You can never step into the same river twice, you can't raise the dead, and you can't bring back an extinct species with genetic engineering. A Texas startup, Colossal Biosciences, claims they are on the way to that last feat, but there are a number of problems with their claims.

Experts have said there is a strong chance a long-lost species, such as mammoths, the dodo and the Tasmanian tiger, could brought back from the dead before 2028 – with the help of Paris Hilton and Chris Hemsworth.

In simple terms, the science behind the mission involves working out the “core” genes that make an extinct animal what it is, and then replicate those genes using the DNA of a close existing relative.

Scientists at Colossal Biosciences are already well on their way to reviving the species using gene-editing technology. 

They aren't. You can't revive an extinct species. What Colossal Biosciences is doing, as noted above, is an act of genetic engineering — in the case of the "mammoth," they will attempt to genetically alter an Asian elephant embryo or egg (the process isn't clear) with what they estimate are the genes that separate the Asian elephant (Elephas Maximus) with presumably the Woolly Mammoth (Mammuthus primigenius.) This, even should they succeed will produce a creature that is neither elephant nor mammoth, but nothing more than a genetically-engineered theme park attraction. There is no way that this could ever result in a true "de-extinction" event, as it remains utterly impossible to create a population of these animals.

I first wrote about this company and their pre-celebrity backer claims in March.

See Related: 'De-Extinction' Company Claims Stem Cell Breakthrough Could Produce New Pseudo-Mammoth Species

About the mammoth, I wrote:

Proboscids in general—African and Indian elephants and, presumably, their extinct relatives like mammoths, mastodons, and gomphotheres—are intelligent animals, and they spend the first few years of their lives learning from their mothers and other herd members how to be elephants. That includes knowing which plants are good to eat, how to find water, how to interact with other elephants and other animals in the environment, and what predators may be dangerous and which may be ignored.

There are no extant elephants or mammoths in any northern biome that can teach these animals what they would need to know to survive.

That's also the stumbling block for pretty much every animal Colossal Biosciences claims to be working on, including the dodo and the Tasmanian tiger (thylacine), as well as the mammoth.

An even bigger problem is habitat. The thylacine and dodo's primary habitats still exist, but the mammoth steppe of the last Ice Age is gone. Even if miracles occurred and allowed Colossal Biosciences to come up with a facsimile of a mammoth, they could never be released into the wild. Not only does the environment they originally lived in no longer exist except, perhaps, in some regions of northern Siberia, Alaska, and Canada, but the animals themselves would have no idea how to survive.

Any animal produced by a process like this would be alone as no animal in the world has ever been alone, a freak created in a lab, the only one of its kind that ever was or ever will be; will live its life in captivity, and will be under constant poking, prodding, and study. That's not what most people would have in mind when talk of "de-extinction" comes up.

Extinction is permanent. In some cases, that's for the best.

See Related: Giant 50-Foot Snake Found in India. Upside: It's Extinct.

Colossal Biosciences appears to be privately funded and as such, they only have to answer to their financiers about what they spend the money on — but this seems like, forgive the term, a colossal waste of resources.