Bitter herbs

Recently, veterinarian Ben Hart gave a talk at the 41st Animal Behavior Society meeting, in Oaxaca, Mexico, describing how some animals use herbal medicine and theorizing how humans came to use herbs medicinally. Nature Science Update reports--Bitterness illuminates plant lore: Use of herbal medicines may have arisen by accident. Here is a taste of Hart's theory:

The animals cannot know exactly what they are doing, Hart argues. With instances of illness few and far between, and plants that vary in speed and effectiveness, it would be impossible for animals to link cause and effect.

This means that the use of herbs as medicines may have been encouraged by natural selection rather than conscious learning, Hart suggests. Animals that eat pain-relieving plants, for instance, would be better able to forage or look after young during a bout of illness.

But how could this habit arise unconsciously, Hart wondered. He searched the records of medical trials of 25 herbal supplements that have proved to be effective in humans. Some 78% of them came from plants that have a bitter or astringent taste.

Animals that happened, by chance, to develop a penchant for bitter plants when feeling off-colour would therefore be less vulnerable to sickness, Hart says. And if they passed that preference on to their offspring, the habit would become a tradition, or an evolved trait.

Emphasis added. The highlighted sentence is misleading. It seems to promote the bogus 'inheritance of acquired characteristics' theory. If the preference for bitter tastes is coded in the genes, then it is not a developed penchant, and it is not by chance that the animals are selected for. The chance aspect of evolution involves the mutations that occur in the genetic code, not in how well the individual organism adapts to the environment.

Now how will this theory be tested? I am not sure what they mean by 'herbal medicine may have arose by accident.' What accident?