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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, 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.