Dynamic finite-element simulations reveal early origin of complex
human birth pattern

Abstract

Human infants are born neurologically immature, potentially owing to
conflicting selection pressures between bipedal locomotion and
encephalization as suggested by the obstetrical dilemma hypothesis.
Australopithecines are ideal for investigating this trade-off, having
a bipedally adapted pelvis, yet relatively small brains. Our
finite-element birth simulations indicate that rotational birth cannot
be inferred from bony morphology alone. Based on a range of pelvic
reconstructions and fetal head sizes, our simulations further imply
that australopithecines, like humans, gave birth to immature,
secondary altricial newborns with head sizes smaller than those
predicted for non-human primates of the same body size especially when
soft tissue thickness is adequately approximated. We conclude that
australopithecines required cooperative breeding to care for their
secondary altricial infants. These prerequisites for advanced
cognitive development therefore seem to have been corollary to
skeletal adaptations for bipedal locomotion that preceded the
appearance of the genus Homo and the increase in encephalization.

Open access:
https://www.nature.com/articles/s42003-022-03321-z

On Tuesday, May 10, 2022 at 4:22:39 PM UTC+1, Pandora wrote:

> https://www.nature.com/articles/s42003-022-03321-z

> our simulations further imply that australopithecines, like
> humans, gave birth to immature, secondary altricial newborns
> [. . .] We conclude that australopithecines required cooperative
> breeding to care for their secondary altricial infants.

They should also have concluded that
australopiths could not have slept in trees --
the usual assumption of standard PA -- since
all other primate infants (whose mothers
sleep in trees) are not altricial. Primate
infants need to be able to hold on to their
mothers all night, using their long strong
arms and their hand-like feet, a capacity they
had and have from birth.

The assumption is nonsensical in any case,
since (especially on stormy nights, or when
threatened by predators) large-bodied
primate mothers need to hold onto branches
with both their hands and feet. Their infants
must hold on to their mothers without any
assistance.

This means that australopiths slept on the
ground, with their infants and, if living
almost anywhere on continental Africa,
would have been subject to intolerable
levels of predation.

Some might have been able to sleep in caves
in dolomitic landscapes, but they are mostly
in Southern Africa. There are none close to
the East African australopith fossil sites.

A theory that "all early hominins slept in
caves" could possibly be proposed. It doesn't
work for me, and I hope that that's not just
unfamiliarity. Firstly, even if some quasi-
chimps, coming down from the trees, might
have slept in caves, they are unlikely to have
been sufficiently isolated from their ancestral
tree-living populations. Secondly, the (proto-)
hominins would still have had to forage in
the open by day, and had no protection from
devastating levels of predation. Thirdly, this
theory provides no basis for the evolution of
bipedalism; it is a much slower form of
locomotion (than quadrupedalism), and those
hominins would always have needed the best
possible speed.

On Wednesday, May 11, 2022 at 6:22:48 PM UTC-4, Paul Crowley wrote:
> On Tuesday, May 10, 2022 at 4:22:39 PM UTC+1, Pandora wrote:
>
> > https://www.nature.com/articles/s42003-022-03321-z
> > our simulations further imply that australopithecines, like
> > humans, gave birth to immature, secondary altricial newborns
> > [. . .] We conclude that australopithecines required cooperative
> > breeding to care for their secondary altricial infants.
> They should also have concluded that
> australopiths could not have slept in trees --
> the usual assumption of standard PA -- since
> all other primate infants (whose mothers
> sleep in trees) are not altricial.

Chimp infants are vastly more altricial vs most mammals and birds.
Apith infants were certainly very altricial.

Primate
> infants need to be able to hold on to their
> mothers all night, using their long strong
> arms and their hand-like feet, a capacity they
> had and have from birth.
>
> The assumption is nonsensical in any case,
> since (especially on stormy nights, or when
> threatened by predators) large-bodied
> primate mothers need to hold onto branches
> with both their hands and feet. Their infants
> must hold on to their mothers without any
> assistance.
>
> This means that australopiths slept on the
> ground, with their infants and, if living
> almost anywhere on continental Africa,
> would have been subject to intolerable
> levels of predation.
>
> Some might have been able to sleep in caves
> in dolomitic landscapes, but they are mostly
> in Southern Africa. There are none close to
> the East African australopith fossil sites.
>
> A theory that "all early hominins slept in
> caves" could possibly be proposed. It doesn't
> work for me, and I hope that that's not just
> unfamiliarity. Firstly, even if some quasi-
> chimps, coming down from the trees, might
> have slept in caves, they are unlikely to have
> been sufficiently isolated from their ancestral
> tree-living populations. Secondly, the (proto-)
> hominins would still have had to forage in
> the open by day, and had no protection from
> devastating levels of predation. Thirdly, this
> theory provides no basis for the evolution of
> bipedalism; it is a much slower form of
> locomotion (than quadrupedalism), and those
> hominins would always have needed the best
> possible speed.

