How the sixth extinction crisis can be stalled – or even stopped

The environment around us is rapidly changing. Experts estimate that the loss of species we are seeing today is between 1,000 and 10,000 times higher than the natural extinction rate. This is the sixth extinction crisis. While you may never notice some of those species, each plays an important role in maintaining the diverse ecosystems that are central to human existence.

“Biodiversity supports human and societal needs, including food and nutrition security, energy, development of medicines and pharmaceuticals and freshwater, which together underpin good health. It also supports economic opportunities, and leisure activities that contribute to overall well-being,” says the World Health Organization.

On a more acute level, changes that affect how ecosystems function or cause significant disruptions to ecosystems can damage our capacity for discovering chemicals and genes within nature that can provide humans with numerous health benefits.

We are also destroying food chains and habitats that are required for human survival. The less diverse our ecosystems are, the less able they are to provide food, shelter and support for the human species.

We need numerous, cooperative and coordinated efforts to stop the sixth extinction crisis. Some of these efforts must focus on stopping fossil fuel emissions, integrating green technologies and encouraging collaborative social action. We must also work to actively stop the process of extinction by building technology, solutions and processes that can help us secure animal DNA and begin to reverse the damage created by humans.

Colossal, a company I co-founded in 2021 with George Church, is focused on de-extinction. Our first ambitious project is to bring back the woolly mammoth in collaboration with Dr George Church of Harvard University. The project requires that we make numerous big scientific leaps that will help us de-extinct other species including our second species, the Tasmanian tiger. Bold de-extinction projects matter because they improve the entire field of de-extinction, conservation and species preservation.

De-extinction reverses plant and animal extinctions by creating new proxy versions of previously lost species. Conservationists frame de-extinction as “deep ecological enrichment” or restoring ecosystem functions lost through the extinctions of keystone species, which leave an ecological void by their absence. This idea is the motivation for de-extinction projects: releasing resurrected animals into suitable habitats so as to increase biodiversity and restore ecosystem resilience. Assisted breeding, cloning and genome editing are species restoration methods undertaken with the goal of re-establishing the dynamic processes that produce healthy ecosystems and restore biodiversity.

To de-extinct species, there are established research methods which include assisted breeding, cloning and genetic engineering.

Assisted breeding uses the principles of biobanking and assisted reproductive technologies to help restore species.

Assisted reproductive scientists have highly characterized assisted breeding technologies in model species. However, non-model species have not been characterized at all, and this set includes many critically endangered species. These technologies enable scientists to increase overall population fitness and heterozygosity within fragmented populations.

One of the best examples of successful assisted reproductive technologies (ART) for species with declining populations is the Northern White Rhino project, which has been under way for decades and continues today. In projects such as these, scientists retrieve and preserve gametes (oocytes and sperm) from populations at the brink of extinction. By doing this, conservationists have increased rates of reproduction, biodiversity and overall longevity in fragmented populations with minimal individuals.

Dr Wendy Kiso leads Colossal’s efforts on ART projects such as ovum pick-up, embryo transfer, cryopreservation and in-vitro fertilization. Colossal aims to standardize this collection of crucial techniques and technologies for all species on the verge of extinction, beginning with elephant and marsupial species.

Cloning is another option useful for continuing a species, but not for returning or bringing back a lost one.

Breakthroughs in cloning or processes that produce genetically identical biological life copies have grown over time. In 1902, Hans Adolf Eduard Driesch, a German scientist, gave life to salamander twins by dividing an embryo into two separate viable embryos. After decades of experimentation, on 5 July 1996, a lamb named Dolly was born from a female sheep – the first mammal cloned from adult animal cells. The scientists used the somatic cell nuclear transfer (SCNT) technique to generate an identical nuclear gene sequence to the donor of the somatic (non-reproductive) cell.

The technique worked and is a feasible de-extinction approach for living species close to extinction because the resulting organism is identical. However, cloning requires intact living cells. As such, the process is more suitable for populations where some individuals remain, not those already extinct. A recent example of this technique was demonstrated by a team cloning a black-footed ferret in order to bring genetic diversity back to the species that has been lost. We have just scraped the surface of what this technology will mean for conservation.

Genome editing and synthetic genomics, using tools like CRISPR, are addressing de-extinction with positive results.

“Bringing back the woolly mammoth or any species is only possible because of the tools and techniques, developed through genome editing, that have been in research and development for the past thirty years,” says Sara Ord, Director of Species Restoration at Colossal. “Since the 1990s, genome editing has been used to manipulate a living organism’s genetic material by deleting, replacing or inserting a DNA sequence.”

Genome editing blends the desired traits that made the species unique with genes from the donor species. That is why the resulting organism is not completely identical to the extinct species but is a hybrid. With extinct species, we insert edited DNA into a nucleus of a reproducing cell which allows us to resurrect species in the form of hybrids between living and extinct organisms.

The process of building high-quality reference genomes, biobanking cells, genome engineering, and SCNT holds boundless potential and is the science we are using at Colossal. The world is just starting to understand how we can use these synthetic biology tools to not only de-extinct species, but to make edits in nature and undo the harm humanity has done to our planet.

We are at the start of the battle against the sixth extinction and we have a long way to go. Luckily, we have seen governments, investors and citizens join us in the fight. Numerous partner organizations around the world support de-extinction techniques and technologies. They recognize that now is the time to fuse science with bold thinking to ensure that our planet remains habitable for all species far into the future.