Britannica Sources used in this answer

How can hemoglobin chains be used to study the evolutionary history of genes?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A diagram showing the tentative evolutionary relationships among hominid species over the past four million years, with skull images and labeled species names connected by solid and dotted lines to indicate proposed evolutionary pathways. — phylogeny Tentative phylogenetic scheme for the evolution of the human lineage. Solid bars indicate the time ranges during which species are thought to have existed, based on fossil evidence. Dotted lines signify evolutionary relationships between hominin species that have been proposed on the basis of the fossil evidence.

Hemoglobin chains are instrumental in studying the evolutionary history of genes because they are homologous, meaning they share a common ancestral sequence and have diverged through gene duplication events over millions of years.12

Researchers use two primary methods to analyze these relationships:

Cross-species comparison: By comparing the same hemoglobin chain (e.g., the $α$ chain) across different species, scientists can determine the evolutionary distance between those organisms. The degree of divergence in the sequences reflects how long ago the lineages diverged.2
Intra-species comparison: By comparing different hemoglobin chains within a single organism (e.g., $α$ versus $β$ chains), researchers can reconstruct the history of gene duplications. Because these genes evolved independently following a duplication event, the divergence between them reveals the timing and sequence of those ancestral duplications.2

Furthermore, studying nucleotide sequences has revealed complex families of functional genes and pseudogenes, providing a detailed record of how these genetic structures have evolved and diversified within the genome.1