<p><span style="font-weight: 400;">In 1801, Jean-Baptiste Lamarck, a contemporary of Charles Darwin, proposed the idea that an animal can pass on characteristics acquired during its lifetime to its offspring. He was laughed out of the scientific community. Today, however, researchers are finding that the memories of life experiences can be passed from an individual animal to its children and grandchildren.</span></p><p><div data-conversation-spotlight=""></div></p><p><span style="font-weight: 400;">In a retrospective study of a rural Swedish population, it was concluded that a grandfather’s early </span><a href="https://www.ncbi.nlm.nih.gov/pubmed/12404098"><span style="font-weight: 400;">exposure to famine</span></a><span style="font-weight: 400;"> had altered his grandchildren’s susceptibility to cardiovascular and metabolic disorders, despite never having experienced food scarcity themselves. The cellular memories were passed along the father's line through a nutrition-linked mechanism that seems to influence the risk for death by cardiovascular and diabetes mellitus. The Swedish study found that diabetes mortality increased if the paternal grandfather had plenty of food and overate during his preteen years—his slow growth period. Too much food and too little food both influenced the risk of diabetes in the man, the man's children and his grandchildren.</span></p><p><span style="font-weight: 400;">Studying a kind of nematode worm, </span><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513350/#CR2"><i><span style="font-weight: 400;">Caenorhabditis elegans</span></i></a><span style="font-weight: 400;">, researchers exposed the original pair of worms to high temperatures. This led to the expression of repressed genetic material and changes in the cellular matter in the early stage embryo of subsequent generations. Only the original pair of worms were exposed to the high temperatures but later generations responded to the environment as if they had been stressed by the high temperatures as well. The effect of the initial high temperatures lasted for more than 10 generations of worms. The worms were used because a generation of the </span><i><span style="font-weight: 400;">Caenorhabditis elegans</span></i><span style="font-weight: 400;"> only takes three days as compared to 20 to 25 years for a human generation. </span></p><p><span style="font-weight: 400;">Other scientists found that non-coding RNA is passed along in mammalian eggs and sperm but is distinct from DNA, which has been traditionally thought of as the only means of passing genetic information from one generation to the next. The non-coding RNA in the </span><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513350/"><span style="font-weight: 400;">sperm of stressed males</span></a><span style="font-weight: 400;"> has been shown to repeat paternal stress patterns in the offspring. The study results suggest that a kind of protein created from the non-coding RNA (HNRNPM family proteins) enable stress resistance and the transmission of cellular memories that pass from one generation to the next even when the stress is no longer present. The HNRNPM family proteins may be important for transmission from the father to the children of epigenetic memories of stress essential for the survival and reproduction of following generations.</span></p><p><span style="font-weight: 400;">Fear of a smell can also be passed down for several generations. </span><a href="https://www.ncbi.nlm.nih.gov/pubmed/24292232"><span style="font-weight: 400;">Mice who were electrically shocked on the foot</span></a><span style="font-weight: 400;"> while smelling the distinctive smell of acetophenone, which smells like cherry blossoms, passed on the memories of the experience to their children and grandchildren. The grandchildren who were not shocked as they smelled the acetophenone, still responded as if they had been shocked. They were more jumpy and responded to lower concentrations of the acetophenone than non-traumatized mice.</span></p><p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5360568/"><span style="font-weight: 400;">Environmental exposure</span></a><span style="font-weight: 400;"> early in development plays a role in susceptibility to disease in later life. Scientists induced seizures by exposing rat pups to a hot hyperthermic environment. The increased seizure susceptibility extended not only in these hyperthermia-treated rats but also in their future offspring, even if the offspring had never experienced fever-related seizures. The transgenerational susceptibility to seizures passed primarily from mothers to their offspring. </span></p><p><a href="https://www.newscientist.com/article/dn24677-fear-of-a-smell-can-be-passed-down-several-generations/"><span style="font-weight: 400;">Moshe Szyf at McGill University in Montreal, Canada</span></a><span style="font-weight: 400;">, describes the results as unprecedented and startling. “It suggests that there is a very particular, specific and organized transgenerational transfer of information.”</span></p><p><a href="https://www.newscientist.com/article/dn24677-fear-of-a-smell-can-be-passed-down-several-generations/"><span style="font-weight: 400;">Marcus Pembrey </span></a><span style="font-weight: 400;">at the University of Bristol, UK agrees. “It is high time public-health researchers took human transgenerational responses seriously. I suspect we will not understand the rise in neuropsychiatric disorders or obesity, diabetes and metabolic disruptions generally, without taking a multigenerational approach.”</span></p>
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