Human Genome Recovered From 5700-Year-Old Chewing Gum

August 10, 2023 2:57 AM

Human Genome Recovered From 5700-Year-Old Chewing Gum [Smithsonian Magazine]. The piece of Birch tar, found in Denmark, also contained the mouth microbes of its ancient chewer, as well as remnants of food to reveal what she ate.
posted by chariot pulled by cassowaries (29 comments total)

This is great, and I love how it shows the value of interdisciplinary interaction and collaboration:

The fact that the discarded artifact survived to reveal so much information about the past isn’t entirely due to luck, Kashuba says. “I think we have to thank the archaeologists who not only preserved these gums but suggested maybe we should try to process them,” she says. “If it hadn’t been for them, I’m not sure most geneticists would have bothered with this kind of material.”
posted by rory at 3:19 AM on August 10, 2023 [3 favorites]

Don't get too excited. There's a big gap between sequencing a genome and cloning an extinct homo sapiens.
posted by phooky at 4:05 AM on August 10, 2023 [4 favorites]

Someone should submit the results to Ancestry.com.
posted by eirias at 4:13 AM on August 10, 2023 [27 favorites]

Further research will investigate whether chewing gum loses its flavor on the bedpost over 5700 years.
posted by zamboni at 4:34 AM on August 10, 2023 [29 favorites]

Hazel nuts and duck. Sounds delicious, though I suspect my frame of reference (Peking duck, and Nutella for dessert?) is not super realistic.

Also learned that gum is plastic??
posted by Baethan at 4:51 AM on August 10, 2023 [3 favorites]

“We determined that she had this striking combination of dark skin, dark hair, and blue eyes,” Schroeder says. “It’s interesting because it’s the same combination of physical traits that apparently was very common in Mesolithic Europe. So all these other ancient [European] genomes that we know about, like La Braña in Spain, they all have this combination of physical traits that of course today in Europe is not so common. Indigenous Europeans have lighter skin color now but that was apparently not the case 5,000 to 10,000 years ago.”

Today I Learned.
posted by clawsoon at 5:45 AM on August 10, 2023 [12 favorites]

The original gum Americans are familiar with was derived from the chicozapote or sapodilla tree. Apparently this is pretty uncommon now, and most gum is made from plastic, commonly polyvinyl. I think the just gum and simply gum are both still based on stuff from trees, no idea how they compare to the gums most people are used to now though.
posted by ockmockbock at 5:53 AM on August 10, 2023 [1 favorite]

The original gum Americans are familiar with...

..was brought to the United States by General Antonio Lopez de Santa Anna (yes THAT General Santa Anna) who was in exile for a failed coup and living on Staten Island (yes, THAT Staten Island) who learned of the raw 'chicle' material used to make rubbery stuff and he intended to sell it to US manufacturers as a means of funding his next attempted coup to take over Mexico. One guy found it was fun to chew on so he added flavoring.

(previously)
posted by AzraelBrown at 6:10 AM on August 10, 2023 [18 favorites]

We determined that she had this striking combination of dark skin, dark hair, and blue eyes

Really? You could tell how her genes expressed?
posted by Tell Me No Lies at 6:11 AM on August 10, 2023

Cheddar Man: Mesolithic Britain's blue-eyed boy
posted by glasseyes at 6:21 AM on August 10, 2023 [4 favorites]

Really? You could tell how her genes expressed?

I don't know about skin and hair, but I seem to recall that (a) the recessive genes for blue eyes are pretty unambiguous to spot, and (b) supposedly all blue-eyed people have a common ancestor, it's actually a freak mutation from the days when homo sapiens population was low, real low.
posted by The Pluto Gangsta at 6:33 AM on August 10, 2023 [4 favorites]

More recently (2021?) Adrian Targett from Cheddar was found to be a direct descendent of Cheddar man through mitochondrial DNA. I can't quite remember the circumstances, something about general DNA testing in the area to find out something about settlement patterns. But I do remember his mother being interviewed on the radio saying rather plaintively that her son was not a caveman.
posted by glasseyes at 6:37 AM on August 10, 2023 [15 favorites]

Cheddar man and his descendants just chillin'.
posted by Meatbomb at 6:41 AM on August 10, 2023 [3 favorites]

By more recently I mean sometime after the DNA analysis of Cheddar Man explained his probable phenotype. The At-Bristol museum (sorry, can't remember which iteration of it's name it's going by now as I always remember it as The Exploratory) has a full-sized model on the ground floor based on the original reconstruction. They have made the skin slightly lighter, and they have the figure draped in "wolfskin" - fur fabric. It looks astounding, so spry, quizzical and alive. An interesting figure to come accross unexpectedly
posted by glasseyes at 6:44 AM on August 10, 2023

So if the Middle Eastern farmers who took over weren't white, and indigenous Europeans weren't white, where did us white people come from?

I think I need to catch myself up on some Hotep science...
posted by clawsoon at 6:45 AM on August 10, 2023 [1 favorite]

So if the Middle Eastern farmers who took over weren't white, and indigenous Europeans weren't white, where did us white people come from?

