But her daughter died within an hour.

Tahlequah, however, didn't leave her body.

And over the next 17 days and 1,600 kilometers,

she kept it afloat atop her own,

diving to retrieve the body whenever it slipped away,

even after it began deteriorating.

By altering her feeding and travel patterns,

Tahlequah's behavior was certainly unusual.

But was she mourning— or just confused?

Do non-human animals grieve?

This question is tricky.

In 1871, Charles Darwin argued that other animals

experience a wide range of emotions, including grief.

But, especially in the absence of a dependable bridge

between our minds and theirs,

many scientists have long been wary

of projecting human emotions onto other animals.

It's also been thought that they might display irregular behaviors after a death

for other adaptive reasons.

And, for a while, the paradigm was that humans were exceptional:

other animals were reacting and surviving,

while we alone were thinking and feeling.

This conception was increasingly challenged during the 20th century.

In 1985, for example, a gorilla called Koko,

who'd been trained to use some signs from American Sign Language,

was told that her kitten companion had died.

She made distress calls, and several weeks later,

looking at a photo of another kitten signed “cry,” “sad,” and “frown.”

Now there's a growing pool of data and observations

suggesting that some animals, including mammals and birds,

might experience what we call grief.

In 2003, Eleanor, an elephant matriarch, collapsed.

Within minutes, another matriarch called Grace neared and helped Eleanor stand,

only for her to fall again.

Grace vocalized, stayed by Eleanor's side, and tried pushing her back up.

When Eleanor died, a female named Maui approached,

positioned herself over Eleanor's body, and rocked back and forth.

Over the course of one week,

elephants from five different families visited Eleanor's body.

On separate occasions,

elephants have been observed carrying the remains of family members,

including jawbones and tusks.

In 2010, a giraffe was born with a deformed foot and had trouble walking.

The calf lived just four weeks.

On the day the calf died, 22 other females and four juveniles

closely attended and occasionally nuzzled the body.

On the third morning, the mother was alone and still not eating,

which giraffes usually do constantly.

Instead, she stayed by her dead calf, even after hyenas ate away at the body.

Scientists have also begun quantitatively assessing other animals'

responses to death.

In 2006, researchers analyzed baboon fecal samples for glucocorticoids,

stress hormones that spike when humans are bereaved.

They compared the samples from females who had lost a close relative

in a predator attack with those who hadn't.

And they found that the glucocorticoid levels of baboons who had

were significantly higher the month following the death.

Those baboons then increased their grooming behavior

and the number of their grooming partners,

broadening and strengthening their social networks.

Within two months, their glucocorticoid levels returned to the baseline.

Researchers have also observed primate mothers engaging in apparently

contradictory behaviors while carrying their dead children.

Like switching between cannibalizing or dragging their child's corpse

and carefully carrying or grooming it,

suggesting that the mothers were experiencing conflicting impulses

towards the bodies.

Our current understanding of the emotional landscapes

of other animals is severely limited.

To get a better grasp on mourning in the animal kingdom,

we need a lot more research.

But where does this leave us for now?

Conversations around whether non-human animals experience emotions, like grief,

can be emotional,

in part because their outcomes have very real implications—

like determining if orcas should be isolated and kept in captivity,

or whether dairy cows should be separated from their newborn calves.

Until we do have more data on the subject,

should we treat non-human animals like they may have the capacity to grieve?

Or assume they don't?

Which belief could cause more harm?