One paper isn't likely to shove the obstetrical dilemma off the scientific stage overnight. But Dunsworth is confident the metabolic argument will hold up.

"Part of the older story is that the birth canal can't get any bigger," she says. "We've shown there's a much better explanation, and we've shown how hard it is to support the old explanation."

Note sure, why but it reminds me of the story of plate tectonics.

Eighteen months in the womb, anyone?

[howaboutno?]

Because if it lasted any longer baby's noggin would be too big to fit out mommy's hoo-ha.

fusillade762: Because if it lasted any longer baby's noggin would be too big to fit out mommy's hoo-ha.

Is that a technical analysis?

fusillade762: Because if it lasted any longer baby's noggin would be too big to fit out mommy's hoo-ha.

No how I know you couldn't read the article?

You know, if I was going to intelligently design the human reproduction system, I'd either go the way of the kangaroo (where the mother gives birth to a tiny maggoty thing and stores it in a pouch), or put the genitals right below the navel. The size of the kid's head vs pelvis wouldn't be an issue.

...And we'd like it that way.

..to get to the other side!

/also see: chicken joke

becuse these babby cant frigth back if they are formed any faster.

Look, if evolution had any kind of intelligent awareness behind it, female mammals wouldn't leave a trail of blood behind them several days a month to aid predators, and babies would come straight out through the navel so that pelvic diameter wasn't an issue at all.

fusillade762: Because if it lasted any longer baby's noggin would be too big to fit out mommy's hoo-ha.

These researchers appear to have a better hypothesis than your old, worn-out one.

Dunno subs, but I've seen some babies arrive much sooner than that after a hasty wedding.

Because the Bible. And God. And America.

Uncle Tractor: You know, if I was going to intelligently design the human reproduction system, I'd either go the way of the kangaroo (where the mother gives birth to a tiny maggoty thing and stores it in a pouch), or put the genitals right below the navel. The size of the kid's head vs pelvis wouldn't be an issue.

How about sperm that thrives at 98* so our testes can be internal. Can we please get that one too?

Hey, ALL of my kids are legitimate!
The first child often only needs 7 months to gestate. Young mothers are just naturally more energetic and build the kid faster. AND WHY ARE YOU COUNTING THE MONTHS ANYWAY, GRANDMA??

/Second kids and beyond always need 9 months, though.

FTFA:...the size and shape of our pelvises are constrained by our bipedal way of getting around in the world. If they got much bigger, mothers wouldn't walk as well.

Anyone ever work out the exact dimensions of a pelvis at the point where it renders a person incapable of walking? Exactly how does a wide pelvis keep you from walking anyway? Computer modelling should be able to to that. That had seemed like an odd excuse to me in the first place since I always wondered why making a woman's pelvis ten percent wider suddenly left her unable to walk.

AbbeySomeone: Dunno subs, but I've seen some babies arrive much sooner than that after a hasty wedding.

Were shotguns involved? ;-)

ModernLuddite: Because the Bible. And God. And America.

o.O - you're weird. Lemme guess.. you were the one who went on the search party to find yourself.. :)

Uncle Tractor: You know, if I was going to intelligently design the human reproduction system, I'd either go the way of the kangaroo (where the mother gives birth to a tiny maggoty thing and stores it in a pouch), or put the genitals right below the navel. The size of the kid's head vs pelvis wouldn't be an issue.

...And we'd like it that way.

Oh pouch system please. Bonus is if you don't feel able to continue the pregnancy that would be so much easier to terminate.

Ah yes, the Republican party - who believes that life begins at conception, but ends at birth.

THE BALEEN WHALE, the largest living animal, has a gullet the size of a softball.

Do you know why?

Because that's the way it is.

FTA: She and her colleagues concluded that a human baby born at a chimp's level of development would require the average human birth canal to be about 3 centimeters bigger, an increase of a little more than an inch in diameter.

That's feasible, the researchers say. "We show that's within the range of variation now," Dunsworth says. "Those people with wider birth canals aren't walking any worse."

Interesting. Alright...

FTA: We humans are able to crank up our metabolism to about twice its normal level and sustain that turbo mode for quite a while.

In fact, pregnant women's metabolism runs at twice the normal level by about the sixth month. By nine months, as the fetus's energy needs increase, the rate is pushing close to 2.1 times normal. And that's pretty much the limit. "Extending gestation even by a month would likely require metabolic investment beyond the mother's capacity," the researchers write.

