Developments in understanding the origins of Homo sapiens Event as iCalendar

02 February 2018

12 - 1pm

Venue: MAC 1 (106-112, Biology Building)

Location: City Campus

Host: Centre for Computational Evolution

Cost: Free

 

Title: The West African Homo iwoeleruensis, our newest and closest relative, along with other developments in understanding the origins of Homo sapiens

Presenter: 
Dr. Peter J Waddell
Institute of Fundamental Sciences, Massey University, and The Ronin Institute

Abstract:
This talk examines progress in resolving phylogenetic structure and tracing major lines of descent in the genus Homo, including notable advances in phylogenetic methodology.

Three decades ago, direct DNA sequence data lead to the Out-of-Africa (OA) hypothesis that Homo sapiens recently evolved in Africa and then spread over the world with little genetic contribution (introgression) from previous non-African populations/species, such as Neanderthals. Evolutionary trees of single loci, namely mtDNA and the Y chromosome, are most consistent with the original population of H. sapiens originating 150–200 kya* in south or southeastern Africa, and in steps occupying Central Africa, West Africa, and northeast Africa. Migration out of Africa occurred ~100–60 kya ago.

Recently, a wide range of analyses of full genomes from living populations corroborate this view, and also suggest that the lineage leading to H. sapiens had a healthy effective population size of ~15–30 thousand, over the duration of Homo, roughly that of a great ape subspecies. Analyses of ancient nuclear genomes from Neanderthals and a Denisovan suggest lower long-term effective population sizes (< 5,000). Evidence for these and other pre-sapiens “ghost lineages” swapping but few genes with each other or H. sapiens, is growing, including in Africa (e.g. near Iwo Eleru, the type of the newly proposed species, Homo iwoeleruensis, our closest extinct relative).

These findings are contrary to a chrono-species/Multi-Regional MR view of the genus, and may be more consistent with group selection for socially networked thinking machines. In contrast to DNA, morphological phylogenetic analyses within Homo have struggled, for example, still no corroborated character matrix for all the key specimens. Serious problems of access to key specimens, data sharing, and transparency of analyses are inconsistent with good science. However, promising phylogenetic analyses of skull shape show congruence with other studies, including phylogenomics.

The challenge of bringing all the archeological, genetic, ecological, developmental, phenotypic, and morphological data into a combined (Bayesian?) phylogenetic analysis of networks of descent for Homo is just beginning. One essential, step towards this goal is being absolutely clear and objective in defining Homo sapiens, that is, as an extant crown-group based taxon.

*kya = thousand years ago