The paper is public.

https://www.science.org/doi/epdf/10.1126/sciadv.add9752

Wild chimpanzee behavior suggests that a savanna- mosaic
habitat did not support the emergence of hominin
terrestrial bipedalism

Bipedalism, a defining feature of the human lineage, is
thought to have evolved as forests retreated in the late
Miocene-Pliocene. Chimpanzees living in analogous
habitats to early hominins offer a unique opportunity
to investigate the ecological drivers of bipedalism that
cannot be addressed via the fossil record alone. We
investigated positional behavior and terrestriality in a
savanna-mosaic community of chimpanzees (P an troglodytes
schweinfurthii) in the Issa Valley, Tanzania as the first
test in a living ape of the hypothesis that wooded,
savanna habitats were a catalyst for terrestrial
bipedalism. Contrary to widely accepted hypotheses of
increased terrestriality selecting for habitual bipedalism,
results indicate that trees remained an essential
component of the hominin adaptive niche, with bipedalism
evolving in an arboreal context, likely driven by foraging
strategy.

"However, to date, locomotor studies have focused only on
forest-dwelling chimpanzees (Fig. 1) (36–38), overlooking
critical comparative data about how behaviors, including
bipedalism and degree of terrestriality, vary across
habitats."

"Issa Valley in western Tanzania is characterized as a
savanna-mosaic (14, 35, 39) similar to the
paleoenvironments reconstructed for the early hominins
...."

"Issa Valley in western Tanzania is characterized as a
savanna-mosaic (14, 35, 39) similar to the
paleoenvironments reconstructed for the early hominins
Orrorin, Ardipithecus ramidus, and Australopithecus
afarensis (9–13) and hosts a recently habituated (2018)
chimpanzee community (P. t. schweinfurthii). The area
is a mosaic of miombo woodland with strips of evergreen
riparian forest (classed as open and closed vegetation,
respectively; Fig. 1). Thus, Issa chimpanzees are well
situated for testing the savanna effect on chimpanzee
positional behavior, not only through comparison to
forest-dwelling communities but also by comparing how
individuals adjust their positional behavior across
vegetation types within a savanna-mosaic habitat. We
quantified locomotor and postural behaviors (table S1)
in Issa chimpanzees for 15 consecutive months within
the open miombo woodland and closed riparian forest to
characterize chimpanzee positional behavior in a
savanna-mosaic habitat. Combined with further
comparison to chimpanzees living in forest habitats
(facilitated by similar behavioral data collection
methods across studies), including at Taï (36, 40),
Kibale (37), Bwindi (38), Mahale, and Gombe (36, 41)
(Fig. 1) , we test the hypothesis that an open habitat
will induce greater terrestriality and terrestrial
bipedalism. Our findings offer a unique opportunity
to examine whether these positional behavioral changes
offer support to the hypothesis that a shift from
forest to a more open, savanna-mosaic habitat in the
late Miocene-Pliocene was a catalyst for the emergence
and evolution of bipedalism in early hominins."

"We obtained 13,743 instantaneous observations of
positional bouts from 13 adults (6 females and 7 males),
including a total of 2847 observations of locomotor
bouts (table S2)."

"In keeping with values reported from forest chimpanzee
communities, bipedalism remained a rare (<1% of all
positional behaviors) and primarily arboreal (>80%)
behavior in the Issa community (table S7). However,
despite no apparent effect of habitat (or vegetation)
type on overall frequency or terrestriality of
bipedalism, bipedal locomotion was four times more
frequent at Issa (25%) than at Mahale and Gombe (6%)
(42), and even more so compared with Bwindi chimpanzees
(0.6%; Fig. 4B) (38)."

"Variation in Issa chimpanzee positional behavior
indicates that terrestriality and bipedalism do not
increase within more open habitats and instead offers
support for hominin bipedalism evolving within an
arboreal context."

