This book was somewhat interesting, but then the author got to the part about mammals consuming mushrooms and presented pure pseudoscience:
The author repeatedly treats speculation as established fact. Animals are said to have a “natural knowledge of the healing properties of plants and fungi,” and their consumption of mushrooms is repeatedly described as self-medication, even when the examples given establish only that the animals eat those fungi. Deer eating maitake, bears eating chaga, gorillas eating Ganoderma, and chimpanzees eating particular mushrooms do not by themselves demonstrate medicinal intent. The book simply assumes that because a fungus has reputed or experimentally observed biological activity, an animal eating it must be using it therapeutically.
The pharmacological claims are similarly careless. Mushrooms are described as providing “immune system enhancement, infection fighting, reduced inflammation, improved digestion, and even protection against parasites,” while compounds such as polysaccharides, triterpenes, and polyphenols are invoked as evidence of “potent pharmacological activities.” But identifying bioactive compounds in a mushroom does not establish that an animal receives a medicinal dose by eating it, or that those compounds produce the claimed effects in that species. The repeated movement from chemical composition to therapeutic benefit skips the basic questions of dosage, absorption, metabolism, and demonstrated physiological effect.
Some of the specific examples make the problem especially obvious. The suggestion that chaga “may help bears stay healthy during their long hibernation periods” is immediately followed by the admission that “there hasn’t been serious research on the bear-chaga connection.” That is not evidence of animal self-medication; it is a conjecture presented in a context that encourages the reader to treat it as biologically meaningful. Likewise, the statement that maintaining strong immune systems is important for deer is used to lend medicinal significance to their consumption of maitake, even though that reasoning does nothing to show that deer eat the mushrooms for their anti-inflammatory properties.
The elephant claims go further still. Finding Ganoderma in elephant dung shows that elephants consumed it. It does not establish that they deliberately sought it as medicine, yet the author describes this as “showcasing a species feeding on medicinal mushrooms for self-medication” and later claims that the evidence confirms a “deliberate quest” for the fungus as a nutritional supplement. Those conclusions require evidence of selective behaviour and a demonstrated benefit, not merely evidence that the fungus passed through the animals’ digestive systems.
The discussion of sloth fur makes the same leap in another form. Fungi isolated from sloth hair are said to be capable of producing compounds with antiparasitic, anticancer, and antibacterial properties, and this is quickly turned into talk of treatments for malaria, Chagas disease, cancer, and antibiotic resistance. The existence of bioactive compounds is a legitimate starting point for research. It is not evidence that sloths are benefiting medicinally from those fungi, nor that those organisms will yield effective human therapies. The book consistently substitutes possibility for demonstration and then presents that possibility in the language of discovery.
(Nate Tricowi)