Neandertal Introgression Sheds Light on Modern Human Endocranial Globularity

Curr Biol. 2019 Jan 7;29(1):120-127.e5. doi: 10.1016/j.cub.2018.10.065. Epub 2018 Dec 13.

Abstract

One of the features that distinguishes modern humans from our extinct relatives and ancestors is a globular shape of the braincase [1-4]. As the endocranium closely mirrors the outer shape of the brain, these differences might reflect altered neural architecture [4, 5]. However, in the absence of fossil brain tissue, the underlying neuroanatomical changes as well as their genetic bases remain elusive. To better understand the biological foundations of modern human endocranial shape, we turn to our closest extinct relatives: the Neandertals. Interbreeding between modern humans and Neandertals has resulted in introgressed fragments of Neandertal DNA in the genomes of present-day non-Africans [6, 7]. Based on shape analyses of fossil skull endocasts, we derive a measure of endocranial globularity from structural MRI scans of thousands of modern humans and study the effects of introgressed fragments of Neandertal DNA on this phenotype. We find that Neandertal alleles on chromosomes 1 and 18 are associated with reduced endocranial globularity. These alleles influence expression of two nearby genes, UBR4 and PHLPP1, which are involved in neurogenesis and myelination, respectively. Our findings show how integration of fossil skull data with archaic genomics and neuroimaging can suggest developmental mechanisms that may contribute to the unique modern human endocranial shape.

Keywords: Neandertal; basal ganglia; brain shape; cerebellum; evolution; gene expression; genetic association; homo sapiens; magnetic resonance imaging; myelination.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Biological Evolution*
  • Female
  • Fossils
  • Humans
  • Hybridization, Genetic*
  • Male
  • Middle Aged
  • Neanderthals / anatomy & histology*
  • Netherlands
  • Phenotype
  • Skull / anatomy & histology*
  • Young Adult