Off the rugged coast 
of the pacific northwest,

pods of killer whales 
inhabit the frigid waters.

Each family is able to survive here

thanks mainly to one member,

its most knowledgeable hunter:

the grandmother.

These matriarchs can live eighty years 
or more,

while most males die off 
in their thirties.

Though killer whales inhabit 
every major ocean,

until recently we knew 
very little about them.

The details of their lives 
eluded scientists

until an organization called 
the Center for Whale Research

began studying a single population

near Washington State and 
British Columbia in 1976.

Thanks to their ongoing work,

we’ve learned a great deal 
about these whales,

known as the Southern Residents.

And the more we learn,

the more this population’s elders’ 
vital role comes into focus.

Each grandmother starts her life as a calf

born into her mother’s family group, 
or matriline.

The family does everything together,

hunting and playing, even communicating 
through their own unique set of calls.

Both sons and daughters spend their entire
lives with their mothers’ families.

That doesn’t mean a young whale 
only interacts with her relatives.

Besides their own special calls,

her matriline shares a dialect 
with nearby families,

and they socialize regularly.

Once a female reaches age fifteen or so,

these meetings become opportunities 
to mate with males from other groups.

The relationships don’t go much 
beyond mating—

she and her calves stay with her family,

while the male returns to his own mother.

Until approximately age forty,

she gives birth every 6 years on average.

Then, she goes through menopause—

which is almost unheard of 
in the animal kingdom.

In fact, humans, killer whales and 
a few other whales

are the only species whose females 
continue to live for years

after they stop reproducing.

After menopause,

grandmothers take the lead 
hunting for salmon,

the Southern Residents’ main food source.

Most of the winter they forage offshore,

supplementing salmon with other fish.

But when the salmon head 
towards shore in droves to spawn,

the killer whales follow.

The matriarch shows the younger whales

where to find the most fertile 
fishing grounds.

She also shares up to 90% of 
the salmon she catches.

With each passing year,

her contributions become more vital:

overfishing and habitat destruction have 
decimated salmon populations,

putting the whales at near-constant 
risk of starvation.

These grandmothers’ expertise

can mean the difference between 
life and death for their families–

but why do they stop having calves?

It’s almost always advantageous for a
female to continue reproducing,

even if she also cares for her existing 
children and grandchildren.

A couple unique circumstances 
change this equation for killer whales.

The fact that neither sons or daughters

leave their families of origin 
is extremely rare—

in almost all animal species,

one or both sexes disperse.

This means that as a female 
killer whale ages,

a greater percentage of her family

consists of her children 
and grandchildren,

while more distant relatives die off.

Because older females are more closely 
related to the group than younger females,

they do best to invest in the family 
as a whole,

whereas younger females should 
invest in reproducing.

In the killer whale’s environment,

every new calf is another mouth to feed

on limited, shared resources.

An older female can further her genes
without burdening her family

by supporting her adult sons,

who sire calves other families will raise.

This might be why the females have evolved

to stop reproducing entirely 
in middle age.

Even with the grandmothers’ contributions,

the Southern Resident killer whales 
are critically endangered,

largely due to a decline in salmon.

We urgently need to invest in restoring 
salmon populations

to save them from extinction.

In the long term, we’ll need more studies 
like the Center for Whale Research’s.

What we’ve learned about 
the Southern Residents

may not hold true for other groups.

By studying other populations closely,

we might uncover more 
startling adaptations,

and anticipate their vulnerabilities 
to human interference

before their survival is at risk.