One wonders: Before anyone realized this, would those multiple copies be considered “junk”?
From New Scientist:
When they studied samples of elephant blood, they found that African elephants have at least 20 copies of the p53 gene from each parent.
P53 is an ancient gene found in all multicellular animals. It detects stress or damage in the cell, and stops the cell from dividing until the stress has passed or the DNA is repaired. Humans inherit one copy from each parent, and it has a crucial role in protecting us from cancer. People who have a defective version – a condition called Li-Fraumeni syndrome – usually get cancer in childhood, and their lifetime risk is close to 100 per cent.
Genome studies in other large animals have uncovered different adaptations that could help keep cancer at bay. Earlier this year, researchers published the genome of the bowhead whale, which lives for more than 200 years and can weigh up to 100 tonnes. They found that it has mutations or duplications in several genes linked to DNA repair and ageing.
See also: Life continues to ignore what evolution experts say
and Why even the best designed systems always feature some junk anyway
Abstract here. (paywall)
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