...so, if I'm reading this correctly, the fact that there are women with wide enough birth canals to accommodate extra development, yet walk no worse is enough to discount the developmental/birth-canal-size theory, then what about women who carry for ten months?

It's not exactly that uncommon, apparently. Common enough that the average pregnancy length strays closer to ten months rather than nine, statistically speaking. I suppose it's possible this is as simple as suggesting that eleven months is therefore the point where metabolic investment is no longer sustainable, but really, if you're going to make this case for one and ignore it in the other, well... science doesn't work that way.

So, I'd really love to know, were they figuring the metabolic budget literally for nine months, or for something closer to the actual average gestation period? Never hurts to check your math.

Nidiot: FTFA:...the size and shape of our pelvises are constrained by our bipedal way of getting around in the world. If they got much bigger, mothers wouldn't walk as well.

Anyone ever work out the exact dimensions of a pelvis at the point where it renders a person incapable of walking? Exactly how does a wide pelvis keep you from walking anyway? Computer modelling should be able to to that. That had seemed like an odd excuse to me in the first place since I always wondered why making a woman's pelvis ten percent wider suddenly left her unable to walk.

One of my coworkers dislocated her hip joint during childbirth. After the C-section (she would have died without it; the baby was 'stuck' according to her doctor) she was quite literally unable to do anything but hobble around slowly. She had to go through months of therapy before the hip joint reset itself and she could start walking normally again.

Bendal: Nidiot: FTFA:...the size and shape of our pelvises are constrained by our bipedal way of getting around in the world. If they got much bigger, mothers wouldn't walk as well.

Anyone ever work out the exact dimensions of a pelvis at the point where it renders a person incapable of walking? Exactly how does a wide pelvis keep you from walking anyway? Computer modelling should be able to to that. That had seemed like an odd excuse to me in the first place since I always wondered why making a woman's pelvis ten percent wider suddenly left her unable to walk.

One of my coworkers dislocated her hip joint during childbirth. After the C-section (she would have died without it; the baby was 'stuck' according to her doctor) she was quite literally unable to do anything but hobble around slowly. She had to go through months of therapy before the hip joint reset itself and she could start walking normally again.

With all due respect, didn't her dislocation of a hip joint have nothing to do with having a wide pelvis? Presumably the baby having become stuck would indicate a too narrow pelvis if anything. I imagine she wouldn't walk too well with a broken leg either. Or are you saying a wider pelvis makes hip dislocation more likely?

Found a different link here:
http://www.eurekalert.org/pub_releases/2012-08/uori-arr082312.php

Anna Warrener, a post-doctoral researcher at Harvard University and one of the paper's co-authors, has studied how hip breadth affects locomotion with women on treadmills. She found that there is no correlation between wider hips and a diminished locomotor economy...
..."Wide hips don't mean you can't walk efficiently."

Turns out that can't walk with wide hips thing was a big fat lie. Who was the idiot that started that one and wtf were they thinking?

Nidiot: FTFA:...the size and shape of our pelvises are constrained by our bipedal way of getting around in the world. If they got much bigger, mothers wouldn't walk as well.

Anyone ever work out the exact dimensions of a pelvis at the point where it renders a person incapable of walking? Exactly how does a wide pelvis keep you from walking anyway? Computer modelling should be able to to that. That had seemed like an odd excuse to me in the first place since I always wondered why making a woman's pelvis ten percent wider suddenly left her unable to walk.

It's not so much a matter of size as shape. If you abstract the pelvis' shape out to a cube (more like a rectangular prism, really), then bipeds' hip joints attach much closer to a single side of the cube -the side we then designate as the bottom- than quadrupeds' hip joints do. Theirs attach more closely to two opposite sides, which we call left and right. It's not so hard to imagine having a tough time walking if your legs jutted out like a quadruped's do.

But there are tradeoffs. Relevant to this article is that a lot of other things are connected to that same side of the pelvis, and there is only a limited amount of space for them all. Hip joints take up a LOT of room, which crowds the whole area and, among other things, severely restricts the possible size of the birth canal. That might not play the primary role in answering why a human pregnancy is only nine months long, but it does have implications for the reproductive process: for example, why, at birth, our bones are so flexible and our heads are so small.