I've seen it suggested that lighter pigmentation was an adaptation to reduced sunlight and therefore reduced vitamin D production in far northern latitudes amongst agrarian humans. One possible mechanism suggested for the change was neoteny...
posted by jim in austin at 7:36 AM on August 10, 2023 [3 favorites]

So it turns out they were wrong--gum can last in your stomach for 5700 years!
posted by praemunire at 7:39 AM on August 10, 2023 [9 favorites]

this striking combination of dark skin, dark hair, and blue eyes
Finnish palaeontologist Björn Kurtén wrote a novel Dance of the Tiger (1978) which featured dark-skinned Cromagnons and white Neanderthals. The gripping yarn was re-issued by UCalPress in 2015.
posted by BobTheScientist at 8:21 AM on August 10, 2023 [1 favorite]

So if the Middle Eastern farmers who took over weren't white, and indigenous Europeans weren't white, where did us white people come from?
From reading David Reich's Who We Are and How We Got Here, I believe pale skin came from the the Near East farmer migration. There was also a major influx from what may be the Indo-Europeans shortly after the Neolithic farmer migration. Modern Europeans are an admixture of at least three different human groups who had been genetically isolated for thousands of years before. Of course, I read it a while ago and may be confusing some details. The book does a good job of going into the different migrations into Europe and explaining the new genetics methods that led to our current understanding.

*Edit: And pale skin only really took off after diets became vitamin D deficient. This is partly why Europeans are so much paler than indigenous people from Polar regions, whose diets contained sufficient vitamin D.
posted by ockmockbock at 8:36 AM on August 10, 2023 [8 favorites]

IMO, the differences in hours of sunlight perfectly explain lightening of skin, as vitamin D is absorbed through the skin via sunlight, not only though food. Northern Europe gets less than 1200 hours (of 8700 total hours in a year ) of sun throughout your average year. As you go south, it increases dramatically to over 3000 hours. Basically the evolutionary version of white people losing their tans in the winter.
posted by The_Vegetables at 9:02 AM on August 10, 2023 [1 favorite]

Other than sunlight and mushrooms(???), the major natural sources of human vitamin D are fish oils and animal livers. This suggests low density hunter/gatherer rather than settled agrarian populations without some sort of adaptation for high latitudes...
posted by jim in austin at 9:17 AM on August 10, 2023

I have been traumatized for many years by recurring nightmares regarding chewing gum, so I am not sure how I feel about the fact that people have been chewing gum for SO.LONG!

but its really really super cool that the scientists were able to extract the DNA from this sample.
posted by supermedusa at 9:20 AM on August 10, 2023

I'm skimming Skin colour and vitamin D: An update, and it says that both the skin-lightening and dietary explanations are attractive but probably incorrect:

The first answer to this question was the hypothesis of Jablonski[8, 9] that the need for efficient vitamin D3 synthesis acted as evolutionary driver for skin lightening (Figure 4, left). Although this theory has attractive simplicity, the recent data on the history of skin lighting in the European population (Figure 2) demonstrated that European hunter-gatherers of central and western Europe survived for 35 000 years with dark skin and got lighter skin only by interbreeding with external populations from western Anatolia and the Russian Steppe migrating into different European regions.

It has been suggested that the introduction of agriculture by these populations, that is dietary change from a hunter-gatherer diet to vitamin D-poor agriculturalist diet, reinforced the selection pressure for light pigmentation.[65, 82] Accordingly, the dark skin of some of today’s Arctic Native people, such as Inuits, has been traditionally explained for their marine diet rich in vitamin D3.[8] However, nitrogen and carbon isotope analysis of northern and western Scandinavian hunter-gatherers revealed their had an extreme marine diet as well and yet developed light skin.[48] Thus, archeogenomic data as well as comparisons of today’s populations did not provide any indication for an evolutionary pressure for light skin created by the need for vitamin D.

So that's two explanations down the drain...
posted by clawsoon at 9:21 AM on August 10, 2023 [7 favorites]

supermedusa: I wish you pleasant dreams full of people going "oh my gosh, most of this gum is made of plastic! and it's exacerbating my tmj disorder! Let's launch it all into the sun" and then they do, and everyone switches to mints and lives happily ever after

While we ponder why there are white people
oh my god Karen you can't just ask someone why they're white
I would also like to ask why humans like chewing on chewy stuff so much
posted by Baethan at 9:32 AM on August 10, 2023 [6 favorites]

So that's two explanations down the drain...

Finishing up skimming through the paper, they seem to be suggesting that Europeans got vitamin D adaptations (mostly increased vitamin D sensitivity) from brown-skinned Siberians, and white skin via genetic drift from western Anatolia and the Russian steppe. Two completely separate processes.

And also:

Moreover, in contrast to previous beliefs, dark pigmentation seems not to be a prominent inhibitor of vitamin D3 synthesis, since the latter happens largely in upper layers of the skin that are less pigmented.

posted by clawsoon at 10:25 AM on August 10, 2023 [1 favorite]

Cheddar Man

"Criminals are a cowardly and lactose intolerant lot . . . "
posted by The Bellman at 10:29 AM on August 10, 2023 [1 favorite]

"Criminals are a cowardly and lactose intolerant lot . . . "

Believe it or not, that's more-or-less a white supremacist talking point.
posted by clawsoon at 10:48 AM on August 10, 2023 [4 favorites]

I would also like to ask why humans like chewing on chewy stuff so much

I also wonder this and assume it’s somehow tied to why jaws clench on MDMA.
posted by Uncle at 8:10 PM on August 10, 2023

@Tell Me No Lies: Really? You could tell how her genes expressed?

Yep! I mean, it's kind of complicated but doable ...

"Model-based prediction of human hair color using DNA variants"
posted by nickzoic at 5:13 AM on August 11, 2023