The Real Science Behind “Anti-Aging” Beauty Products
The beauty market abounds with high-end creams and serums that claim the use of stem cells to rejuvenate aging skin.
Selling on the internet and at department stores like Nordstrom, these products promise "breakthrough" applications to plump, smooth, and "reverse visible signs of aging," and at least one product offers to create a "regenerative firming serum, moisturizer, and eye cream" from customers' own stem cells – for a whopping $1200.
The beauty industry is heavily hyping glimmers of the nascent field of stem cell therapy.
Steeped in clinical-sounding terms like "proteins and peptides from pluripotent stem cells," the marketing of these products evokes a dramatic restoration of youthfulness based on cutting-edge science. But the beauty industry is heavily hyping glimmers of the nascent field of stem cell therapy. So what is real and what's not? And is there in fact a way to harness the potential of stem cells in the service of beauty?
Plant vs. Human Stem Cells
Stem cells do indeed have tremendous promise for treating a wide range of diseases and conditions. The cells come from early-stage embryos or, more commonly, from umbilical cord blood or our own bodies. Embryonic stem cells are considered the body's "master" cells because they can develop into any of our several hundred cell types. Adult stem cells, on the other hand, reside in mature tissues and organs like the brain, bone marrow, and skin, and their versatility is more limited. As an internal repair system for many tissue types, they replenish sick, injured, and worn-out cells.
Nowadays, with some sophisticated chemical coaxing, adult stem cells can be returned to an embryonic-like blank state, with the ability to become any cell type that the body might need.
Beauty product manufacturers convey in their advertising that the rejuvenating power of these cells could hold the key to the fountain of youth. But there's something the manufacturers don't always tell you: their products do not typically use human stem cells.
"The whole concept of stem cells is intriguing to the public," says Tamara Griffiths, a consultant dermatologist for the British Skin Foundation. "But what these products contain is plant stem cells and, more commonly, chemicals that have been derived from plant stem cells."
The plant stem cells are cultured in the lab with special media to get them to produce signaling proteins and peptides, like cytokines and chemokines. These have been shown to be good for reducing inflammation and promoting healthy cell functioning, even if derived from plants. However, according to Griffiths, there are so many active ingredients in these products that it's hard to say just what role each one of them plays. We do know that their ability to replenish human stem cells is extremely limited, and the effects of plant stem cells on human cells are unproven.
"...any cosmetic that is advertised to be anti-aging due to plant stem cells at this time is about as effective as all the skin creams without stem cells."
Whether products containing plant cell-derived ingredients work better than conventional skin products is unknown because these products are not regulated by the U.S. Food and Drug Administration and may rest on dubious, even more or less nonexistent, research. Cosmetics companies have conducted most of the research and the exact formulas they devise are considered proprietary information. They have no incentive to publish their research findings, and they don't have to meet standards imposed by the FDA unless they start using human cells in their products.
"There are biological limits to what you can do with plant cells in the first place," says Griffiths. "No plant stem cell is going to morph into a human skin cell no matter what magic medium you immerse it in. Nor is a plant cell likely to stimulate the production of human stem cells if applied to the skin."
According to Sarah Baucus, a cell biologist, for any type of stem cell to be of any use whatsoever, the cells must be alive. The processing needed to incorporate living cells into any type of cream or serum would inevitably kill them, rendering them useless. The splashy marketing of these products suggests that results may be drastic, but none of these creams is likely to produce the kind of rejuvenating effect that would be on par with a facelift or several other surgical or dermatological procedures.
"Plant stem cell therapy needs to move in the right direction to implement its inherent potential in skin care," researchers wrote in a 2017 paper in the journal Future Science OA. "This might happen in the next 20 years but any cosmetic that is advertised to be anti-aging due to plant stem cells at this time is about as effective as all the skin creams without stem cells."
From Beauty Counter to Doctor's Clinic
Where do you turn if you still want to harness the power of stem cells to reinvigorate the skin? Is there a legitimate treatment using human cells? The answer is possibly, but for that you have to switch from the Nordstrom cosmetics counter to a clinic with a lab, where plastic surgeons work with specialists who culture and manipulate living cells.
