Saving Species from Extinction

Around the world, the variety of living things—defined as biodiversity—is declining, as increasing numbers of species face the risk of extinction. For example, a recent analysis of 14,669 threatened animals and plants found in Europe reveals that about 19% of them face the threat of extinction—including 27% of plants, 24% of invertebrates and 18% of vertebrates—and that agricultural land-use changes (resulting in loss of habitats, overexploitation of biological resources, pollution, and commercial and residential development) pose a significant threat to these species.

In our oceans, globally, it’s a similar story. In a new study, scientists analyzed 13,195 marine fish species considered to be “data deficient” by the International Union for Conservation of Nature (IUCN) and discovered that many more bony fish are at risk of extinction than we previously thought; in fact, up fivefold (12.7%) from the IUCN’s prior estimate of 2.5%. This information—created by using a computational model to predict the likelihood of animal extinctions based on the complex interactions of environmental change and hunting—is causing some to propose a new index called the “predicted IUCN status,” which would serve as a valuable complement to the current “measured IUCN status.” Predicted threatened species tended to have a small geographic range, a large body size and a low growth rate. The extinction risk was also correlated with shallow habitats. The Celebes and Philippine Seas, the South China Sea, and the west coasts of Australia and North America emerged as hot spots for predicted threatened species.

Biodiversity is essential for our own economic welfare, food security and well-being. Luckily, scientists are now creating a visionary framework that merges traditional conservation with biotechnology, aiming to give struggling populations a fighting chance against extinction. New tools—such as gene editing, biobanking, a Megafauna Hunting Pressure Model and trait information from fossils—are already transforming biology. Soon, they could “reinvent” the future of biodiversity itself.

This mass extinction is different

For millions of years, large herbivores like giant deer, giant rhinos and mastodons have shaped the Earth’s ecosystems, which astonishingly stayed stable despite extinctions and upheavals. Only twice in 60 million years did environmental shifts dramatically reorganize these systems: once with a continental land bridge, and again with a climate-driven habitat change. Yet the ecosystems adapted, with new species taking on old roles. Now, a third, human-driven tipping point threatens that ancient resilience.

The first major change occurred around 21 million years ago, when shifting continents closed the ancient Tethys Sea and formed a land bridge between Africa and Eurasia. This new land corridor unleashed a wave of migrations that reshaped ecosystems across the globe. Among the travelers were the ancestors of modern elephants, which had evolved in Africa and now began to spread across Asia and Europe. But deer, pigs, rhinos and many other large plant-eaters also moved into new territories, altering the ecological balance.

The second global shift came around 10 million years ago, as Earth’s climate became cooler and drier. Expanding grasslands and declining forests led to the rise of grazing species with tougher teeth and the gradual disappearance of many forest-dwelling herbivores. This marked the beginning of a long, steady decline in the functional diversity of these animals and the variety of ecological roles they played.

After analyzing fossil records from more than 3,000 large herbivores across 60 million years, however, researchers from Sweden’s University of Gothenburg found that despite these losses, the overall ecological structure of large herbivore communities remained surprisingly steady. Even as many of the largest species, like giant rhinos and mammoths, went extinct in the last 129,000 years, the basic framework of roles within ecosystems endured, with different species coming into play to fulfill similar ecological roles, so that the overall structure remained the same.

This resilience has lasted for the past 4.5 million years, enduring ice ages and other environmental crises up to the present day, state the researchers, who published their findings in the journal Nature Communications in June 2025. However, they caution that the ongoing loss of biodiversity—accelerated by human activity—could eventually overwhelm the system. While their results show that ecosystems have an amazing capacity to adapt, they say the rate of change is faster this time and there’s a limit. If we keep losing species and ecological roles, we may soon reach a third global tipping point, one that we’re helping to accelerate.

Cheating extinction with gene editing

There’s some exciting news on the extinction front, however. Gene editing may hold the key to rescuing endangered species—not just by preserving them, but by restoring their lost genetic diversity using DNA from museum specimens and related species.

In a new Nature Reviews Biodiversity article published in July 2025, the authors—a multidisciplinary team of biotechnologists and conservation geneticists—explore the challenges, ethical considerations and promises of genome engineering and propose an approach for its implementation into biodiversity conservation. They argue that gene editing could recover lost genetic diversity in species at risk of extinction using historical samples, such as DNA from biobanks, museum collections and related species. The same technological advances that allow us to introduce genes of mammoths into the genomes of elephants can be harnessed to rescue species teetering on the brink of extinction.

Conservation successes, such as captive breeding and habitat protection, often focus on boosting population numbers but do little to replenish the gene variants lost when numbers crash, say the scientists. As populations rebound, they can remain trapped with a diminished genetic variation and a high load of harmful mutations, a phenomenon known as “genomic erosion.” Without intervention, species that recovered from a population crash may remain genetically compromised, with reduced resilience to future threats, such as new diseases or shifting climates.

