ArticleSafari: Dolphin DNA Very Close to Human

Seema Kumar, of Discovery Channel Online, writes that scientists have discovered that the genetic make-up of dolphins is amazingly similar to humans. They’re closer to us than cows, horses, or pigs, despite the fact that they live in the water.

The extent of the genetic similarity came as a real surprise to us,” says David Busbee of Texas A&M University. He hopes his research will reveal how long ago humans and dolphins branched off the evolutionary tree. There’s been some speculation that dolphins and whales, who breathe air, may have returned to the water AFTER first evolving into land animals.

Dolphins are marine mammals that swim in the ocean and it was astonishing to learn that we had more in common with the dolphin than with land mammals,” says geneticist Horst Hameister.

Busbee says, “If we can show that humans are similar to dolphins, and anything that endangers dolphins is an equal concern for humans, it may be easier to persuade governments to keep oceans clean.

There are still many mysteries about the beings who share the earth with us. Humans and dolphins may have much more in common than people think, especially when it comes to genetics.

In a Sea Grant-funded project, Texas A&M University veterinarians are comparing human chromosomes to those of dolphins and are finding that the two share many similarities. The scientists hope to use these similarities to identify and map the genes of dolphins.

Genes are organized into segments along the length of a chromosome – a tightly wound spool of DNA. This spool is made up of two, complementary, single strands of DNA bound together. Every living thing has a characteristic number of chromosomes, and each chromosome carries different genes. Dolphins have 44 chromosomes, and humans have 46. Dr. David Busbee and his team applied human “paints,” fluorescently labeled pieces of human chromosomes, to dolphin chromosomes on microscope slides. Scientists broke open dolphin cells, releasing chromosomes onto slides. The dolphin chromosomes were then treated with labled human chromosome pieces, providing the opportunity for complementary DNA strands to match up.

When scientists examined the photos taken with a fluorescence microscope, they found dolphin chromosomes fluorescently tagged with the labeled, or “painted,” pieces of human chromosomes and concluded that dolphins hold many of the same chromosomes as humans. “We started looking at these and it became very obvious to us that every human chromosome had a corollary chromosome in the dolphin,” Busbee said. “We’ve found that the dolphin genome and the human genome basically are the same. It’s just that there’s a few chromosomal rearrangements that have changed the way the genetic material is put together.

Dolphins have been viewed as somehow magical for millennia by humans. They’re one of the only animals that appear to play, leaping out of the water and doing tricks, and the bottlenose dolphin even seems to grin widely at everything. It was inevitable that such a remarkable animal also collected a remarkable mythology that extends through today.

The first documented culture that seems to have mythology associated with the dolphin was the Minoan, a seafaring people in the Mediterranean. They left few written records, but they did leave beautiful murals on the walls of their palaces, murals that show the importance of dolphins in their mythology.

Because they were strongly associated with Poseidon by the later Greeks, this probably explains why the sea god was so often surrounded by dolphins. In one myth about Poseidon, dolphin messengers were sent to bring him a nymph he loved, who he later married. As a reward, he set the dolphin in the sky as a constellation. And he was constantly accompanied by dolphins among other sea creatures.

This wasn’t the last time the Greeks associated dolphins with romance. Aphrodite is often depicted with dolphins, riding them or being accompanied by them. Later, the god Dionysus transformed the way dolphins were perceived in Greek literature. He was set upon while at sea by a band of pirates. Instead of simply destroying the sea raiders, he transformed them into a pod of dolphins, charging them to rescue any distressed sailors in the ocean.


Pirates transforming into dolphins. Drawing from an Etruscan Black Figure Hydria, 510-500 BC


Special thanks to Larry Lawhorn.

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One Response to “ArticleSafari: Dolphin DNA Very Close to Human”

  1. William Charlton says:

    1) Is the human and dolphin genome more similar than the human and chimpanzee genome?

    2) Would the idea that two of the chromosomes in the human genome fused (reducing them to 46 from 48) after humans and chimpanzees diverged, possibly be a similar explanation for the dolphin’s 44 chromosomes (i.e. that the dolphin genome also fused two chromosomes during its divergence from land-dwelling mammals (possibly from an early hominid)?

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