Plastic surgeons are experts in wound healing, a process in which stem cells play a prominent role. Doctors have long used the technique of taking fat from the body and injecting it into hollowed-out or depressed areas of the face to fill in injuries, correct wrinkles, and improve the face's curvature. Lipotransfer, or the harvesting of body fat and injecting it into the face, has been around for many years in traditional plastic surgery clinics. In recent years, some plastic surgeons have started to cull stem cells from fat. One procedure that does just that is called cell-assisted lipotransfer, or CAL.
In CAL, adipose tissue, or fat, is harvested by liposuction, usually from the lower abdomen. Fat contains stem cells that can differentiate into several cell types, including skin, muscle, cartilage, and bone. Fat tissue has an especially stem cell-rich layer. These cells are then mixed with some regular fat, making in effect a very stem cell-rich fat solution, right in the doctor's office. The process of manipulating the fat cells takes about 90 to 110 minutes, and then the solution is ready to be injected into the skin, to fill in the lips, the cheeks, and the nasolabial folds, or the deep folds around the nose and mouth.
Unlike regular fat, which is often injected into the face, some experts claim that the cell-enriched fat has better, longer-lasting results. The tissue graft grows its own blood vessels, an advantage that may lead to a more long-lasting graft – though the research is mixed, with some studies showing they do and other studies showing the complete opposite.
For almost all stem cell products on the market today in the U.S., it is not yet known whether they are safe or effective, despite how they are marketed.
One of the pioneers in CAL, a plastic surgeon in Brazil named Dr. Aris Sterodimas, says that the stem cells secrete growth factors that rejuvenate the skin -- like the plant stem cells that are used in topical creams and serums. Except that these cells are human stem cells and hence have inherently more potential in the human body.
Note that CAL doesn't actually result in large numbers of fresh, new replacement cells, as might be imagined. It's simply fat tissue treated to make it richer in stem cells, to have more of the growth-inducing proteins and peptides delivered to the dermis layer of the skin.
Sterodimas works alongside a tissue engineer to provide CAL in his clinic. He uses it as a way to rebuild soft tissues in people disfigured by accidents or diseases, or who are suffering the after-effects of radiation treatments for cancer.
Plastic surgeons get plenty of these patients. But how widespread is CAL for beauty purposes? Sterodimas says that he regularly performs the procedure for Brazilians, and it's widely available in Europe and Japan. In the U.S., the procedure hasn't taken off because there is no FDA approval for the various methods used by different doctors and clinics. A few major academic centers in the U.S. offer the treatment on a clinical trials basis and there are several trials ongoing.
But there is a downside to all lipotransfers: the transplanted fat will eventually be absorbed by the body. Even the cell-enriched fat has a limited lifespan before reabsorption. That means if you like the cosmetic results of CAL, you'll have to repeat the treatment about every two years to maintain the plumping, firming, and smoothing effects on the skin. The results of CAL are "superior to the results of laser treatments and other plastic surgery interventions, though the effect is not as dramatic as a facelift," says Sterodimas.
Buyer Beware
For almost all stem cell products on the market today in the U.S., it is not yet known whether they are safe or effective, despite how they are marketed. There are around 700 clinics in the U.S. offering stem cell treatments and up to 20,000 people have received these therapies. However, the only FDA-approved stem cell treatments use cells from bone marrow or cord blood to treat cancers of the blood and bone marrow. Safety concerns have prompted the FDA to announce increased oversight of stem cell clinics.
As for CAL, most of the clinical trials so far have been focused on using it for breast reconstruction after mastectomy, and results are mixed. Experts warn that the procedure has yet to be proven safe as well as effective. It's important to remember that this newborn science is in the early stages of research.
One question that has also not been definitively settled is whether the transplanted stem cells may give rise to tumors — a risk that is ever-present any time stem cells are used. More research is required to assess the long-term safety and effectiveness of these treatments.
Given the lack of uniform industry standards, one can easily end up at a clinic that overpromises what it can deliver.
In the journal Plastic Reconstruction Surgery in 2014, Adrian McArdle and a team of Stanford University plastic surgeons examined the common claims of CAL's "stem cell facelifts" being offered by clinics across the world. McArdle and his team write: "…the marketplace is characterized by direct-to-consumer corporate medicine strategies that are characterized by unsubstantiated, and sometimes fraudulent claims, that put our patients at risk." Given the lack of uniform industry standards, one can easily end up at a clinic that overpromises what it can deliver.
But according to McArdle, further research on CAL, including clinical trials, is proceeding apace. It's possible that as more research on the potential of stem cells accrues, many of the technical hurdles will be crossed.
