DirtyGenes: testing for significant changes in gene or bacterial population compositions from a small number of samples.

High throughput genomics technologies are applied widely to microbiomes in humans, animals, soil and water, to detect changes in bacterial communities or the genes they carry, between different environments or treatments. We describe a method to test the statistical significance of differences in bacterial population or gene composition, applicable to metagenomic or quantitative polymerase chain reaction data. Our method goes beyond previous published work in being universally most powerful, thus better able to detect statistically significant differences, and through being more reliable for smaller sample sizes.

Menopause, evolution and changing cultures.

The menopause is an isolated event in a much wider process that was probably an evolutionary adaptation essential for survival in the Pliocene. As a reproductive strategy, it is largely vestigial in the 21st century, part of an era that has seen a doubling of the average human longevity compared with that of the past. This process commences as an accelerated decline in female fertility, usually from the fourth decade of life, culminating in a total cessation of reproductive capacity for those surviving.