Herbalists use plants for medicinal purposes so they are familiar with the fact that nature heals. However, the beneficial effects that exposure to the natural world has on mental and physical health is becoming more widely acknowledged. The increasing amount of evidence on the human need for nature makes it important to understand the drivers behind nature experiences. To add to this growing body of research a 2022 study of twins has revealed that a love of nature appears to be, at least in part, genetic. According to a large-scale study of twins in the United Kingdom, published this month in the open-access journal PLOS Biology, a person’s appreciation of nature, and their tendency to visit natural spaces, are genetic characteristics.

Researchers surveyed 1153 pairs of twins on the TwinsUK registry about how they experience nature, asking them to rate their familiarity with and desire to be in nature, and how frequently they visit natural spaces such as public parks and private gardens. They found that identical twins, who share almost 100% of their genes, were more similar to each other in their orientation towards nature and how frequently they visited nature compared to fraternal twins, who share around 50% of their genetic material. The results help to explain why some people have a stronger desire than others to be in nature.

While the results suggest there is a genetic influence over how people experience nature, environmental factors explained more than half of the differences between individuals. People living in urban environments tended to have less nature experiences, due to things such as limited access to gardens, highlighting the importance of availability in shaping nature-seeking behaviours. These inherited characteristics also declined with age, suggesting that genetics may become less influential as people age and experience a unique set of environmental conditions. This study provides the first evidence for a genetic component to both a predisposition towards nature and a tendency to visit natural spaces. The results also provide evidence of a complex interaction between urbanisation and the environmental effects in shaping a person’s nature experience. It points to the need for diverse urban planning to provide access to natural spaces and the benefits they offer for all.

Reference

People’s desire to be in nature and how they experience it are partially heritable (plos.org)

In this era of evidence-based medicine, where a herb is often only thought of as active if a single chemical substance responsible for its therapeutic effect is discovered or its efficacy is proven in a randomised controlled trial, traditional ways of healing are becoming forgotten.  

One example is the doctrine of signatures which traces back to antiquity. German mystic Jakob Böhme’s 1621 book, The Signature of All Things, gave its name to the doctrine. It is a 16th Century theory popularised by Paracelsus (1493 to 1541), considered the father of modern chemistry, who posited that plants had been signed by their Creator with visible clues to their usefulness. For example, a similarity in shape to various parts of the body meant the herb could be used to treat ailments of those parts of the body. 

Ginkgo (Ginkgo biloba) is often used as a fine example of the doctrine of signatures. Ginkgo’s signature is its curious fan shaped leaves with two hemispheres as the name biloba suggests. They resemble the outline of a brain, especially when grouped together. This, coupled with its long life, resistance to the environment and its being the world’s oldest living tree species, helps explain why this plant has been seen as a brain food for centuries. Eyebright’s (Euphrasia officinalis) signature is its striped flower petals, supposedly reminiscent of bloodshot eyes, and it is traditionally used for eye infections. Barberry (Berberis vulgaris), widely used as a cholagogue to treat liver and gallbladder ailments, has yellow flowers and roots which produce a yellow dye and these features were linked to the yellowing of the skin and eyes of jaundice, a symptom of liver disease. 

The doctrine of signatures is not supported by scientific evidence however recent research supports the therapeutic value of many signature-bearing species and validates their use in folk medicine. While it may be cast off as a fancified romantic notion the doctrine of signatures can, at the very least, be used as a learning aid to assist in remembering the materia medica and as a way to deepen the practice of herbal medicine. It is also a way of communing with nature and, in fact, the word signature is a mix between the words “sign” and “nature.”