If you decide to try CAL in a research or clinical setting, be forewarned. You will be taking part in a young science, with many unknown questions. However, the next time someone offers to sell you stem cells in a jar, you'll know what you're paying for.
These doctors have a heart for recycling
This is part 3 of a three part series on a new generation of doctors leading the charge to make the health care industry more sustainable - for the benefit of their patients and the planet. Read part 1 here and part 2 here.
One could say that over 400 people owe their life to the fact that Carsten Israel fell in love. Twenty years ago, as a young doctor in Frankfurt, Germany, he began to court an au pair from Kenya, Elisabeth, his now-wife of 13 years with whom he has three children. When the couple started visiting her parents in Kenya, Israel wanted to check out the local hospitals, “just out of professional curiosity,“ says the cardiologist, who is currently the head doctor at the Clinic for Interior Medicine in Bielefeld. “I was completely shocked.“
Often he observed there were no doctors in the E.R.s, and hte nurses could render only basic first aid. “When somebody fell into a coma, they fell into a coma,“ Israel remembers. “There weren’t even any defibrillators to restart a patient’s heart,” while defibrillators are standard equipment in most clinics in the U.S. and Europe as lifesaving devices. When Israel finally visited the largest and most modern hospital in Nairobi, he found it better equipped but he learned that its services were only available to patients who could afford them. The cardiologist there had a drawer full of petitions from patients with heart ailments who couldn’t afford lifesaving surgery. Even two decades ago, a pacemaker cost $5,000 in Kenya, which made it unaffordable for most Kenyans who earn an average of $600 per month.
Since 2003, Israel and a team of two doctors and two nurses visit Kenya and Zambia once or twice a year to implant German pacemakers for free. Notably, the pacemakers and defibrillators Israel exports to Africa would end up in the landfill in Germany. Clinics have to pay for specialized services to dispose of this medical equipment. “In Germany, I could go to jail if I used a defibrillator that is one day past its expiration date,“ Israel says, “but in Kenya, people don’t have the money for the cheapest model. What nonsense to throw this precious medical equipment away while people in poorer countries die because they desperately need it.“
Israel works at the breakpoint between the laws in a wealthy country like Germany and the reality in the global South. The U.S. and most European countries have strict laws that ban the reuse of medical implants and enforce strict expiration dates for medical equipment. “But if a pacemaker is a few days past its expiration date, it still works perfectly fine,“ Israel says. “And it also happens that we implant a pacemaker and five months later it turns out that the patient needs a different kind. Then we replace it and we’d have to trash the first one in Germany, though it could easily run another 12 years.“
“If we get this right, we have lots of devices we can implant, hips and knees, etcetera. Where this will lead is limitless," says Eva Kline Rogers, the program coordinator for My Heart, Your Heart.
Israel has been collecting donations of pacemakers and defibrillators from manufacturers but also from other doctors and from funeral homes for his nonprofit Pacemakers for East Africa since 2003. Most funeral homes in the U.S. and Europe are legally obliged to remove pacemakers from the dead before cremation. “Most pacemakers survive their owners,“ says Israel. He sterilizes the pacemakers and finds them a new life in East Africa. Studies show that reused pacemakers carry no greater risk for the patients than new ones.
In the U.S., University of Michigan professor Thomas Crawford heads up a similar initiative, My Heart, Your Heart. “Each year 1 to 2 million individuals worldwide die due to a lack of access to pacemakers and defibrillators,” the organization notes on its website. The nonprofit was founded in 2009, but it took four years for the doctors to get permission from the FDA to export pacemakers. Since receiving permission, the organization has sent dozens of devices to the Philippines, Haiti, Venezuela, Kenya, Sierra Leone and Ukraine. “We were the first doctors ever to implant a pacemaker in Sierra Leone in 2018,” says Crawford, who has traveled extensively to most of the recipient countries.
Even individuals can donate their pacemakers; the organization offers a prepaid envelope. “My mother recently passed and she donated her device,” says Tina Alexandris-Souphis, one of the doctors at University of Michigan who collaborates on My Heart, Your Heart. The organization works with World Medical Relief and the U.K. based charity Pace4Life to maintain a registry of the most urgent patients and send devices to where they are needed the most.
