BACTERIA, fungi, birds, insects, spiders, aquatic life and trees all play a part in helping humans to lead productive and healthy lifestyles. Although we might not recognise it, biodiversity is the foundation for human health: Ecosystem products and services such as the availability of fresh water are necessary for good human health and productive livelihoods. We depend on biodiversity in our daily lives in ways that are not always apparent or appreciated.
Health is our most basic human right. Being healthy does not only mean freedom from illness, but also a state of social, emotional, physical, spiritual and cultural wellness. Being well, and having the capacity to look after our health and that of our family or community, depends on a range of factors, including our economic status and ultimately our environment. The loss of biodiversity represents a direct threat to our health and wellbeing since, without a global environment that is healthy and capable of supporting a diversity of life, no human population can exist.
Biodiversity contributes to human health in various ways including food security, medicine and medical research and controlling infectious diseases.

Food security and livelihoods sustainability
Adequate nutrition is the prime requirement for ensuring the normal development (both physical and mental) of children, as well as the continuing health and productivity of adults. Diets based on a variety of food species promote health, and can help to protect against diseases by addressing the problem of micro-nutrient and vitamin deficiencies.

Biodiversity provides the genetic resources for all crops, livestock, and marine species harvested for food, e.g., harvested marine seafood species now exceed 100 million tons per year and provide about six percent of all protein and 17 percent of animal protein consumed by humans.
Biodiversity plays an important role in world food production as it ensures the sustainable productivity of soils. Organisms such as plants, algae, fungi, earthworms, flatworms, roundworms, insects, spiders and mites, bacteria, and burrowing animals such as moles and groundhogs perform various tasks. Some of these tasks include maintaining soil structure, gas exchanges and carbon sequestration, soil detoxification, decomposition of organic matter and control of pests, parasites, and diseases. Loss of agricultural biodiversity therefore poses a threat to our health, livelihood sustainability and our future security of food and nutrition.
Research and traditional medicine
Many community cultures and livelihoods, particularly indigenous communities, are centred on traditional medicinal practices that utilise wild animals and plants. According to the World Health Organization, approximately 80% of the world’s population from developing countries rely mainly on traditional medicines, mostly derived from plants, for their primary health care. In some countries, traditional medicines are extensively incorporated into the public health system. Drugs derived from wild species include pain killers, e.g., Zinconitide from cone snail toxin, cardiac drugs, e.g., Lanoxin from Digitalis plants, anti-cancer drugs, e.g., Taxol from Taxus trees and treatments for diabetes, e.g., Exanitide from Heloderma lizards.
Apart from providing medicines, biophysical diversity of micro-organisms, flora and fauna provide extensive knowledge which carry important benefits for biological, health, and pharmacological sciences. Significant medical and pharmacological discoveries are made through greater understanding of the earth’s biodiversity. Loss in biodiversity may limit discovery of potential treatments for many diseases and health problems. Examples of species that are of interest to medical science include bears (for insights into osteoporosis, cardio – vascular disorders, renal disease and diabetes), sharks (osmoregulation and immunology) and horse – shoe crabs (optometry/ophthalmology and molecular cell biology).
Regulation and control of infectious diseases
Within ecosystems, there are organisms that are involved in the maintenance or transmission of infectious diseases. The organisms include:
a)    Pathogens (the infectious agents);
b)    their arthropod or other animal vectors (organisms that pass on the pathogens to humans);
c)    the reservoir species that serve as hosts for the pathogens outside of humans; and
d)    the other organisms within ecosystems and landscapes that support the interactions among pathogens, vectors, and reservoirs.
Ecosystem disturbances such as habitat destruction or conversion – particularly through deforestation and reafforestation, changes to local temperature and water cycle- can increase the risk of humans acquiring infectious diseases. In general, top predators are usually more vulnerable to habitat destruction, and since they are effective in regulating the population of prey species that serve as reservoirs of diseases, loss of such predators will result in humans being affected by infectious diseases.

Threats to biodiversity and health
Biodiversity plays a very significant part in maintaining healthy lives. However, human activities are posing a threat to ecosystems that will reduce the benefits we gain from biodiversity. The effects of such activities as deforestation, urbanisation, and the building of a dam across rivers greatly affect ecosystems. Along with these, the increasing emissions of greenhouse gases such as carbon dioxide, contribute to global warming, and inevitably climate change.

Climate is an integral part of ecosystem functioning and human health is impacted directly and indirectly by the results of climatic conditions on both terrestrial and marine ecosystems. Marine biodiversity is affected by ocean acidification due to carbon in the atmosphere. Terrestrial biodiversity is influenced by climate variability, such as extreme weather events (i.e. drought, flooding) that directly influence ecosystem health and the productivity and availability of ecosystem goods and services for human use. Longer term changes in climate affect the viability and health of ecosystems, influencing shifts in the distribution of plants, animals, and even human settlements. These changes will mean that the present gains we receive from biodiversity will not be available in the future; therefore, we need to play our part in ensuring that ecosystems remain intact so that future generations will benefit from all the good biodiversity has to offer.
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