Oldest evidence of abundant C4 grasses and habitat heterogeneity in
eastern Africa

A new habitat for hominoid emergence?

The hominoid lineage underwent a major morphological change in the
Miocene, acquiring strong hind legs and a more upright posture. The
prevailing hypothesis pertaining to these changes has been that they
were adaptive for foraging on fruit in the terminal branches of
tropical forest trees. A pair of papers now argue that, instead, such
changes may have been driven by adaptation to feeding on leaves in
seasonally dry and open forests. Peppe et al. used new data from
fossil mammal study sites and found that the expansion of grassy
biomes dominated by grasses with the C4 photosynthetic pathway in
eastern Africa likely occurred more than 10 million years earlier than
prior estimates. MacLatchy et al. looked at fossils of the earliest
ape in this region at this time, Morotopithecus, and found isotope
evidence of the consumption of water-stressed vegetation and
postcranial morphology indicative of strong hind limbs similar to
modern apes. Together, these papers suggest that early hominoids
emerged in a dryer and more irregular environment than was previously
believed.

Abstract

The assembly of Africa’s iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including
hominins. C4 grasses are thought to have become ecologically dominant
in Africa only after 10 million years ago (Ma). However,
paleobotanical records older than 10 Ma are sparse, limiting
assessment of the timing and nature of C4 biomass expansion. This
study uses a multiproxy design to document vegetation structure from
nine Early Miocene mammal site complexes across eastern Africa.
Results demonstrate that between ~21 and 16 Ma, C4 grasses were
locally abundant, contributing to heterogeneous habitats ranging from
forests to wooded grasslands. These data push back the oldest evidence
of C4 grass–dominated habitats in Africa—and globally—by more than 10
million years, calling for revised paleoecological interpretations of
mammalian evolution.

https://doi.org/10.1126/science.abq2834

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Pandora wrote:

The
prevailing hypothesis pertaining to these changes has been that they
were adaptive for foraging on fruit in the terminal branches of
tropical forest trees.

No it isn't. And where are they pretending the vote took place?

"Spot the lies."

They're never random. Lies aren't random. Like how the media initially
claimed Hunter Biden's laptop was a fake, part of a Russian
disinformation campaign. That was not a random lie. And notice how
not one of them meant to say "Yes, it's Hunter's laptop" but accidentally reported that the handle showed evidence of being chewed on by a
unicorn?

Lies aren't random. Lies. "Mistakes." Omissions. Exaggerations aren't
random. They serve a purpose. Always.




-- --

https://jtem.tumblr.com/post/714435427497558016

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Friday, April 14, 2023 at 6:31:37 AM UTC-7, Pandora wrote:

these papers suggest that early hominoids
emerged in a dryer and more irregular environment than was previously believed.

IOW, these papers suggest that human evolution began with the onset of a climate characterized by a severe and deadly dry season.

C4 grasses are a clear indication of the climate having a deadly annual dry season.

This is exactly what my hypothesis predicts:
https://youtu.be/Z7TwiVul7F0

The assembly of Africa’s iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including
hominins.

They (traditional PA) missed the significance of seasonal deadly annual dry season. This oversight, I suspect, is the result of the fact that PA has been so myopically focused on trying to envision tools in the hands of the earliest hominids to explain
the emergence of human intellect (which itself is based on the concept that tool use underlies the emergence of a kind of evolutionary positive feedback effect which is, to say the least, a highly speculative notion at best and likely erroneous.)

Without the deadly dry season and associated predatory massacres at hominid community sites (at localities that were well watered garden habitat) during the depth of the dry season there is no evolutionary expectation that humans/hominids would emerge..
More specifically, without these factors there is no communal selection. Without communal selection there is no evolutionary mechanism for the communal adaptations that so thoroughly distinguish humans from the other species.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)