My Heart, Your Heart is also conducting a randomized controlled trial to provide further evidence that reused pacemakers pose no additional risk. “Our vision is that we establish this is safe and create a blueprint for organizations around the world to safely reuse these devices instead of them being thrown in the trash,” says Eva Kline Rogers, the program’s coordinator. “If we get this right, we have lots of devices we can implant, hips and knees, etc. Where this will lead is limitless.” She points out that in addition to receiving the donated devices, the doctors in the global South also benefit from the expertise of renowned cardiologists, such as Crawford, who sometimes advise them in complex cases.
And Adrian Baranchuk, a Canadian doctor at the Kingston General Hospital at the Queen’s University, regularly travels through South America with his “cardiology van” to help villagers in remote areas with heart problems.
Israel says that he’s been accused of racism, in thinking that these pacemakers are suitable for those in the global South - many of whom are people of color - even though officials in wealthier countries consider them to be trash. The cardiologist counters such criticism with stories about desperate need of his patients. At his first medical visit to Nairobi that he organized with a local cardiologist, six patients were waiting for him. “In Germany, they would all be considered emergencies,” Israel says. One eighty-year old grandmother had a heartrate of 18. “I’ve never before seen anything like this,” Israel exclaims. “At first I thought I couldn’t find her pulse before I realized that her heart was only beating once every three seconds.” After the surgery, she got up, dressed herself and hurriedly packed her bag, explaining she had a ton of work to accomplish. Her family was in disbelief, Israel says. “They told me she had been bedridden for five years because as soon as she tried to get up she would faint.”
Israel has been accused of racism, in thinking that these pacemakers are suitable for those in the global South even though they're considered to be trash by officials in wealthier countries. The cardiologist counters such criticism with stories about desperate need of his patients.
Carsten Israel
The hospital in Nairobi where Israel conducts the surgeries, charges patients $200 for the use of its facilities. If patients can’t afford that sum, Israel will pay it from the funds of his nonprofit. For some people, $200 far exceeds their resources. Once, a family from the extremely poor Northern region of Kenya told him they couldn’t afford the $3 for the bus ride to Nairobi. Israel suspected this was a pretense because they were afraid of the surgery and agreed to reimburse the $3, “but when they came, they were wearing rags and were so rail-thin, I understood that they really needed every cent they had for food.”
Israel is a renowned cardiologists in Germany. And yet, he considers his work in East Africa to be particularly meaningful. “Generally, most patients in Germany will get the treatment they need,” he says, “and I never before experienced that people have an illness that is easily curable but simply won’t be treated.” He also feels a heavy responsibility. Many patients have his personal cell phone and call him when they have problems or good news about how they’re doing.
Some of those progress reports come much faster than in Israel’s home country. Before he implanted a pacemaker in a tall Massai in Kenya, the man had been picked on by his family because he wouldn’t help much with the hard work on the family peanut farm. “When I examined him, he had a pulse of 40,” Israel says. “It’s a miracle he was even standing upright, let alone hauling heavy bags.” After the surgery, Israel advised his patient to stay the night for observation, but the patient couldn’t wait to leave. Two hours later, he returned, covered in sweat. He’d been running sprints with his brothers to test the new device. Israel shakes his head. In Germany, it would be unthinkable for a patient to engage in athletics immediately after surgery. But the patient was exuberant: “I was the fastest!”
The success stories are notable partly because the challenges remain so steep. In Zambia, for instance, there is a single cardiologist; she determined to become one after losing her younger sister to an easily curable heart disease. Often, the hospitals not only lack pacemakers but also sterile surgery equipment, antibiotics and other essential material. Therefore, Israel and his team import everything they need for the surgeries, including medication. If necessary, they improvise. “I’ve done surgery with a desk lamp hanging from the ceiling by threads,” Israel says. He already knows that he will need to return to Kenya in six months to replace the pacemaker of one of his patients and replace the batteries in others. If he doesn’t travel, lives are at risk.These technologies may help more animals and plants survive climate change
This article originally appeared in One Health/One Planet, a single-issue magazine that explores how climate change and other environmental shifts are making us more vulnerable to infectious diseases by land and by sea - and how scientists are working on solutions.
Along the west coast of South Florida and the Keys, Florida Bay is a nursery for young Caribbean spiny lobsters, a favorite local delicacy. Growing up in small shallow basins, they are especially vulnerable to warmer, more saline water. Climate change has brought tidal floods, bleached coral reefs and toxic algal blooms to the state, and since the 1990s, the population of the Caribbean spiny lobster has dropped some 20 percent, diminishing an important food for snapper, grouper, and herons, as well as people. In 1999, marine ecologist Donald Behringer discovered the first known virus among lobsters, Panulirus argus virus—about a quarter of juveniles die from it before they mature.
