Little things, like taking a shortcut through the park on your way to work each day can make a big difference

to your mental health. Find your little big thing

little big thing at every mind matters. This is

is Scientific American 60 Second Science. I'm Suzanne Bard. Picture a small kangaroo.

You're basically seeing something very much like the Australian marsupial called the swamp wallaby.

They're also known as black stinkers because of their distinctive odor.

I can't really describe it except to say it's quite a pungent smell.

It's not terribly pleasant.

University of Melbourne biologist Marilyn Renfry,

who says that their unique scent isn't the only thing that sets swamp wallabies apart from their evolutionary relatives.

She and her colleagues recently discovered that adult female swamp wallabies can carry two pregnancies in different

stages of development at the same time. That's possible because, like other kangaroos and wallabies they have not just one uterus but two.

But unlike their close relatives, pregnant swamp wallabies made again a day or two before they give birth.

We only know that strategy in one other mammal and that's the European

hair and the European hair does this mating while they're pregnant, a phenomenon known as

superfitations. So the wallabies have effectively a

fetus at an advanced stage pregnancy and a very very early conceptus at the same time.

Renfry and her team confirmed the simultaneous pregnancies using high-resolution

ultrasound.

And so for the first time we were able to actually prove that the swamp wallaby is pregnant for its whole life.

It's never not pregnant.

This revolving cycle of pregnancy means that after a female swamp wallaby gives birth to her first baby from one uterus.

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