The Largest Late Middle Pleistocene Brain

Xujiayao hominid has the biggest known brain of the time

A new paper in the Journal of Human Evolution takes a closer look at the Xujiayao hominin¹. The Xujiayao remains were excavated in the ‘70’s and four years ago the date of these remains were updated to be about 200,000 to 160,000 years old². The Xujiayao fossils are characterized by a mix of Homo erectus and Homo sapiens features. Ultimately, the fossils remains at Xujiayao are difficult to classify and are of an uncertain taxonomic lineage, possibly representing a distinct hominid lineage³.

The Xujiayao hominin remains from Xujiayao, Shanxi, China. Hong Ao, Chun-Ru Liu, Andrew P. Roberts, Peng Zhang, and Xinwen Xu - https://doi.org/10.1016/j.jhevol.2017.01.014

Nonetheless, the authors of the current paper concluded that the cranial capacity of Xujiayao hominid was 1,700 cubic centimeters. While that is smaller than the brain of Xuchang remains by 100 cubic centimeters, the Xujiayo remains are 60,000 years older. This makes it the largest late middle Pleistocene brain… And brain that is this big falls in the upper range of Neanderthals and modern Homo sapiens.

There is no significance to brain size. Rather, the significance of this finding is that it shows us that hominid brains expanded and contracted at different rates and times. As evidenced by Homo floresiensis, for example, who had a brain size of 400 cubic centimeters. Albeit, H. floresiensis was like a hobbit. But it debuted in the paleo-anthropological record at a later time, around 100,000 to 50,000 years ago! Instead, studies like this show us hominid brains did not gradually grow in a linear fashion with time.

1. Wu, X.-J., Bae, C. J., Friess, M., Xing, S., Athreya, S., & Liu, W. (2022). Evolution of cranial capacity revisited: A view from the late Middle Pleistocene cranium from Xujiayao, China. Journal of Human Evolution, 163(103119), 103119. https://doi.org/10.1016/j.jhevol.2021.103119

2. Ao, H., Liu, C.-R., Roberts, A. P., Zhang, P., & Xu, X. (2017). An updated age for the Xujiayao hominin from the Nihewan Basin, North China: Implications for Middle Pleistocene human evolution in East Asia. Journal of Human Evolution, 106, 54–65. https://doi.org/10.1016/j.jhevol.2017.01.014

3. Xing, S., Martinón-Torres, M., Bermúdez de Castro, J. M., Wu, X., & Liu, W. (2015). Hominin teeth from the early Late Pleistocene site of Xujiayao, Northern China: Xujiayao Hominin Teeth. American Journal of Physical Anthropology, 156(2), 224–240. https://doi.org/10.1002/ajpa.22641