“When the water is warm PaV1 progresses much more quickly,” says Behringer, who is based at the Emerging Pathogens Institute at the University of Florida in Gainesville.
Caribbean spiny lobsters are only one example of many species that are struggling in the era of climate change, both at sea and on land. As the oceans heat up, absorbing greenhouse gases and growing more acidic, marine diseases are emerging at an accelerated rate. Marine creatures are migrating to new places, and carrying pathogens with them. The latest grim report in the journal Science, states that if global warming continues at the current rate, the extinction of marine species will rival the Permian–Triassic extinction, sometimes called the “Great Dying,” when volcanoes poisoned the air and wiped out as much as 90 percent of all marine life 252 million years ago.
Similarly, on land, climate change has exposed wildlife, trees and crops to new or more virulent pathogens. Warming environments allow fungi, bacteria, viruses and infectious worms to proliferate in new species and locations or become more virulent. One paper modeling records of nearly 1,400 wildlife species projects that parasites will double by 2070 in the far north and in high-altitude places. Right now, we are seeing the effects most clearly on the fringes—along the coasts, up north and high in the mountains—but as the climate continues changing, the ripples will reach everywhere.
Few species are spared
On the Hawaiian Islands, mosquitoes are killing more songbirds. The dusky gray akikiki of Kauai and the chartreuse-yellow kiwikiu of Maui could vanish in two years, under assault from mosquitoes bearing avian malaria, according to a University of Hawaiʻi 2022 report. Previously, the birds could escape infection by roosting high in the cold mountains, where the pests couldn’t thrive, but climate change expanded the range of the mosquito and narrowed theirs.
Likewise, as more midge larvae survive over warm winters and breed better during drier summers, they bite more white-tailed deer, spreading often-fatal epizootic hemorrhagic disease. Especially in northern regions of the globe, climate change brings the threat of midges carrying blue tongue disease, a virus, to sheep and other animals. Tick-borne diseases like encephalitis and Lyme disease may become a greater threat to animals and perhaps humans.
"If you put all your eggs in one basket and then a pest comes a long, then you are more vulnerable to those risks," says Mehroad Ehsani, managing director of the food initiative in Africa for the Rockefeller Foundation. "Research is needed on resilient, climate smart, regenerative agriculture."
In the “thermal mismatch” theory of wildlife disease, cold-adapted species are at greater risk when their habitats warm, and warm-adapted species suffer when their habitats cool. Mammals can adjust their body temperature to adapt to some extent. Amphibians, fish and insects that cannot regulate body temperatures may be at greater risk. Many scientists see amphibians, especially, as canaries in the coalmine, signaling toxicity.
Early melting ice can foster disease. Climate models predict that the spring thaw will come ever-earlier in the lakes of the French Pyrenees, for instance, which traditionally stayed frozen for up to half the year. The tadpoles of the midwife toad live under the ice, where they are often infected with amphibian chytrid fungus. When a seven-year study tracked the virus in three species of amphibians in Pyrenees’s Lac Arlet, the research team found that, the earlier the spring thaw arrived, the more infection rates rose in common toads— , while remaining high among the midwife toads. But the team made another sad discovery: with early thaws, the common frog, which was thought to be free of the disease in Europe, also became infected with the fungus and died in large numbers.
Changing habitats affect animal behavior. Normally, spiny lobsters rely on chemical cues to avoid predators and sick lobsters. New conditions may be hampering their ability to “social distance”—which may help PaV1 spread, Behringer’s research suggests. Migration brings other risks. In April 2022, an international team led by scientists at Georgetown University announced the first comprehensive overview, published in the journal Nature, of how wild mammals under pressure from a changing climate may mingle with new populations and species—giving viruses a deadly opportunity to jump between hosts. Droughts, for example, will push animals to congregate at the few places where water remains.
Plants face threats also. At the timberline of the cold, windy, snowy mountains of the U.S. west, whitebark pine forests are facing a double threat, from white pine blister rust, a fungal disease, and multiplying pine beetles. “If we do nothing, we will lose the species,” says Robert Keane, a research ecologist for the U.S. Forest Service, based in Missoula, Montana. That would be a huge shift, he explains: “It’s a keystone species. There are over 110 animals that depend on it, many insects, and hundreds of plants.” In the past, beetle larvae would take two years to complete their lifecycle, and many died in frost. “With climate change, we're seeing more and more beetles survive, and sometimes the beetle can complete its lifecycle in one year,” he says.
