The Howard Hughes Medical Institute (HHMI) has a well-deserved reputation among biology teachers for providing outstanding teaching tools free of charge through their BioInteractive website. The annual HHMI Holiday Lectures are one such resource. The lectures are organized around a specific topic (for example, biological clocks or neuroscience) and feature engaging, media-rich presentations by prominent scientists in the field. HHMI makes the lectures available as a live stream, via on-demand streaming, and on DVD. The DVDs and the BioInteractive website are well organized, and it is easy for the teacher to select portions of the lecture that are as long or as short as desired for classroom viewing, or to play only specific animations to illustrate particular concepts.

The 2011 lectures, Bones, Stones, and Genes: The Origin of Modern Humans, was released on DVD in April 2012 and features Drs. John Shea, Sara Tishkoff, and Tim White. The lecture series has four parts: Lecture 1 serves as an overview, Lecture 2 covers the genetics of human origins and adaptation (genes), Lecture 3 addresses the archaeological evidence of human prehistory (stones), and Lecture 4 discusses physical paleoanthropology (bones). All are engaging and informative; Lectures 2 and 4 are probably the most useful to instructors teaching general biology courses at the high school or college level.

Lecture 2 includes discussions of human genetic variation, single-nucleotide polymorphisms (SNPs), the tree of life, primate phylogeny, mitochondrial DNA, and the dispersal of Homo sapiens. Especially compelling is a segment on lactase persistence, in which Dr. Tishkoff outlines the origin and spread of the mutation conferring lactose tolerance in adulthood. This 10-minute segment, brief enough to work into any class, is a powerful case study that makes connections among several topics:

  • Natural selection: lactase persistence may have been selected for in some human populations after the advent of animal husbandry;

  • The Central Dogma: the gene → protein → trait link is made manifest here;

  • Regulation of gene expression: the lactase persistence mutation occurs in a regulatory sequence;

  • Enzyme activity: lactase catalyzes the hydrolysis of the disaccharide lactose, yielding glucose and galactose;

  • Convergent evolution: European and African populations have different mutations that result in the same phenotype;

  • Chromosomal linkage: SNPs near the lactase persistence mutation are inherited together with it, giving geneticists evidence of selection; and

  • Data collection: volunteers in various African populations are shown being tested for the lactase persistence phenotype (ingestion of lactose followed by periodic finger pricks and blood glucose monitoring)

This latest installment in the Holiday Lectures series is a welcome addition to a valuable collection.