One example of this is the Mauritius pink pigeon, whose population has been brought back from the brink of extinction—from about 10 individuals to a population of more than 600 birds—by decades of captive breeding and reintroduction efforts in Mauritius. Several of the article’s authors have studied the pigeon’s genetics, revealing that, despite the pink pigeon’s recovery, it continues to experience substantial genomic erosion and is likely to go extinct in the next 50 to 100 years. The next challenge is to restore the genetic diversity the bird has lost, enabling it to adapt to future environmental changes. Genome engineering could make this possible.

The technology is already common in agriculture: crops resistant to droughts and pests cover millions of acres worldwide. The scientists outline three, main applications for gene editing in conservation:

• Restoring lost variation—bringing back genetic diversity that has been lost from the gene pool of the modern populations of threatened species, using DNA from samples of the species collected decades or even centuries ago, which are stored in natural history museums all over the world.
• Facilitated adaptation—introducing genes from related, better-adapted species to confer traits like heat tolerance or pathogen resistance, equipping threatened species to adapt to rapid environmental change.
• Reducing harmful mutations—populations that have previously crashed in numbers often carry harmful mutations that have become fixed by chance, so targeted gene edits could replace these mutations with the healthy variant from before the population crash, with the potential to improve fertility, survival rates and overall health.

The researchers also address the risks, such as off-target genetic modifications and unintentional further reductions in genetic diversity, cautioning that the approaches remain experimental. The need for phased, small-scale trials and rigorous long-term monitoring of ecological and evolutionary impacts is emphasized, as well as robust engagement with local communities, Indigenous groups and the wider public. The authors stress that genetic interventions must complement, not replace, habitat restoration and traditional conservation actions.

Reviving species with biobanking

An animal that may benefit from genetic engineering—with an assist from biobanking—is the northern white rhino, one of the rarest animals on Earth. Just two females are left, Fatu and Najin, who live at the Ol Pejeta Conservancy in Kenya under 24-hour protection. With no natural way for the species to reproduce, an international team of scientists has recently mapped the entire northern white rhino genome, which represents a crucial step toward bringing the critically endangered species back from the edge. The complete genome, published in May 2025 in the journal Proceedings of the National Academy of Sciences, can be used as a reference to analyze the health of previously developed northern white rhinoceros stem cells. Eventually, those stem cells may be able to generate eggs and sperm to yield new rhinos.

In 2011, scientists produced the first pluripotent, induced stem cells (laboratory-generated cells, created by reprogramming ordinary adult cells [like skin cells] to become similar to embryonic stem cells. These cells are pluripotent, meaning that they have the remarkable ability to develop into any cell type in the body) from northern white rhinos. Since then, other lines of stem cells from nine, different, northern white rhinos have been created. The new, complete genome—the rhino version of the Human Genome Project—was accomplished by using cells previously collected from a male northern white rhinoceros named Angalifu, who lived at the San Diego Zoo Safari Park until his death in 2014. At that time, his skin cells were cryopreserved at the San Diego Zoo Wildlife Alliance Frozen Zoo.

One major hurdle regarding stem cells has always been quality control. Without a reference genome, scientists could never be certain whether any of the stem cells had picked up harmful mutations during lab growth, a common problem. Now, researchers can use the complete genome to analyze the previously created stem cell lineages. In fact, they have discovered that one of the most promising of the stem cell lines had a large chunk of DNA missing—more than 30 million base pairs affecting more than 200 genes, including those involved in reproduction and tumor suppression. If they hadn’t built this new genome, that knowledge would have remained unknown. The reference genome is now the gold standard for screening all rhinoceros stem cells and deciding which cells to move forward with.

The new genome also settled lingering questions about how different northern and southern white rhinos really are. Some earlier data suggested significant DNA differences that might make it risky for southern white rhinos to be implanted with northern white rhino embryos. But updated comparisons show their genomes are strikingly similar, giving scientists confidence that southern white rhinos—which are far more numerous—can serve as surrogates without major complications.

This work also sets a powerful example for other endangered species. From birds and mammals to corals and plants, efforts to save them depend on careful biobanking like that being done by the Frozen Zoo.

Preventing future decimations with a look back

During the Late Pleistocene (approximately 129,000 to 11,700 years ago), California—at least at its lower elevations—was teeming with vegetation. While much of North America was covered in ice age glaciers, here, mastodons lumbered across verdant meadows, stopping to feed on brush, warily eyeing the forest’s edge for saber-toothed cats on the prowl for calves. Humans also flourished along the coastline, which extended hundreds of feet below where it is today.

But by 11,000 years ago, mastodons were extinct. Today, scientists are still debating the reasons for their demise: did human hunting do them in? Climate change? A cataclysmic event? Diminishing genetic diversity? Or some combination of factors?

