When the African savanna is in drought, an old elephant matriarch leads his herd to a body of water he remembers from decades ago. In the cold Pacific Ocean, an old orca guides a pod to elusive salmon and shares the prey when prey is scarce. And above the open ocean, the expert albatross follows a vast, invisible route honed over years, returning unerringly to feed its chicks.
These animals exhibit memories, skills, and experiences accumulated over long lives across land, sea, and air. So what happens when such older adults are selectively removed by hunting, fishing, or other human pressures? Researchers say the losses may not be immediately visible, but they are profound. In other words, the knowledge that supports group survival is beginning to be lost.
For decades, conservation efforts have focused on numbers: how many animals remain in a population. But a growing body of research suggests that this lens is too narrow, and that the loss of older animals can reshape populations in ways that simple numbers don’t capture. “Not all individuals contribute equally,” says Keller Kopp, a senior lecturer at Australia’s Charles Darwin University. “Older animals play a role that is often invisible to simple population counts.”
“There is growing evidence of the knowledge, skills, and leadership role older adults have in society.”
In 2024, a paper in Science led by Kopf introduced the term “longevity preservation” and gave a name to a simple idea. Conservation of wildlife means maintaining the complete age structure of the population, including the oldest individuals. This concept quickly transcended theory. Last year, the International Union for Conservation of Nature adopted a resolution on the issue, formally recognizing the importance of protecting the elderly and elevating the concept into conservation policy. And at the recent United Nations conference on migratory bird species in Brazil, conservation of the “old and wise” animals was a major topic of discussion.
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Scientists say older animals often play several key roles in population functioning, falling into three broad categories: ecological knowledge, reproduction, and immunity. They have knowledge that guides their survival, play a major role in producing the next generation, and have stronger defenses against disease built up over time. Together, these properties can make the difference between a population that survives and one that slowly collapses.
Conservation biology has long been concerned with population dynamics. To measure the health of a population, scientists estimate how many animals remain, how fast they reproduce, and how many animals can be removed without causing a collapse. Shaped primarily by wildlife management and fisheries science, this approach treated populations as sets of interchangeable individuals, with one animal able to replace another as long as the overall number remained constant.
Humpback whale and calf off the coast of Australia.
Philip Thurston / iStock
Research into the specific roles of older animals has been conducted across multiple disciplines for decades, but has remained largely disconnected from conservation biology. Research “has been confined to very siled areas,” Kopf said. Today, silos are breaking down as research on the importance of older animals accumulates and the decline in long-lived species makes it difficult to ignore the findings.
“In recent years, there has been increasing evidence that older adults play knowledge, skill, and leadership roles within society,” said Jennifer Smith, a behavioral ecologist at the University of Wisconsin-Eau Claire.
Few animals are as articulate as the elephant. For decades, older males were often treated as expendable by wildlife managers and hunting officials. This idea was reflected in trophy hunting guidelines, which encouraged the selective harvest of adult bulls on the assumption that they were past their reproductive prime and could be removed without harming the population. But research over the past decade has called that view into question. A study of elephants in Botswana found that young bulls were significantly more likely to behave aggressively toward vehicles, livestock, and other animals when there were fewer older males. Older bulls appear to act as a kind of social buffer, allowing young elephants to better assess risk and reduce stress and aggression. Older men may also directly police destructive behavior.
Because older people survive repeated exposure to disease, they are more likely to inherit traits that confer resistance.
Older elephants are herd leaders, said Ian Redmond, a veteran elephant conservationist with the UK-based international wildlife organization Born Free Foundation. Elephants spend years learning how to survive in changing landscapes, including where to find water and food, when to leave depleted feeding grounds, and how to respond to threats. That knowledge can be important when extreme events such as droughts or floods occur. “Older, wiser animals are the ones that young people rely on,” Redmond says. Science has also found that elephant culling could have a lasting impact on reproduction, as elephants do not reach their reproductive prime until their 40s or 50s.
