Home » Science & Nature » Paleontology » Cloning Extinct Animals I

Cloning Extinct Animals I

© Beverly Eschberger

As a paleontologist, one of the questions I am frequently asked is, "Is it possible to clone dinosaurs?"

You may have seen the programme on the Discovery Channel about the excavation of a frozen mammoth. Paleontologists are slowly thawing the large block of frozen sediment in the hopes of recovering tissue from the mammoth that can be used the further study these extinct animals. Be sure to read my article, "Mammoths, Mastodons, and Elephants" for more information.

Scientists have suggested that it might be possible to clone a mammoth from cells recovered from this and other frozen mammoth specimens (this is not the first frozen mammoth to be found, and certainly will not be the last!). What they have proposed doing is to take sperm recovered from a frozen male mammoth, and to use that sperm to fertilize the egg of a living elephant. This would be possible because mammoths and elephants are genetically similar, despite a difference in the number of chromosomes, and it might be possible to form an elephant-mammoth hybrid that would be about 50% elephant and 50% mammoth. The (female) hybrid could then be fertilized with more mammoth sperm, making a hybrid that would be roughly 75% mammoth. This process could then be continued until we had an animal which contained mostly mammoth DNA. This plan has the drawback that we would have to wait until the animals reached the age of sexual maturity before they could produce the next generation of elephant-mammoth hybrids.

You are probably thinking, "But wait, wouldn't it be easier to just use an egg taken from a frozen female mammoth, and make a 100% mammoth? Or even to find a female mammoth with a recently fertilized ovum?" Yes, this would make things a lot easier and faster. Unfortunately, finding preserved frozen eggs that would still be viable is more difficult than finding viable frozen sperm. Sperm are little more than nuclear DNA with enough mitochondria (energy-producing organelles in the cell) to power the flagellum to reach and fertilize an egg. Eggs, on the other hand, are much larger and more complex cells. They also contain a lot of water. Unless eggs are frozen under the right conditions, ice crystals can form that then rip through the cell walls, destroying the egg.

Elephants are also a difficult species to attempt artificial insemination in. The female elephant has a uterus over four feet long, and curved in such a way that this is a rather difficult procedure!