Explaining what caused the extinctions of large animal species like mastodons is often fraught due to the difficulty of piecing together an accurate picture of the past based on fragmentary evidence about the human and environmental pressures that may have contributed to their disappearance. Now, however, San Diego State University researchers report in the March 2024 issue of Quaternary Research that they have created a computational model to help predict the likelihood of large animal extinctions. Called the “Megafauna Hunting Pressure Model,” this new tool could ultimately aid conservation managers during a time when animal extinctions are skyrocketing.

The model was carefully crafted with understandings from anthropology and archaeology about human behavior and how we interact with nature. In developing it, the researchers turned to the case of Syncerus antiquus, also called the giant African buffalo, a large, grazing ungulate whose horns could reach nearly 10 feet from tip to tip. The species coexisted with humans for several hundred thousand years in Africa before going extinct between 12,000 and 10,000 years ago. There is no consensus in the scientific community about which factors contributed most to the animal’s extinction. Some believe these animals died because of the climate changes associated with the end of the last ice age, and others say humans did it.

In their case study, the San Diego State University researchers considered how the animal’s behavior and demographics, environmental factors and human behavior interacted to form a socioecological system which adapts to changes over time. They based some of their inputs on known life-history characteristics of the cape buffalo (Syncerus caffer), a related species which is still living today, and adjusted them based on differences in the animals’ sizes, for example. They ran computer simulations to see how populations of Syncerus antiquus would fare under 24 scenarios involving different human-hunting pressures and preferences and environmental conditions, including the patchiness of their grassland habitat and length of the growing season. After running the simulations 40 times for each scenario, the researchers calculated the probability that Syncerus antiquus populations would go extinct.

The scientists found that when male buffalo were aggressive—leading hunters to target females, instead—localized extinction was much more likely. If the number of breeding females is reduced by just a small amount, the entire breeding cycle for these slow-reproductive, large-bodied animals is disrupted; and in just a few decades that can have a major impact. When the climate and food sources were unreliable, extinction occurred even more rapidly.

The simulations show that extinction will not occur in every scenario where environmental conditions are unfavorable or hunting pressure is high, whether looking at the paleoanthropological record or to the future. But certain combinations of these conditions will feedback on each other to enhance the likelihood of extinction, helping to explain why some species have gone extinct but others have not.

In the face of the current mass extinction crisis, the model could also be applied to wildlife species at risk today, from black rhinos to desert tortoises, helping to identify tipping points where species are most vulnerable, allowing conservationists to develop more effective strategies to protect them.

Predicting climate change vulnerabilities with fossils

Past climate change (often caused by natural changes in greenhouse gases due to volcanic activity) has been responsible for countless species’ extinctions during the history of life on Earth. But, to date, it has not been clear what factors cause species to be resilient to such change and how the magnitude of climate change affects extinction risk.

Recently, scientists from England’s University of Oxford sought to answer this question by analyzing the fossil record for marine invertebrates (such as sea urchins, shellfish and snails) over the past 485 million years. Marine invertebrates have a rich and well-studied fossil record, making it possible to identify when, and potentially why, species become extinct.

Using more than 290,000 fossil records covering more than 9,200 genera, the researchers collated a dataset of key traits that may affect resilience to extinction, including traits not studied in depth previously, such as preferred temperature. This trait information was integrated with climate simulation data to develop a model to understand which factors were most important in determining the risk of extinction during climate change. They found that:

• Species exposed to greater climate change were more likely to become extinct. In particular, species that experienced temperature changes of 12.6 degrees Fahrenheit or more across geological stages were significantly more vulnerable to extinction.
• Species occupying climatic extremes (for instance, in polar regions) were disproportionately vulnerable to extinction, and animals that could only live in a narrow range of temperatures (especially ranges less than 27 degrees Fahrenheit) were significantly more likely to become extinct.
• However, geographic range size was the strongest predictor of extinction risk. Species with larger geographic ranges were significantly less likely to go extinct. Body size was also important, with smaller-bodied species more vulnerable.
• All the traits studied had a cumulative impact on extinction risk. For instance, species with both small geographic ranges and narrow thermal ranges were even more susceptible to extinction than species that had only one of these traits.

In conclusion, the study, published in the journal Science in March 2024, demonstrates that for marine invertebrates, geographic range is the biggest factor for the likelihood of extinction, but the magnitude of climate change is also important. This should act as a stark warning for us today as we recklessly continue to cause climate change through our burning of fossil fuels.

Matching unusual times with novel solutions

We’re facing the fastest environmental change in Earth’s history; and not only is it difficult for many species to keep up, but they’ve also lost the genetic variation needed to adapt and survive. It’s become essential that we embrace new technological advances—alongside traditional conservation approaches.

It’s our responsibility to reduce the extinction risk faced by thousands of species today. Unprecedented threats demand unprecedented solutions. It’s time.

Here’s to finding your true places and natural habitats,

Candy