Is Bitter Better?

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Foxgloves growing “outside the fence” near Cygnet, Tasmania.

Is Bitter Better?

John Reid

According to a recent article in Science magazine (“How modern humans ate their way to world dominance” by Ann Gibbons) humans have fewer bitter-taste genes than chimps. She writes:

… anthropological geneticist George Perry of Pennsylvania State University, University Park, and his colleagues compared the genomes of modern humans and chimpanzees to the newly published genomes of a Neandertal and one of its close relatives, a mysterious human ancestor known as a Denisovan, known only from a few bones found in a Russian cave. All three groups of humans had lost two bitter taste genes, TAS2R62 and TAS2R64, that are still present in chimpanzees, the team reports this month in the Journal of Human Evolution.

Two million years ago, our early ancestors such as Australopithecus or early members of Homo likely found wild yams and other tubers bitter. But as humans began to cook, they could roast tuberous root vegetables long enough that they weren’t as bitter. (Today, hunter-gatherers still rely on roasted tubers as a major source of calories.) At the same time, hominins—members of the human family—lost those two particular bitter taste genes, so they were presumably able to eat a wider range of tuberous plants. Modern humans, Neandertals, and Denisovans all lost the ability to detect the bitter flavor in some wild plants and eventually modern humans bred varieties of squashes, gourds, and yams that are less bitter than the wild types.

My wife and I have been gardening on the edge of native forest in Southern Tasmania for a decade now and we have had some hands-on experience with native animals and bitter plants.

Rufous wallabies (Thylogale billardierii) are particularly voracious and will even eat potato tops. “Will it grow outside the fence?” is a popular topic among local gardeners. Bulbs such as daffodils will survive and sometimes beds of daffodils can be seen in wild places decades after house and gardener have disappeared.

We have noticed that plants noted for their alkaloid content, particularly foxgloves (digitalis) and tobacco (nicotiana), do quite well outside the fence, presumably because they taste bitter to the animals.

Now here’s the thing: presumably these plants evolved to secrete poisonous alkaloids to protect themselves from being eaten by animals and the taste genes of the animals co-evolved to prevent them from being poisoned by alkaloids. Hence having fewer bitter taste genes should be an evolutionary disadvantage rather than an advantage as the article suggests.

Maybe we humans lost the TAS2R62 and TAS2R64 genes because, having learned how to cook, we no longer needed them.

13 thoughts on “Is Bitter Better?”

  1. It is fortunate for the humans that there was a lack of predators for our species if we tasted better than chimps. It would be interesting to know how the taste of apes compared to humans in the light of the work of Oscar Kiss Maerth in his groundbreaking ‘The Beginning Was The End’ (Econ Verlag 1971).

    Incidentally I am banned from posting on Facebook for 24 hours for using the ‘W’ word!

    1. Ben, I see. Your visit to my blog is merely the outcome of Facebook Deprivation.

      I once burned my hand on a stove when very drunk. It smelled exactly like roast pork.

  2. Yes John,
    My polemic is indeed “supportive of drug culture” as well as funny, as intended.
    Evolution implies extreme experimentation. Hence my cocky infested almond tree, and Denmark’s bog man having 100s of herbs in his gut, many primitive cultures being well known to have been into herbs in a big way, including psycho-active ones. Hence my belief that human ancestors included “druggie apes”. What I wrote was more than a personal indulgence.
    Indeed I believe that there were many druggie overlords in prehistoric times and places where there were few enemies to worry about, as often there were few or no enemies. Recall that humans were thinly spread around a very large Earth indeed, in those days.
    Further evidence is today’s drug tolerance, those missing genes and so on. So yes, I am against The Drug War. Humans should be regarded as the druggies they have always been. Consistent with this view also is contemporary tolerance of much marginal, even criminal behaviour along with Law and Order, mostly because capitalism works better in such an experimental, evolutionary way so akin to human drug taking behaviours.

    1. Didn’t know that about the bog man – you may well have a point. There is also the theory that cave paintings are the manifestation of psychedelic experience (e.g. those in the Drakensberg Mountains in SA). I suspect sensory deprivation was also used to encourage such visions and that this could have been a function of the barrows found in NW Europe and very thick stone walls of temples such as the Ness of Brodgar. We visited Maes Howe in the Orkneys and were told that it was definitely not a burial chamber.