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From elephants to bison to hippos, older large animals shape the ecosystems around them by depositing large amounts of dung that fertilizes the soil, dispersing seeds over long distances, and helping maintain open habitats by felling trees and clearing vegetation. If you shorten their lives, their future activities will disappear. “Every time you shorten the lifespan of one of these animals, you shorten the role that the animal has played,” Redmond said.
The challenge for conservationists is that hunters typically target individuals with the largest horns, blackest manes, and most impressive tusks. These characteristics are often indicative of age, experience, and superiority. In species like lions and leopards, that selectivity can have cascading effects. Removal of an older male lion can lead to younger males taking over the pride, which often involves killing the cubs to restore the mother to reproductive status.
A proud old male lion lives in South Africa’s Kruger National Park.
Anna-Karina Nagel / Shutterstock
In leopards, the effect manifests itself more quietly, but no less profoundly. Each adult male has a territory, and their presence causes young males to disperse in search of their own home range or unrelated mates. “If you shoot an adult male leopard, the territory remains bare, (and) the young subadult males don’t have to disperse,” said Mona Schweitzer, a biologist and trophy hunting expert at Pro Wildlife in Munich, Germany. Without pressure to disperse, young males will stay close to related females, increasing the risk of inbreeding, she says.
If big cats provide a clear case study, whales represent something more dramatic: a global experiment in removing older animals. During the 20th century, industrial whaling targeted the largest individuals and killed millions of whales, depriving them of those that might have stored accumulated knowledge about migratory routes and feeding grounds. “We did this amazing experiment with whales that we didn’t know we were doing,” says Mark Simmons, director of science at ocean conservation organization OceanCare.
Studies of killer whales and sperm whales have shown that older individuals, especially females, play a central role in guiding the group and sharing food, shaping the survival of the entire social unit. Scientists say this type of social knowledge may also extend to how whales find and use their primary habitat. When an older animal is lost, its knowledge can disappear with it. “Probably because there weren’t any individuals left who knew about these habitats and how to take advantage of them,” Simmons says. A recent study found that in some parts of the Mediterranean, gray and right whales are not returning to their former calving grounds.
Among freshwater fishes, the role of large, older fish has long been recognized, but is often overlooked. Some species, such as the sturgeon, are slow growing and very long-lived, sometimes living for over 100 years. Many large fish, including sturgeon, continue to grow throughout their lives. With increasing age, reproductive output increases rapidly. Larger, older females lay far more eggs than younger fish, and often produce eggs of higher quality.
A black-browed albatross flies over nesting grounds in the Falkland Islands. Albatross spend years learning how to travel long distances in search of food.
Martin Zwick / REDA / Universal Images Group via Getty Images
This has obvious implications for management. Fishing often targets the largest individuals and removes those that contribute most to population stability. Without these fish, populations can lose their reproductive engines and long-term resilience. “When you manage the oldest and largest fish, you manage healthy fish populations,” says Zev Hogan, a fish biologist at the University of Nevada, Reno and a trustee of the Convention on Migratory Freshwater Fishes.
Beyond knowledge and reproduction, many older animals have less visible but equally important immunities. Long-lived individuals are more likely to carry and pass on traits that confer resistance because they have survived repeated exposure to disease. When these animals are removed, populations may lose some of their accumulated resilience and become more vulnerable to future infectious disease outbreaks. Although clear examples of this phenomenon are still emerging, there is growing evidence that preserving such individuals makes the population more resistant to disease over the long term, Christian Walzer, professor of conservation medicine at the University of Veterinary Medicine in Vienna, told a United Nations conference in Brazil.
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Researchers say the resolution, adopted last year by the International Union for Conservation of Nature, is useful because it shifts the focus from questions of how many animals are left to how populations are actually functioning. The move will spur research into how to protect older animals and could lead to changes in hunting regulations and fisheries management to avoid unfair removal of older animals.
Conservation groups have long been wary of distinguishing between humans and animals based on similarities. But some researchers say emerging science increasingly reflects our own experiences, showing that older animals, like elders in human societies, pass on knowledge that helps other animals thrive. “I think we can all relate to this because we see the same thing in humans: how important experience is,” Schweitzer says.
