The Sima de los Huesos cervical spine

Area of Science:

• Paleoanthropology
• Human Evolution
• Vertebral Anatomy

Background:

• Limited fossil records hinder understanding of neck evolution in genus Homo.
• Neandertals exhibit distinct cervical vertebrae compared to Homo sapiens.
• The Sima de los Huesos site offers crucial insights into hominin neck evolution.

Purpose of the Study:

• To analyze and compare the cervical spine anatomy of Sima de los Huesos hominins.
• To understand the evolutionary trajectory of the neck within the Neandertal lineage.
• To provide insights into cervical spine evolution at the genus Homo level.

Main Methods:

• Analysis of 172 cervical vertebrae specimens from Sima de los Huesos.
• Morphological and metric comparison with Neandertals, Homo sapiens, Homo erectus, and Homo antecessor.
• Phylogenetic and evolutionary interpretation of anatomical findings.

Main Results:

• Sima de los Huesos hominins display cervical spine morphology closer to Neandertals than Homo sapiens.
• Specific differences noted in the length, robusticity, and spinous process orientation of lower cervical vertebrae.
• The findings align with the proposed phylogenetic placement of Sima de los Huesos hominins.

Conclusions:

• The cervical spine of Sima de los Huesos hominins shows a predominantly Neandertal-like pattern.
• Subtle differences in lower cervical vertebrae may reflect adaptations to increased brain size or skull changes in Neandertals.
• This study enhances understanding of hominin neck evolution and Neandertal lineage development.