The Brain of Sahelanthropus Tchadensis
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- čas přidán 22. 07. 2024
- Sahelanthropus Tchadensis was a hominin species that lived between 6 and 7 million years ago. In this video we will examine all research related to it's brain size, brain shape and brain function.
Sahelanthropus Tchadensis is a hominin species that is based on the fossil remains of a single skull, several teeth and jaw bones, and a femur. A word of caution: Since only a single skull is available any conclusions we draw from these analyses are tentative.
Analyses after the discovery of S. Tchadensis suggested that it may have walked upright. The foramen mangum, which is the opening where the spinal cord enters the brain, is perpendicular to the skull. In modern chimpazees it is in an acute angle. This may have suggested that S. Tchadensis natural posture was upright. However, analyses on the femur bone do not support the hypothesis that it was a habitual biped.
Furthermore, the brain of S. Tchadensis is long and narrow. This is very different from chimpanzees, but also different to later hominins such as A. Africanus. However, it is similar to another australopithecine, A. Anamensis. Whether there is a link between the species is unknown, but differences in facial features suggest it is unlikely.
The relative size of the cerebellum of S. Tchandensis is very similar to great apes, but different from later hominins and humans. Since the cerebellum is crucial for posture, balance and movement learning, movements of S. Tchadensis were probably not that much different from other great apes. This seems to be in line with the hypothesis that it did not habitually walk on two legs.
Finally, there are aspects of S. Tchadensis brain that are unique, such as the flat shape and horizontal temporal region. It may suggest that it is not in our direct ancestoral path, but this is uncertain.
Time stamps:
0:00 Sahelanthropus Tchadensis skull, fossils and brain
1:40 Sahelanthropus Tchadensis walkig upright?
3:30 Sahelanthropus Tchadensis brain compared to other hominins
7:20 Sahelanthropus Tchadensis cerebellum size
9:28 Sahelanthropus Tchadensis nuchal crest and temporal lobe
10:33 Sahelanthropus Tchadensis brain and behavior
References:
Bienvenu, T. (2010). L'Endocrâne de Sahelanthropus Tchadensis (Hominidae, Miocène supérieur du Tchad) : reconstitution 3D et morphologie : comparaison avec les hominoïdes actuels et fossiles. Thèse de doctorat en Paléoprimatologie et paléontologie humaine. www.theses.fr/2010POIT2301
Brunet, M., Guy, F., Pilbeam, D., et al. (2002). A new hominid from the Upper Miocene of Chad, Central Africa. Nature 418, 145-151. doi.org/10.1038/nature00879
Guy, F., Lieberman, D.E., Pilbeam, D., et al. (2005). Morphological affinities of the Sahelanthropus tchadensis (Late Miocene hominid from Chad) cranium. PNAS 102(52), 18836-18841. doi.org/10.1073/pnas.0509564102
Haile-Selassie, Y., Melillo, S.M., Vazzana, A., et al. (2019). A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia. Nature 573, 214-219. doi.org/10.1038/s41586-019-15...
Zollikofer, C.P.E., Ponce de Leon, M.S., Lieberman, D.E., et al. (2005). Virtual cranial reconstruction of Sahelanthropus tchadensis. Nature 434, 755-759. doi.org/10.1038/nature03397
Video material sources:
- About Zoos (CZcams)
- Angela Redmon (CZcams)
- Octavio Mateus (CZcams)
- PLOS Media (CZcams)
- SlicerMorph SlicerMorph (CZcams)
- Tokyo Zoo (CZcams)
- What's in John's Freezer (CZcams)
Narrated by: Miles Wischnewski
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I enjoyed the video very much. Very clear, informative and interesting :)
Glad you liked it!
Hominids seem to really go all out for the truly heavy brow ridges even more so than all other apes. I guess that's why, after our species lost them, we love our brimmed ball caps.
The development of brow ridges in our past certainly is interesting. The reasons why h sapiens does not have them can only be speculated. Probably a combination of natural and sexual selection.
Even nowadays, orbital fractures and cuts around the brow are very common for people who engage in combat sports. I cant Imagine how painful it mustve been to take a blow to the face, when your brow ridges looked like that.
They actually serve the puropose of protecting the face by absorving the blunt of the impact thanks to the extra mass of the brow ridge.@@habibishapur
There are many different kinds of bipedalism. Even chimps display a sort of facultative bipedalism as they will walk on two legs to carry things if needed. They wouldn't be considered to be habitual bipeds because their more normal locomotion is knuckle walking.
Great video.. thanks for sharing
8:00 "Over the last 6 million years, the relative size of the cerebellum has been decreasing!"
Would you share your references please!
Hi, Thank you.
Rilling et al. 1998 report the average volume of modern chimpanzees and modern humans. Based on their reported volumes the cerebellum volume in chimpanzee is about 13.8%, whereas in homo sapiens it is about 10.3%. Since it seems to be the case that early hominids, like Sahelanthropus has similar cerebellum/cerebrum volumes as chimpanzees, it seems that the overall volume decreased.
However, an important note: As I state later, this decrease is only apparent. Given increased gyrification the surface area may actually be larger. On top of that, we always have to consider that these conclusions are all tentative and speculative.
@@real.psyched Thank you
watched the video about afarensis brain size, im now addicted to your content!
Thank you so much! It always takes a while before making a new video of these series, but stay tuned!
The only 1 channel almost everyone watch without skipping 👊💥....
😃 Thanks so much!
@@real.psyched Welcome 😃
1:05 Greetings, I wonder, how did you obtain the model of the skull ?
Sick video brah
Thank you! :)
the fact we evolved from apes is just astounding. we went from tree dwelling primates to rock napping to discussing the very concept on this website. amazing.
It is sooo fascinating! I find it more and more interesting the more I learn about it! :)
Chad so cool he has a country named after him,
And such cool animals that used and now do inhabit it!
Great work i already saw the ardipithecus video!
Great video & channel! Subscribed :)
Thank you for the loverly words! I hope we can bring you more content you will enjoy in the future!
Sahelanthropus Tchadensis always makes me laugh everytime I see it
I swear I saw one walking around Neasden, London. Possibly going to Ikea?
Maybe it was Piltdown man🤔
More data will help, but for now, this looks like a good candidate for a basal human ape. Where does Ardipithecus ramidus fit into all this?
We have a video on ardipithecus too. In the end it is speculation. I think some recent papers argued against Sahelanthropus as a direct ancestor of humans, in favor of a line of Ardipithecus followed by Australopithecus sediba. But in the end different research groups will disagree. As you say, more data would be nice!
Mgsv brought me here. So this is the namesake of a weapon to surpass metal gear.
00:29
9:30
SPEculative, not speCUlative.
Will keep it in mind! :)
08:46 I wonder where Trumpanzees fit into these comparisons?
Haha, maybe that is a good idea for a future video ;)