Nietzsche reprised

Poisonous Euphorbia damarana didn't kill gemsbok, but instead, made them stronger under challenging environmental conditions.
Image: Hans Stieglitz/Wikimedia Commons.
Image: Hans Stieglitz/Wikimedia Commons.

That which does not kill us makes us stronger’ are words attributed to Friedrich Wilhelm Nietzsche, a German philosopher who was much-admired by certain charismatic individuals with ‘leanings towards European domination’ in the first half of the 20th century (yes, that one, with the Chaplinesque moustache and a  personal  ‘struggle’…). And those words have already been discussed on the Annals of Botany blog site in connection with snails, where Herr Nietzsche’s famous pronouncement was allegedly disproven (botanists are a philosophical bunch…). Well, and in support of the moustachioed Prussian’s statement, we now share this example with you botanical blogtrotters. Studying feeding behaviour of the gemsbok – a large antelope found in the arid regions of southern Africa – David Lehmann et al. showed that 25% of the inferred (from stable isotope ratios of potential food sources and three types of tissues – blood, liver and muscle – from the antelope) diet of these grazers consisted of Euphorbia damarana. This spurge is a CAM (Crassulacean Acid Metabolism)  plant that is endemic to the study region in Namibia and is rich in toxic secondary plant compounds – so rich, in fact, that its milky latex is allegedly capable of killing human beings. Clearly, what didn’t poison the gemsbok made them stronger under those challenging environmental conditions. This is also a good illustration of why one can’t rely on the feeding habits of AN Other species as a guide to what may be OK for humans to eat! However, as interesting as that is, I think the more remarkable discovery is that gemsboks feed almost exclusively on C4 and CAM plants at other times when food is plentiful. How can they tell C4/CAM from C3 photosynthesisers? What an amazingly good knowledge of plant photosynthetic biochemistry they must have to enable such a sophisticated degree of discernment!

Eating bad things to keep you well is one thing, but getting ill from eating things supposed to make you better is quite another, and is exemplified in research into aristolochic acids (AA), ‘a family of carcinogenic, mutagenic, and nephrotoxic compounds commonly found in the Aristolochiaceae family of plants, including Aristolochia and Asarum (wild ginger)…’. Plants containing AA have been widely used in traditional Chinese herbal medicine, and – despite the link having been demonstrated between a rapidly progressive renal disease and consumption of AA-containing Chinese herbs (and which is now termed aristolochic acid nephropathy) – such plants are still in use worldwide. It is to be hoped that the latter’s review of the subject will help to raise awareness of the problem and contribute to more intelligent use of the healing powers that do reside within plants.

[Ed. – Interestingly, in PNAS Julia Lee-Thorp et al.  show that Pliocene hominins (ancestral humans…) also seem to have had the ability to discriminate in favour of C4 plants in their diet…Which gives a great trivial pub quiz question: What is the connection between gemsbok and ancient humanoids..?]