As a means of accounting for this and getting a little extra space, womens' hip joints actually do go a little further out to the side than mens' do: not enough to make walking upright impossible, of course, but enough to affect gait. Looking for this is one of the easiest ways to tell the sex of a skeleton.

theorellior: Two things: human gestation is not nine calendar months, it's ten lunar months. Secondly, it's not the size of the hoo-ha that's the problem. The hoo-ha can pass a cantaloupe, but just try to get the cantaloupe from the uterus to the hoo-ha without breaking something. In order to negotiate the pelvic girdle, a human infant has to do a shimmy and a half-twist to get from the uterus to the exit. That's the biomechanical problem here.

It still remains that the whole childbirth thing would be made a tad easier if the human pelvis was, in general, a little wider to allow for the passage of a baby, since apparently it has to do that every now and then.

Another fine use of our tax money.

NPR: ignorance spewed forth with good grammar and articulation.

theorellior: Two things: human gestation is not nine calendar months, it's ten lunar months. Secondly, it's not the size of the hoo-ha that's the problem. The hoo-ha can pass a cantaloupe, but just try to get the cantaloupe from the uterus to the hoo-ha without breaking something. In order to negotiate the pelvic girdle, a human infant has to do a shimmy and a half-twist to get from the uterus to the exit. That's the biomechanical problem here.

This probably sounds crazy to you, but did you know that ten lunar months and nine calendar months are less than a week different from one another, within less than a standard deviation of the human gestational period? The more you know.

Millennium:
It's not so much a matter of size as shape. If you abstract the pelvis' shape out to a cube (more like a rectangular prism, really), then bipeds' hip joints attach much closer to a single side of the cube -the side we then designate as the bottom- than quadrupeds' hip joints do. Theirs attach more closely to two opposite sides, which we call left and right. It's not so hard to imagine having a tough time walking if your legs jutted out like a quadruped's do.

Thanks for that. Failure is on my part no doubt to see the problems in walking simply because the legs spring from points further apart. I am sort of imagining the options being more like a wide wheel base vs narrow wheel base and not seeing how wide wheel base can't work, unless you need to travel narrow roads of course. I'd still like to see some computer modelling as to how far apart the legs can go before the person fails at walking, if only because it would amuse me.

I could see problems with supporting the entire body weight from two points that were not directly underneath, on the bottom side of the cube that you described, but that is a whole new set of issues.

2xcited: NPR: ignorance spewed forth with good grammar and articulation.

So they still have two things over Fox, then. Got it.

LazarusLong42: This probably sounds crazy to you, but did you know that ten lunar months and nine calendar months are less than a week different from one another, within less than a standard deviation of the human gestational period? The more you know.

The average gestational period still leans closer to ten calendar months rather than nine.

And yet there's still time enough for love.

Two things first Pregnancy lasts 40 weeks not 9 months, secondly my wife was horny as hell during the 2nd and third trimesters I know other's mileage may vary but she was not ready to kill me when our daughter was born.

Committee_For_Aesthetic_Deletions: Hey, ALL of my kids are legitimate!
The first child often only needs 7 months to gestate. Young mothers are just naturally more energetic and build the kid faster. AND WHY ARE YOU COUNTING THE MONTHS ANYWAY, GRANDMA??

/Second kids and beyond always need 9 months, though.

My mother's neighbor was convinced that she had to get married, because the wedding was in June and my sister was born in December. I believe a 19 month pregnancy is a record of some sort.

If it's really about how much energy mom can spare the developing fetus, what's up with breast feeding, then? It's not like the mom is giving the newborn breast milk plus the occasional energy bar.

If humans were born as far along on cognitive and neurological scales as rough and ready chimps are, though

It helps if they're British, I think:

Can we just agree that anyone using the "how is babby formed?" meme gets shot in the face?

spelletrader: Can we just agree that anyone using the "how is babby formed?" meme gets shot in the face?

...because these babby can't frihgt back?

SkunkWerks: LazarusLong42: This probably sounds crazy to you, but did you know that ten lunar months and nine calendar months are less than a week different from one another, within less than a standard deviation of the human gestational period? The more you know.

The average gestational period still leans closer to ten calendar months rather than nine.

And yet there's still time enough for love.

That's primarily because people tend to round up to the period they expected, and not down to the actual time they were fertile.

Mr Guy: That's primarily because people tend to round up to the period they expected, and not down to the actual time they were fertile.

Putting aside that I'd very much love to see some citation. The other way around possibly? Rounding up to adjust the time for when it began would tend to shorten what I presume would be re "reported" gestation period. Rounding down I could only imagine would lengthen it. All this is of course allowing for the fact that "being fertile" and "being pregnant" are kinda different things.

I'd love to take on this tangent, but what you're saying isn't real clear to me.