Quintessential crops are under threat too
As some pathogens move north and new ones develop, they pose novel threats to the crops humans depend upon. This is already happening to wheat, coffee, bananas and maize.
Breeding against wheat stem rust, a fungus long linked to famine, was a key success in the mid-20th century Green Revolution, which brought higher yields around the world. In 2013, wheat stem rust reemerged in Germany after decades of absence. It ravaged both bread and durum wheat in Sicily in 2016 and has spread as far as England and Ireland. Wheat blast disease, caused by a different fungus, appeared in Bangladesh in 2016, and spread to India, the world’s second largest producer of wheat.
Insects, moths, worms, and coffee leaf rust—a fungus now found in all coffee-growing countries—threaten the livelihoods of millions of people who grow coffee, as well as everybody’s cup of joe. More heat, more intense rain, and higher humidity have allowed coffee leaf rust to cycle more rapidly. It has grown exponentially, overcoming the agricultural chemicals that once kept it under control.
To identify new diseases and fine-tune crops for resistance, scientists are increasingly relying on genomic tools.
Tar spot, a fungus native to Latin America that can cut corn production in half, has emerged in highland areas of Central Mexico and parts of the U.S.. Meanwhile, maize lethal necrosis disease has spread to multiple countries in Africa, notes Mehrdad Ehsani, Managing Director for the Food Initiative in Africa of the Rockefeller Foundation. The Cavendish banana, which most people eat today, was bred to be resistant to the fungus Panama 1. Now a new fungus, Panama 4, has emerged on every continent–including areas of Latin America that rely on the Cavendish for their income, reported a recent story in the Guardian. New threats are poised to emerge. Potato growers in the Andes Mountains have been shielded from disease because of colder weather at high altitude, but temperature fluxes and warming weather are expected to make this crop vulnerable to potato blight, found plant pathologist Erica Goss, at the Emerging Pathogens Institute.
Science seeks solutions
To protect food supplies in the era of climate change, scientists are calling for integrated global surveillance systems for crop disease outbreaks. “You can imagine that a new crop variety that is drought-tolerant could be susceptible to a pathogen that previous varieties had some resistance against,” Goss says. “Or a country suffers from a calamitous weather event, has to import seed from another country, and that seed is contaminated with a new pathogen or more virulent strain of an existing pathogen.” Researchers at the John Innes Center in Norwich and Aarhus University in Denmark have established ways to monitor wheat rust, for example.
Better data is essential, for both plants and animals. Historically, models of climate change predicted effects on plant pathogens based on mean temperatures, and scientists tracked plant responses to constant temperatures, explains Goss. “There is a need for more realistic tests of the effects of changing temperatures, particularly changes in daily high and low temperatures on pathogens,” she says.
To identify new diseases and fine-tune crops for resistance, scientists are increasingly relying on genomic tools. Goss suggests factoring the impact of climate change into those tools. Genomic efforts to select soft red winter wheat that is resistant to Fusarium head blight (FHB), a fungus that plagues farmers in the Southeastern U.S., have had early success. But temperature changes introduce a new factor.
A fundamental solution would be to bring back diversification in farming, says Ehsani. Thousands of plant species are edible, yet we rely on a handful. Wild relatives of domesticated crops are a store of possibly useful genes that may confer resistance to disease. The same is true for livestock. “If you put all your eggs in one basket and then a pest comes along, then you are more vulnerable to those risks. Research is needed on resilient, climate smart, regenerative agriculture,” Ehsani says.
Jonathan Sleeman, director of the U.S. Geological Survey National Wildlife Health Center, has called for data on wildlife health to be systematically collected and integrated with climate and other variables because more comprehensive data will result in better preventive action. “We have focused on detecting diseases,” he says, but a more holistic strategy would apply human public health concepts to assuring animal wellbeing. (For example, one study asked experts to draw a diagram of relationships of all the factors affecting the health of a particular group of caribou.) We must not take the health of plants and animals for granted, because their vulnerability inevitably affects us too, Sleeman says. “We need to improve the resilience of wildlife populations so they can withstand the impact of climate change.”