Once upon at time millions of years ago the ancestor of today’s Nicobar pigeon flew over the islands of Mauritius and saw paradise. There was abundance of fruits, nuts and fish and a complete lack of natural enemies. It touched down and ate itself into the giant flightless bird we know today as the Dodo.

This blog has been updated with a video interview with de-extinction biologist Ben Novak.

All seemed well until for some reason Dutch sailors had to ruin everything for everyone. The sailors set foot on the island in 1598 and saw a giant flightless birds in need of a natural enemy. The Dodos were captured and brought on their ships. Some for dinner and some just to show off within Europe. The rats onboard their ships saw the abundance of Mauritius and decided to stay. They found an easy catch in the eggs the Dodo laid on the jungle floor. And so the Dodo went extinct just 75 years after. Sad.

The Dodo is one of the best known examples of the destructive ways of Homo Sapiens. Now that we’ve grown wiser, can we be the force that brings the Dodo back?

The first step is Dodo DNA

Dodo DNA is quite rare because DNA decays easy in warm climates and since the dodo was endemic to tropical Mauritius almost all bones found there do not contain viable DNA. However because the Dodo was brought to the more temperate Europe, scientists were able to sequencing Dodo DNA using bones stored in Copenhagen. (Beth Shapiro, 2016). She is currently working on a fully sequenced Dodo genome.

Beth has already fully sequenced the genome of the Nicobar pigeon, the dodo’s closest living relative. To bring back the Dodo we need to compare its DNA to that of the Nicobar pigeon to determine the genes that make a Dodo. This is a difficult process because the Nicobar pigeon has over a billion base pairs and ancient DNA has lots of false mutations.

The Nicobar pigeon is the closest living relative to the Dodo.

There is a lot of innovation in this field however and machine learning is aiding in this process but it still needs time and attention from talented scientist to understand the Dodo genome enough to make sensible edits to Nicobar pigeon DNA. More funding is needed in order to progress the genome research step sufficiently.

Comparing genes, DNA basepairs sequences

The second step is usually cloning, but not for birds.

It is not possible to clone birds via the regular methods of somatic cell nuclear transfer — where you take the nucleus of an egg cell, the part that contains the DNA, and swap it with another edited version. To generate species that lay eggs such as birds a different approach is needed called germ-line transfer.

Primordial germ cells are stem cells that will become egg or sperm cells. To create a Dodo a team will need to edit primordial germ cells of a Nicobar pigeon to have Dodo genes using the gene editing tool CRISPR-Cas9. Edited primordial germ cells can then be injected into a fertile bird egg — making a surrogate mother and a surrogate father that will produce gene-edited offspring.

A Nicobar pigeon however is much smaller than a Dodo, so it may not be able to be a surrogate parent to new dodo chicks. So we need a host for our primordial Dodo germ cells that creates large eggs such as an Emu.

An Emu can become up to 1.8 meters tall and 40kg

To create Dodos, it may be possible to take an Emu egg and during the early stages of embryonic development (the first 24–72 hours), a team of scientists can inject gene-edited Nicobar pigeon primordial germ cells. These new injected cells will find their way to the still developing sex organs.

When the Emu chick hatches, that chick itself will not be genetically altered, but the gene-edited germ cells will be in its sex organs. Meaning that Emu will develop Dodo sperm or egg cells depending on whether the chick is male or female. When that chick then grows up and lays its own eggs some of them will carry Dodo chicks inside waiting to hatch. Only some of the eggs will hold dodo chicks, because the Emu will still make it’s own sperm and eggs, meaning many of the chicks will still be Emu’s.

In order to increase our chances of getting Dodo’s, it may be possible to genetically engineer the Emu so that is does not produce it’s own primordial germ cells. By using sterile Emus as the surrogate parents to inject with “dodo” germ-cells then,100% of the sperm or egg cells in the chicks that develop will be Dodo.

There is good hope that this method will work as it has recently been proven successful in chickens where scientists restored rare chicken breeds using genetically engineered sterile chickens. (Woodcock et al. 2019).

Once there are Dodo chicks they will need to be raised for a life in the wild and for that we need the help of zoos and aviculturists, and eventually when conservationists plan to release dodos to the wild, the birds will need their natural habitat. Mauritius however only has 2% of natural habitat left and is still full of invasive shrews, rats and cats. It however has removed those pest species on smaller island close to the main island which will be ideal locations to reintroduce the new Dodos. To introduce it back onto the mainland as it once roamed freely there will need to be wilderness areas free of invasive mammalian species. Removing these invasive species may be possible humanely with new genetic techniques, like gene drive.

Gene drive is a technique whereby a specific gene can be engineered to be inherited by 100% of offspring instead of the normal 50%. Via that method scientist can cause 100% of offspring to be male for example. The ‘male’ gene will then spread throughout the entire population rapidly and will cause that species to become extinct within just a few generations as there will eventually be no females to mate with. A multi institutional program, named GBIRd, lead by the non-profit Island Conservation has started a program to explore the use of gene drive to eradicate rodents on islands for conservation. These methods are also being considered by New Zealand, which has dedicated a program to eliminate eight invasive mammalian predator species, including rats, from the entire country by 2050.

And that, my friends, is how we can bring back the Dodo.