This comment refers to a post at AAT.io about SIDS Sudden Infant Death Syndrome and new information about an enzyme. I note that when Homo split from arboreal apes, sleeping mother and infant apes were in physical contact all night but sleeping mother and infant Homo were merely in close proximity under a shared roof (domeshield).

-
SIDS & BChE

DDeden <daud.deden@gmail.com>

https://groups.io/g/AAT/message/73812

They discovered that the enzyme butyrylcholinesterase (BChE) was lower in the babies who died compared to living infants. The enzyme plays a major role in the brain’s arousal pathway, researchers said, accounting for why SIDS typically occurs during sleep.
-

As a guess, I'd check if leaf-eating primates have the same enzyme and pathway as humans. It's effects against cocaine might indicate protection from various leaf alkaloids in tropical forest trees. In modern humans, the advent of cooking and adoption of ground based foods (grains, pulses, dairy) may have altered selective advantages against arboreal foliage alkaloids.

Too, the change from arboreal bowl nest sleep of intertwined mother & infant great apes to ground sheltered sleep where mother and infant are physically disconnected but nearby under the same roof might be a factor.

Prophylactic countermeasure against nerve agents
Butyrylcholinesterase is a prophylactic countermeasure against organophosphate nerve agents. It binds nerve agent in the bloodstream before it can exert effects in the nervous system. Because it is a biological scavenger (and universal target), it is currently the only therapeutic agent effective in providing complete stoichiometric protection against the entire spectrum of organophosphate nerve agents.[11]

Prophylactic against cocaine addiction
An experimental new drug was developed for the potential treatment of cocaine abuse and overdose based on the pseudocholinesterase structure (it was a human BChE mutant with improved catalytic efficiency). It was shown to remove cocaine from the body 2000 times as fast as the natural form of BChE. Studies in rats have shown that the drug prevented convulsions and death when administered cocaine overdoses.[12]

Transplantation of skin cells modified to express the enhanced form of butyrylcholinesterase into mice enables the long-term release of the enzyme and efficiently protects the mice from cocaine-seeking behavior and cocaine overdose.[13]

DD

On Wednesday, May 11, 2022 at 6:22:48 PM UTC-4, Paul Crowley wrote:
> On Tuesday, May 10, 2022 at 4:22:39 PM UTC+1, Pandora wrote:
>
> > https://www.nature.com/articles/s42003-022-03321-z
> > our simulations further imply that australopithecines, like
> > humans, gave birth to immature, secondary altricial newborns
> > [. . .] We conclude that australopithecines required cooperative
> > breeding to care for their secondary altricial infants.
> They should also have concluded that
> australopiths could not have slept in trees --
> the usual assumption of standard PA -- since
> all other primate infants (whose mothers
> sleep in trees) are not altricial. Primate
> infants need to be able to hold on to their
> mothers all night, using their long strong
> arms and their hand-like feet, a capacity they
> had and have from birth.
>
> The assumption is nonsensical in any case,
> since (especially on stormy nights, or when
> threatened by predators) large-bodied
> primate mothers need to hold onto branches
> with both their hands and feet. Their infants
> must hold on to their mothers without any
> assistance.
>
> This means that australopiths slept on the
> ground, with their infants and, if living
> almost anywhere on continental Africa,
> would have been subject to intolerable
> levels of predation.
>
> Some might have been able to sleep in caves
> in dolomitic landscapes, but they are mostly
> in Southern Africa. There are none close to
> the East African australopith fossil sites.
>
> A theory that "all early hominins slept in
> caves" could possibly be proposed. It doesn't
> work for me, and I hope that that's not just
> unfamiliarity. Firstly, even if some quasi-
> chimps, coming down from the trees, might
> have slept in caves, they are unlikely to have
> been sufficiently isolated from their ancestral
> tree-living populations. Secondly, the (proto-)
> hominins would still have had to forage in
> the open by day, and had no protection from
> devastating levels of predation. Thirdly, this
> theory provides no basis for the evolution of
> bipedalism; it is a much slower form of
> locomotion (than quadrupedalism), and those
> hominins would always have needed the best
> possible speed.

On Monday 16 May 2022 at 20:07:34 UTC+1, DD'eDeN aka note/nickname/alas_my_loves wrote:

> Chimp infants are vastly more altricial vs most mammals and birds.

Chimp infants are precocious enough to
be able to hold onto their mothers (with
no assistance from the mother)
immediately after birth. They also
quickly learn how climb independently,
so that when threatened by a leopard
at night the infant can climb up high
on thin branches, safe from a leopard.