"Issa chimpanzees remained highly arboreal and did not
use more bipedalism in open vegetation (Figs. 3 and 4A).
Instead, they used more (arboreal) locomotor bipedalism
than forest-dwelling chimpanzees (Fig. 4B), lending
support to bipedal locomotion emerging and evolving as
an arboreal adaptation in early hominins (30, 53)."

"Across the savanna-mosaic habitat of Issa, the
chimpanzees use predominantly two vegetation types:
riparian forest and miombo woodland. The miombo woodland
has half the tree density compared with that of the
forest such that each habitat at Issa can be considered
closed (forest) and open (woodland; Fig. 1 and table S4). "

Op donderdag 15 december 2022 om 06:58:53 UTC+1 schreef Primum Sapienti:

> The paper is public.
> https://www.science.org/doi/epdf/10.1126/sciadv.add9752
> Wild chimpanzee behavior suggests that a savanna- mosaic
> habitat did not support the emergence of hominin
> terrestrial bipedalism

:-DDD
Thanks for the public paper, but why don't you grow up, my litle boy??
Perhaps *you* may descend from a wild chimp in a savanna-mosaic habitat,
but I don't: I descend from a Pleist.archaic Homo along S-Asian coasts,
see my book (academische uitg. Eburon 2022 Utrecht NL):
“De Evolutie van de Mens - waarom wij rechtop lopen en kunnen spreken”,
google “human evolution verhaegen”.

Primum Sapienti wrote:

> Wild chimpanzee behavior suggests that a savanna- mosaic
> habitat did not support the emergence of hominin
> terrestrial bipedalism

I have to object. Chimpanzees have been evolving AWAY from
the LCA for millions of years, starting from an ancestor that was
a great deal closer to "Bipedal" than a "Knuckle Walker." They are
not a good model for human evolution.

> Bipedalism, a defining feature of the human lineage, is
> thought to have evolved as forests retreated in the late
> Miocene-Pliocene.

"Thought?" Dictated!

> Contrary to widely accepted hypotheses of
> increased terrestriality selecting for habitual bipedalism,
> results indicate that trees remained an essential
> component of the hominin adaptive niche, with bipedalism
> evolving in an arboreal context, likely driven by foraging
> strategy.

The Homo/Pan line split.

There was conflict, competition. Put short: The Pan line was
as much prey as it was a competing group.

In short, "The Pan side took to the trees for safety."

More accurately: Their numbers dwindled, with less and less
genetic contribution from any outside the forested environment,
until finally all the "Selective Pressures," all the adaption was
towards an arboreal existence.

There. Homo invented Pan.

-- --

https://jtem.tumblr.com/post/703678017382285312

On Wed, 14 Dec 2022 22:58:49 -0700, Primum Sapienti
<invalide@invalid.invalid> wrote:

>The paper is public.
>
>https://www.science.org/doi/epdf/10.1126/sciadv.add9752
>
>Wild chimpanzee behavior suggests that a savanna- mosaic
>habitat did not support the emergence of hominin
>terrestrial bipedalism

But the common ancestor of humans and chimps was not a chimp.

>Bipedalism, a defining feature of the human lineage, is
>thought to have evolved as forests retreated in the late
>Miocene-Pliocene. Chimpanzees living in analogous
>habitats to early hominins offer a unique opportunity
>to investigate the ecological drivers of bipedalism that
>cannot be addressed via the fossil record alone. We
>investigated positional behavior and terrestriality in a
>savanna-mosaic community of chimpanzees (P an troglodytes
>schweinfurthii) in the Issa Valley, Tanzania as the first
>test in a living ape of the hypothesis that wooded,
>savanna habitats were a catalyst for terrestrial
>bipedalism. Contrary to widely accepted hypotheses of
>increased terrestriality selecting for habitual bipedalism,
>results indicate that trees remained an essential
>component of the hominin adaptive niche, with bipedalism
>evolving in an arboreal context, likely driven by foraging
>strategy.
>
>
>"However, to date, locomotor studies have focused only on
>forest-dwelling chimpanzees (Fig. 1) (36–38), overlooking
>critical comparative data about how behaviors, including
>bipedalism and degree of terrestriality, vary across
>habitats."
>
>"Issa Valley in western Tanzania is characterized as a
>savanna-mosaic (14, 35, 39) similar to the
>paleoenvironments reconstructed for the early hominins
>..."

