Pan prior

"*Pan prior*" is an obsolete species of hominid that lived in Africa or Europe during the Late Miocene.

## History

The designation "*P. prior*" was coined by Richard Wrangham (2001) as the intended Pan-*Homo* concestor. However, this term has largely been abandoned in favour of better terms such as chimpanzee-human LCA (CHLCA), "Pan-cestor" and more. Wrangham argues this concestor was very similar to *Pan*, and should thus be considered as part of Pan as "*P. prior*". However, there is little to no evidence of this species so it is thus a nomen nudum as per the rules of the ICZN. Despite this, some have suggested *Graecopithecus* to be the CHLCA, which would place the split in Europe. This is debated. Regardless of identity, "*P. prior*" was coined as a convenience nickname by Wrangham to be "cheeky" because it "seems reasonable".

## Description

 File:Prior.png
*"Pan prior"* was described as not too different from the first Australopithecines, which Wrangham theorized they evolved into. *P. prior* retained long arms that swiveled at the shoulder, a "small female body" akin to a chimpanzee's in size, a large gut, large jaws and an apelike brain. Presumably, they were still arboreal and did climb and hang from branches. They probably ate food with poor caloric contents, unlike humans. *"Pan prior"* lived in rainforests, were adapted to shearing and chewing foliage and were probably poor at bipedal walking. The earliest Australopith descendant, however, was probably opposite to all of these: they lived in open environments, were adapted at crushing food and started walking bipedally probably due to habit. Wrangham speculates this species had black hair. Some sources claim this concestor looked like a mix of a gorilla and a chimpanzee, at least in the shoulder. Some suggest the *Homo*-*Gorilla* LCAs interbred with the *Homo*-*Pan* LCAs up until the *Pan*-*Homo* lineage splits into two.

A homeotic shift in the sacrococcygeal border suggests that the LCA either had the ancestral vertebral state (7 cervical, 13 thoracic, 4 lumbar, 5 sacral) or had another sacral vertebrae. This 'short-backed' state supports prior hypotheses of hominid evolution, and was determined by using a predictive model that accounts for homeotic and meristic shifts. This is one of the few things about the LCA that can be scientifically tested and based on statistical data/

## Paleoecology

Wrangham speculates "*P. prior*" went extinct in forests, where remaining populations began to die out as their forest habitat did as well 7 million years ago; this may have happened north, east or south of the equatorial forest belt. When their habitats were lost, the leaves and fruits they had eaten would have left *"P. prior"* without food. Wrangham speculates some populations may have had traditions much like some chimpanzee populations do too, proposing a root-eating population evolving after their forests had cleared, possibly using digging sticks. This is where Wrangham theorizes Australopithecines first evolved.

## References

1. ↑ https://en.wikipedia.org/wiki/Chimpanzee–human\_last\_common\_ancestor
2. ↑ http://www.sci-news.com/othersciences/anthropology/hominin-origins-09634.html
3. ↑ 3.0 3.1 3.2 https://books.google.ca/books?id=LavQGJVq5ScC&pg=PA124&redir\_esc=y#v=onepage&q&f=false
4. ↑ http://www.sci-news.com/othersciences/anthropology/science-homo-pan-last-common-ancestor-03220.html
5. ↑ https://www.biorxiv.org/content/early/2017/10/19/134502
6. ↑ https://www.sciencedirect.com/science/article/abs/pii/S0047248423000362