How and why would a hominin, living
in a forest, lose that capacity? How
would selection favour those who
were losing it, over those retaining it?

> Apith infants were certainly very altricial.

It is very clear that apiths did NOT live
in forests where they were under threat
of nocturnal (or any) predation. They
could not live with serious predators,
like larger felids or hyena; nor could
their infants tolerate , medium-sized
omnivores, like wild boar. Nor would
they cope with small canids, felids or
mongooses, any of which might take
a bite from a defenceless infant.

On Wed, 11 May 2022 15:22:47 -0700 (PDT), Paul Crowley
<yelworcp@gmail.com> wrote:

>On Tuesday, May 10, 2022 at 4:22:39 PM UTC+1, Pandora wrote:
>
>> https://www.nature.com/articles/s42003-022-03321-z
>
>> our simulations further imply that australopithecines, like
>> humans, gave birth to immature, secondary altricial newborns
>> [. . .] We conclude that australopithecines required cooperative
>> breeding to care for their secondary altricial infants.
>
>They should also have concluded that
>australopiths could not have slept in trees --
>the usual assumption of standard PA -- since
>all other primate infants (whose mothers
>sleep in trees) are not altricial. Primate
>infants need to be able to hold on to their
>mothers all night, using their long strong
>arms and their hand-like feet, a capacity they
>had and have from birth.
>
>The assumption is nonsensical in any case,
>since (especially on stormy nights, or when
>threatened by predators) large-bodied
>primate mothers need to hold onto branches
>with both their hands and feet. Their infants
>must hold on to their mothers without any
>assistance.

I recently noticed this video of a chimp mother, Jire, who carried her
dead infant, Jokro, around for a month.
https://www.greencorridor.info/en/videos/jokro/

Dead is about as altricial as you can get.

On Friday, May 27, 2022 at 6:04:06 AM UTC-4, Pandora wrote:
> On Wed, 11 May 2022 15:22:47 -0700 (PDT), Paul Crowley
> <yelw...@gmail.com> wrote:
>
> >On Tuesday, May 10, 2022 at 4:22:39 PM UTC+1, Pandora wrote:
> >
> >> https://www.nature.com/articles/s42003-022-03321-z
> >
> >> our simulations further imply that australopithecines, like
> >> humans, gave birth to immature, secondary altricial newborns
> >> [. . .] We conclude that australopithecines required cooperative
> >> breeding to care for their secondary altricial infants.
> >
> >They should also have concluded that
> >australopiths could not have slept in trees --
> >the usual assumption of standard PA -- since
> >all other primate infants (whose mothers
> >sleep in trees) are not altricial. Primate
> >infants need to be able to hold on to their
> >mothers all night, using their long strong
> >arms and their hand-like feet, a capacity they
> >had and have from birth.
> >
> >The assumption is nonsensical in any case,
> >since (especially on stormy nights, or when
> >threatened by predators) large-bodied
> >primate mothers need to hold onto branches
> >with both their hands and feet. Their infants
> >must hold on to their mothers without any
> >assistance.
> I recently noticed this video of a chimp mother, Jire, who carried her
> dead infant, Jokro, around for a month.
> https://www.greencorridor.info/en/videos/jokro/
>
> Dead is about as altricial as you can get.
!

On Friday 27 May 2022 at 11:04:06 UTC+1, Pandora wrote:

> > The assumption is nonsensical in any case,
> > since (especially on stormy nights, or when
> > threatened by predators) large-bodied
> > primate mothers need to hold onto branches
> > with both their hands and feet. Their infants
> > must hold on to their mothers without any
> > assistance.
>
> I recently noticed this video of a chimp mother, Jire, who carried her
> dead infant, Jokro, around for a month.
> https://www.greencorridor.info/en/videos/jokro/
>
> Dead is about as altricial as you can get.

This was the body of a 2.5 y/old infant.
It rapidly became desiccated. But the
main points are (1) the mother could
trap the long arm of her dead infant
under her chin (against her body) with
the infant slung on her back, so that she
could use all four limbs for climbing, etc.
(2) there were no dangerous predators
in the vicinity (the humans would not
have stayed around so casually).

Human infants do not have long arms
(since they are not meant to grip
anything with them). Australopiths
can be assumed to have been similar.
This (very odd) behaviour by this
chimp mother would not have been
possible for a human or australopith.

". . .Based on a range of pelvic reconstructions and fetal head sizes, our
simulations further imply that australopithecines, like humans, gave
birth to immature, secondary altricial newborns with head sizes smaller
than those predicted for non-human primates of the same body size
especially when soft tissue thickness is adequately approximated. We
conclude that australopithecines required cooperative breeding to care
for their secondary altricial infants.. . "

Altriciality in infants rules out regular
tree-climbing (and regular tree-sleeping)
by australopith mother/infant dyads.

