Males are to Blame for MOST Mutations in Species

It seems it’s the sperm that contains many more “opportunities” for DNA mutation than the egg.

You can look at this in two ways, either males are the key to species evolution, or they’re the major reason that animals, including humans, have birth defects.

Why Males Are Biology’s Riskier Sex

But a key paper published in Nature by Hákon Jónsson and colleagues, including impressively large samples of both women and men, has dramatically confirmed mounting indications of major differences in mutation rate between the sexes — between sperms and eggs. Analysis of entire nuclear genome sequences from a large database for thousands of Icelanders clearly showed that mutations accumulate at significantly different rates in sperms and eggs.

The bottom line from the findings reported by Jónsson and colleagues is that children inherit many more mutations from their dads than from their moms.

These findings also have far wider implications that will resonate for some time. Take, for example, a long-standing puzzle with mitochondria. These tiny power houses of the cell are derived from once free-living bacteria that became residents in early organisms with a cell nucleus more than 1.5 billion years ago. Reflecting this origin, each mitochondrion carries a few copies of its own genome, a stripped-down circular strand of DNA. Both eggs and sperms have mitochondria, yet surprisingly those borne by sperms are eliminated after fertilization. This is seemingly counterproductive, as it removes a potential source of variability.


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