  3. All of our almonds from our huge almond tree get taken when still green and very bitter every year by parrots, mostly white cockatoos. My understanding is that the parrots have learned to eat Kaolin clays as an antidote enabler. Maybe humans got into similar combinations. I personally find that fresh fruit and veges greatly improve my tolerance of such exotics as coffee, chocolate and alcohol, stave off headaches. Could this be how, why humans got into milk and dairy products in a big way, and/or various other foods or herbal combinations, consistent with how the wellknown psychoactive drugs are also usually analgesics, i e painkillers (a coincidence ?) !?!?

  4. In Africa, browsing animals like Giraffe and Kudu don’t eat long from one tree. It was found the tree fed bitter compounds into its leaves soon after the animal began feeding.

  5. I forwarded your bit to an archaeologist friend. I asked her how long cooking had been around.

    She replied:

    Certainly 1.5 M, probably 2m.

    For a detailed discussion see Hallam 2014 (revised editon of Fire and Hearth, Afterword), pp177-179.

    The survival value is access to more plant staples – which form the bulk of the diet except in subarctic and very cool temperate latitudes.

    Fire and cooking were not the only mechanisms of detoxificaton. Leaching is used in NT and more widely.

    Pits with identifiable tuberous remains have come from the earliest dated H sapiens levels in island SE Asia, in Niah Cave at 45k.

  6. “Disused, bitter taste genes were mostly gone” was too cryptic, another one of my flags, shorthand for the idea that :
    Within such a druggie ape prehistoric human culture, key psycho-active herbs would generally have been declared sacred early in its history, greatly disadvantaging everyone with either or both of those bitter taste genes because of wellknown extreme health consequences of having to coverup one way or another, in a variety of ways, psycho-socially.
    That this may have been a majority of people is not a problem, people are easily swayed by charismatic leaders, even ones from left field, as history has proved. Hitler was laughed at by the majority for years before he charmed them.
    Milk would have been similarly challenged, and would have had a similar prehistory. That sacred drugs may not have been as physically poisonous as milk was to lactose intolerant individuals (originally a majority), is also not a problem, mental illness being as real (to humans) as physical illness.
    The scene was thus set for Natural Selection to take out nearly all of the deniers, skeptics, hypochondriacs complaining of headaches and so on, and other crazies, the majority of whom would have had one or both of those bitter taste genes, consistent with what happened to lactose intolerant individuals in prehistoric cow milking societies surrounding the Baltic Sea.
    Hence today’s milk and/or drug tolerant majority . . .

    1. Fang, your polemic supporting the drug culture is among the best I have read on that topic.

      A couple of points – I believe adult lactose intolerance is the norm among Homo Sapiens. Those people who do not have it tend to have ancestors who were cattle herders.

      The comment on Hitler reminds of Barry Humphries: “When I said I wanted to be a comedian they all laughed. But they are not laughing now.”

      1. Yes John, corroborative. Proof of how open humans are to being charmed and “turned around”, the term used by spy agencies to explain their important use of “turning around” foreign agents to produce double agents, another corroboration. An important factor I forgot to spell out was that prehistoric societies did not always have enemies or even neighbours to worry about thanks to their having a very large Earth to expand into. Or even a sky for getting into astrology if you were in tropical rainforest. So, with no enemies or sky and nothing much else to worry about, what else for young men to get into . . .

  7. Genetic changes like this generally have survival value. Hence their Natural Selection. So , How ?
    My suggestion is that what distinguished humans from chimps was that the humans were more wilful, did not give up messing with herbs just because they got a headache.
    Humans looked for and found other herbs, containing aspirin, opium, cocaine and so on, that cured the headaches, and proved even better (than say daffodil) for tripping, having parties, getting girlfriends, casting spells, conning , inventing, firestick farming, and so on . . . And voila :
    After 1,000s of years of such tripping, including unusually wild fucking, proto-druggies outbred proto-puritans.
    Rivals, forests and disused, bitter taste genes were mostly gone, and we were on track to
    Where we are now . . .

  8. Perhaps it is not so much knowing how to cook but knowing how to prepare food. Some foods such as yams and various beans are poisonous unless they are first soaked in water overnight.

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