Survival of the druggies

New Scientist: Taking narcotics may be part of our evolutionary inheritance


Taking narcotics may be part of our evolutionary inheritance

IF DRUGS are so bad for us, why do so many people use them? Because they helped our ancestors survive, argue two anthropologists.

Our predilection for psychotropic substances is usually seen as a biological accident. The conventional view is that drugs fool the brain into thinking it is getting a reward when in fact it isn’t.

But anthropologists Roger Sullivan of the University of Auckland and Edward Hagen of the University of California at Santa Barbara point out that our ancestors were exposed to plants containing narcotic substances for millions of years. In the April issue of Addiction, they argue that we are predisposed to drug-taking because we evolved to seek out plants rich in alkaloids.

Consuming such plants could have been a basic survival strategy. “Stimulant alkaloids like nicotine and cocaine could have been exploited by our human ancestors to help them endure harsh environmental conditions ” Sullivan says. For example, until recently Australian Aborigines used the nicotine-rich plant pituri to help them endure desert travel without food. And Andeans still chew coca leaves to help them work at high altitudes.

Archaeological evidence shows that drug use was widespread in ancient cultures. Betel nut, for example, was chewed at least 13,000 years ago in Timor, to the north of Australia. Artefacts date the use of coca in Ecuador to at least 5000 years ago.

Many of these substances were potent: pituri contains up to 5 per cent nicotine, whereas tobacco today contains about 1.5 per cent. What’s more, these drug pioneers sometimes “freebased” drugs by chewing them together with an alkali such as lime or wood ash. This releases the free form of the drug and allows it to be directly absorbed into the bloodstream.

But in Pacific cultures where chewing betel nut is still widespread, it is seen more as a source of food and energy than as a drug, Sullivan says. And some drugs do have real nutritional value. For example, 100 grams of coca leaf contains more than the US recommended daily intake of calcium, phosphorus, iron and vitamins A, B2 and E.

And in some marginal environments, people’s diets may have been so poor that they struggled to produce enough neurotransmitters of their own. Consuming plants containing substances that mimic neurotransmitters could have helped make up for the shortfall, Sullivan and Hagen speculate. They say this part of their theory could be tested by depriving animals of certain neurotransmitters and seeing if they then choose to eat food rich in substitutes.

Sullivan’s adaptive model of drug use is definitely plausible, says Wayne Hall of the University of Queensland, who until recently was head of the National Drug and Alcohol Research Centre in Sydney. “There is certainly evidence that plants evolved to mimic the neurotransmitters of mammals,” he says. “But the problem today is that we have much larger doses of much more purified drugs.”

Abbie Thomas, Sydney

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9 thoughts on “Survival of the druggies

  1. todd x

    This is interesting, more interesting is the way these scientists intend use animals in a lab setting to test the theory. What the heck is going to be gained by this? This sounds more like a couple of scientsts manufacturing a study just to get paid. Alix Fano’s book Lethal Laws is a great study of toxicity testing on animals and how desired results can be achieved.

    What kind of validity is to be achieved from such a study? Apart from the varibles and the basic difference in species, what possible setting could these test animals be placed in that they would mimic the reasons that led to human consumption of plants rich in neurotransmitter substitutes?

    Heck deprive me of neurotransmitters and i sure as hell would not be able to pick out plants rich in a substitute let alone know i was being deprived of neurotransmitters unless someone told me.

    Which leaves me wondering wouldn’t a investigation to how early scientists figured out the benefits of narcotics? Regardless of what we think today, the medicine men and women, shamans, priests, etc. were scientists.

  2. barb dybwad

    It’s unfortunate that this particular study tips a bit into the pseudoscience category, because it’s refreshing to see a study that is not hellbent on proving that “drugs = bad.”

  3. Kayleigh

    i think drugs are foul,the people who take drugs could hurt themselves and others around them,i wish that drugs were never introduced to this world,except medical drugs that are given to sick people at hospitals.I also don’t like it when people is bad for their health and bad for other peoples health so please if anyone reads this cpmment if u take drugs or smoke please stop,not just for your safety but for other people around u!!!!!

  4. William

    I think it’s really bad to hear someone like kayleigh say how bad drugs are! She mentioned that it’s fine for sick people in hospitals! What about sick people on the street that have no insurance or ability to pay? Did you really take the time to think about your comment? Maybe you should put that silver spoon back in your mouth!!!


  5. chantelle

    i can empathise with people who lose family and friends and loved ones to drugs in december 2004 i lost my dad to drugs and im still tryin to pick up the pieces i was 14 im nearly 16 now and they say it gets easier in time but i dont feel it has to me the pain is always going to be just as strong and it has crippled me and the rest of me dads family he was 31 he was clean for 15 months and someone set him a poisonous cocktail of drugs to kill him and it worked and wrecked the rest of us with it so people who od on drugs it doesnt just kill one person it kills the rest of the people who care and love u inside sorry im goin on a bit i could forever but theres only so much u can say thanks xxx

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