getting a sense of the difference between chemistry and biology. I prefer the bodily fluids in my subjects to be fresh, preferably spurting; chemists seem to favor observing the degradation and volatilization of fluids from dead things. Chemists may offer their repudiations of my sentiments in the comments.

Comments

  1. says

    Yay Inorganic Chem! The smells are less ….um… yeuchy!!

    btw not really that much of a coincidence, but last night one of my kids (who’s an undergrad at Cornell) called me and happened to mention that he is currently taking part in a similar study of the ‘input and output’ of students. Now that’s poop I wouldn’t like to examine…

  2. bbgunn says

    Wonder how long before one of those fictional television shows about crime scene investigation incorporate time of death calculations via VOCs into their sixty minute crime solution formula?

  3. says

    Having attended many autopsies, I can say without doubt that people are really, really stinky on the inside.
    Actually, they smell pretty bad on the inside dead or alive.

    I would recommend everyone attend at least one autopsy if they can. It is an amazing experience and really drives home how incredibly complex and messy we are. It’s astounding that our bodies work at all.

  4. busterggi says

    I look forward to other applications of this technique, now we can find out if cave bears shat in the woods.

  5. davidnangle says

    You keep investigating the areas around 50,000 year-old newspapers and you’re bound to step in something like that.

  6. sawells says

    I’m a physicist but as of two weeks ago I work in a chemistry department and my case studies might be biology, so I have absolutely no idea what to say about these subject divisions except that I wish funding agencies didn’t use them to decide not to fund me. (Biology funding: No that’s physics. Physics funding: no that’s biology.)

    Hey, actually I even got to use the word “evolution” in a paper!

    http://onlinelibrary.wiley.com/doi/10.1002/prot.24630/abstract

  7. Louis says

    HEY! Chemists don’t just do analyses of stinky things. Some of us make things too…

    …Okay some of those things stink and also need analysing but that’s just a coincidence.

    Curse you Pee Zed Ngmijwhush and your anti-chemist prejudices! You’re nearly as bad as the physicists.

    ;-)

    Louis

  8. caseloweraz says

    PZ: I think I’m getting a sense of the difference between chemistry and biology. I prefer the bodily fluids in my subjects to be fresh, preferably spurting; chemists seem to favor observing the degradation and volatilization of fluids from dead things. Chemists may offer their repudiations of my sentiments in the comments.

    This fits reasonably well with the common definitions of the sciences:

    If it stinks or pops, it’s chemistry.
    If it bites or scratches, it’s biology.
    If it doesn’t work, it’s physics.

  9. bbgunn says

    Zeno @ 8 and davidnangle @10: CSI: Out House? Law & Ordure? Hill Street Browns?

    Stinking badges mandatory?

  10. Artor says

    Hey, PZ. My girlfriend & I are on the same page as you. We both like fresh, spurting body fluids too! TMI?

  11. Louis says

    PZ,

    Actually, yeah that IS fair. Mostly we get ignored or blamed for everything. So the chemtrails, vaccines giving kids homosexuality, and Illuminati mind control drug things are true*, big dea….I’ve said too much…

    …Say, apropos of nothing, can anyone else hear black helicopters converging on their location?

    Louis

    *Also DHMO is lethal and homoeopathy wor…wor…wor…nope can’t even say it as a joke.

  12. Louis says

    Artor,

    I’m guessing it depends on which fluids as to just how appropriate that comment is! :-)

    I mean fresh, spurting blood, sure it’s a sign of a healthy circulatory system. At least temporarily. It’s also indicative of a fairly serious “leak”…

    Louis

  13. moarscienceplz says

    I have no doubt that PZ’s lab, full as it is with dozens of glass vats full of dilute fish poop, smells daisy fresh.
    ;-)

  14. magistramarla says

    caseloweraz @ 14,
    As the wife of a computer science student, allow me to add to your science definitions:

    If the damn machine won’t work. it’s computer science.

  15. Monsanto says

    I’m surprised you didn’t mention diamines. Two of my favorites are putrecine and cadaverine, also found in halitosis, vaginosis, and semen (along with spermine and spermidine). Who would have suspected you can tell how ripe a body is by its aroma?

  16. Esteleth, [an error occurred while processing this directive] says

    And then there’s medicine, where we’re up to our elbows in poop.

    Specifically, your poop. And then we wipe gently, apply barrier cream, and add the diaper.

  17. jste says

    Esteleth:

    Specifically, your poop. And then we wipe gently, apply barrier cream, and add the diaper.

    If I were to guess you are a nurse, work around nurses, or are studying nursing, how far off the mark would I be?

  18. Esteleth, [an error occurred while processing this directive] says

    What, the mark you’re standing on?

  19. jste says

    What, the mark you’re standing on?

    I suspect I may have an advantage in that you’ve discussed it in the lounge at some point in the past, but your comment was very reminiscent of the humour I’ve come to expect from my nursing friends!

    And on the topic of smelly things:

    If the damn machine won’t work. it’s computer science.

    And if it smells like popcorn, the computer scientist managed to blow it up ;)

  20. ttch says

    From The Pleasure of Finding Things Out – The Best Short Works of Richard P. Feynman (this from a BBC television interview):
    When I became a member of the National Academy of Sciences, I had ultimately to resign because that was another organization most of whose time was spent in choosing who was “illustrious” enough to join, to be allowed to join us in “our” organization, including such questions as we physicists [have to] stick together because they’ve a very good chemist that they’re trying to get in and we haven’t got enough room for so-and-so. What’s the matter with chemists? The whole thing was rotten, because its purpose was mostly to decide who could have this honor, okay? I don’t like honors.

  21. Callinectes says

    I have noticed that the popular science, skeptic, atheist, and so forth movements seem to be lacking in notable Chemist personalities. Is this why?

  22. says

    If it stinks or pops, it’s chemistry.
    If it bites or scratches, it’s biology.
    If it doesn’t work, it’s physics.

    Chemie ist wenn es kracht und stinkt
    Physik wenn der Versuch misslingt

    (It’s chemistry if it goes bang and stinks, it’s physics if the experiment fails)

    I should mention that our chemistry teacher’s favourite method of demonstrating diffusion was to open a can of buturic acid and to wait when which row of students would complain.
    Unfortunately my classroom was in the science tract and he did this every year with about 6 classes which made the whole building stink for about two weeks

  23. Esteleth, [an error occurred while processing this directive] says

    There’s a chemical that is very commonly used as a component of cell culture media.

    It is very useful, and is relatively cheap.

    But hot damn does β-mercaptoethanol stink.