On Sat, 28 May 2022 04:54:29 -0700 (PDT), Paul Crowley
<yelworcp@gmail.com> wrote:

>On Friday 27 May 2022 at 11:04:06 UTC+1, Pandora wrote:
>
>> > The assumption is nonsensical in any case,
>> > since (especially on stormy nights, or when
>> > threatened by predators) large-bodied
>> > primate mothers need to hold onto branches
>> > with both their hands and feet. Their infants
>> > must hold on to their mothers without any
>> > assistance.
>>
>> I recently noticed this video of a chimp mother, Jire, who carried her
>> dead infant, Jokro, around for a month.
>> https://www.greencorridor.info/en/videos/jokro/
>>
>> Dead is about as altricial as you can get.
>
>This was the body of a 2.5 y/old infant.
>It rapidly became desiccated. But the
>main points are (1) the mother could
>trap the long arm of her dead infant
>under her chin (against her body) with
>the infant slung on her back, so that she
>could use all four limbs for climbing, etc.
>(2) there were no dangerous predators
>in the vicinity (the humans would not
>have stayed around so casually).

There are definitely leopards in the Mount Nimba area.

>Human infants do not have long arms
>(since they are not meant to grip
>anything with them). Australopiths
>can be assumed to have been similar.
>This (very odd) behaviour by this
>chimp mother would not have been
>possible for a human or australopith.

I'm not suggesting that apiths would carry an infant like that, but as
indicated by the humerofemoral and intermembral index they had
relatively longer arms than humans (86.6 and 85.5 respectively in StW
573, 70.9 and 68.8 in human females, 102.6 and 109.4 in female
chimps).
The point is that if a dead infant can be carried along then who knows
how creative a mom can be with a slightly more cooperative living
infant.

On Monday, May 30, 2022 at 7:59:27 AM UTC-4, Pandora wrote:
> On Sat, 28 May 2022 04:54:29 -0700 (PDT), Paul Crowley
> <yelw...@gmail.com> wrote:
>
> >On Friday 27 May 2022 at 11:04:06 UTC+1, Pandora wrote:
> >
> >> > The assumption is nonsensical in any case,
> >> > since (especially on stormy nights, or when
> >> > threatened by predators) large-bodied
> >> > primate mothers need to hold onto branches
> >> > with both their hands and feet. Their infants
> >> > must hold on to their mothers without any
> >> > assistance.
> >>
> >> I recently noticed this video of a chimp mother, Jire, who carried her
> >> dead infant, Jokro, around for a month.
> >> https://www.greencorridor.info/en/videos/jokro/
> >>
> >> Dead is about as altricial as you can get.
> >
> >This was the body of a 2.5 y/old infant.
> >It rapidly became desiccated. But the
> >main points are (1) the mother could
> >trap the long arm of her dead infant
> >under her chin (against her body) with
> >the infant slung on her back, so that she
> >could use all four limbs for climbing, etc.
> >(2) there were no dangerous predators
> >in the vicinity (the humans would not
> >have stayed around so casually).
> There are definitely leopards in the Mount Nimba area.
> >Human infants do not have long arms
> >(since they are not meant to grip
> >anything with them). Australopiths
> >can be assumed to have been similar.
> >This (very odd) behaviour by this
> >chimp mother would not have been
> >possible for a human or australopith.
> I'm not suggesting that apiths would carry an infant like that, but as
> indicated by the humerofemoral and intermembral index they had
> relatively longer arms than humans (86.6 and 85.5 respectively in StW
> 573, 70.9 and 68.8 in human females, 102.6 and 109.4 in female
> chimps).
> The point is that if a dead infant can be carried along then who knows
> how creative a mom can be with a slightly more cooperative living
> infant.

Good points all. PC constantly harps on the uselessness of modern babies, but he ignores the behavior of H&G babies , and presumes sedentary agriculture, domestication, technology had no effect on infant care & behavior.

On Tuesday 31 May 2022 at 03:28:21 UTC+1, DD'eDeN aka note/nickname/alas_my_loves wrote:

> Good points all. PC constantly harps on the uselessness of modern
> babies,

Human babies are 'useless' because they
need to be. No mother of a two-month old
would want a lively mobile baby that she had
to watch all the time. Selection against
physical precociousness works. Babies that
get too active too early get into trouble, and
suffer accidents, such as falling into shallow
pools of water and drowning.

> but he ignores the behavior of H&G babies , and presumes sedentary
> agriculture, domestication, technology had no effect on infant care &
> behavior.

Human babies are the same the world over.
You've got some far-fetched sentimental
ideas about H/G infants, derived from fake
romantic stories.