Unique Origin Research Discovering Human Uniqueness
Author

Ann Gauger

Couple linking index fingers
Close up of a couple linking index fingers. Man and woman in love linking index fingers against brown background

A First Couple? Here’s the Backstory

The publication of our new BIO-Complexity paper, “A Single-Couple Human Origin Is Possible,” announced here on Monday, is actually the culmination and continuation of the work of several people. I do not want to leave the impression that the work by my co-author Ola Hössjer and myself was done in isolation. Far from it! We began the modeling project in earnest in 2014 and published the first model in 2016, but in 2017 some very interesting events took place, described below. What follows is an updated version of a post I wrote on March 5, 2018. Read More ›

Effective Population Size

Haplo has a large number of parameters. Two of those describe how the population reproduces. There is one parameter, alpha, a which controls variablility of fertility, and another, beta, which controls rates of monogamy. One interesting concept in population genetics is that these two parameters can be fudged together with the real population size, into an effective population size. Here is an intuitive / visual example of why that works.

150312dna

Basic Population Genetics

All mutations start as single copy-errors but some of them increase in the population by random processes.  Random differences in reproductive success cause some lineages to branch, and others to go extinct. Mutations are presumed to happen randomly at a more-or-less constant rate and accumulate as they are inherited by descendants. See the figure below. Each row represents a generation, with the present at the bottom, and each ball is a chromosome. The colored dots are different mutations or Single Nucleotide Polymorphisms (SNPs) the chromosome carries. The links from generation to generation show the ancestral lineage of each chromosome going back in time. Mutation and Genetic Drift Usually people think of generations as growing forward in time, with twigs coming Read More ›