Meet the animal with 30× more DNA than humans — and it’s a fish.

 

 

Meet the animal with 30× more DNA than humans — and it’s a fish.

The South American lungfish now holds the record for the largest sequenced animal genome ever discovered. Its DNA contains about 91 billion base pairs, roughly 30 times more than a human genome, yet it still carries around the same number of genes — about 20,000.

So where does all that extra DNA come from?

Most of it consists of repetitive, self-copying sequences often called “selfish DNA.” These segments duplicate themselves again and again without adding new genes. Scientists estimate the lungfish has been accumulating DNA at a staggering rate — roughly the equivalent of an entire human genome every 10 million years.

 

This matters because lungfish are considered living fossils and are among the closest living relatives of the ancient fish that first moved onto land. Studying their genome offers a rare window into early vertebrate evolution and the genetic steps that eventually led to reptiles, mammals, and humans.

 

But carrying so much DNA comes at a cost. Many of the lungfish’s chromosomes are each as large as the entire human genome, requiring enormous energy just to copy and maintain them. Too much DNA can also increase the risk of errors in gene regulation if the system becomes unbalanced.

 

Plants may still dominate the overall genome size rankings, but among animals, this fish stands alone — evolution’s ultimate DNA hoarder.