“When we tug at anything in nature, we find that it is attached to everything else in the universe,” wrote the celebrated naturalist John Muir. Indeed nature, with its abundant biodiversity, provides evidence of such interdependence. Yet, follies of human behaviour are damaging biodiversity at an alarming speed. A report in 2018 estimated that while humans constitute only 0.01% of all living things by mass, we have caused the loss of 83% of all wild animals and half of all plants on earth. By this, we not only deny ourselves the aesthetic pleasure of enjoying nature’s beauty in its splendid array of diverse life forms but also imperil our own health and well-being.
Loss of biodiversity affects human health in many ways. We deprive ourselves of many nutrient-rich foods. We cannot benefit from medicinal plants and drugs derived from other animal species. We speed up climate change by contributing to global warming. We lose protection against pests and pathogenic microorganisms. We become more vulnerable to natural disasters. Apart from physical health, our mental health too will suffer as we lose our connect with the healing powers of our planet’s amazing biodiversity. Many innovative medical devices and biomaterials that are inspired by their structural elegance and functional utility in other species will be lost to us.
Healthy diets require a balance of several nutrients drawn from a variety of food sources. Most of them are derived from plants. The large array of grains, fruits, vegetables and nuts that humans consume are the gift of a rich natural biodiversity of the plant kingdom. Even the animal foods that humans consume draw on plants as primary sources, ranging from grasses and leaves. Wild plants yield a variety of fruit such as berries. Honey is a pollen product delivered to us by bees. An array of edible and medicinal oils are drawn from plants.
Even the staples in our diet reflect shrinking biodiversity. In Asia, the varieties of cultivated rice have fallen to just a few dozen from several thousands that reflected a rich biodiversity not so long ago. Biodiversity builds soil health, from a variety of decaying plants and animals. Soil nutrients, in turn, determine the health of plants and animals that derive nutrition from it. Isn’t it ironic that humans who like to pick from a wide range of choices offered on a restaurant’s menu card are increasingly limiting the range of foods that can nourish the soil, plants, animals and us?
Deforestation strips the planet’s protective green cover against global warming. Scientists estimate that nature-based solutions can provide upto 37% of the carbon dioxide mitigation needed to counter global warming and contain the rise of the earth’s temperature below a 2% limit. Deforestation eliminates many pollinator species that help new plants bloom. Of the many animals and birds that act as pollinators, bees are among the most energetic in assisting plants to reproduce. Habitat loss, pesticide use and global warming are endangering several species of bees. If the pollinators disappear, we will lose much of our foliage and fruit.
Biodiversity builds resilience against natural disasters like floods and storms, besides offering protective barriers against pandemics. Loss of over 35% of the earth’s mangrove forests has made us vulnerable to floods and is resulting in rising sea levels that threaten coastal agriculture. Deforestation, with loss of multiple plant species, is damaging soil integrity and causing landslides precipitated by loose soil. Deforestation also leads to increased spread of zoonotic infections, by removing the protective boundaries between wildlife and human communities. It destroys the natural hosts of forest-dwelling microbes and offers them an easy passage to veterinary and human hosts.
Medicine has greatly benefited from several plant- and animal-derived products. Several antibiotics, antimalarials, anti-cancer drugs, anti-inflammatory medicines, heart and blood pressure drugs owe their origins to plants. Traditional medicine systems across the world have depended on the healing powers of herbal products. As we understand more about the role of the microbiome in guiding our health and nutrition, our appreciation of natural foods and medicines is increasing. Animal products derived from snake and scorpion venom have been used to develop anti-clotting drugs. Anti-hypertensive medicines like captopril and enalapril, used in modern medicine, have been refined from snake venoms.
Many innovations in medicine and surgery have borrowed ideas from natural designs. Scientists in Massachusetts recently used a spinach leaf’s delicate veinous system to overcome a block in tissue engineering of the human heart. Cellulose is a biocompatible material that has been used in bone and tissue cartilage engineering. By destroying many species, we will deprive ourselves of the benefits of many intelligent designs perfected by nature.
As we are well reminded by the marine biologist Enric Sala, “Every morsel of food, every sip of water, the air we breathe is the result of work done by other species. Nature gives us everything we need to survive. Without them, there is no us.”
(Views are personal)
Dr K Srinath Reddy
Cardiologist, Epidemiologist and President, Public Health Foundation of India (PHFI)