Similar in broad terms. See for example:
https://www.researchgate.net/publication/23689121

"The paleoenvironment was composed of open areas with dry and humid
grasslands, prevailing over wooded habitats. Water was also widely
available as freshwater bodies and certainly swamps. It appears that
the high habitat diversity of the landscape is a common feature among
paleoenvironments associated with early hominids."

>"Issa Valley in western Tanzania is characterized as a
>savanna-mosaic (14, 35, 39) similar to the
>paleoenvironments reconstructed for the early hominins
>Orrorin, Ardipithecus ramidus, and Australopithecus
>afarensis (9–13) and hosts a recently habituated (2018)
>chimpanzee community (P. t. schweinfurthii). The area
>is a mosaic of miombo woodland with strips of evergreen
>riparian forest (classed as open and closed vegetation,
>respectively; Fig. 1). Thus, Issa chimpanzees are well
>situated for testing the savanna effect on chimpanzee
>positional behavior, not only through comparison to
>forest-dwelling communities but also by comparing how
>individuals adjust their positional behavior across
>vegetation types within a savanna-mosaic habitat. We
>quantified locomotor and postural behaviors (table S1)
>in Issa chimpanzees for 15 consecutive months within
>the open miombo woodland and closed riparian forest to
>characterize chimpanzee positional behavior in a
>savanna-mosaic habitat. Combined with further
>comparison to chimpanzees living in forest habitats
>(facilitated by similar behavioral data collection
>methods across studies), including at Taï (36, 40),
>Kibale (37), Bwindi (38), Mahale, and Gombe (36, 41)
>(Fig. 1) , we test the hypothesis that an open habitat
>will induce greater terrestriality and terrestrial
>bipedalism. Our findings offer a unique opportunity
>to examine whether these positional behavioral changes
>offer support to the hypothesis that a shift from
>forest to a more open, savanna-mosaic habitat in the
>late Miocene-Pliocene was a catalyst for the emergence
>and evolution of bipedalism in early hominins."
>
>"We obtained 13,743 instantaneous observations of
>positional bouts from 13 adults (6 females and 7 males),
>including a total of 2847 observations of locomotor
>bouts (table S2)."
>
>"In keeping with values reported from forest chimpanzee
>communities, bipedalism remained a rare (<1% of all
>positional behaviors) and primarily arboreal (>80%)
>behavior in the Issa community (table S7). However,
>despite no apparent effect of habitat (or vegetation)
>type on overall frequency or terrestriality of
>bipedalism, bipedal locomotion was four times more
>frequent at Issa (25%) than at Mahale and Gombe (6%)
>(42), and even more so compared with Bwindi chimpanzees
>(0.6%; Fig. 4B) (38)."
>
>"Variation in Issa chimpanzee positional behavior
>indicates that terrestriality and bipedalism do not
>increase within more open habitats and instead offers
>support for hominin bipedalism evolving within an
>arboreal context."
>
>"Issa chimpanzees remained highly arboreal and did not
>use more bipedalism in open vegetation (Figs. 3 and 4A).
>Instead, they used more (arboreal) locomotor bipedalism
>than forest-dwelling chimpanzees (Fig. 4B), lending
>support to bipedal locomotion emerging and evolving as
>an arboreal adaptation in early hominins (30, 53)."

That's interesting. So, basically it's still a more open environment
that's associated with increased bipedalism, but in the trees not on
the ground.

"A fundamental question of early hominin evolution remains whether a
savanna-mosaic environment acted as a selective driver of
terrestriality and thus locomotor bipedalism or, alternatively,
whether bipedal locomotion evolved as an arboreal adaptation (e.g.,
for foraging) that was then exapted for moving terrestrially during
later periods of hominin evolution."