How to Bring an Extinct Animal Back to Life

De-extinction is the process of bringing back to life an extinct animal species where one big motivation for de-extinction is to increase biodiversity where another reason we might want to bring back lost species is to learn from them where many medicines and technological innovations developed from initial discoveries in nature where there may be a moral obligation to bring back animals that humans are responsible for eradicating.

We are currently living through Earth’s sixth mass extinction period called the Holocene extinction where this mass extinction closely correlates to human activity through hunting deforestation pollution climate change and other side effects of human expansion where we may have lost close to seven percent of all species on the planet.

Having a variety of animals plants and insects in an ecosystem is important as all of these different creatures perform different vital roles where predators like wolves and bears keep populations of smaller mammals in check where beavers build dams that slow down rivers to create safe environments for other water-loving animals where pollinators like bees and wasps help plants reproduce where if one animal dies out it can cause knock-on effects that destabilize the entire ecosystem.

There may be a moral obligation to bring back animals that humans are responsible for eradicating where the extinction rate now is thought to be a thousand times faster than before humans became the planet’s dominant species.

The extinction rate now is thought to be a thousand times faster than before humans became the planet’s dominant species where a quarter of all mammals now are at risk of extinction where every day between 30 and 150 species of animal die out on Earth for good.

With current technology that relies heavily on DNA and well-preserved tissue it’s unlikely we’ll be able to de-extinct anything that died out more than ten thousand years ago because DNA doesn’t last that long where for better or worse that rules out the dinosaurs.

When an organism dies cells break down exposing DNA in the nucleus to damage by enzymes and microorganisms where this means that in really old tissue DNA is either non-existent or only present in tiny amounts.

It’s also much harder to de-extinct birds or reptiles compared to mammals because we know so much more about mammalian reproduction compared to birds and reptiles.

Researchers in South Africa attempt to recreate the quagga an extinct subspecies of zebra where quaggas only have stripes on the front half of their bodies and brown coloring on their rear where scientists select individual zebras that express similar traits such as zebras with fewer stripes on the back half or more brown coloring then breed them together where the back breeding project started over 30 years ago and has produced multiple breeding groups of nearly quaggas after several generations.

There are some downsides and challenges to back breeding where first of all we’d need a really close relative of the extinct species to act as our starting point where for animals extinct many thousands of years ago this may not be possible where it’s also a really long process where the gestation period for a zebra is 12 months where if we need to repeat the breeding process several times it could be years or even decades before a herd is ready where it’s an imprecise process where you can’t guarantee the traits you expect to see will materialize.

The most reliable method is probably SCNT somatic cell nuclear transfer where this is the method pioneered by the creators of Dolly the sheep the first cloned mammal where the nuclei from frozen skin cells were removed and injected into donor eggs which had their own nuclei removed where by adding some chemicals and a jolt of electricity the process of embryonic development was started.

It began in 1999 when researchers captured the last surviving Pyrenean ibex a female named Celia where they obtained skin biopsies and froze the tissue in liquid nitrogen where in 2009 those skin cells were used to clone Celia in the first ever case of actual de-extinction where of the 208 embryos the researchers implanted only seven pregnancies resulted and just one ibex made it to term where this was a huge accomplishment the first ever extinct animal brought back into existence however the baby ibex died almost immediately from respiratory failure.

Most embryos derived from clones don’t develop properly where we don’t fully know why where research suggests that it’s not just one stage of the cloning process that is causing damage to the resulting embryos but in fact many if not all stages contribute from the act of moving the nucleus from one cell to another to the use of chemicals to kickstart embryonic development.

In 2019 a major breakthrough occurred when a team in Japan successfully transferred the nucleus from a frozen mammoth cell into the egg of a mouse where the nucleus came from a 28,000 year old preserved mammoth named Yuka where the mouse cell machinery did manage to fix some parts of the damaged DNA and there were some very early signs of the mechanics that underpin DNA replication but ultimately the mouse egg could only do so much where the mammoth DNA was too badly damaged and so it’s nearly impossible to reconstitute it enough to actually bring it back to life.

Researchers at Harvard University are trying to use CRISPR technology to splice mammoth genes into Asian elephant DNA but it’s a monumental task where there are around 1.4 million known gene mutations separating mammoths and Asian elephants where not all of the mutations will relate to the mammoth phenotype where it will take a long while yet to work out which mammoth genes need to be swapped into elephant DNA to recreate a woolly mammoth but the idea may be the most promising yet.

Long dead species could end up doing more harm than good because of the changes those ecosystems have undergone in the intervening period where it could create similar problems to those we’ve seen when releasing non-native species into new areas where when the poisonous cane toad was introduced to Australia to control the grey-backed cane beetle the toad quickly spread and pushed out native toad populations where an extinct species might out-compete one that has developed in its absence.

One of the most mysterious and strange animals to ever live on our planet was the thylacine found in Australia Tasmania and New Guinea where it was the largest carnivorous marsupial with a body that looks like a cross between a cat and a dog also known as the Tasmanian tiger where it was wiped from the continent of Australia 3,000 years ago and survived in Tasmania until the 1930s when humans finally hunted it into extinction where geneticists are working to resurrect this enigmatic animal with CRISPR and cloning working with a tiny relative of the thylacine a numbat.