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from the why-male-wallabies-smile-a-lot dept.
This marsupial is the only animal that's always pregnant
Most mammals can become pregnant several times during adulthood, but for the vast majority, there is a healthy pause after each birth, while mothers nurse their babies. For some, of course, it's normal to only have one or a couple offspring in a lifetime.
But swamp wallabies, small hopping marsupials found throughout eastern Australia, are far outside the norm: New research suggests that most adult females are always pregnant. As described in a paper published March 2 in the Proceedings of the National Academy of Science, the animals typically conceive one to two days before giving birth.
Like all marsupials, swamp wallabies (Wallabia bicolor) give birth to tiny, immature babies that crawl to a special pouch where they nurse on their mother's milk. Some marsupials, like kangaroos, can mate and conceive about a day after birth, but not before, says Brandon Menzies, a study co-author and researcher with the University of Melbourne.
These wallabies are the only animal, besides the European brown hare, that can become pregnant while already pregnant. But the hares have distinct breeding seasons and are not continuously pregnant most or all of their adult lives, as female swamp wallabies are.
The study is important because "understanding the biology and endocrinology of reproduction in any species may have valuable lessons for human reproduction too," says David Gardner, at the same university, who wasn't involved in the paper.
(Score: -1, Offtopic) by Anonymous Coward on Wednesday March 04 2020, @12:44PM
Can't be shocked anymore. Just can't.
(Score: 1, Insightful) by Anonymous Coward on Wednesday March 04 2020, @01:15PM (4 children)
"For some, of course, it's normal to only have one or a couple offspring in a lifetime."
No, that's not "normal." If a significant fraction of the females in a species do this, the species quickly goes extinct.
(Score: 2) by NateMich on Wednesday March 04 2020, @09:18PM (3 children)
Thank you, I wanted to point that out as well. Even if the females of a species only ever had 2 offspring (and let's assume they all did have 2), they would still eventually go extinct, regardless of how large of a population you're talking about.
(Score: 1) by khallow on Wednesday March 04 2020, @11:24PM (2 children)
(Score: 0) by Anonymous Coward on Thursday March 05 2020, @02:44AM (1 child)
There's some really good game-theoretic reasons why species have a male to female ratio very close to 1:1. The only exceptions are hive species that have some weird genetics going on.
(Score: 0) by Anonymous Coward on Thursday March 05 2020, @06:51AM
Mormons?
(Score: 1, Informative) by Anonymous Coward on Wednesday March 04 2020, @02:09PM (4 children)
Unless I'm missing something, cats are yet another animal that can become pregnant while pregnant [lovetoknow.com]:
It's apparently not very common but it's definitely possible. A female cat can go into heat while already pregnant, and if she mates then, she might gestate a second litter of kittens even after bringing the first one to term. If that's not "becoming pregnant while already pregnant" then they might have a different meaning in mind than the obvious one.
(Score: 2) by Booga1 on Wednesday March 04 2020, @03:30PM (3 children)
Humans can also become pregnant while pregnant. It's exceptionally rare, but I think this is a case of oversimplification for the purpose of not getting to the point of distraction in the article. This is National Geographic, not a biology science journal.
Still, kangaroos can support three joeys at once. One that has left the pouch, one that is still nursing in the pouch, and one pregnancy that's on pause. Not quite the same thing as getting pregnant while pregnant, but still a continuous cycle so long as resource conditions are favorable.
From http://kangaroocreekfarm.com/about-roos/ [kangaroocreekfarm.com]
(Score: 0) by Anonymous Coward on Wednesday March 04 2020, @05:46PM
(Score: 2) by Grishnakh on Thursday March 05 2020, @03:49AM (1 child)
Humans can also become pregnant while pregnant. It's exceptionally rare
I was about to post something about this too. However, if you're talking about what I'm thinking of, it's an extremely rare mutation some women have where they have 2 uteruses (uteri?), each connected to its own single ovary and fallopian tube. I don't think it's possible for a normal human woman to become pregnant while already pregnant.
(Score: 2) by Booga1 on Thursday March 05 2020, @08:54AM
The Wikipedia article seems to be a bit skeptical about whether "superfetation" is possible, but Time magazine reports [time.com] 10 cases of happening.
Another report is of a surrogate pregnancy [insideedition.com] where the woman's natural cycle still happened and the woman ended up carrying two babies from separate parents. Of course, that took some man-made interference.
(Score: 2) by vux984 on Wednesday March 04 2020, @04:31PM
"Swamp Wallabies are the only animal that's always pregnant"
(Score: 0) by Anonymous Coward on Wednesday March 04 2020, @04:49PM (1 child)
"Some marsupials, like kangaroos, can mate and conceive about a day after birth, but not before"
omg! "but not before"... that's like having sex whilst still inside.
(Score: 0) by Anonymous Coward on Thursday March 05 2020, @06:56AM
Yah technically it's a 3-some.
(Score: 2) by ilsa on Wednesday March 04 2020, @04:54PM
The first animal to always be pregnant are XBox chat moms.
(Score: -1, Troll) by Anonymous Coward on Wednesday March 04 2020, @11:43PM
When they got paid based on the number of pickaninnies they birthed, many ghetto-dwellers were also always pregnant.
(Score: 2) by darkfeline on Thursday March 05 2020, @01:32AM (2 children)
I'm sure there's a "your mom" joke here somewhere...
Join the SDF Public Access UNIX System today!
(Score: -1, Troll) by Anonymous Coward on Thursday March 05 2020, @07:12AM (1 child)
Your mom thought so too, then you posted and everyone saw it was a fail.
(Score: 2) by Bot on Friday March 06 2020, @08:56AM
Factoid, darkfeline is son of anonymous coward.
Account abandoned.
(Score: 3, Funny) by KritonK on Thursday March 05 2020, @08:15AM (1 child)
Are they also born pregnant [wikipedia.org]?
(Score: 2) by Bot on Friday March 06 2020, @09:02AM
The gypsy ones among them are born pregnant and receive subsidies from the day after pregnancy test is positive. Don't know why.
Account abandoned.