As a cardiologist specializing in cardiac imaging, Barbara Natterson-Horowitz, a professor of medicine at the University of California (UCLA) Los Angeles, has done hundreds of echocardiograms, but in 2005 there was one that changed her life. She went to the Los Angeles Zoo and for the first time, the patient was not a human but a chimpanzee.
Cardiovascular diseases are the main cause of death in captive great apes and, in this case, the veterinarians thought that knowledge of human medicine – after all, humans are also apes – could be useful to them. The experience had a major impact on Natterson-Horowitz, leading him to investigate interspecies health connections. Later, he worked with gorillas, lions, marine mammals or condor birds, among other animals, and this idea of connecting human medicine, veterinary medicine and evolutionary biology, which he named 'Zoobiquity', became even more established in science. mind of him
In 2012, together with Kathryn Bowers, he published his first book: 'Zoobiquity', where they analyze different diseases that affect humans, but from an animal perspective. In 2019 they wrote 'Wildhood', in which they compared the phase between puberty and maturity between animals and humans. More recently she has put the focus on women's health and, last April, she published her most recent study on this topic in the scientific journal PNAS. We spoke with her about this turn in her career and the scope of this innovative discipline.
Barbara Natterson-Horowitz performs an echocardiogram on a gorilla. /
Human medicine, veterinary medicine and evolutionary biology are disciplines with a long history, why is the intersection of the three (zoobiquity) so recent?
As physicians, for information on human health, we focus on the study of Homo sapiens and a few species of laboratory animals, but this is a very anthropocentric approach. We think of ourselves and our problems as higher beings, but our species is only 200,000 years old. We share common ancestors with chimpanzees and even with our dog. That is, we are so young as a species that most of our biology resembles that of animals that have preceded us; but our culture, history and tradition have made us believe that our species is unique.
When writing 'Zoobiquity' we felt that investigating human health through the lens of a single species was limiting, so we expanded that window to include the rest of the planet's animals and the evolutionary history we share with them. This helps us better understand the causes of diseases and develop more precise strategies to prevent and treat them. For example, I knew that all mammals have breasts and that they lactate and nurse their young, but I had never thought about breast cancer in marine mammals. When I began to investigate, I learned that a small epidemic of breast cancer affected a group of beluga whales in north-eastern Canada a few decades ago. The outbreak turned out to be related to chemicals produced by a nearby factory. What is surprising is that these same pollutants were causing similar problems for women living on the coast.
As you say, laboratory animals are already used to study human diseases, how is that different from zoobiquity?
The model organisms that are used in the laboratory to study human diseases are mainly four: mice, zebra fish, flies and worms. What justifies our belief that mouse biology is relevant to human biology is that we share a common ancestry and evolutionary history. What if we were to expand that window to include the other 163,000 animal species with which we currently share the Earth and start looking for the vulnerabilities we share? But not only that, what if we opened the window even more and included species from the entire evolutionary history? It would really help us better understand the causes of the disease and innovate better solutions.
I have been educated in the best universities, like Harvard, and I have had great professors, like the famous biologists EO Wilson and Stephen Jay Gould, but I do not remember a single time in which a professor mentioned the disease that we were studying in an animal species that were not those four. Laboratory animal medicine is very important and valuable, but it has focused on a few species. Zoobiquity, on the other hand, goes further and includes the rest of the hundreds of thousands of animal species with which we live.
What is the position of human medicine before this inclusive approach?
In general, there is a lot of ignorance about the connections that exist between the health of animals and that of humans, because it is not something that is studied in the medical career. Furthermore, historically veterinary medicine has been subordinated to human medicine, precisely because of the idea that humans are superior or more special than other animals, which is why this knowledge tends to be underestimated instead of taking advantage of it.
