Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Paul Anderson on 14/01/2009 08:56:30
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Paul Anderson asked the Naked Scientists:
Hi Chris and team,
In the old days, if I were a ruler, I could get one of my slaves to eat something and if he didn't die, I might try eating it, but slaves have gone out of fashion these days.
If my plane crashes in an Amazonian jungle and I am the only survivor, how can I determine what plants I can safely eat? Obviously if a see a lot of dead animals around a plant, I can infer that they may have ingested the foliage and died from that plant, so I skip that one, but things will not be that obvious.
The other thing is that the bacteria in my gut will be different from that in various other animals.
My garden currently has luxurious growth. It's a pity they are all weeds. Why can we not eat weeds? If we could eat kikuyu grass I would have food for life.
Comments welcome.
Regards
Paul
NZ
What do you think?
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Well Paul, as far as kikuyu grass goes, I'm not a big fan of it. I would think that many plants that we can eat are just too fibrous to pass through into the bloodstream. It would be like trying to swallow some flax!
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The ability to know what to eat perhaps started from humans seeing and then eating plants that animals ate. It would be a reasonable basic assumption that if an animal can eat it, the likelihood that it is poisonous/deletarious to humans is reduced (though of course not wholly gone). I guess that there was also a deal of trial and error. This would probably have been passed down by word of mouth.
The capacity to go into an alien environment and instinctively know what is edible is not a likely premise. Various armed forces are trained extensively on survival techniques, which includes food. I would say that you are more likley to survive well if you can catch herbivorous animals and fish, and find potable water rather than relying on vegetation.
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I've done a little Jungle training out in Indonesia, and we were taught that you should go through the following process to work out what is safe...
Firstly, see if anything else eats it, and have a look at it's contruction - is it dry and fibrous (if so, probably not so good to eat) or is it thick and succulent? What sort of juices come out? Clear, white, sticky? Generally, white juice isn't good (think rubber trees).
Secondly, take a small amount of the plant (start with the juices) and rub it on your wrist. As long as you know whereabouts, you can do this for several different plants or parts of one plant (With Rattan, for example, the leaves are unpalatable, but the heart is delicious).
Thirdly, chew a small amount of the plant, but do not swallow. If it blisters your mouth or causes irritation, leave well alone.
Finally, eat a very, very small amount, and ensure you have plenty of water on hand, in case it cause you to void your stomach (if you know what I mean!).
Should you cope with the small amount, gradually start eating more of it.
Ideally, for each stage you should start with it boiled, then work your way up to raw. Generally, leaves are more likely to contain defensive chemicals, so try hearts and tubers (though many tubers are also poisonous).
You should do this with only one plant at a time (so that you know which ones are ok, and which are not). It's therefore best to start working out what you can eat long before you run out of the food you know is okay, as this can be a long process.
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There are many plants and 'weeds' you can eat. What you call a 'weed' may be a 'garden plant' to someone else, they are not 'weeds', they are wild plants.
You can eat dandelion for example and Nasturtium, in fact we eat only a very small variety of plants which are edible. Take a look at this site http://www.pfaf.org/leaflets/edible_uses.php (http://www.pfaf.org/leaflets/edible_uses.php)
Who tried them all? It certainly wasn't me.