A Mother's Age Leaves a Biological Mark on Offspring Across Many Species, Study Shows

A mother's age can leave a lasting biological imprint on her offspring's physical and behavioral traits, a pattern seen across many species including humans, elephants, other primates and other mammals. Scientists still do not fully understand the biological mechanisms behind these "maternal age effects," or why evolution has allowed them to persist. "Nearly all forms of life show some level of maternal age effect, and most are negative effects caused by advanced maternal age," said Kristin Gribble, an associate scientist in the Bay Paul Center at the Marine Biological Laboratory.

To investigate how information about a mother's age reaches the next generation, Gribble's lab studies rotifers, tiny aquatic animals that reproduce quickly and can be tracked across generations. "Understanding the mechanism in these simple invertebrates can help us understand how maternal age effects occur in people as well," she said. The lab's experiments point toward an epigenetic explanation, changes in how genes are switched on or off rather than mutations in the DNA sequence itself.

Work by postdoctoral scientist Alyssa Liguori, now an assistant professor at SUNY-New Paltz, examined two genotypes of the same rotifer species and found that maternal age effects did not grow progressively stronger with each generation; instead, they could disappear within a single generation. That rapid reversal argues against the idea that the effects simply reflect a gradual buildup of age-related cellular damage or DNA mutations. The lab is now testing whether histone modification, an epigenetic process that can switch gene expression on or off, or mitochondrial DNA, which is usually inherited from the mother, help carry this information between generations.

Genetic variation also appears to change how strongly offspring are affected: in one strain the researchers studied, offspring of older mothers had a longer lifespan, suggesting a genetic mechanism can sometimes produce a beneficial effect. Gribble suspects that maternal age effects persist evolutionarily because natural selection's influence declines at older ages, particularly in rotifers, which do most of their living and reproducing very young, leaving little evolutionary pressure to weed out late-life effects.

The findings were published in the journal The American Naturalist by Alyssa Liguori, Sovannarith Korm, Alex Profetto, Emily Richters and Kristin E. Gribble. Gribble said the work could eventually inform precision medicine, since "your health potentially depends on the health and environment of your mom and grandmother and great grandmother."