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Orca Momma’s Boys

October 11, 2012

Killer whale moms live long past menopause, apparently to support and protect their adult sons.

Transcript

BOB HIRSHON (host):

Orca momma’s boys.  I’m Bob Hirshon and this is Science Update.

Adult male killer whales, or orcas, are surprisingly dependent on their moms. This according to University of Exeter animal behaviorist Emma Foster. She and her colleagues studied survival rates in orcas.

EMMA FOSTER (University of Exeter, England):

If a mother died, a male over thirty had almost a fourteen-fold increase that he was going to die in the subsequent year. Whereas for a female of the same age, she only had a fivefold increase.

HIRSHON:

Foster says this may reflect the mother whales’ evolutionary strategy.  She notes that orcas, along with humans, are among the few species where females live well past menopause. After they can’t reproduce themselves anymore, mothers can continue to pass on their genes by making sure their offspring produce lots of grandchildren. And since sons can sire more progeny, which end up being raised by other orca families, it’s in Grandma’s genetic interest to put more energy into protecting her boys.  I’m Bob Hirshon for AAAS, the Science Society.

Killer whales are a highly social species. (Robert Pittman/NOAA)