"Skeptics of the hologenome idea—that microbes and host comprise a single evolutionary unit—argue that microbes aren’t always passed like heirlooms between gene

"Skeptics of the hologenome idea—that microbes and host comprise a single evolutionary unit—argue that microbes aren’t always passed like heirlooms between generations. And if they’re not, then does the holobiont really persist over evolutionary time?" Genes aren't always passed like heirlooms between generations either; only half of each parent. This doesn't make much sense to me as a criticism. It sounds from this article alone like a repeatedly observed element of the process of selection. I would suppose a hologenome trait may only last for a few generations of human generations, perhaps many more. How much need we concern ourselves with the exact details of the dizzying number of bacterial generations.