Barbara Natterson-Horowitz listening to a lioness. /
When I was writing the 'Zoobiquity' book, a doctor asked me why I was wasting time with animals. It was an ignorant and hurtful comment, but I think if I showed him my current research that person would reconsider. What we lose by not bringing together the fields of medicine, veterinary medicine and evolutionary biology is so much that it is surprising that anthropocentrism is still so alive in the scientific community, but at least there is now a dialogue about it and things are changing, even if be slowly.
What has Covid-19 taught us about the close relationship between animal and human disease?
In medicine, when vulnerability or resistance to Covid-19 is studied, lifestyle, genetics or other aspects are analyzed, but always of the same species, the human. Instead, veterinarians do the same by analyzing different species of animals, which has given rise to studies such as the one published in the PNAS journal in 2020 on the degree of vulnerability of multiple species to Covid-19.
These investigations project a broader vision of the mechanisms of resistance to the coronavirus that some animals have developed, or not. For example, while chimpanzees or dolphins are more sensitive; dogs, African elephants, horses or pigs are much less susceptible to contracting the virus. This knowledge is very interesting to compare it with our own species and look for solutions inspired by natural biology.
More recently you have focused on the study of the connections between the health of female animals and women, what have you discovered?
Until a few years ago, the National Institutes of Health in the United States did not require the use of female animals in preclinical studies that seek to find out what is the best treatment for a pathology, nor did it require women to be included in subsequent clinical trials, which which has caused, for decades, many diseases to be misdiagnosed or late in women. Furthermore, the World Health Organization has explicitly stated that climate change is disproportionately affecting the female sex. That got me thinking about how useful the connections between women's health and female animals could be.
For example, cardiovascular problems were long thought to affect mainly men, yet they are the leading cause of death in women. For example, arteriosclerosis is associated with lifestyle (smoking, sedentary lifestyle, obesity...), however, this disease affects many birds that neither smoke, are sedentary, nor are obese. So why do they suffer?
"If we are wise enough to call ourselves 'Homo sapiens', we should also be wise enough to recognize the power of nature"
One possibility is that certain environmental factors are playing a role, but it could also be caused by bacteria or a virus. In other words, when we look at the disease from another point of view, we can ask ourselves how these birds have evolved to become vulnerable to arteriosclerosis, and that opens up many avenues for investigating the causes of our suffering from it, as well as helping to find solutions inspired by the nature.
How does that knowledge become a solution?
Zoobiquity is not only focused on finding common diseases between humans and animals, but also on observing the resistance that nature has developed to different pathologies throughout evolution, as an inspiration to find solutions to diseases that seriously affect to the humans. It is similar to what the
biomimeticbut focused on health.
For example, high blood pressure forces our heart to pump more blood to the rest of the body. This strain causes the organ to enlarge and weaken, causing heart failure and increasing the risk of death. On the other hand, the blood pressure of an adult giraffe is very high and that is not a problem for it. Giraffes have evolved over the last 11 billion years to have increasingly long necks that allow them to access food from the treetops, and their hearts have adapted and thickened so that the pumped blood reaches the brain. That can give us clues to develop treatments.
When will we see treatments or medicines inspired by zoobiquity?
That is the goal. For example, we know that African elephants have evolved to generate extra copies of a wide variety of genes associated with tumor suppression, so companies are already developing treatments inspired by that animal mechanism to prevent or cure cancer in animals. humans. Darwin said that "natural selection is a power incessantly ready for action and immeasurably superior to the feeble efforts of man," and that is precisely what zoobiquity preaches. If we are wise enough to call ourselves 'Homo sapiens' (Latin for 'wise man'), we should also be wise enough to recognize the power of nature and use it for our own benefit.
What are your future study plans?
I am developing studies related to fertility in a project with giraffes and also another one on mental illnesses in different species. Problems like depression or anxiety are highly stigmatized in our society and make people feel ashamed. Those same problems exist in the animal kingdom and are part of our evolutionary legacy. I hope this new approach will make it easier for people to remove some of the stigma and shame and lead them to seek help and take care of their mental health.